Light measuring device

Abstract

A light measuring device (1) is provided with a variable light attenuator (4). The variable light attenuator (4) includes a plurality of light attenuation filters and a driving device (5). The plurality of light attenuation filters each includes an interference multilayer film and a transparent substrate. A combination of any two of the plurality of light attenuation filters is set as a first light attenuation filter (light attenuation filter (10)) and a second light attenuation filter (light attenuation filter (20)). A first optical path length of a first transparent substrate (transparent substrate (11)) of the first light attenuation filter is different from a second optical path length of a second transparent substrate (transparent substrate (21)) of the second light attenuation filter.

Description

Technical Field

[0001] This invention relates to a photometric device. Background Technology

[0002] Japanese Patent Application Publication No. 8-15012 (Patent Document 1) discloses a spectrometer comprising a spectrometer, an optical attenuation unit, and a photodetector. The optical attenuation unit includes a rotating plate, multiple ND filters mounted on the rotating plate, and a motor for rotating the rotating plate. The multiple ND filters have different optical attenuation rates. Based on the intensity of the light incident on the spectrometer, the ND filter with the most appropriate optical attenuation rate is inserted into the optical path of that light. This prevents photodetector saturation and ensures that the intensity of the light incident on the photodetector is within the dynamic range of the photodetector.

[0003] Patent Document 1: Japanese Patent Application Publication No. 8-15012 Summary of the Invention

[0004] However, in the spectral measurement device disclosed in Patent Document 1, the light attenuation unit is rotated using multiple ND filters mounted on a rotating plate and a motor, thus increasing the size of the light attenuation unit. The present invention was made in view of this problem, and its object is to provide a photometric device with a more compact size and capable of measuring light with higher accuracy.

[0005] The photometric device of the present invention includes a variable optical attenuator and a photodetector. The variable optical attenuator includes multiple optical attenuation filters and a driving device. The photodetector receives light passing through the variable optical attenuator. The driving device enables the multiple optical attenuation filters to be independently inserted into and withdrawn from the optical axis of light. The multiple optical attenuation filters are arranged at different positions along the optical axis. Each of the multiple optical attenuation filters includes an interference multilayer film and a transparent substrate supporting the interference multilayer film. Any combination of any two of the multiple optical attenuation filters is designated as a first optical attenuation filter and a second optical attenuation filter. Along the optical axis, the second optical attenuation filter is closer to the photodetector than the first optical attenuation filter. The first optical attenuation filter includes a first interference multilayer film as an interference multilayer film and a first transparent substrate as a transparent substrate. The second optical attenuation filter includes a second interference multilayer film as an interference multilayer film and a second transparent substrate as a transparent substrate. The first optical path length of the first transparent substrate is different from the second optical path length of the second transparent substrate.

[0006] Preferably, the light has an incident angle distribution oriented towards the variable light attenuator, and the photometer satisfies the following condition (1).

[0007] |OPD θmax1 -OPD θmin1 | / λ>0.5…(1)

[0008] Among them, OPD θmax1 =(OP) 1220max -OP 1022max ). OPD θmin1 =(OP) 1220min -OP 1022min λ represents the wavelength of light within the range that the photometer can measure. OP 1220max Let be the optical path length of the light that undergoes secondary reflection from the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter, at the maximum angle of incidence. The maximum angle of incidence light is the light with the largest angle of incidence towards the variable optical attenuator. OP 1022max OP is the optical path length of the maximum angle of incidence light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter. 1220min Let be the optical path length of the light that undergoes secondary reflection from the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter. The light with the smallest angle of incidence is the light with the smallest angle of incidence toward the variable optical attenuator. OP 1022min The path length of the light with the smallest incident angle that passes through the first optical attenuation filter without being reflected by the first optical attenuation filter and is reflected twice by the second optical attenuation filter.

[0009] Preferably, the photometric device is a spectrometer capable of measuring spectral information.

[0010] Preferably, the photometer satisfies the following condition (2).

[0011] OPD 12 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(2)

[0012] Among them, OPD 12 =|OP 1220 -OP 1022 |λ represents the wavelength of light within the range that the photometer can measure. Δλ a OP represents the half-width of the spectroscopic responsivity spectrum of the photodetector's optical elements. 1220 OP represents the optical path length of light that is reflected twice by the first optical attenuation filter, and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter. 1022 The optical path length of light that passes through the first optical attenuation filter without being reflected by the first optical attenuation filter and is reflected twice by the second optical attenuation filter.

[0013] Preferably, the photometer satisfies the following condition (3).

[0014] OPD 13×(1 / λ-1 / (λ+Δλ b ))>0.5…(3)

[0015] Among them, OPD 13 =|OP 1220 -OP 1022 |λ represents the wavelength of light within the range that the photometer can measure. Δλ b OP represents the linewidth of the light emitted from the object being measured. 1220 OP represents the optical path length of light that is reflected twice by the first optical attenuation filter, and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter. 1022 The optical path length of light that passes through the first optical attenuation filter without being reflected by the first optical attenuation filter and is reflected twice by the second optical attenuation filter.

[0016] Preferably, the first thickness of the first transparent substrate is different from the second thickness of the second transparent substrate.

[0017] Preferably, the first refractive index of the first transparent substrate is different from the second refractive index of the second transparent substrate.

[0018] Preferably, the interference multilayer film of each of the multiple optical attenuation filters is formed of the same material, and the transparent substrate of each of the multiple optical attenuation filters is formed of the same material.

[0019] Preferably, the multiple optical attenuation filters are each configured at the same angle relative to the optical axis.

[0020] Preferably, the photometer also includes a collimating lens, which is disposed on the incident side of a plurality of light attenuation filters.

[0021] Preferably, the photometer satisfies the following conditions (4) and (5).

[0022] |OPD θmax2 -OPD θmin2 | / λ>0.5…(4)

[0023] |OPD θmax3 -OPD θmin3 | / λ>0.5…(5)

[0024] Among them, OPD θmax2 =(OP) 1420max -OP 1022max ). OPD θmin2 =(OP) 1420min -OP 1022min ). OPD θmax3 =(OP) 1024max -OP 1220max ). OPDθmin3=(OP1024min -OP 1220min ). OP 1420max OP represents the optical path length of the light beam with the maximum angle of incidence that passes through the second optical attenuation filter after four reflections from the first attenuation filter and without reflection from the second attenuation filter. 1022max OP is the optical path length of the maximum angle of incidence light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter. 1420min OP represents the optical path length of the light that, after four reflections from the first optical attenuation filter and without reflection from the second optical attenuation filter, passes through the second optical attenuation filter at the minimum angle of incidence. 1022min OP is the optical path length of the minimum angle of incidence light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter. 1024max The optical path length of the beam with the maximum angle of incidence that passes through the first optical attenuation filter without being reflected by it and is reflected four times by the second optical attenuation filter. OP 1220max OP represents the optical path length of the light beam with the maximum angle of incidence that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter. 1024min The path length of the light with the smallest incident angle that passes through the first optical attenuation filter without being reflected by it and is reflected four times by the second optical attenuation filter. OP 1220min The optical path length of the light that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter.

[0025] Preferably, the photometer satisfies the following conditions (6) and (7).

[0026] OPD 21 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(6)

[0027] OPD 22 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(7)

[0028] Among them, OPD 21 =|OP 1420 -OP 1022 |. OPD 22 =|OP 1024 -OP 1220 |。OP 1420 Let be the optical path length of light that has been reflected four times by the first optical attenuation filter and has not been reflected by the second optical attenuation filter, but has passed through the second optical attenuation filter. OP 1022The optical path length of light that passes through the first optical attenuation filter without being reflected by it, and is then reflected twice by the second optical attenuation filter. OP 1024 The optical path length of light that passes through the first optical attenuation filter without being reflected by it, and is reflected four times by the second optical attenuation filter. OP 1220 The optical path length of light that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter.

[0029] Preferably, the photometer satisfies the following conditions (8) and (9).

[0030] OPD 21 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(8)

[0031] OPD 22 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(9)

[0032] Among them, OPD 21 =|OP 1420 -OP 1022 |. OPD 22 =|OP 1024 -OP 1220 |。OP 1420 Let be the optical path length of light that has been reflected four times by the first optical attenuation filter and has not been reflected by the second optical attenuation filter, but has passed through the second optical attenuation filter. OP 1022 The optical path length of light that passes through the first optical attenuation filter without being reflected by it, and is then reflected twice by the second optical attenuation filter. OP 1024 The optical path length of light that passes through the first optical attenuation filter without being reflected by it, and is reflected four times by the second optical attenuation filter. OP 1220 The optical path length of light that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter.

[0033] Preferably, the plurality of optical attenuation filters includes a third optical attenuation filter as a first optical attenuation filter and a fourth optical attenuation filter as a second optical attenuation filter. The third optical attenuation filter and the fourth optical attenuation filter are any two adjacent optical attenuation filters among the plurality of optical attenuation filters. The photometric device satisfies the following conditional equations (10) and (11).

[0034] |OPD θmax4 -OPD θmin4 | / λ>0.5…(10)

[0035] |OPD θmax5 -OPD θmin5 | / λ>0.5…(11)

[0036] Among them, OPD θmax4 =(OP) 3240max -OP 30G240max ). OPD θmin4 =(OP) 3240min -OP 30G240min ). OPD θmax5 =(OP) 3042max -OP 30G240max ). OPD θmin5 =(OP) 3042min -OP 30G240min ). OP 3240max OP represents the optical path length of the light beam with the maximum angle of incidence that is reflected twice by the third optical attenuator and passes through the fourth optical attenuator without being reflected by the fourth optical attenuator. 30G240max OP is the optical path length of the maximum angle of incidence light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection by the layer between the third and fourth optical attenuation filters. 3240min OP represents the optical path length of the light that is reflected twice by the third optical attenuation filter and passes through the fourth optical attenuation filter without being reflected by the fourth optical attenuation filter. 30G240min OP is the optical path length of the minimum incident angle light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection by the layer between the third and fourth optical attenuation filters. 3042max OP is the optical path length of the maximum angle of incidence light that passes through the third optical attenuation filter without being reflected by it and is then reflected twice by the fourth optical attenuation filter. 3042min The path length of the light with the smallest incident angle that passes through the third optical attenuation filter without being reflected by the third optical attenuation filter and is reflected twice by the fourth optical attenuation filter.

[0037] Preferably, the plurality of optical attenuation filters includes a third optical attenuation filter as a first optical attenuation filter and a fourth optical attenuation filter as a second optical attenuation filter. The third optical attenuation filter and the fourth optical attenuation filter are any two adjacent optical attenuation filters among the plurality of optical attenuation filters. The photometric device satisfies the following conditional equations (12) and (13).

[0038] OPD g1 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(12)

[0039] OPD g2 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(13)

[0040] Among them, OPD g1 =|OP 3240 -OP 30G240 |. OPD g2 =|OP 3042 -OP 30G240 |。OP 3240 OP represents the optical path length of light that is reflected twice by the third optical attenuation filter, and passes through the fourth optical attenuation filter without being reflected by the fourth optical attenuation filter. 30G240 OP is the optical path length of light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection from the layer between the third and fourth optical attenuation filters. 3042 The optical path length of light that passes through the third optical attenuation filter without being reflected by the third optical attenuation filter and is reflected twice by the fourth optical attenuation filter.

[0041] Preferably, the plurality of optical attenuation filters includes a third optical attenuation filter as a first optical attenuation filter and a fourth optical attenuation filter as a second optical attenuation filter. The third optical attenuation filter and the fourth optical attenuation filter are any two adjacent optical attenuation filters among the plurality of optical attenuation filters. The photometric device satisfies the following conditional equations (14) and (15).

[0042] OPD g1 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(14)

[0043] OPD g2 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(15)

[0044] Among them, OPD g1 =|OP 3240 -OP 30G240 |. OPD g2 =|OP 3042 -OP 30G240 |。OP 3240 OP represents the optical path length of light that is reflected twice by the third optical attenuation filter, and passes through the fourth optical attenuation filter without being reflected by the fourth optical attenuation filter. 30G240OP is the optical path length of light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection from the layer between the third and fourth optical attenuation filters. 3042 The optical path length of light that passes through the third optical attenuation filter without being reflected by the third optical attenuation filter and is reflected twice by the fourth optical attenuation filter.

[0045] According to the present invention, a photometer with a more compact size and capable of measuring light with higher accuracy can be provided. Attached Figure Description

[0046] Figure 1 This is a schematic perspective view of the photometer device according to the embodiment.

[0047] Figure 2 This is a schematic block diagram of the variable optical attenuator implementation method.

[0048] Figure 3 This is a schematic diagram of a variable optical attenuator implemented in this way.

[0049] Figure 4 This is a schematic partial enlarged view of the photodetector in the embodiment.

[0050] Figure 5 This is a schematic diagram illustrating the first interference in a variable optical attenuator according to an embodiment.

[0051] Figure 6 This is a schematic diagram illustrating the first interference in a variable optical attenuator according to an embodiment.

[0052] Figure 7 This is a schematic diagram illustrating the second interference in a variable optical attenuator according to an embodiment.

[0053] Figure 8 This is a schematic diagram illustrating the second interference in a variable optical attenuator according to an embodiment.

[0054] Figure 9 This is a schematic diagram illustrating the second interference in a variable optical attenuator according to an embodiment.

[0055] Figure 10 This is a schematic diagram illustrating the second interference in a variable optical attenuator according to an embodiment.

[0056] Figure 11 This is a schematic diagram illustrating the third interference in a variable optical attenuator according to an embodiment.

[0057] Figure 12 This is a schematic diagram illustrating the third interference in a variable optical attenuator according to an embodiment.

[0058] Figure 13This is a schematic diagram illustrating the third interference in a variable optical attenuator according to an embodiment.

[0059] Figure 14 This is a schematic diagram illustrating the third interference in a variable optical attenuator according to an embodiment.

[0060] Figure 15 It is a graph showing the distribution of the incident angle of light incident on the variable optical attenuator in Embodiment 1.

[0061] Figure 16 This is a graph showing the relative intensity of the interfering light caused by the first interference when the incident angle of the measured light toward the variable optical attenuator is 5°.

[0062] Figure 17 It is a graph showing the relative intensity of the interfering light caused by the first interference when the incident angle of the measured light toward the variable optical attenuator is 3° or more and 7° or less (5° ± 2°).

[0063] Figure 18 This is a graph showing the relative intensity of the interfering light caused by the second interference when the incident angle of the measured light toward the variable optical attenuator is 5°.

[0064] Figure 19 It is a graph showing the relative intensity of the interference light caused by the second interference when the incident angle of the measured light toward the variable optical attenuator is 3° or more and 7° or less (5° ± 2°).

[0065] Figure 20 This is a graph showing the relative intensity of the interference light caused by a third interference when the incident angle of the measured light toward the variable optical attenuator is 5°.

[0066] Figure 21 It is a graph showing the relative intensity of the interference light caused by the third interference when the incident angle of the measured light toward the variable optical attenuator is greater than 3° and less than 7° (5°±2°).

[0067] Figure 22 It is a graph showing the spectroscopic responsivity spectrum of one of the multiple photodetectors included in the photodetector.

[0068] Figure 23 It is a graph showing the spectrum of light emitted from the object being measured. Detailed Implementation

[0069] Reference Figures 1 to 4The light measuring device 1 of the embodiment will now be described. The light measuring device 1 is a device for measuring the light emitted from the object to be measured 2 (the measured light). The object to be measured 2 is not particularly limited, and may be, for example, a flat panel display such as a liquid crystal display or an organic EL display.

[0070] Reference Figure 1 The photometer 1 mainly includes a variable light attenuator 4 and a photodetector 8. The photometer 1 may also include a spectroscopic element 6, or a device capable of measuring the spectroscopic information (e.g., the spectrum of the light being measured) of the object 2 being measured (e.g., a spectroscopic measuring device). The photometer 1 may also include a collimating lens 3 and a condenser lens 7.

[0071] Collimating lens 3 is positioned on the incident side of variable optical attenuator 4 (multiple optical attenuation filters 10, 20). Collimating lens 3 collimates the light emitted from the object being measured 2.

[0072] Reference Figure 1 and Figure 2 The variable optical attenuator 4 is disposed on the exit side of the collimating lens 3. The light collimated by the collimating lens 3 is incident on the variable optical attenuator 4. The variable optical attenuator 4 includes multiple optical attenuation filters 10 and 20, and a driving device 5.

[0073] Each of the multiple optical attenuation filters 10 and 20 can be arranged at the same angle relative to the optical axis 2p of the light incident on the variable optical attenuator 4. Each of the multiple optical attenuation filters 10 and 20 can also be tilted at the same angle relative to the optical axis 2p of the light incident on the variable optical attenuator 4. The multiple optical attenuation filters 10 and 20 can also be arranged parallel to each other. Therefore, the variable optical attenuator 4 can be miniaturized, and the photometering device 1 can be miniaturized.

[0074] Reference Figure 3 Each of the plurality of optical attenuation filters 10, 20 includes: interference multilayer films 12, 13, 22, 23, and transparent substrates 11, 21 supporting the interference multilayer films 12, 13, 22, 23. A combination of any two of the plurality of optical attenuation filters 10, 20 is designated as a first optical attenuation filter (e.g., optical attenuation filter 10) and a second optical attenuation filter (e.g., optical attenuation filter 20). In the direction along the optical axis 2p, the second optical attenuation filter is closer to the photodetector 8 than the first optical attenuation filter. The first optical attenuation filter includes a first interference multilayer film (e.g., at least one of interference multilayer films 12, 13) as an interference multilayer film, and a first transparent substrate (e.g., transparent substrate 11) as a transparent substrate. The second optical attenuation filter includes a second interference multilayer film (at least one of interference multilayer films 22, 23) as an interference multilayer film, and a second transparent substrate (e.g., transparent substrate 21) as a transparent substrate.

[0075] The first optical path length of the first transparent substrate (e.g., transparent substrate 11) is different from the second optical path length of the second transparent substrate (e.g., transparent substrate 21). The first optical path length of the first transparent substrate is provided by the product of the first refractive index (e.g., refractive index n1) and the first thickness (e.g., thickness d1) of the first transparent substrate. The second optical path length of the second transparent substrate is provided by the product of the second refractive index (e.g., refractive index n2) and the second thickness (e.g., thickness d2) of the second transparent substrate. The thicknesses of the interference multilayer films 12, 13, 22, and 23 are negligible compared to the thicknesses of the transparent substrates 11 and 21, therefore, the difference between the first optical path length of the first transparent substrate (e.g., transparent substrate 11) and the second optical path length of the second transparent substrate (e.g., transparent substrate 21) means that the optical path length of the first optical attenuation filter (e.g., optical attenuation filter 10) is different from the optical path length of the second optical attenuation filter (e.g., optical attenuation filter 20).

[0076] The transparent substrates 11 and 21 are formed of optical materials that are transparent to the light being measured, such as glass, plastic, crystal, or sapphire. The transparent optical materials forming the transparent substrates 11 and 21 can be appropriately selected according to the wavelength range of the light being measured.

[0077] Interference multilayer films 12, 13, 22, and 23 are each formed on at least one of the incident surfaces 14 and 24 or the emission surfaces 15 and 25 of the corresponding transparent substrates 11 and 21. Specifically, the optical attenuation filter 10 includes at least one of interference multilayer films 12 and 13. Interference multilayer film 12 is formed on the incident surface 14 of the transparent substrate 11. Interference multilayer film 13 is formed on the emission surface 15 of the transparent substrate 11. The optical attenuation filter 20 includes at least one of interference multilayer films 22 and 23. Interference multilayer film 22 is formed on the incident surface 24 of the transparent substrate 21. Interference multilayer film 23 is formed on the emission surface 25 of the transparent substrate 21.

[0078] Specifically, interference multilayer films 12, 13, 22, and 23 are each formed on both the incident surfaces 14 and 24 and the emission surfaces 15 and 25 of their respective transparent substrates 11 and 21. Specifically, the light attenuation filter 10 includes an interference multilayer film 12 formed on the incident surface 14 of the transparent substrate 11 and an interference multilayer film 13 formed on the emission surface 15 of the transparent substrate 11. The light attenuation filter 20 includes an interference multilayer film 22 formed on the incident surface 24 of the transparent substrate 21 and an interference multilayer film 23 formed on the emission surface 25 of the transparent substrate 21.

[0079] Interference multilayer films 12, 13, 22, and 23 may have identical or different multilayer film structures. Interference multilayer films 12, 13, 22, and 23 may be formed from identical or different materials. For example, dielectric materials such as SiO2 or MgF2, metal oxide materials such as Al2O3, TiO2, Nb2O5, or NbO, or metallic materials such as Cr or Nb can be used as materials for each layer of the interference multilayer films 12, 13, 22, and 23.

[0080] As optical attenuation filters, absorption-type optical attenuation filters that absorb light within a substrate (e.g., a glass substrate) are known. The design freedom for the transmission spectrum of absorption-type optical attenuation filters is relatively low. Furthermore, absorption-type optical attenuation filters exhibit relatively low stability relative to ambient temperature and humidity. In contrast, interference-type optical attenuation filters (e.g., optical attenuation filters 10 and 20 including interference multilayer films 12, 13, 22, and 23) offer relatively high freedom in designing their transmission spectrum. Furthermore, interference-type optical attenuation filters exhibit relatively high stability relative to ambient temperature and humidity.

[0081] Reference Figure 2 The drive unit 5 enables multiple optical attenuation filters 10 and 20 to be independently inserted into and withdrawn from the optical axis 2p of the light incident on the variable optical attenuator 4. Therefore, saturation of the photodetector 8 can be prevented, ensuring that the intensity of the measured light incident on the photodetector 8 remains within its dynamic range. Furthermore, the photometer 1 has a more compact size. The drive unit 5 is, for example, a linear actuator.

[0082] Reference Figure 1 The beam splitter 6 splits the light that has passed through the variable optical attenuator 4. The beam splitter 6 is, for example, a diffraction grating. The condenser lens 7 focuses the light split by the beam splitter 6 onto the photodetector 8.

[0083] Reference Figure 1 and Figure 4 The photodetector 8 receives light that has passed through the variable light attenuator 4. Specifically, the photodetector 8 receives light that has been split by the beam splitter 6. The photodetector 8 is a line sensor comprising multiple photodetector elements 9. The multiple photodetector elements 9 respectively detect multiple wavelengths of light that are different from each other included in the light being measured. Each of the multiple photodetector elements 9 is, for example, a charge-coupled device (CCD) sensor or a complementary metal-oxide-semiconductor (CMOS) sensor.

[0084] The light reflectance of the light attenuation filters 10 and 20, which include interfering multilayer films 12, 13, 22, and 23, tends to be greater than that of the absorption-type light attenuation filters. Therefore, the reflected light generated in the light attenuation filters 10 and 20, which include interfering multilayer films 12, 13, 22, and 23, may negatively affect the measurement results of the photometer 1. As described below, in this embodiment, this negative impact is reduced.

[0085] When multiple optical attenuation filters are repeatedly inserted into the optical axis 2p, it is difficult to ensure that the relative tilt angle between any two optical attenuation filters (e.g., optical attenuation filters 10, 20) remains perfectly equal. If multiple optical attenuation filters are repeatedly inserted into the optical axis 2p, the relative tilt angle between any two optical attenuation filters (e.g., optical attenuation filters 10, 20) may sometimes vary slightly. Furthermore, due to temperature variations in the environment where the multiple optical attenuation filters are located, the relative tilt angle between any two optical attenuation filters (e.g., optical attenuation filters 10, 20) may also sometimes vary slightly.

[0086] When the optical path lengths of multiple optical attenuation filters are equal, the measurement results of the photometer can vary considerably due to slight variations in the relative tilt angle between any two optical attenuation filters (e.g., optical attenuation filters 10 and 20). Therefore, it is difficult to stably measure light using the photometer. Since the thicknesses of the interference multilayer films 12, 13, 22, and 23 are negligible compared to the thicknesses of the transparent substrates 11 and 21, the equal optical path lengths of the multiple optical attenuation filters 10 and 20 essentially mean that the equal optical path lengths of the multiple transparent substrates 11 and 21 are also equal.

[0087] The inventors have discovered that the significant variation in the measurement results of the photometer 1 is due to the variation in interference intensity caused by interference between multiple multiple reflections generated in the multiple optical attenuation filters 10 and 20. For example, if the difference in optical path length between two multiple reflections generated in two optical attenuation filters 10 and 20 varies only below the wavelength of the light measured by the photometer 1 (e.g., above tens of nm and below hundreds of nm when the measured light is visible light), the variation in interference intensity between the two multiple reflections becomes larger. Even a slight change in the relative tilt angle between the two optical attenuation filters 10 and 20 causes a significant variation in the measurement results of the photometer 1. Such interference between multiple multiple reflections mainly includes the following three types of interference (first interference, second interference, and third interference).

[0088] The first interference is the interference between the secondary reflected light generated by the first optical attenuation filter (optical attenuation filter 10) and the secondary reflected light generated by the second optical attenuation filter (optical attenuation filter 20) (see reference). Figure 5 and Figure 6 The second interference is the interference between the secondary reflected light generated by one of the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) and the quaternary reflected light generated by the other of the first optical attenuation filter and the second optical attenuation filter (see reference). Figures 7 to 10 The third interference is the interference between secondary reflected light generated by one of the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) and secondary reflected light generated by the layer (e.g., air layer) between the third and fourth optical attenuation filters (see reference). Figures 11 to 14 Furthermore, the third optical attenuation filter corresponds to the first optical attenuation filter, and the fourth optical attenuation filter corresponds to the second optical attenuation filter. The third and fourth optical attenuation filters refer to any two adjacent optical attenuation filters among a plurality of optical attenuation filters.

[0089] In most cases, the first of the three interferences has the greatest impact on the variation of the measurement results of the photometer 1. The reason is as follows: The number of reflections of the multiple-reflected light in the second interference is greater than the number of reflections of the multiple-reflected light in the first interference. Therefore, in most cases, the variation in interference intensity caused by the second interference is smaller than the variation in interference intensity caused by the first interference. Furthermore, generally, in most cases, the reflectivity of the light attenuation filter using the interference multilayer film for light incident from the air layer side to the interference multilayer film is lower than the reflectivity of the light attenuation filter using the interference multilayer film for light incident from the inner side (transparent substrate side) of the light attenuation filter to the interference multilayer film. Thus, in most cases, the variation in interference intensity caused by the third interference is smaller than the variation in interference intensity caused by the first interference.

[0090] Therefore, by reducing the variation component of the interference intensity caused by the first interference, the variation in the measurement results of the photometer 1 can be effectively reduced, enabling the photometer 1 to measure light stably and with high accuracy. Preferably, in addition to the first interference, at least one of the variation components of the interference intensity caused by the second interference or the variation component of the interference intensity caused by the third interference is also reduced. Therefore, the variation in the measurement results of the photometer 1 can be reduced more effectively, enabling the photometer 1 to measure light with further improved accuracy.

[0091] Furthermore, the interference between multiple multiple reflections generated in the multiple optical attenuation filters 10 and 20 includes not only the first, second, and third interferences, but also higher-order interferences. However, the number of reflections of the multiple reflections in the higher-order interferences is greater than any one of the number of reflections of the multiple reflections in the first, second, and third interferences. Therefore, the variation in interference intensity caused by the higher-order interferences is smaller than any one of the variation in interference intensity caused by the first, second, and third interferences, and can be ignored.

[0092] In this embodiment, the first optical path length of the first transparent substrate (e.g., transparent substrate 11) of the first optical attenuation filter (e.g., optical attenuation filter 10) is different from the second optical path length of the second transparent substrate (e.g., transparent substrate 21) of the second optical attenuation filter (e.g., optical attenuation filter 20). Therefore, the period of the interference waveform caused by interference between multiple multiple reflections generated in the plurality of optical attenuation filters 10, 20 is shortened. The interference waveform is averaged, and the variation component of the interference intensity between the multiple multiple reflections generated in the plurality of optical attenuation filters 10, 20 is reduced. Even if the relative tilt angle between the first and second optical attenuation filters changes, the measurement result of the photometer 1 remains almost unchanged. The photometer 1 is able to measure the light emitted from the object 2 being measured with higher accuracy.

[0093] Hereinafter, Examples 1 to 3 will describe the reduction of the variation component of interference intensity caused by the first interference, the second interference, and the third interference; Examples 4 to 6 will describe the reduction of the variation component of interference intensity caused by the first interference; Examples 7 to 9 will describe the reduction of the variation component of interference intensity caused by the first interference and the second interference; and Examples 10 to 12 will describe the reduction of the variation component of interference intensity caused by the first interference and the third interference.

[0094] <Example 1, Example 2, Example 3>

[0095] Reference Figures 1 to 23Examples 1 to 3 will be described below. In Examples 1 to 3, the plurality of optical attenuation filters 10 and 20 are composed of two optical attenuation filters 10 and 20. The first optical attenuation filter is optical attenuation filter 10, and the second optical attenuation filter is optical attenuation filter 20. Since optical attenuation filter 10 and optical attenuation filter 20 are adjacent to each other, optical attenuation filter 10 is also a third optical attenuation filter, and optical attenuation filter 20 is also a fourth optical attenuation filter. Optical attenuation filter 10 includes interference multilayer films 12 and 13, and a transparent substrate 11 supporting interference multilayer films 12 and 13. Optical attenuation filter 20 includes interference multilayer films 22 and 23, and a transparent substrate 21 supporting interference multilayer films 22 and 23.

[0096] The structures of the variable optical attenuator 4 in Examples 1 to 3 are shown in Table 1. Therefore, the optical path length of the transparent substrate 11 is different from that of the transparent substrate 21. The reflectivity of the incident surface 14 and the emission surface 15 of the transparent substrate 11 are both 10%. The reflectivity of the incident surface 14 of the transparent substrate 11 is the reflectivity of the interfering multilayer film 12. The reflectivity of the emission surface 15 of the transparent substrate 11 is the reflectivity of the interfering multilayer film 13. The reflectivity of the incident surface 24 and the emission surface 25 of the transparent substrate 21 are both 10%. The reflectivity of the incident surface 24 of the transparent substrate 11 is the reflectivity of the interfering multilayer film 22. The reflectivity of the emission surface 25 of the transparent substrate 21 is the reflectivity of the interfering multilayer film 23. Figure 5 , 7 In 8, 11, and 12, the relative tilt angle θ between the optical attenuation filter 10 and the optical attenuation filter 20 (e.g., the tilt angle of the optical attenuation filter 10 relative to the optical attenuation filter 20) is 0.0°. Figure 6 , 9 In 10, 13, and 14, the relative tilt angle θ between optical attenuation filter 10 and optical attenuation filter 20 is 0.1°.

[0097] [Table 1]

[0098]

[0099] (a) The distribution of the incident angle of the measured light incident on the variable optical attenuator 4; (b) The half-width Δλ of the spectrophotometric responsivity spectrum of the optical detection element 9. a (c) The linewidth Δλ of the light emitted from the object being measured 2 (the measured light). bAt least one of the components reduces the variation in interference intensity caused by interference between multiple reflected lights, and reduces the variation in the measurement results of the photometer 1 when the relative tilt angle θ between the optical attenuation filter 10 and the optical attenuation filter 20 changes slightly. Furthermore, in this specification, the incident angle of the measured light incident on the variable optical attenuator 4 is defined as the incident angle of the measured light (in the case where the measured light has an incident angle distribution, the component of the measured light having the incident angle at the center of the incident angle distribution) relative to the optical axis of the variable optical attenuator 4. The linewidth Δλ of the measured light... b It is defined as the half-width of the spectrum of the light being measured.

[0100] In Example 1, the reduction of the variation components of interference intensity caused by the first, second, and third interferences, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4 as described in (a), was studied. In Example 2, the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 as described in (b) was studied. a The reduction in the variation components of interference intensity caused by the first, second, and third interferences was achieved. In Example 3, the linewidth Δλ of the light emitted from the test object 2 (the measured light) described above (c) was investigated. b The achieved reduction in the variation components of interference intensity caused by the first, second, and third interferences. Furthermore, the longer the wavelength λ of the light, the smaller the value on the left side of each of the conditions (1) to (15). Moreover, the smaller the value on the left side of each of the conditions (1) to (15), the greater the variation component of interference intensity caused by interference between multiple reflected lights. Therefore, in Examples 1 to 3, the wavelength λ of the light is set to the wavelength of the largest variation component of interference intensity caused by interference between multiple reflected lights, i.e., the maximum wavelength range that the photometric device 1 can measure.

[0101] <Example 1>

[0102] In this embodiment, the photometer 1 can measure wavelengths ranging from 380 nm to 780 nm. The incident angle of the light incident on the variable optical attenuator 4 is distributed within an incident angle range of 3° to 7° (an incident angle range of 5° ± 2°) (refer to Table 2), and the light intensity is the same within this incident angle range (refer to Table 2). Figure 15 The photometric device 1 is a spectrometer (polychromator), and the photodetector 8 includes multiple photodetector elements 9. The spectroscopic responsivity spectrum of the photodetector element 9 corresponding to the largest wavelength in the measurable wavelength range of the photometric device 1 has a Gaussian shape with a peak wavelength of 780 nm. The half-width Δλ of the spectroscopic responsivity spectrum of this photodetector element 9 is... aThe wavelength is 10 nm (refer to Table 2). The spectrum of the light emitted from the sample 2 (the measured light) has a Gaussian shape with a peak wavelength of 780 nm. The linewidth Δλ of the light emitted from the sample 2 (the measured light) is... b It is 0.01nm (refer to Table 2).

[0103] [Table 2]

[0104] Incident angle distribution 5°±2° <![CDATA[Half-value width Δλ a > 10nm <![CDATA[Line width Δλ b > 0.01nm

[0105] Due to the linewidth Δλ of the light emitted from the object being measured (the measured light) b The value is sufficiently small, therefore the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 in (b) above is... a The linewidth Δλ of the light emitted from the object 2 (the measured light) as described in (c) above. b The reduction in the variation of interference intensity caused by interference between multiple multiple reflected beams is so small as to be negligible. In Example 1, the reduction in the variation of interference intensity caused by the first, second, and third interference between multiple multiple reflected beams, achieved by studying the distribution of the incident angle of the measured light incident on the variable light attenuator 4 as described above (a), was investigated.

[0106] <The reduction in the variation of the interference intensity caused by the first interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0107] In this embodiment, the following condition (1) is satisfied.

[0108] |OPD θmax1 -OPD θmin1 | / λ>0.5…(1)

[0109] OPD θmax1 =(OP) 1220max -OP 1022max ). OPD θmin1 =(OP) 1220min -OP 1022min ). λ

[0110] The wavelength of light included in the wavelength range that the photometric device 1 can measure is denoted by.

[0111] OP 1220max This refers to the optical path length of the light with the maximum angle of incidence that passes through the second optical attenuation filter (20) after secondary reflection by the first optical attenuation filter (optical attenuation filter 10) and without reflection by the second optical attenuation filter (20). The maximum angle of incidence is the light with the largest angle of incidence towards the variable optical attenuator 4 among the light incident on it. OP 1022maxOP is the optical path length of the maximum angle of incidence light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter. 1220min This refers to the optical path length of the light that undergoes secondary reflection from the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter, with the smallest angle of incidence. The minimum angle of incidence light is the light with the smallest angle of incidence towards the variable optical attenuator 4 among the light incident on it. OP 1022min The path length of the light with the smallest incident angle that passes through the first optical attenuation filter without being reflected by the first optical attenuation filter and is reflected twice by the second optical attenuation filter.

[0112] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 3.571. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 3.368. Therefore, this embodiment satisfies condition (1).

[0113] Under the condition (1), the variation in interference intensity caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. (Refer to...) Figure 16 and Figure 17 When the incident angle of the measured light incident on the variable optical attenuator 4 is between 3° and 7° (5° ± 2°), the variation in relative interference intensity caused by the first interference is smaller than when the incident angle of the measured light incident on the variable optical attenuator 4 is 5°. In this specification, relative interference intensity is the interference intensity normalized to the reference intensity of light transmitted through the optical attenuator filters 10 and 20 without reflection, and is obtained by converting this reference intensity to a relative intensity of zero. The reason for reducing the variation component of interference intensity caused by the first interference by adjusting the distribution of the incident angle of the measured light incident on the variable optical attenuator 4 is as follows.

[0114] If the incident angle of the measured light incident on the variable light attenuator 4 changes, then Figure 16 The interference waveform is shifted laterally. Figure 17The interference waveform is composed of multiple waveforms that are laterally offset by different amounts based on the incident angles of the light being measured incident on the variable optical attenuator 4. Figure 16 The waveform is obtained by adding and averaging the interference waveforms. Therefore, when the incident angle of the measured light incident on the variable light attenuator 4 is between 3° and 7° (5°±2°), the variation in interference intensity caused by the first interference is smaller than when the incident angle of the measured light incident on the variable light attenuator 4 is 5°.

[0115] The left side of conditional equation (1) represents the situation between the case where the incident angle of the measured light incident on the variable optical attenuator 4 is the largest and the case where the incident angle of the measured light incident on the variable optical attenuator 4 is the smallest. Figure 16 The interference waveform deviates by several times the period of the interference waveform. If condition (1) is satisfied, a higher averaging effect is obtained, which can reduce the variation in interference intensity caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)). Specifically, the variation in the measured value of the photometer 1 caused by the first interference when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is 0.26%. In this specification, the variation in the measured value of the photometer 1 is defined as the difference between the relative interference intensity of light with a wavelength of 780nm at a relative tilt angle θ of 0.0° and the relative interference intensity of light with a wavelength of 780nm at a relative tilt angle θ of 0.1°. Therefore, even if the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes slightly, the variation in interference intensity caused by the first interference is reduced, and the measured light can be measured with good accuracy.

[0116] <The reduction in the variation of the interference intensity caused by the second interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0117] In this embodiment, the following conditions (4) and (5) are satisfied.

[0118] |OPD θmax2 -OPD θmin2 | / λ>0.5…(4)

[0119] |OPD θmax3 -OPD θmin3 | / λ>0.5…(5)

[0120] OPD θmax2 =(OP) 1420max -OP 1022max ). OPD θmin2 =(OP)1420min -OP 1022min ).

[0121] OPD θmax3 =(OP) 1024max -OP 1220max ). OPD θmin3 =(OP) 1024min -OP 1220min ).

[0122] OP 1420max It is the optical path length of the light with the maximum angle of incidence that is reflected four times by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20). OP 1022max It is the optical path length of the maximum angle of incidence light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter. OP 1420min It is the optical path length of the light that is reflected four times by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter. OP 1022min It is the optical path length of the smallest incident angle light that passes through the first optical attenuation filter without being reflected by the first optical attenuation filter and is reflected twice by the second optical attenuation filter.

[0123] OP 1024max It is the optical path length of the light with the maximum angle of incidence that passes through the first optical attenuation filter (optical attenuation filter 10) without being reflected by the first optical attenuation filter and is reflected four times by the second optical attenuation filter (optical attenuation filter 20). OP 1220max It is the optical path length of the light with the maximum angle of incidence that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter. OP 1024min It is the optical path length of the smallest incident angle light that passes through the first optical attenuation filter without being reflected by it and is reflected four times by the second optical attenuation filter. OP 1220min It is the optical path length of the minimum incident angle light that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter.

[0124] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 3.061. With the relative tilt angle θ between the first and second optical attenuation filters being 0.1° (refer to...) Figure 9 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 2.797. Therefore, this embodiment satisfies condition (4). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter is 0.0° (refer to...) Figure 8 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 13.772. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 13.367. Therefore, this embodiment satisfies condition (5).

[0125] Under the condition (4), it is possible to reduce the variation in interference intensity caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)). Figure 18 and Figure 19 When the incident angle of the measured light incident on the variable optical attenuator 4 is between 3° and 7° (5°±2°), the variation in relative interference intensity caused by the second interference is smaller than when the incident angle of the measured light incident on the variable optical attenuator 4 is 5°. The reason for reducing the variation in interference intensity caused by the second interference by adjusting the distribution of the incident angle of the measured light incident on the variable optical attenuator 4 is the same as the reason for reducing the variation in interference intensity caused by the first interference: the averaging effect of the interference waveform.

[0126] Specifically, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the variation in the measured value of the photometer 1 caused by the second interference (interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.01%. Therefore, even if the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes slightly, the variation in the interference intensity caused by the second interference is reduced, and the measured light can be measured with good accuracy.

[0127] When condition (5) is satisfied, similarly to when condition (4) is satisfied, the variation in interference intensity caused by the second interference (interference between light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and light reflected four times by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. Specifically, when the relative tilt angle θ between the first and second optical attenuation filters changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference is 0.00%. Therefore, even if the relative tilt angle θ between the first and second optical attenuation filters changes slightly, the variation in interference intensity caused by the second interference is reduced, and the measured light can be measured with good accuracy.

[0128] <The reduction in the variation of interference intensity caused by the third interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0129] In this embodiment, the following conditions (10) and (11) are satisfied.

[0130] |OPD θmax4 -OPD θmin4 | / λ>0.5…(10)

[0131] |OPD θmax5- OPD θmin5 | / λ>0.5…(11)

[0132] OPD θmax4 =(OP) 3240max -OP 30G240max ). OPD θmin4 =(OP) 3240min -OP 30G240min ).

[0133] OPD θmax5 =(OP) 3042max -OP 30G240max ). OPD θmin5 =(OP) 3042min -OP 30G240min ).

[0134] OP 3240max It is the optical path length of the light with the maximum angle of incidence that is reflected twice by the third optical attenuation filter (optical attenuation filter 10) and does not pass through the fourth optical attenuation filter (optical attenuation filter 20). OP 30G240max It is the optical path length of the maximum angle of incidence light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection by the layer (e.g., an air layer) between the third and fourth optical attenuation filters. OP3240min It is the optical path length of the minimum incident angle light that is reflected twice by the third optical attenuation filter and passes through the fourth optical attenuation filter without being reflected by the fourth optical attenuation filter.

[0135] OP 30G240min It is the optical path length of the minimum angle of incidence light that passes through the third and fourth optical attenuation filters without being reflected by them and is subject to secondary reflection by the layer (e.g., air layer) between the third and fourth optical attenuation filters. OP 3042max It is the optical path length of the maximum angle of incidence light that passes through the third optical attenuation filter without being reflected by it and is then reflected twice by the fourth optical attenuation filter. OP 3042min It is the optical path length of the smallest incident angle light that passes through the third optical attenuation filter without being reflected by the third optical attenuation filter and is reflected twice by the fourth optical attenuation filter.

[0136] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 13 ), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 40.164. With a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...) Figure 16 ), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 40.774. Therefore, this embodiment satisfies condition (10). When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.0° (refer to...) Figure 12 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 36.594. When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...) Figure 10 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 The value is 37.274. Therefore, this embodiment satisfies condition (11).

[0137] Under the condition (10), it is possible to reduce the variation in interference intensity caused by the third interference (the interference between light reflected twice by the third optical attenuation filter (optical attenuation filter 10) and light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter (optical attenuation filter 20)). Figure 20 and Figure 21 When the incident angle of the measured light incident on the variable optical attenuator 4 is between 3° and 7° (5°±2°), the variation in relative interference intensity caused by the third interference is smaller than when the incident angle of the measured light incident on the variable optical attenuator 4 is 5°. The reason for reducing the variation in interference intensity caused by the third interference by adjusting the distribution of the incident angle of the measured light incident on the variable optical attenuator 4 is the same as the reason for reducing the variation in interference intensity caused by the first interference: the averaging effect of the interference waveform.

[0138] Specifically, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the variation in the measured value of the photometer 1 caused by the third interference (interference between light reflected twice by the third optical attenuation filter and light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) is 0.01%. Therefore, even if the relative tilt angle θ between the third and fourth optical attenuation filters changes slightly, the variation in the interference intensity caused by the third interference is reduced, and the measured light can be measured with good accuracy.

[0139] When condition (11) is satisfied, similarly to when condition (10) is satisfied, the variation in interference intensity caused by the third interference (interference between light reflected twice by the fourth optical attenuation filter (optical attenuation filter 20) and light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter) can be reduced. Specifically, the change in the measured value of the photometer 1 caused by the third interference when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%. Therefore, even if the relative tilt angle θ between the third and fourth optical attenuation filters changes slightly, the variation in interference intensity caused by the third interference is reduced, and the measured light can be measured with good accuracy.

[0140] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 0.26%. If the absolute value of the variation in the measured value of the photometer 1 is within 5%, the measured light can be measured with good accuracy. It is more preferable if the absolute value of the variation in the measured value of the photometer 1 is within 1%. Since the absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 1%, the measured light can be measured with good accuracy.

[0141] <Example 2>

[0142] The photometer 1 in this embodiment is the same as the photometer 1 in Embodiment 1, but differs mainly in the following aspects: There is no incident angle distribution of light incident on the variable light attenuator 4; the incident angle of light onto the variable light attenuator 4 is 5° (refer to Table 3). The half-width Δλ of the spectroscopic responsivity spectrum of the photodetector 9... a 3nm (refer to Table 3 and Figure 22 The linewidth Δλ of the light emitted from the object being measured (the measured light). b The value is 300nm (refer to Table 3).

[0143] [Table 3]

[0144] Angle of incidence 5° <![CDATA[Half-value width Δλ a > 3nm <![CDATA[Line width Δλ b > 300nm

[0145] The half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 a The linewidth Δλ of the light emitted from the object being measured (the measured light) b Compared to being sufficiently small, the reduction in the variation component of interference intensity caused by interference between multiple multiple reflected lights depends on the half-width Δλ of the spectroscopic responsivity spectrum of the photodetector element 9 described above (b). a And the linewidth Δλ of the light emitted from the object 2 (the measured light) as described in (c) above. b The half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 in (b) above. a Furthermore, in this embodiment, there is no distribution of the incident angle of the measured light incident on the variable light attenuator 4, therefore, there is no reduction in the variation component of interference intensity caused by interference between multiple multiple reflected lights, as achieved by the incident angle distribution of the measured light incident on the variable light attenuator 4 described in (a) above. In this embodiment, the half-width Δλ of the spectroscopic responsivity spectrum of the photodetector element 9 described in (b) above is studied. a The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0146] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0147] In this embodiment, the following condition (2) is satisfied.

[0148] OPD 12 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(2)

[0149] OPD 12 =|OP 1220 -OP 1022 | λ represents the wavelength of light within the range that the photometric device 1 can measure. Δλ a The half-width of the spectrophotometric responsivity spectrum of the photodetector 9 is given.

[0150] OP 1220 The optical path length of light that is reflected twice by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20) is (refer to) the optical path length of light that is reflected twice by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20). Figure 5 ). OP 1022 The optical path length of light that passes through the first optical attenuation filter (optical attenuation filter 10) and is reflected twice by the second optical attenuation filter (optical attenuation filter 20) (refer to) Figure 6 ).

[0151] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 5.236. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 5.237. Therefore, this embodiment satisfies condition (2).

[0152] Under condition (2), the variation component of the interference intensity caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. The measured value determined by the photodetector 8 is the spectrum of the relative interference intensity caused by the first interference (refer to...). Figure 16 The spectrophotometric responsivity spectrum of the photodetector 9 (refer to...) Figure 22 The product of ) is provided. The left side of condition (2) indicates that in Figure 22 The half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 shown. a It includes several cycles Figure 16 The interference waveform shown. If condition (2) is satisfied, a higher averaging effect of the interference waveform can be obtained, which can reduce the variation in interference intensity caused by the first interference.

[0153] Specifically, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%. Therefore, even if the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes slightly, the variation in the interference intensity caused by the first interference is reduced, and the measured light can be measured with good accuracy.

[0154] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0155] In this embodiment, the following conditions (6) and (7) are satisfied.

[0156] OPD 21 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(6)

[0157] OPD 22 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(7)

[0158] OPD 21 =|OP 1420 -OP 1022 |. OPD 22 =|OP 1024 -OP 1220 |

[0159] OP1420 The optical path length of light that is reflected four times by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20) is (refer to) the optical path length of light that passes through the second optical attenuation filter (refer to) the first optical attenuation filter (optical attenuation filter 10). Figure 7 and Figure 9 ). OP 1022 The optical path length of light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter (refer to...). Figure 7 and Figure 9 ). OP 1024 The optical path length of light that passes through the first optical attenuation filter without being reflected by it, and is reflected four times by the second optical attenuation filter (refer to...). Figure 8 and Figure 10 ). OP 1220 The optical path length of light that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter (refer to...). Figure 8 and Figure 10 ).

[0160] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (6) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 4.488. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (6) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 4.489. Therefore, this embodiment satisfies condition (6). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter is 0.0° (refer to...), Figure 8 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 20.194. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 20.196. Therefore, this embodiment satisfies condition (7).

[0161] Under condition (6), the variation in interference intensity caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. The measured value determined by the photodetector 8 is the spectrum of the relative interference intensity caused by the second interference (refer to...). Figure 18 The spectrophotometric responsivity spectrum of the photodetector 9 (refer to...) Figure 22 The product of ) is provided. The left side of condition (6) represents the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9. a It includes several cycles Figure 18 The interference waveform shown. If condition (6) is satisfied, a higher averaging effect of the interference waveform can be obtained, which can reduce the variation in interference intensity caused by the second interference.

[0162] Specifically, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference is 0.00%. Therefore, even if the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes slightly, the variation in the interference intensity caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is reduced, and the measured light can be measured with good accuracy.

[0163] When condition (7) is satisfied, similarly to when condition (6) is satisfied, the variation in interference intensity caused by the second interference (interference between light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and light reflected four times by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. As a result, even if the relative tilt angle θ between the first and second optical attenuation filters changes slightly, the interference intensity caused by the second interference remains almost unchanged. Specifically, the change in the measured value of the photometer 1 caused by the second interference when the relative tilt angle θ between the first and second optical attenuation filters changes from 0.0° to 0.1° is 0.00%. Therefore, even if the relative tilt angle θ between the first and second optical attenuation filters changes slightly, the variation in interference intensity caused by the second interference is reduced, and the measured light can be measured with good accuracy.

[0164] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0165] In this embodiment, the following conditions (12) and (13) are satisfied.

[0166] OPD g1 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(12)

[0167] OPD g2 ×(1 / λ-1 / (λ+Δλ a ))>0.5…(13)

[0168] OPD g1 =|OP 3240 -OP 30G240 |. OPD g2 =|OP 3042 -OP 30G240 |

[0169] OP 3240 It is the optical path length of light that is reflected twice by the third optical attenuation filter (optical attenuation filter 10) and does not pass through the fourth optical attenuation filter (optical attenuation filter 20). OP 30G240 It is the optical path length of light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection by the layer (e.g., air layer) between the third and fourth optical attenuation filters. OP 3042 It is the optical path length of light that passes through the third optical attenuation filter without being reflected by the third optical attenuation filter and is reflected twice by the fourth optical attenuation filter.

[0170] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 19.637. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 13 ), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 19.634. Therefore, this embodiment satisfies condition (12). When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.0° (refer to...), Figure 12 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ aThe value is 14.402. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 14 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 14.398. Therefore, this embodiment satisfies condition (13).

[0171] Under condition (12), the variation component of the interference intensity caused by the third interference (the interference between light reflected twice by the third optical attenuation filter (optical attenuation filter 10) and light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20)) can be reduced. The measured value determined by the photodetector 8 is the spectrum of the relative interference intensity caused by the third interference (refer to...) Figure 20 The spectrophotometric responsivity spectrum of the photodetector 9 (refer to...) Figure 22 The product of ) is provided. The left side of condition (12) represents the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9. a It includes several cycles Figure 20 The interference waveform shown. If condition (12) is satisfied, a higher averaging effect of the interference waveform can be obtained, which can reduce the variation in interference intensity caused by the third interference.

[0172] Specifically, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the third interference is 0.00%. Therefore, even if the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes slightly, the variation in the interference intensity caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) is reduced, and the measured light can be measured with good accuracy.

[0173] When condition (13) is satisfied, similarly to when condition (12) is satisfied, the variation in interference intensity caused by the third interference (interference between light reflected twice by the fourth optical attenuation filter (optical attenuation filter 20) and light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter) can be reduced. As a result, even if the relative tilt angle θ between the third and fourth optical attenuation filters changes slightly, the interference intensity caused by the third interference remains almost unchanged. Specifically, the change in the measured value of the photometer 1 caused by the third interference when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%. Therefore, even if the relative tilt angle θ between the third and fourth optical attenuation filters changes slightly, the variation in interference intensity caused by the third interference is reduced, and the measured light can be measured with good accuracy.

[0174] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 0.00%. If the absolute value of the variation in the measured value of the photometer 1 is within 5%, the measured light can be measured with good accuracy. It is more preferable if the absolute value of the variation in the measured value of the photometer 1 is within 1%. Since the absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 1%, the measured light can be measured with good accuracy.

[0175] <Example 3>

[0176] The photometer 1 in this embodiment is the same as the photometer 1 in Embodiment 1, but differs mainly in the following aspects: There is no incident angle distribution of light incident on the variable light attenuator 4; the incident angle of light onto the variable light attenuator 4 is 5° (refer to Table 4). The half-width Δλ of the spectroscopic responsivity spectrum of the photodetector 9... a The linewidth Δλ of the light emitted from the object being measured (the measured light) is 20 nm (refer to Table 4). b 1nm (refer to Table 4 and Figure 23 ).

[0177] [Table 4]

[0178] Angle of incidence 5° <![CDATA[Half-value width Δλ a > 20nm <![CDATA[Line width Δλ b > 1nm

[0179] The linewidth Δλ of the light emitted from the object being measured (the measured light) b The half-width Δλ of the spectroscopic responsivity spectrum of the photodetector element 9 aCompared to being sufficiently small, the reduction in the variation component of interference intensity caused by interference between multiple multiple reflected lights depends on the half-width Δλ of the spectroscopic responsivity spectrum of the photodetector element 9 described above (b). a and the linewidth Δλ of the light emitted from the object 2 (the measured light) as described in (c) above. b The linewidth Δλ of the light emitted from the object 2 (the measured light) mentioned above (c) is... b Furthermore, in this embodiment, there is no distribution of the incident angle of the measured light incident on the variable light attenuator 4, therefore, there is no reduction in the variation component of interference intensity caused by interference between multiple multiple reflected lights, as achieved by the incident angle distribution of the measured light incident on the variable light attenuator 4 described above (a). In this embodiment, the linewidth Δλ of the light emitted from the object 2 (measured light) described above (c) is studied. b The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0180] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0181] In this embodiment, the following condition (3) is satisfied.

[0182] OPD 13 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(3)

[0183] OPD 13 =|OP 1220 -OP 1022 | λ represents the wavelength of light within the range that the photometric device 1 can measure. Δλ b The linewidth of the light emitted from the object being measured 2 (the measured light).

[0184] OP 1220 The optical path length of light that is reflected twice by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20) is (refer to) the optical path length of light that is reflected twice by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20). Figure 5 ). OP 1022 The optical path length of light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter (refer to...). Figure 5 ).

[0185] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 1.750. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 1.750. Therefore, this embodiment satisfies condition (3).

[0186] Under condition (3), the variation component of the interference intensity caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. The measured value determined by the photodetector 8 is the spectrum of the relative interference intensity caused by the first interference (refer to...). Figure 16 The spectrum of light emitted from the sample 2 (the measured light) and the spectrum of light emitted from the sample 2 (reference) Figure 23 The product of ) is provided. The left side of condition (3) indicates that in Figure 23 The linewidth Δλ of the light emitted from the object being measured 2 (the measured light) is shown. b It includes several cycles Figure 16 The interference waveform shown. If condition (3) is satisfied, a higher averaging effect of the interference waveform can be obtained, which can reduce the variation in relative interference intensity caused by the first interference.

[0187] Specifically, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%. Therefore, even if the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes slightly, the variation in the interference intensity caused by the first interference is reduced, and the measured light can be measured with good accuracy.

[0188] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0189] In this embodiment, the following conditions (8) and (9) are satisfied.

[0190] OPD 21 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(8)

[0191] OPD 22 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(9)

[0192] OPD 21 =|OP 1420 -OP 1022 |. OPD 22 =|OP 1024 -OP 1220 |

[0193] OP 1420 The optical path length of light that is reflected four times by the first optical attenuation filter (optical attenuation filter 10) and does not pass through the second optical attenuation filter (optical attenuation filter 20) is (refer to) the optical path length of light that passes through the second optical attenuation filter (refer to) the first optical attenuation filter (optical attenuation filter 10). Figure 7 and Figure 9 ). OP 1022 The optical path length of light that passes through the first optical attenuation filter without being reflected by it and is then reflected twice by the second optical attenuation filter (refer to...). Figure 7 and Figure 9 ). OP 1024 The optical path length of light that passes through the first optical attenuation filter without being reflected by it, and is reflected four times by the second optical attenuation filter (refer to...). Figure 8 and Figure 10 ). OP 1220 The optical path length of light that is reflected twice by the first optical attenuation filter and passes through the second optical attenuation filter without being reflected by the second optical attenuation filter (refer to...). Figure 8 and Figure 10 ).

[0194] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ b The value is 1.500. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ bThe value is 1.500. Therefore, this embodiment satisfies condition (8). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter is 0.0° (refer to...), Figure 8 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 6.749. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 6.749. Therefore, this embodiment satisfies condition (9).

[0195] Under condition (8), the variation component of the interference intensity caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and the light reflected twice by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. The measured value determined by the photodetector 8 is the spectrum of the relative interference intensity caused by the second interference (refer to...). Figure 18 The spectrum of light emitted from the sample 2 (the measured light) and the spectrum of light emitted from the sample 2 (reference) Figure 23 The product of ) is provided. The left side of condition (8) indicates that in Figure 23 The linewidth Δλ of the light emitted from the object being measured 2 (the measured light) is shown. b It includes several cycles Figure 18 The interference waveform shown. If condition (8) is satisfied, a higher averaging effect of the interference waveform can be obtained, which can reduce the variation in interference intensity caused by the second interference.

[0196] Specifically, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference is 0.00%. Therefore, even if the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes slightly, the variation in the interference intensity caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is reduced, and the measured light can be measured with good accuracy.

[0197] When condition (9) is satisfied, similarly to when condition (8) is satisfied, the variation in interference intensity caused by the second interference (interference between light reflected twice by the first optical attenuation filter (optical attenuation filter 10) and light reflected four times by the second optical attenuation filter (optical attenuation filter 20)) can be reduced. As a result, even if the relative tilt angle θ between the first and second optical attenuation filters changes slightly, the interference intensity caused by the second interference remains almost unchanged. Specifically, the change in the measured value of the photometer 1 caused by the second interference when the relative tilt angle θ between the first and second optical attenuation filters changes from 0.0° to 0.1° is 0.00%. Therefore, even if the relative tilt angle θ between the first and second optical attenuation filters changes slightly, the variation in interference intensity caused by the second interference is reduced, and the measured light can be measured with good accuracy.

[0198] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0199] In this embodiment, the following conditions (14) and (15) are satisfied.

[0200] OPD g1 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(14)

[0201] OPD g2 ×(1 / λ-1 / (λ+Δλ b ))>0.5…(15)

[0202] OPD g1 =|OP 3240 -OP 30G240 |. OPD g2 =|OP 3042 -OP 30G240 |

[0203] OP 3240 It is the optical path length of light that is reflected twice by the third optical attenuation filter (optical attenuation filter 10) and does not pass through the fourth optical attenuation filter (optical attenuation filter 20). OP 30G240 It is the optical path length of light that passes through the third and fourth optical attenuation filters without being reflected by them, and is subject to secondary reflection by the layer (e.g., air layer) between the third and fourth optical attenuation filters. OP 3042It is the optical path length of light that passes through the third optical attenuation filter without being reflected by the third optical attenuation filter and is reflected twice by the fourth optical attenuation filter.

[0204] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 6.562. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 13 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 6.562. Therefore, this embodiment satisfies condition (14). When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.0° (refer to...), Figure 12 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 4.813. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 14 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 4.812. Therefore, this embodiment satisfies condition (15).

[0205] Under condition (14), the variation component of the interference intensity caused by the third interference (the interference between light reflected twice by the third optical attenuation filter (optical attenuation filter 10) and light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter (optical attenuation filter 20)) can be reduced. The measured value determined by the photodetector 8 is the spectrum of the relative interference intensity caused by the third interference (refer to...). Figure 20 The spectrum of light emitted from the sample 2 (the measured light) and the spectrum of light emitted from the sample 2 (reference) Figure 23 The product of ) is provided. The left side of condition (14) indicates that in Figure 23 The linewidth Δλ of the light emitted from the object being measured 2 (the measured light) is shown. b It includes several cycles Figure 20 The interference waveform shown. If condition (14) is satisfied, a higher averaging effect of the interference waveform can be obtained, which can reduce the variation in interference intensity caused by the third interference.

[0206] Specifically, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the third interference is 0.00%. Therefore, even if the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes slightly, the variation in the interference intensity caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) is reduced, and the measured light can be measured with good accuracy.

[0207] When condition (15) is satisfied, similarly to when condition (14) is satisfied, the variation in interference intensity caused by the third interference (interference between light reflected twice by the fourth optical attenuation filter (optical attenuation filter 20) and light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter) can be reduced. As a result, even if the relative tilt angle θ between the third and fourth optical attenuation filters changes slightly, the interference intensity caused by the third interference remains almost unchanged. Specifically, the change in the measured value of the photometer 1 caused by the third interference when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%. Therefore, even if the relative tilt angle θ between the third and fourth optical attenuation filters changes slightly, the variation in interference intensity caused by the third interference is reduced, and the measured light can be measured with good accuracy.

[0208] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 0.00%. If the absolute value of the variation in the measured value of the photometer 1 is within 5%, the measured light can be measured with good accuracy. It is more preferable if the absolute value of the variation in the measured value of the photometer 1 is within 1%. Since the absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 1%, the measured light can be measured with good accuracy.

[0209] <Example 4, Example 5, Example 6>

[0210] Reference Figures 1 to 23 Examples 4 to 6 will be described. The photometer 1 of Examples 4 to 6 has the same structure as the photometer 1 of Examples 1 to 3, but differs mainly in the following aspects.

[0211] The structures of the variable optical attenuator 4 in Examples 4 to 6 are shown in Table 5. Therefore, the optical path length of the transparent substrate 11 is different from that of the transparent substrate 21.

[0212] [Table 5]

[0213]

[0214] <Example 4>

[0215] In this embodiment, the incident angle distribution of light incident on the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are described. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b The incident angle distribution of light incident on the variable optical attenuator 4 in Example 1, and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those in Example 1. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 2. Therefore, in this embodiment, similar to Example 1, the reduction of the variation components of interference intensity caused by the first, second, and third interferences among multiple multiple reflected light, achieved by studying the distribution of the incident angle of the measured light incident on the variable light attenuator 4 as described above (a), is investigated.

[0216] <The reduction in the variation of the interference intensity caused by the first interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0217] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 5.101. With the relative tilt angle θ between the first and second optical attenuation filters being 0.1° (refer to...) Figure 6 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 4.898. Therefore, this embodiment satisfies condition (1). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.03%.

[0218] <The reduction in the variation of the interference intensity caused by the second interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0219] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 0.000. When the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...) Figure 9 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 0.203. Therefore, this embodiment does not satisfy condition (4). The change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is -0.20%.

[0220] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 15.303. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 14.897. Therefore, this embodiment satisfies condition (5). The change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0221] <The reduction in the variation of interference intensity caused by the third interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0222] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 13), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 5.038. With a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...) Figure 16 ), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 5.243. Therefore, this embodiment satisfies condition (10). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 0.03%.

[0223] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 0.063. When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...) Figure 10 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 0.244. Therefore, this embodiment does not satisfy condition (11). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is -2.04%.

[0224] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is -2.24%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 1. Therefore, the photometer 1 in Embodiment 1 is more preferred than the photometer 1 in this embodiment.

[0225] <Example 5>

[0226] In this embodiment, the incident angle of light to the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are... a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b The incident angle of light to the variable optical attenuator 4 in Example 2 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those of the variable optical attenuator 4 in Example 2. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 3. Therefore, in this embodiment, similar to Example 2, the half-width Δλ of the spectroscopic responsivity spectrum of the photodetector 9 described above (b) is investigated. a The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0227] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0228] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 7.479. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 7.480. Therefore, this embodiment satisfies condition (2). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0229] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0230] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (6) is OPD21 ×(1 / λ-1 / (λ+Δλ a The value is 0.000. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (6) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 0.001. Therefore, this embodiment does not satisfy condition (6). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.20%.

[0231] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 22.438. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 22.440. Therefore, this embodiment satisfies condition (7). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) is 0.00%.

[0232] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0233] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 7.397. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 13), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 7.395. Therefore, this embodiment satisfies condition (12). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0234] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 0.083. This is assuming the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...). Figure 14 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 0.085. Therefore, this embodiment does not satisfy condition (13). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 1.37%.

[0235] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 1.16%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 2. Therefore, the photometer 1 in Embodiment 2 is more preferred than the photometer 1 in this embodiment.

[0236] <Example 6>

[0237] In this embodiment, the incident angle of light to the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are... a and the linewidth Δλ of the light emitted from the object being measured (the measured light).b The incident angle of light to the variable optical attenuator 4 in Example 3 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those of the variable optical attenuator 4 in Example 3. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 4. Therefore, in this embodiment, similar to Example 3, the linewidth Δλ of the light emitted from the object 2 (the measured light) described above (c) is investigated. b The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0238] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0239] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 2.500. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 2.500. Therefore, this embodiment satisfies condition (3). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0240] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0241] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ bThe value is 0.000. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ b The value is 0.000. Therefore, this embodiment does not satisfy condition (8). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.20%.

[0242] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 7.499. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 7.499. Therefore, this embodiment satisfies condition (9). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) is 0.00%.

[0243] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0244] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 2.472. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 13 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλb The value is 2.471. Therefore, this embodiment satisfies condition (14). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0245] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 0.028. This is when the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...). Figure 14 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 0.028. Therefore, this embodiment does not satisfy condition (15). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 2.30%.

[0246] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 2.10%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 3. Therefore, the photometer 1 in Embodiment 3 is more preferred than the photometer 1 in this embodiment.

[0247] <Examples 7, 8, and 9>

[0248] Reference Figures 1 to 23 Examples 7 to 9 will be described below. The photometer 1 of Examples 7 to 9 has the same structure as the photometer 1 of Examples 1 to 3, but differs mainly in the following aspects.

[0249] The structures of the variable optical attenuator 4 in Examples 7 to 9 are shown in Table 6. Therefore, the optical path length of the transparent substrate 11 is different from that of the transparent substrate 21.

[0250] [Table 6]

[0251]

[0252] <Example 7>

[0253] In this embodiment, the incident angle distribution of light incident on the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are described. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b The incident angle distribution of light incident on the variable optical attenuator 4 in Example 1, and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those in Example 1. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 2. Therefore, in this embodiment, similar to Example 1, the reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light, achieved by studying the distribution of the incident angle of the measured light incident on the variable light attenuator 4 as described above (a), is investigated.

[0254] <The reduction in the variation of the interference intensity caused by the first interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0255] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 2.040. With the relative tilt angle θ between the first and second optical attenuation filters being 0.1° (refer to...) Figure 6 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 1.838. Therefore, this embodiment satisfies condition (1). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.05%.

[0256] <The reduction in the variation of the interference intensity caused by the second interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0257] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 6.121. When the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...) Figure 9 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 5.797. Therefore, this embodiment satisfies condition (4). The change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0258] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 12.242. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 11.837. Therefore, this embodiment satisfies condition (5). The change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0259] <The reduction in the variation of interference intensity caused by the third interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0260] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 13), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 0.362. With a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...) Figure 16 ), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 0.120. Therefore, this embodiment does not satisfy condition (10). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is -2.41%.

[0261] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 2.402. When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...) Figure 10 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 2.120. Therefore, this embodiment satisfies condition (11). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.07%.

[0262] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is -2.39%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 1. Therefore, the photometer 1 in Embodiment 1 is more preferred than the photometer 1 in this embodiment.

[0263] <Example 8>

[0264] In this embodiment, the incident angle of light to the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are... a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b The incident angle of light to the variable optical attenuator 4 in Example 2 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those of the variable optical attenuator 4 in Example 2. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 3. Therefore, in this embodiment, similar to Example 2, the half-width Δλ of the spectroscopic responsivity spectrum of the photodetector 9 described above (b) is investigated. a The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0265] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0266] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 2.992. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 2.993. Therefore, this embodiment satisfies condition (2). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0267] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0268] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (6) is OPD21 ×(1 / λ-1 / (λ+Δλ a The value is 8.975. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (6) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 8.977. Therefore, this embodiment satisfies condition (6). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0269] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 17.950. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 17.952. Therefore, this embodiment satisfies condition (7). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) is 0.00%.

[0270] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0271] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 0.266. This is when the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...). Figure 13), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 0.265. Therefore, this embodiment does not satisfy condition (12). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 2.74%.

[0272] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 2.725. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 14 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 2.727. Therefore, this embodiment satisfies condition (13). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%.

[0273] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 2.74%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 2. Therefore, the photometer 1 in Embodiment 2 is more preferred than the photometer 1 in this embodiment.

[0274] <Example 9>

[0275] In this embodiment, the incident angle of light to the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are... a and the linewidth Δλ of the light emitted from the object being measured (the measured light).b The incident angle of light to the variable optical attenuator 4 in Example 3 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those of the variable optical attenuator 4 in Example 3. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 4. Therefore, in this embodiment, similar to Example 3, the linewidth Δλ of the light emitted from the object 2 (the measured light) described above (c) is investigated. b The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0276] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0277] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 1.000. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 1.000. Therefore, this embodiment satisfies condition (3). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.01%.

[0278] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0279] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ bThe value is 2.999. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ b The value is 3.000. Therefore, this embodiment satisfies condition (8). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0280] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 5.999. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 5.999. Therefore, this embodiment satisfies condition (9). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) is 0.00%.

[0281] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0282] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 0.089. This is assuming the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...). Figure 13 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ bThe value is 0.088. Therefore, this embodiment does not satisfy condition (14). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 3.43%.

[0283] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 0.911. This is when the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...). Figure 14 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 0.911. Therefore, this embodiment satisfies condition (15). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.06%.

[0284] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is 3.50%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 3. Therefore, the photometer 1 in Embodiment 3 is more preferred than the photometer 1 in this embodiment.

[0285] <Example 10, Example 11, Example 12>

[0286] Reference Figures 1 to 23 Examples 10 to 12 will be described below. The photometer 1 of Examples 10 to 12 has the same structure as the photometer 1 of Examples 1 to 3, but differs mainly in the following aspects.

[0287] The structures of the variable optical attenuator 4 in Examples 10 to 12 are shown in Table 7. Therefore, the optical path length of the transparent substrate 11 is different from that of the transparent substrate 21.

[0288] [Table 7]

[0289]

[0290] <Example 10>

[0291] In this embodiment, the incident angle distribution of light incident on the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are described. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b The incident angle distribution of light incident on the variable optical attenuator 4 in Example 1, and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those in Example 1. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 2. Therefore, in this embodiment, similar to Example 1, the reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light, achieved by studying the distribution of the incident angle of the measured light incident on the variable light attenuator 4 as described above (a), is investigated.

[0292] <The reduction in the variation of the interference intensity caused by the first interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0293] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 5.101. With the relative tilt angle θ between the first and second optical attenuation filters being 0.1° (refer to...) Figure 6 ), the left side of condition (1) is |OPD θmax1 -OPD θmin1 | / λ is 4.898. Therefore, this embodiment satisfies condition (1). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.03%.

[0294] <The reduction in the variation of the interference intensity caused by the second interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0295] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 0.000. When the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...) Figure 9 ), the left side of condition (4) is |OPD θmax2 -OPD θmin2 | / λ is 0.203. Therefore, this embodiment does not satisfy condition (4). The change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is -0.20%.

[0296] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 15.303. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (5) is |OPD θmax3 -OPD θmin3 | / λ is 14.897. Therefore, this embodiment satisfies condition (5). The change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) when the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0297] <The reduction in the variation of interference intensity caused by the third interference, achieved by the distribution of the incident angle of the measured light incident on the variable optical attenuator 4>

[0298] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 13), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 41.694. With a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...) Figure 16 ), the left side of condition (10) is |OPD θmax4 -OPD θmin4 | / λ is 42.274. Therefore, this embodiment satisfies condition (10). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 0.03%.

[0299] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 36.594. When the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...) Figure 10 ), the left side of condition (11) is |OPD θmax5 -OPD θmin5 | is 37.274. Therefore, this embodiment satisfies condition (11). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%.

[0300] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is -0.21%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light.

[0301] <Example 11>

[0302] In this embodiment, the incident angle of light to the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are... aand the linewidth Δλ of the light emitted from the object being measured (the measured light). b The incident angle of light to the variable optical attenuator 4 in Example 2 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those of the variable optical attenuator 4 in Example 2. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 3. Therefore, in this embodiment, similar to Example 2, the half-width Δλ of the spectroscopic responsivity spectrum of the photodetector 9 described above (b) is investigated. a The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0303] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0304] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 7.479. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (2) is OPD 12 ×(1 / λ-1 / (λ+Δλ a The value is 7.480. Therefore, this embodiment satisfies condition (2). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0305] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0306] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (6) is OPD 21 ×(1 / λ-1 / (λ+Δλ aThe value is 0.000. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (6) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 0.001. Therefore, this embodiment does not satisfy condition (6). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.20%.

[0307] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 22.438. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (7) is OPD 21 ×(1 / λ-1 / (λ+Δλ a The value is 22.440. Therefore, this embodiment satisfies condition (7). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) is 0.00%.

[0308] < Half-width Δλ of the spectroscopic responsivity spectrum of optical detection element 9 a The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0309] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλ a The value is 21.881. This is assuming the relative tilt angle θ between the third and fourth optical attenuation filters is 0.1° (refer to...). Figure 13 ), the left side of condition (12) is OPD g1 ×(1 / λ-1 / (λ+Δλa The value is 21.878. Therefore, this embodiment satisfies condition (12). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0310] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 14.402. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 14 ), the left side of condition (13) is OPD g2 ×(1 / λ-1 / (λ+Δλ a The value is 14.398. Therefore, this embodiment satisfies condition (13). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%.

[0311] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is -0.20%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 2. Therefore, the photometer 1 in Embodiment 2 is more preferred than the photometer 1 in this embodiment.

[0312] <Example 12>

[0313] In this embodiment, the incident angle of light to the variable optical attenuator 4 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are... a and the linewidth Δλ of the light emitted from the object being measured (the measured light). bThe incident angle of light to the variable optical attenuator 4 in Example 3 and the half-width Δλ of the spectroscopic responsivity spectrum of the optical detection element 9 are respectively compared with those of the variable optical attenuator 4 in Example 3. a and the linewidth Δλ of the light emitted from the object being measured (the measured light). b Same as in Table 4. Therefore, in this embodiment, similar to Example 3, the linewidth Δλ of the light emitted from the object 2 (the measured light) described above (c) is investigated. b The achieved reduction of the variation components of interference intensity caused by the first, second, and third interferences between multiple multiple reflected light.

[0314] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of the interference intensity caused by the first interference is greater than

[0315] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 5 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 2.500. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 6 ), the left side of condition (3) is OPD 13 ×(1 / λ-1 / (λ+Δλ b The value is 2.500. Therefore, this embodiment satisfies condition (3). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the first interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is 0.00%.

[0316] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the second interference is achieved >

[0317] In this embodiment, when the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 7 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ b The value is 0.000. This is when the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 9 ), the left side of condition (8) is OPD 21 ×(1 / λ-1 / (λ+Δλ b The value is 0.000. Therefore, this embodiment does not satisfy condition (8). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected four times by the first optical attenuation filter and the light reflected twice by the second optical attenuation filter) is -0.20%.

[0318] When the relative tilt angle θ between the first optical attenuation filter (optical attenuation filter 10) and the second optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 8 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 7.499. This is assuming the relative tilt angle θ between the first and second optical attenuation filters is 0.1° (refer to...). Figure 10 ), the left side of condition (9) is OPD 22 ×(1 / λ-1 / (λ+Δλ b The value is 7.499. Therefore, this embodiment satisfies condition (9). When the relative tilt angle θ between the first optical attenuation filter and the second optical attenuation filter changes from 0.0° to 0.1°, the change in the measured value of the photometer 1 caused by the second interference (the interference between the light reflected twice by the first optical attenuation filter and the light reflected four times by the second optical attenuation filter) is 0.00%.

[0319] < Linear width Δλ of the light emitted from the object being measured (the measured light) b The reduction in the variation component of interference intensity caused by the third interference is achieved >

[0320] In this embodiment, when the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...), Figure 11 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 7.312. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 13 ), the left side of condition (14) is OPD g1 ×(1 / λ-1 / (λ+Δλ bThe value is 7.311. Therefore, this embodiment satisfies condition (14). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the third optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third optical attenuation filter and the fourth optical attenuation filter) when the relative tilt angle θ between the third optical attenuation filter and the fourth optical attenuation filter changes from 0.0° to 0.1° is 0.00%.

[0321] When the relative tilt angle θ between the third optical attenuation filter (optical attenuation filter 10) and the fourth optical attenuation filter (optical attenuation filter 20) is 0.0° (refer to...) Figure 12 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 4.813. This is assuming a relative tilt angle θ of 0.1° between the third and fourth optical attenuation filters (refer to...). Figure 14 ), the left side of condition (15) is OPD g1 ×(1 / λ-1 / (λ+Δλ b The value is 4.812. Therefore, this embodiment satisfies condition (15). The change in the measured value of the photometer 1 caused by the third interference (the interference between the light reflected twice by the fourth optical attenuation filter and the light reflected twice by the layer (e.g., air layer) between the third and fourth optical attenuation filters) when the relative tilt angle θ between the third and fourth optical attenuation filters changes from 0.0° to 0.1° is 0.00%.

[0322] The variation in the measured value of the photometer 1 in this embodiment is provided by the sum of the variation in the measured value caused by the first interference, the variation in the measured value caused by the second interference, and the variation in the measured value caused by the third interference. The variation in the measured value of the photometer 1 in this embodiment is -0.20%. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is within 5%, thus enabling accurate measurement of the measured light. The absolute value of the variation in the measured value of the photometer 1 in this embodiment is larger than the absolute value of the variation in the measured value of the photometer 1 in Embodiment 3. Therefore, the photometer 1 in Embodiment 3 is more preferred than the photometer 1 in this embodiment.

[0323] (Modified Example)

[0324] Alternatively, the optical path lengths of the transparent substrate 11 and the transparent substrate 21 can be made different by making the refractive index n1 of the transparent substrate 11 different from that of the transparent substrate 21.

[0325] The photometer 1 of the embodiment includes two optical attenuation filters, but it may also include three or more optical attenuation filters. Any two of the multiple optical attenuation filters included in the photometer 1 may satisfy the conditional expression shown in the embodiment.

[0326] The photometer 1 described in this embodiment can also be applied to photometers such as colorimeters with direct stimulus readings. In this case, the spectral width of the spectrophotometric response of the light detection element 9 is relatively large, around 50 nm or more. However, as long as the conditions shown in this embodiment are met, a photometer 1 can be provided that can achieve a wide dynamic range, has a compact size, and can measure light with higher accuracy.

[0327] In this embodiment, it is assumed that two optical attenuation filters are inserted or retracted, but multiple filters can also be fixed on the optical axis 2p. Even when multiple filters are fixed on the optical axis 2p, the relative tilt angle between the multiple filters may sometimes change slightly due to variations in the ambient temperature around the photometer 1 or vibrations or shocks applied to the photometer 1. Thus, even with multiple filters fixed on the optical axis 2p and slight variations in the relative tilt angle between the multiple filters, light can be measured with higher accuracy and greater stability.

[0328] The photometric device 1 of the embodiment is not limited to an optical attenuation filter, and may also include an interference filter, such as a shortcut filter, a longcut filter, or a bandpass filter, which has characteristics different from an optical attenuation filter. The photometric device 1 equipped with an interference filter having characteristics different from an optical attenuation filter can perform optical measurements with different characteristics.

[0329] The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of this disclosure is defined by the claims, including all modifications within the meaning and scope equivalent to those claims.

[0330] Explanation of reference numerals in the attached figures: 1…Measuring device; 2…Object to be measured; 2p…Optical axis; 3…Collating lens; 4…Variable light attenuator; 5…Driver; 6…Spectrometer; 7…Condenser lens; 8…Photodetector; 9…Photodetector element; 10, 20…Light attenuation filter; 11, 21…Transparent substrate; 12, 13, 22, 23…Interference multilayer film; 14, 24…Incident surface; 15, 25…Emission surface.

Claims

1. A light measuring device comprising: a variable optical attenuator including a plurality of optical attenuation filters and a driving device; and a light detector that receives light that has passed through the variable optical attenuator, the driving device being capable of causing the plurality of optical attenuation filters to be inserted into and withdrawn from an optical axis of the light independently of one another, the plurality of optical attenuation filters being disposed at mutually different positions in a direction along the optical axis, each of the plurality of optical attenuation filters including an interference multilayer film and a transparent substrate that supports the interference multilayer film, if a combination of any two of the plurality of optical attenuation filters is set as a first optical attenuation filter and a second optical attenuation filter, the second optical attenuation filter is closer to the light detector than the first optical attenuation filter in the direction along the optical axis, the first optical attenuation filter includes a first interference multilayer film as the interference multilayer film and a first transparent substrate as the transparent substrate, the second optical attenuation filter includes a second interference multilayer film as the interference multilayer film and a second transparent substrate as the transparent substrate, a first optical path length of the first transparent substrate is different from a second optical path length of the second transparent substrate, the light has a distribution of an angle of incidence into the variable optical attenuator, the light measuring device satisfies a conditional expression (1) below, where λ is a wavelength of the light included in a range of wavelengths capable of being measured by the light measuring device, 0 < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) < (λ / 2) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ |OPD θmax1 -OPD θmin1 | / λ>0.5…(1) ​ OPD θmax1 = (OP 1220max - OP 1022max ), OPD θmin1 = (OP 1220min - OP 1022min ), ​ OP 1220max a path length of light of a maximum incident angle that passes through the second light-attenuation filter by being reflected by the first light-attenuation filter and not being reflected by the second light-attenuation filter, the light of the maximum incident angle being light of the light whose incident angle to the variable light-attenuator is the largest, OP 1022max a path length of the maximum incident angle light that passes through the first light attenuation filter without being reflected by the first light attenuation filter and is twice reflected by the second light attenuation filter, OP 1220min a path length of light of a minimum incident angle that passes through the second light-attenuation filter by being reflected by the first light-attenuation filter and not being reflected by the second light-attenuation filter, the light of the minimum incident angle being light of the light whose incident angle to the variable light-attenuator is the smallest, OP 1022min a path length of the minimum incident angle light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is twice reflected by the second light-attenuating filter. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ |OPD θmax2 -OPD θmin2 | / λ>0.5…(4) |OPD θmax3 -OPD θmin3 | / λ>0.5…(5) ​ OPD θmax2 = (OP 1420max - OP 1022max ), OPD θmin2 = (OP 1420min - OP 1022min ), OPD θmax3 = (OP 1024max - OP 1220max ), OPD θmin3 = (OP 1024min - OP 1220min ), OP 1420max a path length of the maximum incident angle light that is reflected four times by the first light-attenuation filter and that passes through the second light-attenuation filter without being reflected by the second light-attenuation filter, OP 1022max a path length of the maximum incident angle light that passes through the first light attenuation filter without being reflected by the first light attenuation filter and is twice reflected by the second light attenuation filter, OP 1420min a path length of the minimum incident angle light that is reflected four times by the first light-attenuation filter and that passes through the second light-attenuation filter without being reflected by the second light-attenuation filter, OP 1022min a path length of the minimum incident angle light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is twice reflected by the second light-attenuating filter, OP 1024max a path length of the maximum incident angle light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is reflected four times by the second light-attenuating filter, OP 1220max a path length of the maximum incident angle light that is reflected by the first light-attenuation filter and that passes through the second light-attenuation filter without being reflected by the second light-attenuation filter, OP 1024min a path length of the minimum incident angle light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is reflected four times by the second light-attenuating filter, OP 1220min a path length of the minimum incident angle light that is reflected by the first light-attenuation filter and that passes through the second light-attenuation filter without being reflected by the second light-attenuation filter. ​ ​ ​ |OPD θmax4 -OPD θmin4 | / λ>0.5…(10) |OPD θmax5 -OPD θmin5 | / λ>0.5…(11) ​ OPD θmax4 = (OP 3240max - OP 30G240max ), OPD θmin4 = (OP 3240min - OP 30G240min ), OPD θmax5 = (OP 3042max - OP 30G240max ), OPD θmin5 = (OP 3042min - OP 30G240min ), OP 3240max a path length of the maximum incident angle light that passes through the fourth light-attenuation filter by being reflected twice by the third light-attenuation filter and not being reflected by the fourth light-attenuation filter, OP 30G240max for light that passes through the third and fourth light-attenuating filters without being reflected by the third and fourth light-attenuating filters, and a path length of the maximum incident angle light that is twice reflected by the layer between the third and fourth light-attenuating filters, OP 3240min a path length of the minimum incident angle light that is reflected by the third light-attenuation filter and that passes through the fourth light-attenuation filter without being reflected by the fourth light-attenuation filter, OP 30G240min to pass through the third and fourth light-attenuation filters without being reflected by the third and fourth light-attenuation filters, and the optical path length of the minimum incident angle light that is twice reflected by the layer between the third and fourth light-attenuation filters, OP 3042max a path length of the maximum incident angle light that passes through the third light attenuation filter without being reflected by the third light attenuation filter and is twice reflected by the fourth light attenuation filter, OP 3042min a path length of the minimum incident angle light that passes through the third light-attenuating filter without being reflected by the third light-attenuating filter and is twice reflected by the fourth light-attenuating filter. ​ ​ a light detector that receives light that has passed through the variable light attenuator, the driving device is capable of causing the plurality of light attenuation filters to be inserted into and withdrawn from the optical axis of the light independently of one another, the plurality of light attenuation filters are disposed at mutually different positions in the direction along the optical axis, each of the plurality of light attenuation filters includes an interference multilayer film and a transparent substrate that supports the interference multilayer film, if a combination of any two of the plurality of light attenuation filters is set as a first light attenuation filter and a second light attenuation filter, in the direction along the optical axis, the second light attenuation filter is closer to the light detector than the first light attenuation filter, the first light attenuation filter includes a first interference multilayer film as the interference multilayer film and a first transparent substrate as the transparent substrate, the second light attenuation filter includes a second interference multilayer film as the interference multilayer film and a second transparent substrate as the transparent substrate, a first optical path length of the first transparent substrate is different from a second optical path length of the second transparent substrate, the photometric device is a spectrometer that is capable of measuring spectral information, the photometric device satisfies the following conditional expression (2), OPD 12 x (1 / λ - 1 / (λ + Δλ a )) > 0.5 (2) wherein OPD 12 = |OP 1220 -OP 1022 |, λ is a wavelength of the light included in a range of wavelengths capable of being measured by the photometric device, the Δλ a is a half-value width of a spectral responsivity spectrum of a light-detecting element included in the light detector, OP 1220 a path length of the light that passes through the second light-attenuating filter by being reflected twice by the first light-attenuating filter and not reflected by the second light-attenuating filter, OP 1022 an optical path length of the light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is twice reflected by the second light-attenuating filter.

10. The photometric device according to claim 9, wherein a first thickness of the first transparent substrate is different from a second thickness of the second transparent substrate.

11. The photometric device according to claim 9, wherein a first refractive index of the first transparent substrate is different from a second refractive index of the second transparent substrate.

12. The photometric device according to claim 9, wherein the interference multilayer film of each of the plurality of light attenuation filters is formed of the same material, the transparent substrate of each of the plurality of light attenuation filters is formed of the same material.

13. The photometric device according to claim 9, wherein each of the plurality of light attenuation filters is disposed at the same angle with respect to the optical axis.

14. The photometric device according to any one of claims 9 to 13, wherein the photometric device further includes a collimator lens disposed on an incident side of the plurality of light attenuation filters.

15. The photometric device according to claim 9, wherein the photometric device satisfies the following conditional expressions (6) and (7), OPD 21 x (1 / λ - 1 / (λ + Δλ a )) > 0.5 (6) OPD 22 x (1 / λ - 1 / (λ + Δλ a )) > 0.5 (7) wherein OPD 21 = |OP 1420 -OP 1022 |, OPD 22 = |OP 1024 -OP 1220 |, OP 1420 a path length of the light that passes through the second light-attenuating filter four times reflected by the first light-attenuating filter and not reflected by the second light-attenuating filter, OP 1022 a path length of the light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is twice reflected by the second light-attenuating filter, OP 1024 a path length of the light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is reflected four times by the second light-attenuating filter, OP 1220 a path length of the light that passes through the second light-attenuating filter by being reflected twice by the first light-attenuating filter and not reflected by the second light-attenuating filter.

16. The photometric device according to claim 9 or 15, wherein the plurality of light attenuation filters include a third light attenuation filter as the first light attenuation filter and a fourth light attenuation filter as the second light attenuation filter, the third light attenuation filter and the fourth light attenuation filter being any two light attenuation filters of the plurality of light attenuation filters that are adjacent to each other, the photometric device satisfies the following conditional expressions (12) and (13), OPD g1 x (1 / λ - 1 / (λ + Δλ a )) > 0.5 (12) OPD g2 x (1 / λ - 1 / (λ + Δλ a )) > 0.5 (13) wherein OPD g1 = |OP 3240 -OP 30G240 |, OPD g2 = |OP 3042 -OP 30G240 |, OP 3240 a path length of the light that passes through the fourth light-attenuating filter by being reflected twice by the third light-attenuating filter and not reflected by the fourth light-attenuating filter, OP 30G240 for the light that passes through the third light-attenuating filter and the fourth light-attenuating filter without being reflected by the third light-attenuating filter and the fourth light-attenuating filter, and the optical path length of the light that is twice reflected by the layer between the third light-attenuating filter and the fourth light-attenuating filter, OP 3042 an optical path length of the light that passes through the third light-attenuating filter without being reflected by the third light-attenuating filter and is twice reflected by the fourth light-attenuating filter.

17. A photometric device, comprising: a variable light attenuator including a plurality of light attenuation filters and a driving device; and a light detector that receives light that has passed through the variable light attenuator, the driving device is capable of causing the plurality of light attenuation filters to be inserted into and withdrawn from the optical axis of the light independently of one another, the plurality of light attenuation filters are disposed at mutually different positions in the direction along the optical axis, each of the plurality of light attenuation filters includes an interference multilayer film and a transparent substrate that supports the interference multilayer film, if a combination of any two of the plurality of light attenuation filters is set as a first light attenuation filter and a second light attenuation filter, in the direction along the optical axis, the second light attenuation filter is closer to the light detector than the first light attenuation filter, the first light attenuation filter includes a first interference multilayer film as the interference multilayer film and a first transparent substrate as the transparent substrate, the second light attenuation filter includes a second interference multilayer film as the interference multilayer film and a second transparent substrate as the transparent substrate, a first optical path length of the first transparent substrate is different from a second optical path length of the second transparent substrate, the photometric device is a spectrometer that is capable of measuring spectral information, the photometric device satisfies the following conditional expression (2), wherein λ is a wavelength of the light included in a range of wavelengths capable of being measured by the photometric device, 10. The photometric device according to claim 9, wherein a first thickness of the first transparent substrate is different from a second thickness of the second transparent substrate.

11. The photometric device according to claim 9, wherein a first refractive index of the first transparent substrate is different from a second refractive index of the second transparent substrate.

12. The photometric device according to claim 9, wherein the interference multilayer film of each of the plurality of light attenuation filters is formed of the same material, the transparent substrate of each of the plurality of light attenuation filters is formed of the same material.

13. The photometric device according to claim 9, wherein each of the plurality of light attenuation filters is disposed at the same angle with respect to the optical axis.

14. The photometric device according to any one of claims 9 to 13, wherein the photometric device further includes a collimator lens disposed on an incident side of the plurality of light attenuation filters.

15. The photometric device according to claim 9, wherein the photometric device satisfies the following conditional expressions (6) and (7), wherein 16. The photometric device according to claim 9 or 15, wherein the plurality of light attenuation filters include a third light attenuation filter as the first light attenuation filter and a fourth light attenuation filter as the second light attenuation filter, the third light attenuation filter and the fourth light attenuation filter being any two light attenuation filters of the plurality of light attenuation filters that are adjacent to each other, the photometric device satisfies the following conditional expressions (12) and (13), wherein 17. A photometric device, comprising: a variable light attenuator including a plurality of light attenuation filters and a driving device; and a light detector that receives light that has passed through the variable light attenuator, The driving device is capable of causing the plurality of light-attenuation filters to be inserted into and evacuated from the optical axis of the light independently of one another, The plurality of light-attenuation filters are disposed at mutually different positions in a direction along the optical axis, Each of the plurality of light-attenuation filters includes an interference multilayer film and a transparent substrate that supports the interference multilayer film, If a combination of any two of the plurality of light-attenuation filters is set as a first light-attenuation filter and a second light-attenuation filter, In the direction along the optical axis, the second light-attenuation filter is closer to the light detector than the first light-attenuation filter, The first light-attenuation filter includes a first interference multilayer film as the interference multilayer film and a first transparent substrate as the transparent substrate, The second light-attenuation filter includes a second interference multilayer film as the interference multilayer film and a second transparent substrate as the transparent substrate, A first optical path length of the first transparent substrate is different from a second optical path length of the second transparent substrate, The photometric device satisfies the following conditional expression (3), OPD 13 x (1 / λ - 1 / (λ + Δλ b )) > 0.5 (3) wherein OPD 13 = |OP 1220 -OP 1022 |, λ is a wavelength of the light included in a range of wavelengths capable of being measured by the photometric device, the Δλ b a line width of the light emitted from the object to be measured, OP 1220 a path length of the light that passes through the second light-attenuating filter by being reflected twice by the first light-attenuating filter and not reflected by the second light-attenuating filter, OP 1022 an optical path length of the light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is twice reflected by the second light-attenuating filter.

18. The photometric device according to claim 17, wherein A first thickness of the first transparent substrate is different from a second thickness of the second transparent substrate.

19. The photometric device according to claim 17, wherein A first refractive index of the first transparent substrate is different from a second refractive index of the second transparent substrate.

20. The photometric device according to claim 17, wherein The interference multilayer film of each of the plurality of light-attenuation filters is formed of the same material, The transparent substrate of each of the plurality of light-attenuation filters is formed of the same material.

21. The photometric device according to claim 17, wherein Each of the plurality of light-attenuation filters is disposed at the same angle with respect to the optical axis.

22. The photometric device according to any one of claims 17 to 21, wherein The photometric device further includes a collimator lens disposed on an incident side of the plurality of light-attenuation filters.

23. The photometric device according to claim 17, wherein The photometric device satisfies the following conditional expressions (8) and (9), OPD 21 x (1 / λ - 1 / (λ + Δλ b )) > 0.5 (8) OPD 22 x (1 / λ - 1 / (λ + Δλ b )) > 0.5 (9) wherein OPD 21 = |OP 1420 -OP 1022 |, OPD 22 = |OP 1024 -OP 1220 |, OP 1420 a path length of the light that passes through the second light-attenuating filter four times reflected by the first light-attenuating filter and not reflected by the second light-attenuating filter, OP 1022 a path length of the light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is twice reflected by the second light-attenuating filter, OP 1024 a path length of the light that passes through the first light-attenuating filter without being reflected by the first light-attenuating filter and is reflected four times by the second light-attenuating filter, OP 1220 a path length of the light that passes through the second light-attenuating filter by being reflected twice by the first light-attenuating filter and not reflected by the second light-attenuating filter.

24. The photometric device according to claim 17 or 23, wherein The plurality of light-attenuation filters include a third light-attenuation filter as the first light-attenuation filter and a fourth light-attenuation filter as the second light-attenuation filter, the third light-attenuation filter and the fourth light-attenuation filter being any two light-attenuation filters of the plurality of light-attenuation filters that are adjacent to each other, The photometric device satisfies the following conditional expressions (14) and (15), OPD g1 x (1 / λ - 1 / (λ + Δλ b )) > 0.5 (14) OPD g2 x (1 / λ - 1 / (λ + Δλ b )) > 0.5 (15) wherein OPD g1 = |OP 3240 -OP 30G240 |, OPD g2 = |OP 3042 -OP 30G240 |, OP 3240 a path length of the light that passes through the fourth light-attenuating filter by being reflected twice by the third light-attenuating filter and not reflected by the fourth light-attenuating filter, OP 30G240 for the light that passes through the third light-attenuating filter and the fourth light-attenuating filter without being reflected by the third light-attenuating filter and the fourth light-attenuating filter, and the optical path length of the light that is twice reflected by the layer between the third light-attenuating filter and the fourth light-attenuating filter, OP 3042 an optical path length of the light that passes through the third light-attenuating filter without being reflected by the third light-attenuating filter and is twice reflected by the fourth light-attenuating filter.

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