beam splitter

Abstract

To provide a spectrometer that can improve position resolving power of light dispersed for each wavelength.SOLUTION: A spectrometer 1 comprises: a slit member 10 that has an opening part 11 transmitting incident light LA formed; a first optical system 20 upon which the light passing through the opening part 11 of the slit member 10 is incident; a diffraction grating 30 up which light converged by the first optical system 20 is incident; a second optical system 40 that converges diffraction light LB diffracted by the diffraction grating 30; and detector 50 that detects the light converged by the second optical system 40. An image of the opening part 11 of the slit member 10 is formed by the first optical system 20 and second optical system 40, and the opening part 11 of the slit member 10 is arranged in a displaced position in an optical axis direction of the first optical system 20 from a front side focus plane 23 of the first optical system 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a spectrometer. [Background technology]

[0002] Conventional spectrometers, such as those described in Patent Document 1, have been known. Such spectrometers require high resolution. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] U.S. Patent No. 5438407 [Overview of the project]

[0004] The spectrometer according to the present invention is a spectrometer that spectrally separates and detects incident light according to its wavelength, and comprises a slit member having an opening through which the incident light passes, a first optical system into which the light that has passed through the opening of the slit member is incident, a diffraction grating into which the light focused by the first optical system is incident, a second optical system that focuses the diffracted light diffracted by the diffraction grating, and a detector that detects the light focused by the second optical system, wherein an image of the opening of the slit member is formed by the first optical system and the second optical system, and the opening of the slit member is positioned at a location displaced in the optical axis direction of the first optical system from the front focal plane of the first optical system. [Brief explanation of the drawing]

[0005] [Figure 1] This is a diagram showing a spectrometer according to the first embodiment. [Figure 2] This figure shows the light passing through the opening of the slit member and the light reaching the detector in the spectrometer according to the first embodiment. [Figure 3] This is a spot diagram relating to a spectrometer according to the first embodiment. [Figure 4] This figure shows a comparative example of the spectrometer according to the first embodiment. [Figure 5] It is a diagram showing light passing through the opening of the slit member in the comparative example of the spectroscope according to the first embodiment and light reaching the detector. [Figure 6] It is a spot diagram regarding the comparative example of the spectroscope according to the first embodiment. [Figure 7] It is a diagram showing the first modification of the spectroscope according to the first embodiment. [Figure 8] It is a spot diagram regarding the first modification of the spectroscope according to the first embodiment. [Figure 9] It is a diagram showing the second modification of the spectroscope according to the first embodiment. [Figure 10] It is a spot diagram regarding the second modification of the spectroscope according to the first embodiment. [Figure 11] It is a diagram showing the third modification of the spectroscope according to the first embodiment. [Figure 12] It is a spot diagram regarding the third modification of the spectroscope according to the first embodiment. [Figure 13] It is a diagram showing the fourth modification of the spectroscope according to the first embodiment. [Figure 14] It is a spot diagram regarding the fourth modification of the spectroscope according to the first embodiment. [Figure 15] It is a diagram showing the spectroscope according to the second embodiment. [Figure 16] It is a spot diagram regarding the spectroscope according to the second embodiment. [Figure 17] It is a diagram showing the comparative example of the spectroscope according to the second embodiment. [Figure 18] It is a spot diagram regarding the comparative example of the spectroscope according to the second embodiment. [Figure 19] It is a diagram showing the first modification of the spectroscope according to the second embodiment. [Figure 20] It is a spot diagram regarding the first modification of the spectroscope according to the second embodiment. [Figure 21] It is a diagram showing the second modification of the spectroscope according to the second embodiment. [Figure 22]This is a spot diagram relating to a second modified example of the spectrometer according to the second embodiment. [Figure 23] This figure shows a third modified example of the spectrometer according to the second embodiment. [Figure 24] This is a spot diagram relating to a third modified example of the spectrometer according to the second embodiment. [Figure 25] This figure shows a fourth modified example of the spectrometer according to the second embodiment. [Figure 26] This is a spot diagram relating to a fourth modified example of the spectrometer according to the second embodiment. [Figure 27] This is a diagram showing a spectrometer according to the third embodiment. [Figure 28] This is a spot diagram relating to a spectrometer according to the third embodiment. [Figure 29] This figure shows a comparative example of the spectrometer according to the third embodiment. [Figure 30] This is a spot diagram relating to a comparative example of the spectrometer according to the third embodiment. [Figure 31] This figure shows a first modified example of the spectrometer according to the third embodiment. [Figure 32] This is a spot diagram relating to a first modified example of the spectrometer according to the third embodiment. [Figure 33] This figure shows a second modified example of the spectrometer according to the third embodiment. [Figure 34] This is a spot diagram relating to a second modified example of the spectrometer according to the third embodiment. [Figure 35] This figure shows a third modified example of the spectrometer according to the third embodiment. [Figure 36] This is a spot diagram relating to a third modified example of the spectrometer according to the third embodiment. [Figure 37] This figure shows a fourth modified example of the spectrometer according to the third embodiment. [Figure 38] This is a spot diagram relating to a fourth modified example of the spectrometer according to the third embodiment. [Figure 39] This is a diagram showing a spectrometer according to the fourth embodiment. [Figure 40] This is a spot diagram relating to a spectrometer according to the fourth embodiment. [Figure 41] This figure shows a comparative example of the spectrometer according to the fourth embodiment. [Figure 42] This is a spot diagram relating to a comparative example of the spectrometer according to the fourth embodiment. [Figure 43] This figure shows a first modified example of the spectrometer according to the fourth embodiment. [Figure 44] This is a spot diagram relating to a first modified example of the spectrometer according to the fourth embodiment. [Figure 45] This figure shows a second modified example of the spectrometer according to the fourth embodiment. [Figure 46] This is a spot diagram relating to a second modified example of the spectrometer according to the fourth embodiment. [Figure 47] This figure shows a third modified example of the spectrometer according to the fourth embodiment. [Figure 48] This is a spot diagram relating to a third modified example of the spectrometer according to the fourth embodiment. [Figure 49] This figure shows a fourth modified example of the spectrometer according to the fourth embodiment. [Figure 50] This is a spot diagram relating to a fourth modified example of the spectrometer according to the fourth embodiment. [Figure 51] This figure shows an example of a detection-side slit member. [Modes for carrying out the invention]

[0006] The embodiments of the present invention will be described below. Each embodiment of the spectrometer is provided in, for example, a multispectral camera or a hyperspectral camera. Mera and hyperspectral cameras are spectroscopic cameras that detect light from an object by splitting it into wavelengths, and are used, for example, in aerial surveying.

[0007] Next, a spectrometer according to the first embodiment will be described. As shown in Figure 1, the spectrometer 1 according to the first embodiment is an Evert-type spectrometer that detects incident light LA ​​by spectrally separating it according to its wavelength. The spectrometer 1 according to the first embodiment comprises a slit member 10 having an aperture 11 through which incident light LA ​​passes, a first optical system 20, a diffraction grating 30, a second optical system 40, and a detector 50.

[0008] As shown in Figures 1 and 2, the slit member 10 is formed in the shape of a thin plate with a rectangular opening 11 in its center. The opening 11 extends in a direction perpendicular to the optical axis A1 of the first optical system 20. In each embodiment, the direction along the optical axis A1 of the first optical system 20 and the optical axis B1 of the second optical system 40 may be referred to as the Z direction. The longitudinal direction of the opening 11 of the slit member 10, which is perpendicular to the Z direction, may be referred to as the X direction. The direction perpendicular to both the Z direction and the X direction may be referred to as the Y direction. The opening 11 of the slit member 10 is positioned at a location away from the optical axis A1 of the first optical system 20 in the +Y direction, and at a position displaced from the front focal plane 23 of the first optical system 20 in the optical axis direction (Z direction) of the first optical system 20.

[0009] Light (incident light LA) passing through the opening 11 of the slit member 10 enters the first optical system 20. As shown in Figure 1, the first optical system 20 includes a first mirror portion 21 formed on a concave mirror M. The first optical system 20 and the second optical system 40 are so-called off-axis optical systems. The first mirror portion 21 of the first optical system 20 and the second mirror portion 41 of the second optical system 40 are integrally formed on a single mirror M. The optical axis A1 of the first optical system 20, the optical axis B1 of the second optical system 40, and the optical axis C1 of the mirror M are common axes to each other. The first mirror portion 21 is formed on the mirror M at a distance from the optical axis A1 of the first optical system 20, on the same side as the opening 11 of the slit member 10. The first mirror portion 21 has a spherical first concave surface 22. The first concave surface 22 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A1 of the first optical system 20. As a result, the first mirror portion 21 of the first optical system 20 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A1 of the first optical system 20 and focuses it.

[0010] Light focused by the first optical system 20 (incident light LA) is incident on the diffraction grating 30. The diffraction grating 30 is positioned on the optical axis A1 of the first optical system 20. The diffraction grating 30 is a reflective type. However, the diffraction grating 30 may also be a transmissive type. When light from the first optical system 20 is incident on the diffraction grating 30, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 30 at different emission angles for each wavelength. In the plane containing the light rays spectrally separated by the diffraction grating 30 for each wavelength (planes extending along the Y and Z directions), the direction that intersects the propagation direction of the light rays spectrally separated by the diffraction grating 30 is defined as the spectral direction. If the arrangement direction of each grating constituting the diffraction grating 30 is one-dimensional, then the arrangement direction of the grating becomes the spectral direction. The opening 11 of the slit member 10 has a shape that extends in the direction (X direction) that intersects the spectral direction by the diffraction grating 30.

[0011] To make the diagram easier to understand, Figure 1 shows only one diffracted light LB having a predetermined wavelength (wavelength of light to be spectrally separated) as an example of diffracted light diffracted by the diffraction grating 30. The diffracted light LB emitted from the diffraction grating 30 is incident on the second optical system 40. As shown in Figure 1, the second optical system 40 includes a second mirror portion 41 formed on the mirror M. The second mirror portion 41 is formed on the mirror M at a position away from the optical axis B1 of the second optical system 40 on the opposite side from the opening 11 of the slit member 10. The second mirror portion 41 has a spherical second concave surface 42. The second concave surface 42 reflects the diffracted light LB emitted from the diffraction grating 30 toward the detector 50. As a result, the second mirror portion 41 of the second optical system 40 reflects the diffracted light LB emitted from the diffraction grating 30 toward the detector 50. The light is reflected and focused towards the detector 50.

[0012] The detector 50 is configured using an image sensor such as a CCD (Charge Coupled Device). As shown in Figures 1 and 2, the detector 50 comprises a plurality of light-detecting elements 51 arranged in two directions (X and Y directions) perpendicular to the optical axis B1 of the second optical system 40. The plurality of detection elements 51 of the detector 50 form a detection surface 53 perpendicular to the optical axis B1 of the second optical system 40 on the surface of the detector 50. The detector 50 detects light (diffracted light LB) focused on at least a portion of the detection surface 53 by the second mirror section 41 of the second optical system 40.

[0013] The detector 50 is positioned away from the optical axis B1 of the second optical system 40 on the opposite side of the aperture 11 of the slit member 10, and displaced from the rear focal plane 43 of the second optical system 40 in the optical axis direction (Z direction). Alternatively, the detector 50 may be positioned at the image formation position where the image of the aperture 11 of the slit member 10 is formed by the first optical system 20 and the second optical system 40. In this case, the image of the aperture 11 of the slit member 10 may be formed on the detection surface 53 of the detector 50.

[0014] In the spectrometer 1 according to the first embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror 21 of the first optical system 20 to become focused light and is incident on the diffraction grating 30. When light from the first optical system 20 is incident on the diffraction grating 30, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 30 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 30 is reflected by the second mirror 41 of the second optical system 40 and focused on the detection surface 53 of the detector 50. As a result, an image of the opening 11 of the slit member 10 is formed on the detection surface 53 of the detector 50 by the combined optical system of the first optical system 20 and the second optical system 40. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror 41 of the second optical system 40.

[0015] As mentioned above, the opening 11 of the slit member 10 is formed to extend in the X direction perpendicular to the optical axis A1 of the first optical system 20. Therefore, for example, as shown in Figure 2, the incident light LA1 corresponding to the first field of view in the combined optical system of the first optical system 20 and the second optical system 40 passes through the -X end of the opening 11 of the slit member 10. The incident light LA2 corresponding to the second field of view (field of view = 0 degrees) in the combined optical system of the first optical system 20 and the second optical system 40 passes through the central part of the opening 11 of the slit member 10. The incident light LA3 corresponding to the third field of view in the combined optical system of the first optical system 20 and the second optical system 40 passes through the +X end of the opening 11 of the slit member 10.

[0016] Furthermore, the light (diffracted light) spectrally separated by the diffraction grating 30 according to wavelength reaches different positions in the Y direction on the detection surface 53 via the second optical system 40, because the emission angle relative to the diffraction grating 30 is different for each wavelength. For example, as shown in Figure 2, the incident light LA1 corresponding to the aforementioned first field of view is spectrally separated by the diffraction grating 30 into diffracted light LB1λ1 of the first wavelength, diffracted light LB1λ2 of the second wavelength, and diffracted light LB1λ3 of the third wavelength, which reach different positions in the Y direction on the -X edge side of the detection surface 53. The incident light LA2 corresponding to the aforementioned second field of view is spectrally separated by the diffraction grating 30 into diffracted light LB2λ1 of the first wavelength, diffracted light LB2λ2 of the second wavelength, and diffracted light LB2λ3 of the third wavelength, which reach different positions in the Y direction on the central part of the detection surface 53. The diffraction grating 30 spectrally separates the incident light LA3 corresponding to the aforementioned third field of view, resulting in diffracted light LB3λ1 of the first wavelength, diffracted light LB3λ2 of the second wavelength, and diffracted light LB3λ3 of the third wavelength, which reach different positions in the Y direction on the +X direction end side of the detection surface 53.

[0017] Therefore, the detector 50 focuses light onto the detection surface 53 by the second optical system 40, and detects multiple types of light with different fields of view and wavelengths in the combined optical system of the first optical system 20 and the second optical system 40. The refracted light can be detected individually. In this way, the spectrometer 1 according to the first embodiment detects the incident light LA ​​by spectrally separating it according to its wavelength.

[0018] According to the first embodiment, the aperture 11 of the slit member 10 is positioned at a location displaced in the optical axis direction of the first optical system 20 from the front focal plane 23 of the first optical system 20. Specifically, the displacement of the aperture 11 of the slit member 10 in the optical axis direction of the first optical system 20 is determined so astigmatism at the image formation position of the aperture 11 of the slit member 10, caused by the first optical system 20, the second optical system 40, and the diffraction grating 30, is reduced. As a result, the spot diameter of the light focused by the second optical system 40 (second mirror section 41) can be reduced, and the detector 50 can detect the light focused by the second optical system 40 with high positional accuracy. Therefore, it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength.

[0019] Furthermore, the detector 50 is positioned at a location displaced in the optical axis direction of the second optical system 40 from the rear focal plane 43 of the second optical system 40. This reduces the spot diameter of the light focused by the second optical system 40 (second mirror section 41), allowing the detector 50 to detect the light focused by the second optical system 40 with high positional accuracy. As a result, it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength.

[0020] The aperture 11 of the slit member 10 has a shape that extends in a direction intersecting the spectral direction of the diffraction grating 30. The detector 50 comprises a plurality of detection elements 51 arranged in two directions (X direction and Y direction) and is positioned at the image-forming position of the aperture 11 of the slit member 10 by the first optical system 20 and the second optical system 40. In other words, the aperture 11 of the slit member 10 is formed by extending in a direction perpendicular to the optical axis A1 of the first optical system 20 (X direction). The detector 50 is a two-dimensional detector that detects light focused on a detection surface 53 perpendicular to the optical axis B1 of the second optical system 40 by the second mirror portion 41 of the second optical system 40. This makes it possible to spectrally separate and individually detect incident light corresponding to different fields of view in the combined optical system of the first optical system 20 and the second optical system 40, that is, incident light from different positions in the direction in which the field of view widens, according to their wavelength.

[0021] The light (diffracted light) separated by the diffraction grating 30 according to wavelength reaches different positions depending on the wavelength via the second optical system 40. This allows the incident light to be separated into multiple beams of light according to wavelength and detected individually.

[0022] The first optical system 20 is positioned at a distance from the optical axis A1 of the first optical system 20, on the same side as the opening 11 of the slit member 10, and includes a first mirror section 21 that deflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A1 of the first optical system 20. The second optical system 40 is positioned at a distance from the optical axis B1 of the second optical system 40, on the opposite side from the opening 11 of the slit member 10, and includes a second mirror section 41 that collects the diffracted light diffracted by the diffraction grating 30. By making the first optical system 20 and the second optical system 40 off-axis optical systems, it becomes possible to incident light that is close to parallel light onto the diffraction grating 30, and the diffraction grating 30 can easily obtain diffracted light.

[0023] The first mirror portion 21 of the first optical system 20 has a first concave surface 22 that reflects light that has passed through the opening 11 of the slit member 10, and the second mirror portion 41 of the second optical system 40 has a second concave surface 42 that reflects diffracted light diffracted by the diffraction grating 30. By making the first optical system 20 and the second optical system 40 reflective optical systems, the occurrence of chromatic aberration can be prevented.

[0024] Furthermore, the spectrometer 1 according to the first embodiment may satisfy the following condition (1).

[0025]

number

[0026] However, λ is the shortest wavelength of the incident light. NA1 is the first optical system and the second optical system. This is the numerical aperture on the slit side of the composite optical system with the other components. L1 is the front focal plane of the first optical system. This is the positional displacement of the opening of the slit member relative to the normal. k is a coefficient expressed by the following equation, where θ1 is the angle of incidence of light from the first optical system with respect to the normal of the diffraction grating, and θ2 is the angle of emission of diffracted light relative to the diffraction grating.

[0027]

number

[0028] By satisfying condition (1), it becomes possible to generate astigmatism to cancel out astigmatism at the image formation position of the aperture 11 of the slit member 10 caused by the first optical system 20, the second optical system 40, and the diffraction grating 30. As a result, the spot diameter of the light focused by the second optical system 40 (second mirror section 41) can be reduced, so that the detector 50 can detect the light focused by the second optical system 40 with high positional accuracy. Therefore, it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength. In the first embodiment, the upper limit of condition (1) may be set to 24, or the upper limit of condition (1) may be set to 19. Alternatively, the lower limit of condition (1) may be set to 6.

[0029] The spectrometer 1 according to the first embodiment may satisfy the following condition (2).

[0030]

number

[0031] However, λ is the shortest wavelength of the incident light. NA1 is the first optical system and the second optical system. This is the numerical aperture on the slit side of the composite optical system with the other components. L1 is the front focal plane of the first optical system. This is the positional displacement of the opening of the slit member relative to the normal. k is a coefficient expressed by the following equation, where θ1 is the angle of incidence of light from the first optical system with respect to the normal of the diffraction grating, and θ2 is the angle of emission of diffracted light relative to the diffraction grating.

[0032]

number

[0033] By satisfying condition (2), it becomes possible to generate astigmatism to cancel out the astigmatism at the image formation position of the aperture 11 of the slit member 10 caused by the first optical system 20, the second optical system 40, and the diffraction grating 30. This makes it possible to reduce the spot diameter of the light focused by the second optical system 40 (second mirror section 41), so that the detector 50 can detect the light focused by the second optical system 40 with high positional accuracy. Therefore, it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength. In one embodiment, the upper limit of condition expression (2) may be set to 27, or the upper limit of condition expression (2) may be set to 22. Alternatively, the lower limit of condition expression (2) may be set to 7.

[0034] Next, the specifications of the spectrometer 1 according to the first embodiment will be described. Table 1, shown below, is a table showing the specifications of the spectrometer 1 according to the first embodiment. In the [Overall Specifications] of Table 1, λ represents the wavelength (unit: nm) of the light spectrally separated from the incident light, but it may also be the shortest wavelength of the incident light. NA1 is the combined optical system of the first optical system 20 and the second optical system 40. This indicates the numerical aperture on the slit member side. Δλ indicates the wavelength resolution (unit: nm).

[0035] In Table 1, under [First Mirror Section], R1 represents the radius of curvature (unit: mm) of the first concave surface 22 in the first mirror section 21 of the first optical system 20 (the radius of curvature is considered positive when the concave surface is oriented in the +Z direction). D11 represents the distance (unit: mm) from the center of the mirror M to the front focal plane 23 of the first optical system 20. In Table 1, under [Second Mirror Section], R2 represents the radius of curvature (unit: mm) of the second concave surface 42 in the second mirror section 41 of the second optical system 40 (the radius of curvature is considered positive when the concave surface is oriented in the +Z direction). D12 represents the distance (unit: mm) from the center of the mirror M to the rear focal plane 43 of the second optical system 40.

[0036] In the [Slit Member] in Table 1, L1 is relative to the front focal plane 23 of the first optical system 20. This indicates the positional displacement (in mm) of the opening 11 of the slit member 10 (positional displacement in the +Z direction is considered a positive value). D13 indicates the distance (in mm) from the optical axis A1 of the first optical system 20 to the opening 11 of the slit member 10. In the [Detector] section of Table 1, L2 is the second light This shows the positional displacement (in mm) of the detector 50 relative to the rear focal plane 43 of the optical system 40 (positional displacement in the +Z direction is considered a positive value). D14 indicates the distance (in mm) from the optical axis B1 of the second optical system 40 to the center of the detector 50.

[0037] In Table 1, under [Diffraction Grating], m represents the order of diffraction of the diffracted light. d represents the grating spacing of the diffraction grating 30 (unit: mm). j represents the eccentricity angle of the diffraction grating 30 around the X-axis (unit: degrees) (a clockwise eccentricity angle viewed from the -X direction side is considered a positive value). Φ represents the effective diameter of the diffraction grating 30 (unit: mm). θ1 is the angle of incidence of light relative to the normal of the diffraction grating 30 (single The position (in degrees) is shown. θ2 indicates the emission angle of the diffracted light relative to the diffraction grating 30 (unit: degrees). D 15 indicates the distance (in mm) from the center of mirror M to the center of diffraction grating 30. Table 1 shows the corresponding values ​​for each condition in the [Conditional Expression Corresponding Values] section.

[0038] Table 1 below shows the specifications of the spectrometer 1 according to the first embodiment.

[0039] (Table 1) [Overall Specifications] λ = 1500 NA1 = 0.05 Δλ = 0.18 [First Mirror Section] R1 = -400 D11=200 [Mirror Section 2] R2 = -400 D12=203 [Slit member] L1 = -28.0 D13=40 [Detector] L2 = 26.1 D14=33 [Diffraction grating] m=1 d = 0.004 j=10 Φ=22 θ1 = 21.48 θ² = 0.51 D15=199 [Conditional expression corresponding value] Condition (1): 13 Condition (2):14

[0040] Figure 3 is a spot diagram of the spectrometer 1 according to the first embodiment. In Figure 3, DE indicates the amount of defocus relative to the rear focal plane of the second optical system 40. SD indicates the spot diameter of the light focused by the second optical system 40. From the spot diagram shown in Figure 3, it can be seen that the spectrometer 1 according to the first embodiment has a small spot diameter of light focused by the second optical system 40.

[0041] Next, a comparative example of the spectrometer according to the first embodiment will be described. As shown in Figure 4, the spectrometer 1re according to the comparative example of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed explanation is omitted. The spectrometer 1re according to the comparative example of the first embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 20, a diffraction grating 30, a second optical system 40, and a detector 50.

[0042] The opening 11 of the slit member 10 is positioned at a location away from the optical axis A1 of the first optical system 20 in the +Y direction, and at the front focal plane 23 of the first optical system 20. As a result, the first mirror portion 21 of the first optical system 20 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A1 of the first optical system 20, making it parallel. The detector 50 is positioned at a location away from the optical axis B1 of the second optical system 40 on the opposite side from the opening 11 of the slit member 10, and at the rear focal plane 43 of the second optical system 40.

[0043] In the spectrometer 1re according to a comparative example of the first embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror portion 21 of the first optical system 20 to become parallel light and is incident on the diffraction grating 30. When light from the first optical system 20 is incident on the diffraction grating 30, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 30 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 30 is reflected by the second mirror portion 41 of the second optical system 40 and focused on the detection surface 53 of the detector 50. As a result, the first optical system 20 and the second optical system 40 form an image of the opening 11 of the slit member 10 on the detection surface 53 of the detector 50. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror portion 41 of the second optical system 40.

[0044] As mentioned above, the opening 11 of the slit member 10 is formed extending in the X direction perpendicular to the optical axis A1 of the first optical system 20. Therefore, for example, as shown in Figure 5, the incident light LA1 corresponding to the first field of view in the combined optical system of the first optical system 20 and the second optical system 40 passes through the -X end of the opening 11 of the slit member 10. The incident light LA2 corresponding to the second field of view (field of view = 0 degrees) in the combined optical system of the first optical system 20 and the second optical system 40, The incident light LA3, which corresponds to the third field of view in the combined optical system of the first optical system 20 and the second optical system 40, passes through the +X end of the opening 11 of the slit member 10.

[0045] Furthermore, the light (diffracted light) spectrally separated by the diffraction grating 30 according to wavelength reaches different positions in the Y direction of the detection surface 53 via the second optical system 40, because the emission angle relative to the diffraction grating 30 is different for each wavelength. For example, as shown in Figure 5, the incident light LA1 corresponding to the aforementioned first field of view is spectrally separated by the diffraction grating 30 into diffracted light LB1λ1 of the first wavelength, diffracted light LB1λ2 of the second wavelength, and diffracted light LB1λ3 of the third wavelength, which reach different positions in the Y direction at the -X edge of the detection surface 53. The incident light LA2 corresponding to the aforementioned second field of view is spectrally separated by the diffraction grating 30 into diffracted light LB2λ1 of the first wavelength, diffracted light LB2λ2 of the second wavelength, and diffracted light LB2λ3 of the third wavelength, which reach different positions in the Y direction at the center of the detection surface 53. The diffraction grating 30 spectrally separates the incident light LA3 corresponding to the aforementioned third field of view, resulting in diffracted light LB3λ1 of the first wavelength, diffracted light LB3λ2 of the second wavelength, and diffracted light LB3λ3 of the third wavelength, which reach different positions in the Y direction at the +X direction end of the detection surface 53.

[0046] Next, the specifications of the spectrometer 1re, a comparative example of the first embodiment, will be described. Table 2, shown below, is a table showing the specifications of the spectrometer 1re, a comparative example of the first embodiment. The parameters λ, NA1, and Δλ in the [Overall Specifications] of Table 2 are the same as the parameters λ, NA1, and Δλ in the [Overall Specifications] of Table 1. The parameters R1 and D11 in the [First Mirror Section] of Table 2 are the same as the parameters R1 and D11 in the [First Mirror Section] of Table 1. The parameters R2 and D12 in the [Second Mirror Section] of Table 2 are the same as the parameters R2 and D12 in the [Second Mirror Section] of Table 1.

[0047] The L1 and D13 parameters in the [Slit Member] section of Table 2 are the same as the L1 and D13 parameters in the [Slit Member] section of Table 1. The L2 and D14 parameters in the [Detector] section of Table 2 are the same as those in Table 1. These are the same parameters as L2 and D14 in the [detector]. See Table 2 for [diffraction grating]. The parameters m, d, j, Φ, θ1, θ2, and D15 are the same as those in the [Diffraction Grating] section of Table 1.

[0048] Table 2 below shows the specifications of the spectrometer 1re related to the comparative example of the first embodiment.

[0049] (Table 2) [Overall Specifications] λ = 1500 NA1 = 0.05 Δλ = 2.7 [First Mirror Section] R1 = -400 D11=200 [Mirror Section 2] R2 = -400 D12=203 [Slit member] L1=0 D13=40 [Detector] L2=0 D14=33 [Diffraction grating] m=1 d = 0.004 j=10 Φ=22 θ1 = 21.48 θ² = 0.51 D15=199

[0050] Figure 6 is a spot diagram of the spectrometer 1re according to a comparative example of the first embodiment. The DE and SD in Figure 6 are the same parameters as those in Figure 3. From the spot diagram shown in Figure 6, it can be seen that the spectrometer 1re according to the comparative example of the first embodiment has a larger spot diameter of light focused by the second optical system 40.

[0051] In the spectrometer 1re according to the comparative example of the first embodiment, astigmatism occurs at the image formation position of the aperture 11 due to the aperture 11 of the slit member 10 being positioned away from the optical axis A1 of the first optical system 20. As a result, the spot diameter of the light focused by the second optical system 40 becomes larger. Therefore, as shown in Figure 5, for example, it becomes difficult for the detector 50 to individually detect multiple types of diffracted light that have different fields of view and different wavelengths in the combined optical system of the first optical system 20 and the second optical system 40, which are focused on the detection surface 53 by the second optical system 40.

[0052] From the spot diagrams shown in Figures 3 and 6, it can be seen that the spectrometer 1 according to the first embodiment has a smaller spot diameter of light focused by the second optical system 40 compared to the spectrometer 1re according to the comparative example of the first embodiment. Thus, with the spectrometer 1 according to the first embodiment, the detector 50 can detect the light focused by the second optical system 40 with high positional accuracy, making it possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength.

[0053] Next, a first modified example of the spectrometer according to the first embodiment will be described. As shown in Figure 7, the spectrometer 1a according to the first modified example of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed explanation is omitted. The spectrometer 1a according to the first modified example of the first embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 20, a diffraction grating 30, a second optical system 40, and a detector 50.

[0054] In the spectrometer 1a according to the first modification of the first embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 23 of the first optical system 20 is smaller than in the case of the first embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 43 of the second optical system 40 is smaller than in the case of the first embodiment described above.

[0055] Next, the specifications of the spectrometer 1a according to the first modification of the first embodiment will be described. Table 3, shown below, is a table showing the specifications of the spectrometer 1a according to the first modification of the first embodiment. As mentioned above, the spectrometer 1a according to the first modification of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 3 lists the specifications of the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0056] In Table 3, L1 and D13 in the [Slit Member] correspond to L1 in Table 1. These are the same parameters as D13. L2 and D14 in [Detector] in Table 3 are the same as in Table 1. These are the same parameters as L2 and D14 in the [detector]. Below, the corresponding values ​​for each conditional expression are shown.

[0057] Table 3 below shows the specifications of the spectrometer 1a according to the first modified example of the first embodiment.

[0058] (Table 3) [Slit member] L1 = -2.2 D13=40 [Detector] L2 = 2.1 D14=33 [Conditional expression corresponding value] Condition (1): 1 Condition (2):1

[0059] Figure 8 is a spot diagram of the spectrometer 1a according to the first modified example of the first embodiment. The DE and SD in Figure 8 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 8, it can be seen that the spectrometer 1a according to the first modified example of the first embodiment has a smaller spot diameter of light focused by the second optical system 40 compared to the spectrometer 1re according to the comparative example of the first embodiment. As a result, the spectrometer 1a according to the first modified example of the first embodiment can obtain the same effect as the spectrometer 1 according to the first embodiment.

[0060] Next, a second modified example of the spectrometer according to the first embodiment will be described. As shown in Figure 9, the spectrometer 1b according to the second modified example of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed description is omitted. The spectrometer 1b according to the second modified example of the first embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 20, a diffraction grating 30, a second optical system 40, and a detector 50.

[0061] In the spectrometer 1b according to the second modification of the first embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 23 of the first optical system 20 is smaller than in the first embodiment described above, but larger than in the first modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 43 of the second optical system 40 is smaller than in the first embodiment described above, but larger than in the first modification described above.

[0062] Next, the specifications of the spectrometer 1b according to the second modification of the first embodiment will be described. Table 4, shown below, is a table showing the specifications of the spectrometer 1b according to the second modification of the first embodiment. As mentioned above, the spectrometer 1b according to the second modification of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 4 lists the specifications of the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0063] The L1 and D13 parameters in the [Slit Member] section of Table 4 are the same as the L1 and D13 parameters in the [Slit Member] section of Table 1. The L2 and D14 parameters in the [Detector] section of Table 4 are the same as those in Table 1. These are the same parameters as L2 and D14 in the [detector]. Below, the corresponding values ​​for each conditional expression are shown.

[0064] Table 4 below shows the specifications of the spectrometer 1b according to the second modified example of the first embodiment.

[0065] (Table 4) [Slit member] L1 = -14.0 D13=40 [Detector] L2 = 13.1 D14=33 [Conditional expression corresponding value] Condition (1): 6 Condition (2): 7

[0066] Figure 10 is a spot diagram of the spectrometer 1b according to a second modification of the first embodiment. The DE and SD in Figure 10 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 10, it can be seen that the spectrometer 1b according to the second modification of the first embodiment has a smaller spot diameter of light focused by the second optical system 40 compared to the spectrometer 1re according to the comparative example of the first embodiment. As a result, the spectrometer 1b according to the second modification of the first embodiment can obtain the same effect as the spectrometer 1 according to the first embodiment.

[0067] Next, a third modified example of the spectrometer according to the first embodiment will be described. As shown in Figure 11, the spectrometer 1c according to the third modified example of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed explanation is omitted. The spectrometer 1c according to the third modified example of the first embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 20, a diffraction grating 30, a second optical system 40, and a detector 50.

[0068] In the spectrometer 1c according to the third modification of the first embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 23 of the first optical system 20 is greater than in the case of the first embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 43 of the second optical system 40 is greater than in the case of the first embodiment described above.

[0069] Next, the specifications of the spectrometer 1c according to the third modification of the first embodiment will be described. Table 5, shown below, is a table showing the specifications of the spectrometer 1c according to the third modification of the first embodiment. As mentioned above, the spectrometer 1c according to the third modification of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment, except that the positions of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 5 lists the specifications for the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0070] The L1 and D13 parameters in the [Slit Member] section of Table 5 are the same as the L1 and D13 parameters in the [Slit Member] section of Table 1. The L2 and D14 parameters in the [Detector] section of Table 5 are the same as those in Table 1. These are the same parameters as L2 and D14 in the [detector]. Below, the corresponding values ​​for each conditional expression are shown.

[0071] Table 5 below shows the specifications of the spectrometer 1c according to the third modified example of the first embodiment.

[0072] (Table 5) [Slit member] L1 = -42.0 D13=40 [Detector] L2 = 39.2 D14=33 [Conditional expression corresponding value] Condition (1): 19 Conditional expression (2):22

[0073] Figure 12 is a spot diagram of the spectrometer 1c according to the third modification of the first embodiment. The DE and SD in Figure 12 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 12, it can be seen that the spectrometer 1c according to the third modification of the first embodiment has a smaller spot diameter of light focused by the second optical system 40 compared to the spectrometer 1re according to the comparative example of the first embodiment. As a result, the spectrometer 1c according to the third modification of the first embodiment can obtain the same effect as the spectrometer 1 according to the first embodiment.

[0074] Next, a fourth modified example of the spectrometer according to the first embodiment will be described. As shown in Figure 13, the spectrometer 1d according to the fourth modified example of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed description is omitted. The spectrometer 1d according to the fourth modified example of the first embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 20, a diffraction grating 30, a second optical system 40, and a detector 50.

[0075] In the spectrometer 1d according to the fourth modification of the first embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 23 of the first optical system 20 is greater than in the first embodiment and the third modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 43 of the second optical system 40 is greater than in the first embodiment and the third modification described above.

[0076] Next, the specifications of the spectrometer 1d according to the fourth modification of the first embodiment will be described. Table 6, shown below, is a table showing the specifications of the spectrometer 1d according to the fourth modification of the first embodiment. As mentioned above, the spectrometer 1d according to the fourth modification of the first embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 6 lists the specifications of the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0077] The L1 and D13 parameters in the [Slit Member] section of Table 6 are the same as the L1 and D13 parameters in the [Slit Member] section of Table 1. The L2 and D14 parameters in the [Detector] section of Table 6 are the same as those in Table 1. These are the same parameters as L2 and D14 in the [detector]. Below, the corresponding values ​​for each conditional expression are shown.

[0078] Table 6 below shows the specifications of the spectrometer 1d according to the fourth modified example of the first embodiment.

[0079] (Table 6) [Slit member] L1 = -53.0 D13=40 [Detector] L2 = 49.5 D14=33 [Conditional expression corresponding value] Condition (1): 24 Conditional expression (2): 27

[0080] Figure 14 is a spot diagram of the spectrometer 1d according to the fourth modification of the first embodiment. DE and SD in Figure 14 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 14, it can be seen that the spectrometer 1d according to the fourth modification of the first embodiment has a smaller spot diameter of light focused by the second optical system 40 compared to the spectrometer 1re according to the comparative example of the first embodiment. As a result, the spectrometer 1d according to the fourth modification of the first embodiment can obtain the same effect as the spectrometer 1 according to the first embodiment.

[0081] Next, a spectrometer according to the second embodiment will be described. As shown in Figure 15, the spectrometer 101 according to the second embodiment is a Czerny-Turner type spectrometer that detects incident light LA ​​by spectrally separating it according to its wavelength. The spectrometer 101 according to the second embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the first optical system 120, the diffraction grating 130, and the second optical system 140 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed explanation is omitted. The spectrometer 101 according to the second embodiment comprises a slit member 10 with an opening 11 for passing incident light LA, a first optical system 120, a diffraction grating 130, a second optical system 140, and a detector 50.

[0082] The opening 11 of the slit member 10 is positioned at a location away from the optical axis A2 of the first optical system 120 in the +Y direction, and displaced from the front focal plane 123 of the first optical system 120 in the optical axis direction (Z direction). Light (incident light LA) passing through the opening 11 of the slit member 10 enters the first optical system 120.

[0083] As shown in Figure 15, the first optical system 120 includes a first mirror section 121 which is a concave mirror. The first optical system 120 and the second optical system 140 are so-called off-axis optical systems. The first mirror section 121 of the first optical system 120 and the second mirror section 141 of the second optical system 140 are formed by shifting and rotating a concave mirror (not shown) from the optical axis. The optical axis A2 of the first optical system 120 and the optical axis B2 of the second optical system 140 are common axes to each other. The first mirror section 121 is formed at a distance from the optical axis A2 of the first optical system 120, on the same side as the opening 11 of the slit member 10. The first mirror section 121 has a spherical first concave surface 122. The first concave surface 122 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A2 of the first optical system 120. As a result, the first mirror portion 121 of the first optical system 120 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A2 of the first optical system 120 and focuses it.

[0084] The light (incident light LA) focused by the first optical system 120 is incident on the diffraction grating 130. The diffraction grating 130 is positioned on the optical axis A2 of the first optical system 120. The diffraction grating 130 is formed in the same manner as the diffraction grating 30 of the first real-world embodiment. The opening 11 of the slit member 10 has a shape that extends in a direction (X direction) intersecting the spectral direction of the diffraction grating 130.

[0085] To make the diagram easier to understand, Figure 15 shows only one diffracted light beam LB having a predetermined wavelength (wavelength of light to be spectrally separated) as an example of diffracted light diffracted by the diffraction grating 130. The diffracted light beam LB emitted from the diffraction grating 130 is incident on the second optical system 140. As shown in Figure 15, the second optical system 140 includes a second mirror section 141 which is a concave mirror. The second mirror section 141 is formed at a position away from the optical axis B2 of the second optical system 140, on the opposite side from the opening 11 of the slit member 10. The second mirror section 141 has a second concave surface 142 with a spherical shape. 142 reflects the diffracted light LB emitted from the diffraction grating 130 toward the detector 50. As a result, the second mirror section 141 of the second optical system 140 reflects the diffracted light LB emitted from the diffraction grating 130 toward the detector 50 and focuses it.

[0086] The detector 50 is positioned away from the optical axis B2 of the second optical system 140 on the opposite side of the aperture 11 of the slit member 10, and displaced from the rear focal plane 143 of the second optical system 140 in the optical axis direction (Z direction). Alternatively, the detector 50 may be positioned at the image formation position where the image of the aperture 11 of the slit member 10 is formed by the first optical system 120 and the second optical system 140. In this case, the image of the aperture 11 of the slit member 10 may be formed on the detection surface 53 of the detector 50.

[0087] In the spectrometer 101 according to the second embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror portion 121 of the first optical system 120 to become focused light and is incident on the diffraction grating 130. When light from the first optical system 120 is incident on the diffraction grating 130, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 130 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 130 is reflected by the second mirror portion 141 of the second optical system 140 and focused on the detection surface 53 of the detector 50. As a result, an image of the opening 11 of the slit member 10 is formed on the detection surface 53 of the detector 50 by the combined optical system of the first optical system 120 and the second optical system 140. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror portion 141 of the second optical system 140.

[0088] Similar to the first embodiment, the detector 50 can individually detect multiple types of diffracted light with different field of view and wavelengths in the combined optical system of the first optical system 120 and the second optical system 140, which are focused onto the detection surface 53 by the second optical system 140. In this way, the spectrometer 101 according to the second embodiment spectrally analyzes and detects the incident light LA ​​according to its wavelength. Therefore, the second embodiment can obtain the same effects as the first embodiment.

[0089] Furthermore, the spectrometer 101 according to the second embodiment may satisfy the aforementioned condition (1). By satisfying condition (1), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the second embodiment, the upper limit of condition (1) may be set to 282, or the upper limit of condition (1) may be set to 194. Also, the lower limit of condition (1) may be set to 62.

[0090] The spectrometer 101 according to the second embodiment may satisfy the aforementioned condition (2). By satisfying condition (2), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the second embodiment, the upper limit of condition (2) may be set to 350, or the upper limit of condition (2) may be set to 240. Alternatively, the lower limit of condition (2) may be set to 76.

[0091] Next, the specifications of the spectrometer 101 according to the second embodiment will be described. Table 7 below shows the specifications of the spectrometer 101 according to the second embodiment. In the [Overall Specifications] of Table 7, λ represents the wavelength (unit: nm) of the light spectrally separated from the incident light, but it may also be the shortest wavelength of the incident light. NA1 is the first optical system 120 and the second optical system 140 and This indicates the numerical aperture on the slit member side of the composite optical system. Δλ indicates the wavelength resolution (unit: nm).

[0092] In Table 7, under [First Mirror Section], R1 represents the radius of curvature (unit: mm) of the first concave surface 122 in the first mirror section 121 of the first optical system 120 (the radius of curvature is considered positive when the concave surface is oriented in the +Z direction). D21 represents the distance (unit: mm) from the center of the first mirror section 121 to the front focal plane 123 of the first optical system 120. D22 represents the first optical system 120 This indicates the distance (in mm) from the optical axis A2 to the center of the first mirror section 121. J21 indicates the eccentricity angle (in degrees) of the first mirror section 121 around the X axis (a clockwise eccentricity angle viewed from the -X direction side is considered a positive value). In Table 7, under [Second Mirror Section], R2 indicates the radius of curvature (in mm) of the second concave surface 142 in the second mirror section 141 of the second optical system 140 (a radius of curvature when the concave surface is oriented in the +Z direction is considered a positive value). D23 indicates the distance (in mm) from the center of the second mirror section 141 to the rear focal plane 143 of the second optical system 140. D24 indicates the distance (in mm) from the optical axis B2 of the second optical system 140 to the center of the second mirror section 141. J22 indicates the eccentricity angle (in degrees) of the second mirror section 141 around the X-axis (a clockwise eccentricity angle viewed from the -X direction side is considered a positive value).

[0093] In the [Slit Member] in Table 7, L1 is relative to the front focal plane 123 of the first optical system 120. This indicates the positional displacement (in mm) of the opening 11 of the slit member 10 (positional displacement in the +Z direction is considered a positive value). D25 indicates the distance (in mm) from the optical axis A2 of the first optical system 120 to the opening 11 of the slit member 10. In Table 7, under [Detector], L2 is, This shows the positional displacement (in mm) of the detector 50 relative to the rear focal plane 143 of the second optical system 140 (positional displacement in the +Z direction is considered a positive value). D26 indicates the distance (in mm) from the optical axis B2 of the second optical system 140 to the center of the detector 50.

[0094] In Table 7, under [Diffraction Grating], m represents the order of diffraction of the diffracted light. d represents the grating spacing of the diffraction grating 130 (unit: mm). j represents the eccentricity angle of the diffraction grating 130 around the X-axis (unit: degrees) (a clockwise eccentricity angle viewed from the -X direction side is considered a positive value). Φ represents the effective diameter of the diffraction grating 130 (unit: mm). θ1 is the input of light relative to the normal of the diffraction grating 130. The angle of emission (in degrees) is shown. θ2 is the angle of emission of diffracted light relative to the diffraction grating 130 (in degrees). This is shown. D27 represents the distance in the optical axis direction from the center of the first mirror section 121 and the second mirror section 141 to the center of the diffraction grating 130 (unit: mm). In Table 1, under [Conditional Expression Corresponding Values], the conditional expression corresponding values ​​for each conditional expression are shown.

[0095] Table 7 below shows the specifications of the spectrometer 101 according to the second embodiment.

[0096] (Table 7) [Overall Specifications] λ = 550 NA1 = 0.05 Δλ = 0.07 [First Mirror Section] R1 = -400 D21=200 D22=40 J21=-10 [Mirror Section 2] R2 = -400 D23=200 D24=40 J22=-10 [Slit member] L1 = -71.0 D25=40 [Detector] L2 = 49.9 D26=40 [Diffraction grating] m=1 d = 0.002 j=8.4 Φ=25 θ1 = 28.4 θ² = 11.57 D27=110 [Conditional expression corresponding value] Condition (1): 125 Condition (2): 155

[0097] Figure 16 is a spot diagram of the spectrometer 101 according to the second embodiment. The DE and SD in Figure 16 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 16, it can be seen that the spectrometer 101 according to the second embodiment has a small spot diameter of light focused by the second optical system 140.

[0098] Next, a comparative example of the spectrometer according to the second embodiment will be described. As shown in Figure 17, the spectrometer 101re according to the comparative example of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 101 according to the second embodiment, and a detailed explanation is omitted. The spectrometer 101re according to the comparative example of the second embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 120, a diffraction grating 130, a second optical system 140, and a detector 50.

[0099] The opening 11 of the slit member 10 is positioned at a location away from the optical axis A2 of the first optical system 120 in the +Y direction, and at the front focal plane 123 of the first optical system 120. As a result, the first mirror portion 121 of the first optical system 120 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A2 of the first optical system 120, making it parallel. The detector 50 is positioned at a location away from the optical axis B2 of the second optical system 140 on the opposite side from the opening 11 of the slit member 10, and at the rear focal plane 143 of the second optical system 140.

[0100] In the spectrometer 101re according to the comparative example of the second embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror portion 121 of the first optical system 120 to become parallel light and is incident on the diffraction grating 130. When light from the first optical system 120 is incident on the diffraction grating 130, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 130 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 130 is reflected by the second mirror portion 141 of the second optical system 140 and focused on the detection surface 53 of the detector 50. As a result, the first optical system 120 and the second optical system 140 form an image of the opening 11 of the slit member 10 on the detection surface 53 of the detector 50. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror portion 141 of the second optical system 140.

[0101] Next, the specifications of the spectrometer 101re according to the comparative example of the second embodiment will be described. Table 8, shown below, is a table showing the specifications of the spectrometer 101re according to the comparative example of the second embodiment. λ, NA1, and Δλ in the [Overall Specifications] of Table 8 are the same as those in the [Overall Specifications] of Table 7. These are the same parameters as λ, NA1, and Δλ. R1 and D in the [First Mirror Section] of Table 8. 21, D22, and J21 are the same parameters as R1, D21, D22, and J21 in the [First Mirror Section] of Table 7. R2, D23, D24, and J22 in the [Second Mirror Section] of Table 8 are the same parameters as R2, D23, D24, and J22 in the [Second Mirror Section] of Table 7.

[0102] The L1 and D25 parameters in the [Slit Member] section of Table 8 are the same as the L1 and D25 parameters in the [Slit Member] section of Table 7. The L2 and D26 parameters in the [Detector] section of Table 8 are the same as those in Table 7. These are the same parameters as L2 and D26 in the [detector]. See Table 8 for [diffraction grating]. The parameters m, j, Φ, θ1, θ2, and D27 are the same as those in the [Diffraction Grating] section of Table 7.

[0103] Table 8 below shows the specifications of the spectrometer 101re related to the comparative example of the second embodiment.

[0104] (Table 8) [Overall Specifications] λ = 550 NA1 = 0.05 Δλ = 4.5 [First Mirror Section] R1 = -400 D21=200 D22=40 J21=-10 [Mirror Section 2] R2 = -400 D23=200 D24=40 J22=-10 [Slit member] L1=0 D25=40 [Detector] L2=0 D26=40 [Diffraction grating] m=1 d = 0.002 j=8.4 Φ=25 θ1 = 28.4 θ² = 11.57 D27=110

[0105] Figure 18 is a spot diagram of the spectrometer 101re according to the comparative example of the second embodiment. DE and SD in Figure 18 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 18, it can be seen that the spectrometer 101re according to the comparative example of the second embodiment has a larger spot diameter of light focused by the second optical system 140. Also, from the spot diagrams shown in Figures 16 and 18, it can be seen that the spectrometer 101 according to the second embodiment has a smaller spot diameter of light focused by the second optical system 140 compared to the spectrometer 101re according to the comparative example of the second embodiment. Thus, according to the spectrometer 101 according to the second embodiment, the detector 50 can detect the light focused by the second optical system 140 with high positional accuracy, making it possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength.

[0106] Next, a first modified example of the spectrometer according to the second embodiment will be described. As shown in Figure 19, the spectrometer 101a according to the first modified example of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 101 according to the second embodiment, and a detailed description is omitted. The spectrometer 101a according to the first modified example of the second embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 120, a diffraction grating 130, a second optical system 140, and a detector 50.

[0107] In the spectrometer 101a according to the first modification of the second embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 123 of the first optical system 120 is smaller than in the case of the second embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 143 of the second optical system 140 is smaller than in the case of the second embodiment described above.

[0108] Next, the specifications of the spectrometer 101a according to the first modification of the second embodiment will be described. Table 9, shown below, is a table showing the specifications of the spectrometer 101a according to the first modification of the second embodiment. As mentioned above, the spectrometer 101a according to the first modification of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 9 lists the specifications for [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0109] The L1 and D25 parameters in the [Slit Member] section of Table 9 are the same as the L1 and D25 parameters in the [Slit Member] section of Table 7. The L2 and D26 parameters in the [Detector] section of Table 9 are the same as those in Table 7. These are the same parameters as L2 and D26 in the [detector]. Below, the corresponding values ​​for each conditional expression are shown.

[0110] Table 9 below shows the specifications of the spectrometer 101a according to the first modified example of the second embodiment.

[0111] (Table 9) [Slit member] L1 = -0.6 D25=40 [Detector] L2 = 0.5 D26=40 [Conditional expression corresponding value] Condition (1): 1 Condition (2):1

[0112] Figure 20 is a spot diagram of the spectrometer 101a according to the first modified example of the second embodiment. DE and SD in Figure 20 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 20, it can be seen that the spectrometer 101a according to the first modified example of the second embodiment has a smaller spot diameter of light focused by the second optical system 140 compared to the spectrometer 101re according to the comparative example of the second embodiment. As a result, the spectrometer 101a according to the first modified example of the second embodiment can obtain the same effect as the spectrometer 101 according to the second embodiment.

[0113] Next, a second modified example of the spectrometer according to the second embodiment will be described. As shown in Figure 21, the spectrometer 101b according to the second modified example of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Since it is a component, the same reference numerals are used for the same components as in the spectrometer 101 according to the second embodiment, and a detailed description is omitted. The spectrometer 101b according to the second modified example of the second embodiment comprises a slit member 10 having an aperture 11 for passing incident light LA, a first optical system 120, a diffraction grating 130, a second optical system 140, and a detector 50.

[0114] In the spectrometer 101b according to the second modification of the second embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 123 of the first optical system 120 is smaller than in the second embodiment described above, but larger than in the first modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 143 of the second optical system 140 is smaller than in the second embodiment described above, but larger than in the first modification described above.

[0115] Next, the specifications of the spectrometer 101b according to the second modification of the second embodiment will be described. Table 10, shown below, is a table showing the specifications of the spectrometer 101b according to the second modification of the second embodiment. As mentioned above, the spectrometer 101b according to the second modification of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 10 lists the specifications for [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0116] In Table 10, L1 and D25 in the [Slit Member] correspond to the same values ​​in Table 7. These are the same parameters as L1 and D25. L2 and D26 in Table 10 [Detector] are the same parameters as L2 and D26 in Table 7 [Detector]. [Conditional Expression Correspondence] In the [Value] section, the corresponding value for each conditional expression is shown.

[0117] Table 10 below shows the specifications of the spectrometer 101b according to the second modified example of the second embodiment.

[0118] (Table 10) [Slit member] L1 = -35.0 D25=40 [Detector] L2 = 27.6 D26=40 [Conditional expression corresponding value] Condition (1): 62 Conditional expression (2): 76

[0119] Figure 22 is a spot diagram of the spectrometer 101b according to a second modification of the second embodiment. The DE and SD in Figure 22 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 22, it can be seen that the spectrometer 101b according to the second modification of the second embodiment has a smaller spot diameter of light focused by the second optical system 140 compared to the spectrometer 101re according to the comparative example of the second embodiment. As a result, the spectrometer 101b according to the second modification of the second embodiment can obtain the same effect as the spectrometer 101 according to the second embodiment.

[0120] Next, a third modified example of the spectrometer according to the second embodiment will be described. As shown in Figure 23, the spectrometer 101c according to the third modified example of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 101 according to the second embodiment. Detailed explanation is omitted. The spectrometer 101c according to the third modified example of the second embodiment comprises a slit member 10 having an aperture 11 for passing incident light LA, a first optical system 120, a diffraction grating 130, a second optical system 140, and a detector 50.

[0121] In the spectrometer 101c according to the third modification of the second embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 123 of the first optical system 120 is greater than in the case of the second embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 143 of the second optical system 140 is greater than in the case of the second embodiment described above.

[0122] Next, the specifications of the spectrometer 101c according to the third modification of the second embodiment will be described. Table 11 shown below is a table showing the specifications of the spectrometer 101c according to the third modification of the second embodiment. As mentioned above, the spectrometer 101c according to the third modification of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 11 lists the specifications for [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0123] In Table 11, L1 and D25 in the [Slit Member] correspond to the same values ​​in Table 7. These are the same parameters as L1 and D25. L2 and D26 in Table 11 [Detector] are the same parameters as L2 and D26 in Table 7 [Detector]. [Conditional Expression Correspondence] In the [Value] section, the corresponding value for each conditional expression is shown.

[0124] Table 11 below shows the specifications of the spectrometer 101c according to the third modified example of the second embodiment.

[0125] (Table 11) [Slit member] L1 = -110.0 D25=40 [Detector] L2 = 69.1 D26=40 [Conditional expression corresponding value] Conditional expression (1): 194 Conditional expression (2): 240

[0126] Figure 24 is a spot diagram of the spectrometer 101c according to the third modified example of the second embodiment. The DE and SD in Figure 24 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 24, it can be seen that the spectrometer 101c according to the third modified example of the second embodiment has a smaller spot diameter of light focused by the second optical system 140 compared to the spectrometer 101re according to the comparative example of the second embodiment. As a result, the spectrometer 101c according to the third modified example of the second embodiment can obtain the same effect as the spectrometer 101 according to the second embodiment.

[0127] Next, a fourth modified example of the spectrometer according to the second embodiment will be described. As shown in Figure 25, the spectrometer 101d according to the fourth modified example of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 101 according to the second embodiment, and a detailed explanation is omitted. The spectrometer 101d according to the fourth modified example of the second embodiment includes a slit member 10 with an opening 11 for passing incident light LA, a first optical system 120, and a diffraction It comprises a grid 130, a second optical system 140, and a detector 50.

[0128] In the spectrometer 101d according to the fourth modification of the second embodiment, the amount of positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 123 of the first optical system 120 is greater than in the case of the second embodiment and the third modification described above. The amount of positional displacement of the detector 50 with respect to the rear focal plane 143 of the second optical system 140 is greater than in the case of the second embodiment and the third modification described above.

[0129] Next, the specifications of the spectrometer 101d according to the fourth modification of the second embodiment will be described. Table 12, shown below, is a table showing the specifications of the spectrometer 101d according to the fourth modification of the second embodiment. As mentioned above, the spectrometer 101d according to the fourth modification of the second embodiment has the same configuration as the spectrometer 101 according to the second embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 12 lists the specifications of the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0130] In Table 12, L1 and D25 in the [Slit Member] correspond to the same values ​​in Table 7. These are the same parameters as L1 and D25. L2 and D26 in Table 12 [Detector] are the same parameters as L2 and D26 in Table 7 [Detector]. [Conditional Expression Correspondence] In the [Value] section, the corresponding value for each conditional expression is shown.

[0131] Table 12 below shows the specifications of the spectrometer 101d according to the fourth modified example of the second embodiment.

[0132] (Table 12) [Slit member] L1 = -160.0 D25=40 [Detector] L2 = 88.6 D26=40 [Conditional expression corresponding value] Conditional expression (1): 282 Condition (2): 350

[0133] Figure 26 is a spot diagram of the spectrometer 101d according to the fourth modification of the second embodiment. DE and SD in Figure 26 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 26, it can be seen that the spectrometer 101d according to the fourth modification of the second embodiment has a smaller spot diameter of light focused by the second optical system 140 compared to the spectrometer 101re according to the comparative example of the second embodiment. As a result, the spectrometer 101d according to the fourth modification of the second embodiment can obtain the same effect as the spectrometer 101 according to the second embodiment.

[0134] Next, a spectrometer according to the third embodiment will be described. As shown in Figure 27, the spectrometer 201 according to the third embodiment is a Czerny-Turner type spectrometer that detects incident light LA ​​by spectrally separating it according to its wavelength. The spectrometer 201 according to the third embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the first optical system 220, the diffraction grating 230, and the second optical system 240 are different, so the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed explanation is omitted. The spectrometer 201 according to the third embodiment includes a slit member 10 with an opening 11 formed therein for passing incident light LA, the first optical system 220, and the diffraction grating 230. It comprises a second optical system 240 and a detector 50.

[0135] The opening 11 of the slit member 10 is positioned at a location away from the optical axis A3 of the first optical system 220 in the +Y direction, and at a position displaced from the front focal plane 223 of the first optical system 220 in the optical axis direction (Z direction). Light (incident light LA) passing through the opening 11 of the slit member 10 is incident on the first optical system 220.

[0136] As shown in Figure 27, the first optical system 220 includes a first mirror section 221 having a first concave surface 222, and is configured similarly to the first optical system 120 of the second embodiment. The light focused by the first optical system 220 (incident light LA) is incident on the diffraction grating 230.

[0137] The diffraction grating 230 is positioned on the optical axis A3 of the first optical system 220. The diffraction grating 230 is formed in the same manner as the diffraction grating 30 of the first real-world embodiment. The opening 11 of the slit member 10 has a shape that extends in a direction (X direction) intersecting the spectral direction of the diffraction grating 230.

[0138] To make the diagram easier to understand, Figure 27 shows only one diffracted light beam LB having a predetermined wavelength (wavelength of light to be spectrally separated) as an example of diffracted light diffracted by the diffraction grating 230. The diffracted light beam LB emitted from the diffraction grating 230 is incident on the second optical system 240. As shown in Figure 27, the second optical system 240 includes a second mirror section 241 having a second concave surface 242 and is configured similarly to the second optical system 140 of the second embodiment.

[0139] The detector 50 is positioned away from the optical axis B3 of the second optical system 240 on the opposite side of the aperture 11 of the slit member 10, and displaced from the rear focal plane 243 of the second optical system 240 in the optical axis direction (Z direction). Alternatively, the detector 50 may be positioned at the image formation position where the image of the aperture 11 of the slit member 10 is formed by the first optical system 220 and the second optical system 240. In this case, the image of the aperture 11 of the slit member 10 may be formed on the detection surface 53 of the detector 50.

[0140] In the spectrometer 201 according to the third embodiment, light (incident light LA) passing through the aperture 11 of the slit member 10 is reflected by the first mirror 221 of the first optical system 220 to become focused light and is incident on the diffraction grating 230. When light from the first optical system 220 is incident on the diffraction grating 230, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 230 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 230 is reflected by the second mirror 241 of the second optical system 240 and focused on the detection surface 53 of the detector 50. As a result, an image of the aperture 11 of the slit member 10 is formed on the detection surface 53 of the detector 50 by the combined optical system of the first optical system 220 and the second optical system 240. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror 241 of the second optical system 240.

[0141] Similar to the first embodiment, the detector 50 can individually detect multiple types of diffracted light with different field of view and wavelengths in the combined optical system of the first optical system 220 and the second optical system 240, which are focused onto the detection surface 53 by the second optical system 240. In this way, the spectrometer 201 according to the third embodiment spectrally detects the incident light LA ​​according to its wavelength. Therefore, the same effects as in the first embodiment can be obtained according to the third embodiment.

[0142] Furthermore, the spectrometer 201 according to the third embodiment may satisfy the aforementioned condition (1). By satisfying condition (1), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the third embodiment, the upper limit of condition (1) may be set to 61, or the upper limit of condition (1) may be set to 46. Also, the lower limit of condition (1) may be set to 14.

[0143] The spectrometer 201 according to the third embodiment may satisfy the aforementioned condition (2). By satisfying condition (2), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the third embodiment, the upper limit of condition (2) may be set to 67, or the upper limit of condition (2) may be set to 50. The lower limit of condition (2) may also be set to 15.

[0144] Next, the specifications of the spectrometer 201 according to the third embodiment will be described. Table 13, shown below, is a table showing the specifications of the spectrometer 201 according to the third embodiment. Each parameter of the specifications shown in Table 13 is the same as each parameter of the specifications shown in Table 7 in the second embodiment.

[0145] Table 13 below shows the specifications of the spectrometer 201 according to the third embodiment.

[0146] (Table 13) [Overall Specifications] λ = 550 NA1 = 0.05 Δλ = 0.04 [First Mirror Section] R1 = -400 D21=200 D22=20 J21=-5 [Mirror Section 2] R2 = -400 D23=200 D24=20 J22=-5 [Slit member] L1 = -34.0 D25=20 [Detector] L2 = 28.3 D26=20 [Diffraction grating] m=1 d = 0.002 j=8.0 Φ=25 θ1 = 18.0 θ² = 1.95 D27=113 [Conditional expression corresponding value] Condition (1): 29 Condition (2): 32

[0147] Figure 28 is a spot diagram of the spectrometer 201 according to the third embodiment. The DE and SD in Figure 28 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 28, it can be seen that the spectrometer 201 according to the third embodiment has a small spot diameter of light focused by the second optical system 240.

[0148] Next, a comparative example of the spectrometer according to the third embodiment will be described. As shown in Figure 29, the spectrometer 201re according to the comparative example of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 201 according to the third embodiment, and a detailed description is omitted. The spectrometer 201re according to the comparative example of the third embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 220, a diffraction grating 230, a second optical system 240, and a detector 50.

[0149] The opening 11 of the slit member 10 is positioned at a location away from the optical axis A3 of the first optical system 220 in the +Y direction, and at the front focal plane 223 of the first optical system 220. As a result, the first mirror portion 221 of the first optical system 220 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A3 of the first optical system 220, making it parallel. The detector 50 is positioned at a location away from the optical axis B3 of the second optical system 240 on the opposite side from the opening 11 of the slit member 10, and at the rear focal plane 243 of the second optical system 240.

[0150] In the spectrometer 201re according to the comparative example of the third embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror portion 221 of the first optical system 220 to become parallel light and is incident on the diffraction grating 230. When light from the first optical system 220 is incident on the diffraction grating 230, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 230 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 230 is reflected by the second mirror portion 241 of the second optical system 240 and focused on the detection surface 53 of the detector 50. As a result, the first optical system 220 and the second optical system 240 form an image of the opening 11 of the slit member 10 on the detection surface 53 of the detector 50. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror portion 241 of the second optical system 240.

[0151] Next, the specifications data of the spectroscope 201re according to the comparative example of the third embodiment will be described. Table 14 shown below is a table showing the specifications data of the spectroscope 201re according to the comparative example of the third embodiment. Each parameter of the specifications data shown in Table 14 is the same as each parameter of the specifications data shown in Table 8 in the second embodiment.

[0152] The following Table 14 shows the specifications data of the spectroscope 201re according to the comparative example of the third embodiment.

[0153] (Table 14) [Overall specifications] λ = 550 NA1 = 0.05 Δλ = 1.1 [First mirror section] R1 = -400 D21 = 200 D22 = 20 J21 = -5 [Second mirror section] R2 = -400 D23 = 200 D24 = 20 J22 = -5 [Slit member] L1 = 0 D25 = 20 [Detector] L2 = 0 D26 = 20 [Diffraction grating]<00009​​​​​​​​​​​​​​​​Figure 30 is a spot diagram of the spectrometer 201re according to the comparative example of the third embodiment. DE and SD in Figure 30 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 30, it can be seen that the spectrometer 201re according to the comparative example of the third embodiment has a larger spot diameter of light focused by the second optical system 240. Also, from the spot diagrams shown in Figures 28 and 30, it can be seen that the spectrometer 201 according to the third embodiment has a smaller spot diameter of light focused by the second optical system 240 compared to the spectrometer 201re according to the comparative example of the third embodiment. Thus, according to the spectrometer 201 according to the third embodiment, the detector 50 can detect the light focused by the second optical system 240 with high positional accuracy, making it possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength.

[0155] Next, a first modified example of the spectrometer according to the third embodiment will be described. As shown in Figure 31, the spectrometer 201a according to the first modified example of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 201 according to the third embodiment, and a detailed description will be omitted. The spectrometer 201a according to the first modified example of the third embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 220, a diffraction grating 230, a second optical system 240, and a detector 50.

[0156] In the spectrometer 201a according to the first modification of the third embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 223 of the first optical system 220 is smaller than in the case of the third embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 243 of the second optical system 240 is smaller than in the case of the third embodiment described above.

[0157] Next, the specifications of the spectrometer 201a according to the first modification of the third embodiment will be described. Table 15, shown below, is a table showing the specifications of the spectrometer 201a according to the first modification of the third embodiment. As mentioned above, the spectrometer 201a according to the first modification of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 15 lists the specifications for [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0158] In Table 15, L1 and D25 in the [Slit Member] are the same as in Table 13, [Slit Member]. These are the same parameters as L1 and D25. L2 and D26 in Table 15 [Detector] are the same parameters as L2 and D26 in Table 13 [Detector]. [Conditional Expression] in Table 15 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0159] Table 15 below shows the specifications of the spectrometer 201a according to the first modified example of the third embodiment.

[0160] (Table 15) [Slit member] L1 = -1.2 D25=20 [Detector] L2 = 1.1 D26=20 [Conditional expression corresponding value] Condition (1): 1 Condition (2):1

[0161] Figure 32 is a spot diagram of the spectrometer 201a according to the first modified example of the third embodiment. The DE and SD in Figure 32 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 32, it can be seen that the spectrometer 201a according to the first modified example of the third embodiment has a smaller spot diameter of light focused by the second optical system 240 compared to the spectrometer 201re according to the comparative example of the third embodiment. As a result, the spectrometer 201a according to the first modified example of the third embodiment can obtain the same effect as the spectrometer 201 according to the third embodiment.

[0162] Next, a second modified example of the spectrometer according to the third embodiment will be described. As shown in Figure 33, the spectrometer 201b according to the second modified example of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 201 according to the third embodiment, and a detailed description is omitted. The spectrometer 201b according to the second modified example of the third embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 220, a diffraction grating 230, a second optical system 240, and a detector 50.

[0163] In the spectrometer 201b according to the second modification of the third embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 223 of the first optical system 220 is smaller than in the third embodiment described above, but larger than in the first modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 243 of the second optical system 240 is smaller than in the third embodiment described above, but larger than in the first modification described above.

[0164] Next, the specification data of the spectroscope 201b according to the second modification of the third embodiment will be described. Table 16 shown below is a table showing the specification data of the spectroscope 201b according to the second modification of the third embodiment. As described above, the spectroscope 201b according to the second modification of the third embodiment has the same configuration as the spectroscope 201 according to the aforementioned third embodiment, except that the positions of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the specification data regarding [Slit member], [Detector], and [Condition formula corresponding value] are described in Table 16, and the description of other specification data is omitted.

[0165] L1 and D25 in [Slit member] of Table 16 are the same parameters as L1 and D25 in [Slit member] of Table 13. L2 and D26 in [Detector] of Table 16 are the same parameters as L2 and D26 in [Detector] of Table 13. In [Condition formula corresponding value] of Table 16, the condition formula corresponding values of each condition formula are shown.

[0166] The following Table 16 shows the specification data of the spectroscope 201b according to the second modification of the third embodiment. .

[0167] (Table 16) [Slit member] L1 = -16.0 D25 = 20 [Detector] L2 = 14.3 D26 = 20 [Condition formula corresponding value] Condition formula (1): 14 <00​​​​Figure 34 is a spot diagram of the spectrometer 201b according to the second modification of the third embodiment. The DE and SD in Figure 34 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 34, it can be seen that the spectrometer 201b according to the second modification of the third embodiment has a smaller spot diameter of light focused by the second optical system 240 compared to the spectrometer 201re according to the comparative example of the third embodiment. As a result, the spectrometer 201b according to the second modification of the third embodiment can obtain the same effect as the spectrometer 201 according to the third embodiment.

[0169] Next, a third modified example of the spectrometer according to the third embodiment will be described. As shown in Figure 35, the spectrometer 201c according to the third modified example of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 201 according to the third embodiment, and a detailed description will be omitted. The spectrometer 201c according to the third modified example of the third embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 220, a diffraction grating 230, a second optical system 240, and a detector 50.

[0170] In the spectrometer 201c according to the third modification of the third embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 223 of the first optical system 220 is greater than in the case of the third embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 243 of the second optical system 240 is greater than in the case of the third embodiment described above.

[0171] Next, the specifications of the spectrometer 201c according to the third modification of the third embodiment will be described. Table 17, shown below, is a table showing the specifications of the spectrometer 201c according to the third modification of the third embodiment. As mentioned above, the spectrometer 201c according to the third modification of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 17 lists the specifications for the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0172] In Table 17, L1 and D25 in the [Slit Member] are the same as in Table 13, [Slit Member] These are the same parameters as L1 and D25. L2 and D26 in Table 17 [Detector] are the same parameters as L2 and D26 in Table 13 [Detector]. [Conditional Expression] in Table 17 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0173] Table 17 below shows the specifications of the spectrometer 201c according to the third modified example of the third embodiment.

[0174] (Table 17) [Slit member] L1 = -53.0 D25=20 [Detector] L2 = 41.3 D26=20 [Conditional expression corresponding value] Condition (1): 46 Condition (2): 50

[0175] Figure 36 is a spot diagram of the spectrometer 201c according to the third modified example of the third embodiment. The DE and SD in Figure 36 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 36, it can be seen that the spectrometer 201c according to the third modified example of the third embodiment has a smaller spot diameter of light focused by the second optical system 240 compared to the spectrometer 201re according to the comparative example of the third embodiment. As a result, the spectrometer 201c according to the third modified example of the third embodiment can obtain the same effect as the spectrometer 201 according to the third embodiment.

[0176] Next, a fourth modified example of the spectrometer according to the third embodiment will be described. As shown in Figure 37, the spectrometer 201d according to the fourth modified example of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 201 according to the third embodiment, and a detailed description is omitted. The spectrometer 201d according to the fourth modified example of the third embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 220, a diffraction grating 230, a second optical system 240, and a detector 50.

[0177] In the spectrometer 201d according to the fourth modification of the third embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 223 of the first optical system 220 is greater than in the case of the third embodiment and the third modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 243 of the second optical system 240 is greater than in the case of the third embodiment and the third modification described above.

[0178] Next, the specifications of the spectrometer 201d according to the fourth modification of the third embodiment will be described. Table 18, shown below, is a table showing the specifications of the spectrometer 201d according to the fourth modification of the third embodiment. As mentioned above, the spectrometer 201d according to the fourth modification of the third embodiment has the same configuration as the spectrometer 201 according to the third embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 18 lists the specifications for [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0179] In Table 18, L1 and D25 in the [Slit Member] are the same as in Table 13, [Slit Member]. These are the same parameters as L1 and D25. L2 and D26 in Table 18 [Detector] are the same parameters as L2 and D26 in Table 13 [Detector]. [Conditional Expression] in Table 18 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0180] Table 18 below shows the specifications of the spectrometer 201d according to the fourth modified example of the third embodiment.

[0181] (Table 18) [Slit member] L1 = -71.0 D25=20 [Detector] L2 = 52.2 D26=20 [Conditional expression corresponding value] Condition (1): 61 Conditional expression (2): 67

[0182] Figure 38 is a spot diagram of the spectrometer 201d according to the fourth modification of the third embodiment. DE and SD in Figure 38 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 38, it can be seen that the spectrometer 201d according to the fourth modification of the third embodiment has a smaller spot diameter of light focused by the second optical system 240 compared to the spectrometer 201re according to the comparative example of the third embodiment. As a result, the spectrometer 201d according to the fourth modification of the third embodiment can obtain the same effect as the spectrometer 201 according to the third embodiment.

[0183] Next, a spectrometer according to the fourth embodiment will be described. As shown in Figure 39, the spectrometer 301 according to the fourth embodiment is a Czerny-Turner type spectrometer that detects incident light LA ​​by spectrally separating it according to its wavelength. The spectrometer 301 according to the fourth embodiment has the same configuration as the spectrometer 1 according to the first embodiment described above, except that the first optical system 320, the diffraction grating 330, and the second optical system 340 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 1 according to the first embodiment, and a detailed explanation is omitted. The spectrometer 301 according to the fourth embodiment comprises a slit member 10 with an opening 11 for passing incident light LA, a first optical system 320, a diffraction grating 330, a second optical system 340, and a detector 50.

[0184] The opening 11 of the slit member 10 is positioned away from the optical axis A4 of the first optical system 320 in the +Y direction, and displaced from the front focal plane 323 of the first optical system 320 in the optical axis direction (Z direction). Light (incident light LA) passing through the opening 11 of the slit member 10 is incident on the first optical system 320.

[0185] As shown in Figure 39, the first optical system 320 includes a first mirror section 321 having a first concave surface 322, and is configured similarly to the first optical system 120 of the second embodiment. The light focused by the first optical system 320 (incident light LA) is incident on the diffraction grating 330.

[0186] The diffraction grating 330 is positioned on the optical axis A4 of the first optical system 320. The diffraction grating 330 is formed in the same manner as the diffraction grating 30 of the first real-world embodiment. The opening 11 of the slit member 10 has a shape that extends in a direction (X direction) intersecting the spectral direction of the diffraction grating 330.

[0187] To make the diagram easier to understand, Figure 38 shows only one diffracted light beam LB having a predetermined wavelength (wavelength of light to be spectrally separated) as an example of diffracted light diffracted by the diffraction grating 330. The diffracted light beam LB emitted from the diffraction grating 330 is incident on the second optical system 340. As shown in Figure 38, the second optical system 340 includes a second mirror section 341 having a second concave surface 342 and is configured similarly to the second optical system 140 of the second embodiment.

[0188] The detector 50 is positioned away from the optical axis B4 of the second optical system 340 on the opposite side of the aperture 11 of the slit member 10, and is displaced from the rear focal plane 343 of the second optical system 340 in the optical axis direction (Z direction). The detector 50 is also positioned where the image of the aperture 11 of the slit member 10 formed by the first optical system 320 and the second optical system 340 is formed. It may be positioned at the image formation location. In this case, the image of the opening 11 of the slit member 10 may be formed on the detection surface 53 of the detector 50.

[0189] In the spectrometer 301 according to the fourth embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror 321 of the first optical system 320 to become focused light and is incident on the diffraction grating 330. When light from the first optical system 320 is incident on the diffraction grating 330, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 330 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 330 is reflected by the second mirror 341 of the second optical system 340 and focused on the detection surface 53 of the detector 50. As a result, an image of the opening 11 of the slit member 10 is formed on the detection surface 53 of the detector 50 by the combined optical system of the first optical system 320 and the second optical system 340. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror 341 of the second optical system 340.

[0190] Similar to the first embodiment, the detector 50 can individually detect multiple types of diffracted light with different field of view and wavelengths in the combined optical system of the first optical system 320 and the second optical system 340, which are focused onto the detection surface 53 by the second optical system 340. In this way, the spectrometer 301 according to the fourth embodiment spectrally analyzes and detects the incident light LA ​​according to its wavelength. Therefore, the fourth embodiment can obtain the same effects as the first embodiment.

[0191] Furthermore, the spectrometer 301 according to the fourth embodiment may satisfy the aforementioned condition (1). By satisfying condition (1), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the fourth embodiment, the upper limit of condition (1) may be set to 369. Alternatively, the lower limit of condition (1) may be set to 105.

[0192] The spectrometer 301 according to the fourth embodiment may satisfy the aforementioned condition (2). By satisfying condition (2), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the fourth embodiment, the upper limit of condition (2) may be set to 499. Alternatively, the lower limit of condition (2) may be set to 142.

[0193] Next, the specifications of the spectrometer 301 according to the fourth embodiment will be described. Table 19, shown below, is a table showing the specifications of the spectrometer 301 according to the fourth embodiment. Each parameter of the specifications shown in Table 19 is the same as each parameter of the specifications shown in Table 7 in the second embodiment.

[0194] Table 19 below shows the specifications of the spectrometer 301 according to the fourth embodiment.

[0195] (Table 19) [Overall Specifications] λ = 550 NA1 = 0.05 Δλ = 0.09 [First Mirror Section] R1 = -400 D21=200 D22=60 J21=-10 [Mirror Section 2] R2 = -400 D23=208 D24=61 J22=-10 [Slit member] L1 = -94.0 D25=60 [Detector] L2 = 65.0 D26=61 [Diffraction grating] m=1 d = 0.002 j=9.0 Φ=25 θ1 = 34.85 θ² = 17.24 D27=128 [Conditional expression corresponding value] Condition (1): 224 Condition (2): 303

[0196] Figure 40 is a spot diagram of the spectrometer 401 according to the fourth embodiment. The DE and SD in Figure 40 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 40, it can be seen that the spectrometer 401 according to the fourth embodiment has a small spot diameter of light focused by the second optical system 340.

[0197] Next, a comparative example of the spectrometer according to the fourth embodiment will be described. As shown in Figure 41, the spectrometer 301re according to the comparative example of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 301 according to the fourth embodiment, and a detailed explanation is omitted. The spectrometer 301re according to the comparative example of the fourth embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 320, a diffraction grating 330, a second optical system 340, and a detector 50.

[0198] The opening 11 of the slit member 10 is positioned at a location away from the optical axis A4 of the first optical system 320 in the +Y direction, and at the front focal plane 323 of the first optical system 320. As a result, the first mirror portion 321 of the first optical system 320 reflects the light that has passed through the opening 11 of the slit member 10 toward the optical axis A4 of the first optical system 320, making it parallel. The detector 50 is positioned at a location away from the optical axis B4 of the second optical system 340 on the opposite side from the opening 11 of the slit member 10, and at the rear focal plane 343 of the second optical system 340.

[0199] In the spectrometer 301re according to the comparative example of the fourth embodiment, light (incident light LA) passing through the opening 11 of the slit member 10 is reflected by the first mirror portion 321 of the first optical system 320 to become parallel light and is incident on the diffraction grating 330. When light from the first optical system 320 is incident on the diffraction grating 330, multiple types of diffracted light with different wavelengths are emitted from the diffraction grating 330 at different emission angles for each wavelength. The diffracted light LB emitted from the diffraction grating 330 is reflected by the second mirror portion 341 of the second optical system 340 and focused on the detection surface 53 of the detector 50. As a result, the first optical system 320 and the second optical system 340 form an image of the opening 11 of the slit member 10 on the detection surface 53 of the detector 50. The detector 50 detects the light (diffracted light LB) that has been focused on at least a part of the detection surface 53 by the second mirror portion 341 of the second optical system 340.

[0200] Next, the specifications of the spectrometer 301re according to the comparative example of the fourth embodiment will be described. Table 20, shown below, is a table showing the specifications of the spectrometer 301re according to the comparative example of the fourth embodiment. Each parameter of the specifications shown in Table 20 is the same as each parameter of the specifications shown in Table 8 in the second embodiment.

[0201] Table 20 below shows the specifications of the spectrometer 301re related to the comparative example of the fourth embodiment.

[0202] (Table 20) [Overall Specifications] λ = 550 NA1 = 0.05 Δλ = 8.4 [First Mirror Section] R1 = -400 D21=200 D22=60 J21=-10 [Mirror Section 2] R2 = -400 D23=208 D24=61 J22=-10 [Slit member] L1=0 D25=60 [Detector] L2=0 D26=61 [Diffraction grating] m=1 d = 0.002 j=9.0 Φ=25 θ1 = 34.85 θ² = 17.24 D27=128

[0203] Figure 42 is a spot diagram of the spectrometer 301re according to the comparative example of the fourth embodiment. DE and SD in Figure 42 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 42, it can be seen that the spectrometer 301re according to the comparative example of the fourth embodiment has a larger spot diameter of light focused by the second optical system 340. Also, from the spot diagrams shown in Figures 40 and 42, it can be seen that the spectrometer 301 according to the fourth embodiment has a smaller spot diameter of light focused by the second optical system 340 compared to the spectrometer 301re according to the comparative example of the fourth embodiment. Thus, according to the spectrometer 301 according to the fourth embodiment, the detector 50 can detect the light focused by the second optical system 240 with high positional accuracy, making it possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength.

[0204] Next, a first modified example of the spectrometer according to the fourth embodiment will be described. As shown in Figure 43. The spectrometer 301a according to the first modification of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 301 according to the fourth embodiment, and a detailed description is omitted. The spectrometer 301a according to the first modification of the fourth embodiment comprises a slit member 10 having an opening 11 for passing incident light LA, a first optical system 320, a diffraction grating 330, a second optical system 340, and a detector 50.

[0205] In the spectrometer 301a according to the first modification of the fourth embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 323 of the first optical system 320 is smaller than in the case of the fourth embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 343 of the second optical system 340 is smaller than in the case of the fourth embodiment described above.

[0206] Next, the specifications of the spectrometer 301a according to the first modification of the fourth embodiment will be described. Table 21, shown below, is a table showing the specifications of the spectrometer 301a according to the first modification of the fourth embodiment. As mentioned above, the spectrometer 301a according to the first modification of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 21 lists the specifications for the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0207] In Table 21, L1 and D25 in the [Slit Member] are the same as in Table 19, [Slit Member]. These are the same parameters as L1 and D25. L2 and D26 in Table 21 [Detector] are the same parameters as L2 and D26 in Table 19 [Detector]. [Conditional Expression] in Table 21 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0208] Table 21 below shows the specifications of the spectrometer 301a according to the first modified example of the fourth embodiment.

[0209] (Table 21) [Slit member] L1 = -0.4 D25=60 [Detector] L2 = 0.3 D26=61 [Conditional expression corresponding value] Condition (1): 1 Condition (2):1

[0210] Figure 44 is a spot diagram of the spectrometer 301a according to the first modified example of the fourth embodiment. The DE and SD in Figure 44 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 44, it can be seen that the spectrometer 301a according to the first modified example of the fourth embodiment has a smaller spot diameter of light focused by the second optical system 340 compared to the spectrometer 301re according to the comparative example of the fourth embodiment. As a result, the spectrometer 301a according to the first modified example of the fourth embodiment can obtain the same effect as the spectrometer 301 according to the fourth embodiment.

[0211] Next, a second modified example of the spectrometer according to the fourth embodiment will be described. As shown in Figure 45, the spectrometer 301b according to the second modified example of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Since it is a composite, the same reference numerals are used for the same components as in the spectrometer 301 of the fourth embodiment, and a detailed description is omitted. The spectrometer 301b according to the second modified example of the fourth embodiment comprises a slit member 10 having an aperture 11 for passing incident light LA, a first optical system 320, a diffraction grating 330, a second optical system 340, and a detector 50.

[0212] In the spectrometer 301b according to the second modification of the fourth embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 323 of the first optical system 320 is smaller than in the fourth embodiment described above, but larger than in the first modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 343 of the second optical system 340 is smaller than in the fourth embodiment described above, but larger than in the first modification described above.

[0213] Next, the specifications of the spectrometer 301b according to the second modification of the fourth embodiment will be described. Table 22, shown below, is a table showing the specifications of the spectrometer 301b according to the second modification of the fourth embodiment. As mentioned above, the spectrometer 301b according to the second modification of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 22 lists the specifications for the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0214] In Table 22, L1 and D25 in the [Slit Member] are the same as in Table 19, [Slit Member]. These are the same parameters as L1 and D25. L2 and D26 in Table 22 [Detector] are the same parameters as L2 and D26 in Table 19 [Detector]. [Conditional Expression] in Table 22 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0215] Table 22 below shows the specifications of the spectrometer 301b according to the second modified example of the fourth embodiment.

[0216] (Table 22) [Slit member] L1 = -44.0 D25=60 [Detector] L2 = 34.2 D26=61 [Conditional expression corresponding value] Condition (1): 105 Conditional expression (2): 142

[0217] Figure 46 is a spot diagram of the spectrometer 301b according to the second modification of the fourth embodiment. The DE and SD in Figure 46 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 46, it can be seen that the spectrometer 301b according to the second modification of the fourth embodiment has a smaller spot diameter of light focused by the second optical system 340 compared to the spectrometer 301re according to the comparative example of the fourth embodiment. As a result, the spectrometer 301b according to the second modification of the fourth embodiment can obtain the same effect as the spectrometer 301 according to the fourth embodiment.

[0218] Next, a third modified example of the spectrometer according to the fourth embodiment will be described. As shown in Figure 47, the spectrometer 301c according to the third modified example of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 301 according to the fourth embodiment. Detailed explanation is omitted. The spectrometer 301c according to the third modified example of the fourth embodiment comprises a slit member 10 having an aperture 11 for passing incident light LA, a first optical system 320, a diffraction grating 330, a second optical system 340, and a detector 50.

[0219] In the spectrometer 301c according to the third modification of the fourth embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 323 of the first optical system 320 is greater than in the case of the fourth embodiment described above. The positional displacement of the detector 50 with respect to the rear focal plane 343 of the second optical system 340 is greater than in the case of the fourth embodiment described above.

[0220] Next, the specifications of the spectrometer 301c according to the third modification of the fourth embodiment will be described. Table 23, shown below, is a table showing the specifications of the spectrometer 301c according to the third modification of the fourth embodiment. As mentioned above, the spectrometer 301c according to the third modification of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 23 lists the specifications for the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0221] In Table 23, L1 and D25 in the [Slit Member] are the same as in Table 19, [Slit Member]. These are the same parameters as L1 and D25. L2 and D26 in Table 23 [Detector] are the same parameters as L2 and D26 in Table 19 [Detector]. [Conditional Expression] in Table 23 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0222] Table 23 below shows the specifications of the spectrometer 301c according to the third modified example of the fourth embodiment.

[0223] (Table 23) [Slit member] L1 = -155.0 D25=60 [Detector] L2 = 94.5 D26=61 [Conditional expression corresponding value] Conditional expression (1): 369 Condition (2): 499

[0224] Figure 48 is a spot diagram of the spectrometer 301c according to the third modification of the fourth embodiment. The DE and SD in Figure 48 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 48, it can be seen that the spectrometer 301c according to the third modification of the fourth embodiment has a smaller spot diameter of light focused by the second optical system 340 compared to the spectrometer 301re according to the comparative example of the fourth embodiment. As a result, the spectrometer 301c according to the third modification of the fourth embodiment can obtain the same effect as the spectrometer 301 according to the fourth embodiment.

[0225] Next, a fourth modified example of the spectrometer according to the fourth embodiment will be described. As shown in Figure 49, the spectrometer 301d according to the fourth modified example of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, the same reference numerals are used for the same components as in the spectrometer 301 according to the fourth embodiment, and a detailed explanation is omitted. The spectrometer 301d according to the fourth modified example of the fourth embodiment includes a slit member 10 with an opening 11 for passing incident light LA, a first optical system 320, and a diffraction It comprises a grid 330, a second optical system 340, and a detector 50.

[0226] In the spectrometer 301d according to the fourth modification of the fourth embodiment, the positional displacement of the opening 11 of the slit member 10 with respect to the front focal plane 323 of the first optical system 320 is greater than in the case of the fourth embodiment and the third modification described above. The positional displacement of the detector 50 with respect to the rear focal plane 343 of the second optical system 340 is greater than in the case of the fourth embodiment and the third modification described above.

[0227] Next, the specifications of the spectrometer 301d according to the fourth modification of the fourth embodiment will be described. Table 24, shown below, is a table showing the specifications of the spectrometer 301d according to the fourth modification of the fourth embodiment. As mentioned above, the spectrometer 301d according to the fourth modification of the fourth embodiment has the same configuration as the spectrometer 301 according to the fourth embodiment described above, except that the position of the opening 11 of the slit member 10 and the detector 50 are different. Therefore, Table 24 lists the specifications of the [slit member], [detector], and [conditional expression corresponding value], and omits the description of other specifications.

[0228] In Table 24, L1 and D25 in the [Slit Member] are the same as in Table 19, [Slit Member]. These are the same parameters as L1 and D25. L2 and D26 in Table 24 [Detector] are the same parameters as L2 and D26 in Table 19 [Detector]. [Conditional Expression] in Table 24 In the [Corresponding Values] section, the corresponding values ​​for each conditional expression are shown.

[0229] Table 24 below shows the specifications of the spectrometer 301d according to the fourth modified example of the fourth embodiment.

[0230] (Table 24) [Slit member] L1 = -224.0 D25=60 [Detector] L2 = 120.1 D26=61 [Conditional expression corresponding value] Condition (1): 533 Conditional expression (2): 722

[0231] Figure 50 is a spot diagram of the spectrometer 301d according to the fourth modification of the fourth embodiment. DE and SD in Figure 50 are the same parameters as DE and SD in Figure 3. From the spot diagram shown in Figure 50, it can be seen that the spectrometer 301d according to the fourth modification of the fourth embodiment has a smaller spot diameter of light focused by the second optical system 340 compared to the spectrometer 301re according to the comparative example of the fourth embodiment. As a result, the spectrometer 301d according to the fourth modification of the fourth embodiment can obtain the same effect as the spectrometer 301 according to the fourth embodiment.

[0232] Here, we will briefly explain the process of deriving the lower limit of condition (1) and the lower limit of condition (2). First, as mentioned above, when the angle of incidence of light from the first optical system with respect to the normal of the diffraction grating is θ1, and the angle of emission of diffracted light with respect to the diffraction grating is θ2, let k be the coefficient expressed in the following equation (3).

[0233]

number

[0234] Let f1 be the focal length of the first optical system, f2 be the focal length of the second optical system, and let β be the transverse magnification in the XZ direction of the combined optical system of the first and second optical systems. X Let's assume that the first optical system and the second optical system Transverse magnification β in the XZ direction of the composite optical system X This can be expressed by the following equation (4).

[0235]

number

[0236] The transverse magnification in the YZ direction of the combined optical system of the first and second optical systems is β. Y Let's assume that the first optical system is the first optical system. Transverse magnification β in the XZ direction of the combined optical system of the system and the second optical system. X And the first optical system and the second optical system Transverse magnification β in the YZ direction of the composite optical system YThe relationship with it is expressed by the following formula (5).

[0237]

Number

[0238] From formula (4) and formula (5), the lateral magnification β in the YZ direction of the combined optical system of the first optical system and the second optical system Y is expressed by the following formula (6).

[0239]

Number

[0240] The numerical aperture NA1 on the slit member side of the combined optical system of the first optical system and the second optical system is common in the XZ direction and the YZ direction. Let the numerical aperture in the XZ direction on the detector side of the combined optical system of the first optical system and the second optical system be NA 2X . The numerical aperture NA 2X in the XZ direction on the detector side of the combined optical system of the first optical system and the second optical system is expressed by the following formula (7).

[0241]

Number

[0242] Let the numerical aperture in the YZ direction on the detector side of the combined optical system of the first optical system and the second optical system be NA 2Y . The numerical aperture NA 2Y in the YZ direction on the detector side of the combined optical system of the first optical system and the second optical system is expressed by the following formula (8).

[0243]

Number

[0244] From formula (5), formula (7) and formula (8), the numerical aperture NA in the XZ direction on the detector side of the combined optical system of the first optical system and the second optical system 2X ​And, the numerical aperture NA in the YZ direction on the detector side of the combined optical system of the first optical system and the second optical system. 2Y The relationship is expressed by the following equation (9).

[0245]

number

[0246] Let δ1 be the depth of focus on the slit member side of the combined optical system of the first optical system and the second optical system. The depth of focus δ1 on the slit member side of the combined optical system of the first optical system and the second optical system is in the XZ direction and Y It is common in the Z direction and can be expressed by the following equation (10).

[0247]

number

[0248] The depth of focus in the XZ direction on the detector side of the combined optical system of the first optical system and the second optical system is δ 2X The depth of focus δ in the XZ direction on the detector side of the combined optical system of the first optical system and the second optical system is as follows. 2X This can be expressed by the following equation (11).

[0249]

number

[0250] The depth of focus in the YZ direction on the detector side of the combined optical system of the first optical system and the second optical system is δ 2Y The depth of focus δ in the YZ direction on the detector side of the combined optical system of the first optical system and the second optical system is as follows. 2Y This can be expressed by the following equation (12).

[0251]

number

[0252] From equations (9), (11), and (12), the depth of focus δ in the XZ direction on the detector side of the combined optical system of the first optical system and the second optical system is obtained. 2X And the depth of focus δ in the YZ direction on the detector side of the combined optical system of the first optical system and the second optical system 2Y The relationship is expressed by the following equation (13).

[0253]

number

[0254] The amount of defocus in the XZ direction relative to the rear focal plane of the second optical system (i.e., the positional displacement of the detector relative to the rear focal plane of the second optical system) is L. 2X Let's assume that the amount of defocus L in the XZ direction relative to the rear focal plane of the second optical system is as follows. 2X This can be expressed by the following equation (14).

[0255]

number

[0256] The amount of defocus in the YZ direction relative to the rear focal plane of the second optical system (i.e., the positional displacement of the detector relative to the rear focal plane of the second optical system) is L. 2Y The amount of defocus L in the YZ direction relative to the rear focal plane of the second optical system is assumed to be... 2Y This can be expressed by the following equation (15).

[0257]

number

[0258] Defocus amount L in the XZ direction relative to the rear focal plane of the second optical system 2X And the amount of defocus L in the YZ direction relative to the rear focal plane of the second optical system. 2Y The difference Δ is expressed by the following equation (16).

[0259]

number

[0260] The conditions under which astigmatism occurs include the amount of defocus L in the XZ direction relative to the rear focal plane of the second optical system. 2X And the amount of defocus L in the YZ direction relative to the rear focal plane of the second optical system. 2Y One possible scenario is when the difference Δ is greater than or equal to the depth of focus on the detector side of the combined optical system of the first and second optical systems. The conditions in this case are expressed by the following equation (17).

[0261]

number

[0262] The lower limit of condition expression (1) is derived from equations (7), (11), (16), and (17). The upper limit of condition expression (1) is set to 533 as the maximum value of condition expression (1), based on the corresponding value of condition expression (1) in the fourth modified example of the fourth embodiment. Alternatively, the upper limit of condition expression (1) may be set to 369, based on the corresponding value of condition expression (1) in the third modified example of the fourth embodiment.

[0263] The spectrometer 301 according to the fourth embodiment may satisfy the aforementioned condition (2). By satisfying condition (2), it becomes possible to improve the positional resolution (wavelength resolution) of the light spectrally separated for each wavelength, as in the first embodiment. In the fourth embodiment, the upper limit of condition (2) may be set to 499. Alternatively, the lower limit of condition (2) may be set to 142.

[0264] One condition under which astigmatism occurs is when the spot diameter in the Y direction of the light focused at the rear focal point in the XZ direction by the second optical system is greater than or equal to the Airy disk diameter. This condition is expressed by the following equation (18).

[0265]

number

[0266] The lower limit of condition expression (2) is derived from equations (5), (8), (16), and (19). The upper limit of condition expression (2) is set to 722 as the maximum value of condition expression (2), based on the corresponding value of condition expression (2) in the fourth modified example of the fourth embodiment. Alternatively, the upper limit of condition expression (1) may be set to 499, based on the corresponding value of condition expression (2) in the third modified example of the fourth embodiment.

[0267] In each of the embodiments described above, the detector 50 is provided with a plurality of detection elements 51 arranged in two directions, but is not limited thereto. For example, the detector may be configured with a plurality of detection elements arranged in one direction, for example, using a line CCD. In this case, the detector may be provided in a plurality corresponding to the number of light spectrally separated according to wavelength. Near the plurality of detectors, a detection-side slit member with a plurality of apertures may be provided. For example, as shown in Figure 51, the detection-side slit member 60 may have four apertures 61a, 61b, 61c, and 61d that allow light of four different wavelengths focused by the second optical system to pass through.

[0268] In each of the embodiments described above, the detector 50 is positioned at the image-forming position of the aperture 11 of the slit member 10 by the first optical system and the second optical system, but is not limited to this, and may be positioned at a position optically conjugate to the image-forming position. Furthermore, in each of the embodiments described above, a focusing lens for focusing light may be provided at the aperture 11 of the slit member 10, and the light focused by the focusing lens may be configured to pass through the aperture 11 of the slit member 10 as incident light.

[0269] In each of the embodiments described above, the optical axis of the first optical system and the optical axis of the second optical system are common axes, but are not limited to this, and do not have to be common axes. Also, at least one of the optical axes of the first optical system and the optical axis of the second optical system may be called the reference axis.

[0270] In each of the embodiments described above, the first optical system includes a first mirror section that deflects light passing through the opening 11 of the slit member 10 toward the optical axis of the first optical system, but is not limited to this. For example, instead of the first mirror section, the first optical system may include a first lens section that deflects light passing through the opening 11 of the slit member 10 toward the optical axis of the first optical system.

[0271] In each of the embodiments described above, the second optical system includes a second mirror section that focuses the diffracted light diffracted by the diffraction grating, but is not limited to this. For example, the second optical system may include a second lens section that focuses the diffracted light diffracted by the diffraction grating instead of the second mirror section. [Explanation of symbols]

[0272] 1. Spectrometer (First Embodiment) 10 Slit member 11 Opening 20 1st optical system 21 First mirror section (first optical element) 22 First concave surface 23 Front focal plane 30 Diffraction Gratings 40 Second optical system 41 Second mirror section (second optical element) 42 Second concave surface 43 Back focal plane 50 detectors 51 Detection element 53 Detection surface 101 Spectrometer (Second Embodiment) 121 First mirror section (first optical element) 122 First concave surface 123 Front focal plane 130 Diffraction Gratings 140 Second optical system 141 Second mirror section (second optical element) 142 Second concave surface 143 Back focal plane 201 Spectrometer (Third Embodiment) 221 First mirror section (first optical element) 222 First concave surface 223 Front focal plane 230 Diffraction Gratings 240 Second optical system 241 Second mirror section (second optical element) 242 Second concave surface 243 Back focal plane 301 Spectrometer (Fourth Embodiment) 321 First mirror section (first optical element) 322 First concave surface 323 Front focal plane 330 Diffraction Gratings 340 Second optical system 341 Second mirror section (second optical element) 342 Second concave surface 343 Back focal plane

Claims

1. In a spectrometer that detects incident light by spectrally analyzing it according to its wavelength, A slit member having an opening formed to allow the incident light to pass through, A first optical system into which light passing through the opening of the slit member is incident, A diffraction grating into which light focused by the first optical system is incident, A second optical system that collects the diffracted light diffracted by the diffraction grating, The system comprises a detector that detects the light focused by the second optical system, The first optical system and the second optical system form an image of the opening of the slit member. The opening of the slit member is positioned at a location displaced in the optical axis direction of the first optical system from the front focal plane of the first optical system. The detector is positioned at a location displaced in the optical axis direction from the rear focal plane of the second optical system. A spectrometer in which the displaced position of the opening of the slit member is further from the first optical system than the front focal plane of the first optical system, and the displaced position of the detector is closer to the second optical system than the rear focal plane of the second optical system.

2. The spectrometer according to claim 1, wherein the detector comprises a plurality of detection elements arranged in at least one direction, and is positioned at an image formation position where an image of the aperture of the slit member is formed by the first optical system and the second optical system, or at a position optically conjugate to the image formation position.

3. A spectrometer that detects incident light by spectrally separating it according to its wavelength, A slit member having an opening formed to allow the incident light to pass through, A first optical system into which light passing through the opening of the slit member is incident, A diffraction grating into which light focused by the first optical system is incident, A second optical system that collects the diffracted light diffracted by the diffraction grating, The system comprises a detector that detects the light focused by the second optical system, The detector comprises a plurality of detection elements arranged in at least one direction, and is positioned at an image formation position where an image of the aperture of the slit member is formed by the first optical system and the second optical system, or at a position optically conjugate to the image formation position. The opening of the slit member is positioned at a location displaced in the optical axis direction of the first optical system from the front focal plane of the first optical system. The detector is a spectrometer positioned at a location displaced in the optical axis direction from the rear focal plane of the second optical system.

4. The spectrometer according to any one of claims 1 to 3, wherein the light dispersed by the diffraction grating according to wavelength reaches different positions according to the wavelength via the second optical system.

5. The spectrometer according to any one of claims 1 to 4, wherein the opening of the slit member has a shape that extends in a direction intersecting the spectral direction by the diffraction grating.

6. The spectrometer according to any one of claims 1 to 5, wherein the opening of the slit member is positioned away from the optical axis of the first optical system.

7. The spectrometer according to any one of claims 1 to 6, wherein the displacement of the opening of the slit member in the optical axis direction is determined such that astigmatism at the position where an image of the opening caused by the first optical system, the second optical system, and the diffraction grating is formed is reduced.

8. The first optical system is positioned at a distance from the optical axis of the first optical system, on the same side as the opening of the slit member, and includes a first optical element that deflects light passing through the opening of the slit member toward the optical axis of the first optical system. The diffraction grating is positioned on the optical axis of the first optical system, The second optical system is positioned away from the optical axis of the second optical system on the opposite side of the opening of the slit member, and includes a second optical element that collects the diffracted light diffracted by the diffraction grating. The spectrometer according to any one of claims 1 to 7, wherein the detector is positioned away from the optical axis of the second optical system on the opposite side of the opening of the slit member, and detects the light focused by the second optical element.

9. The opening of the slit member is formed to extend in a direction perpendicular to the optical axis of the first optical system. The spectrometer according to claim 8, wherein the detector is a two-dimensional detector that detects light focused by the second optical element onto a detection plane perpendicular to the optical axis of the second optical system.

10. The first optical element has a first concave surface that reflects light that has passed through the opening of the slit member toward the optical axis of the first optical system, The spectrometer according to claim 8 or 9, wherein the second optical element has a second concave surface that reflects and focuses the diffracted light diffracted by the diffraction grating.

11. A spectrometer according to any one of claims 1 to 10, satisfying the following conditional expression. [Math 1] However, λ: the shortest wavelength among the wavelengths of the incident light. NA1: Numerical aperture on the slit member side of the composite optical system of the first optical system and the second optical system. L1: Amount of positional displacement of the opening of the slit member with respect to the front focal plane of the first optical system. k: A coefficient expressed by the following equation, where θ1 is the angle of incidence of light from the first optical system with respect to the normal of the diffraction grating, and θ2 is the angle of emission of the diffracted light with respect to the diffraction grating. 【Number 2】

12. A spectrometer according to any one of claims 1 to 11, satisfying the following conditional expression. [Math 3] However, λ: the shortest wavelength among the wavelengths of the incident light. NA1: Numerical aperture on the slit member side of the composite optical system of the first optical system and the second optical system. L1: Amount of positional displacement of the opening of the slit member with respect to the front focal plane of the first optical system. k: A coefficient expressed by the following equation, where θ1 is the angle of incidence of light from the first optical system with respect to the normal of the diffraction grating, and θ2 is the angle of emission of the diffracted light with respect to the diffraction grating. [Math 4]

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