Measurement device

Abstract

The present technology pertains to a measurement device capable of suitably measuring the spectrum of a measurement light. A measurement device according to the present technology is provided with: a luminous flux splitting unit for splitting substantially parallel luminous flux into a first luminous flux and a second luminous flux, refracting and emitting the first luminous flux, and emitting the second luminous flux in a direction symmetrical to the emission direction of the first luminous flux on the basis of a first reference plane that includes the traveling direction of the substantially parallel luminous flux, thereby causing the first luminous flux and the second luminous flux to interfere with each other; a light-condensing unit for condensing the first luminous flux and the second luminous flux on a second reference plane that includes the traveling direction of the substantially parallel luminous flux and is orthogonal to the first reference plane; a sensor unit for detecting interference light between the first luminous flux and the second luminous flux; and a calculation unit for calculating the spectrum of the substantially parallel luminous flux on the basis of a detection result by the sensor unit. The present technology can be applied to, for example, a spectroscopic measurement device.

Description

Measuring equipment

[0001] The present technology relates to a measurement device, and more particularly to a measurement device that is capable of suitably measuring the spectrum of measurement light.

[0002] Spectroscopic measurements can provide a variety of information about the object being measured. The mid-infrared wavelength range, approximately 6 to 13 μm, is also known as the molecular fingerprint region, where absorption due to various functional groups can be observed. The mid-infrared wavelength range is used to identify and quantify the substances that make up the object being measured.

[0003] Spectrometers using a Michelson interferometer are widely used as devices for measuring absorption spectra in the mid-infrared region. However, because Michelson interferometer-based spectrometers have moving parts, they are less robust and less portable. Furthermore, because a Michelson interferometer-based spectrometer requires a certain amount of time for a mirror to scan in order to measure a single spectrum, it is not suitable for applications such as measuring moving samples or observing time responses to some kind of stimulus.

[0004] International Publication No. WO 2016 / 180551 International Publication No. WO 2014 / 054708

[0005] For example, Patent Document 1 describes a technology for performing Fourier spectroscopy by splitting an incident light beam into two, changing the phase of one of the two split light beams, and focusing it on a line sensor to generate interference fringes (interferograms). In the technology described in Patent Document 1, the light is once propagated to the side of the system by a beam splitter, which increases the external size of the measurement device.

[0006] For example, in Patent Document 2, the wavefront of a portion of a substantially parallel light beam is tilted using an optical element called a phase shifter, and then the light beam is focused on a detection unit using a cylindrical lens. In the technology described in Patent Document 2, the light travels substantially on a single axis, and the use of a cylindrical lens makes it possible to focus the light beam over a short distance, thereby enabling the entire measurement device to be made smaller.

[0007] However, in the technology described in Patent Document 2, a line sensor cannot be used because the interference fringes are not vertical but tilted. Also, in the technology described in Patent Document 2, because the actual interference fringes contain a bias component, a large gain cannot be applied to the detection result by the detection unit, and the spectrum cannot be measured with high accuracy.

[0008] The present technology has been made in view of such circumstances, and makes it possible to suitably measure the spectrum of measurement light.

[0009] A measurement device according to one aspect of the present technology includes: a beam splitting unit that splits a substantially parallel beam into a first beam and a second beam, refracts the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam, with a first reference plane including a traveling direction of the substantially parallel beam as a reference, thereby causing the first beam and the second beam to interfere with each other; a focusing unit that focuses the first beam and the second beam on a second reference plane that includes the traveling direction of the substantially parallel beam and is orthogonal to the first reference plane; a sensor unit that detects interference light between the first beam and the second beam; and a calculation unit that calculates a spectrum of the substantially parallel beam based on a detection result by the sensor unit.

[0010] In one aspect of the present technology, a substantially parallel light beam is split into a first light beam and a second light beam, the first light beam is refracted and emitted, and the second light beam is emitted in a direction symmetrical to the emission direction of the first light beam, with a first reference plane including the traveling direction of the substantially parallel light beam as a reference, thereby causing the first light beam and the second light beam to interfere with each other, and the first light beam and the second light beam are focused on a second reference plane including the traveling direction of the substantially parallel light beam and orthogonal to the first reference plane, interference light between the first light beam and the second light beam is detected, and a spectrum of the substantially parallel light beam is calculated based on the detection result of the interference light.

[0011] 1 is a diagram illustrating a configuration example of a spectroscopic measurement device according to a first embodiment of the present technology. FIG. 1 is a top view and a side view of the spectroscopic measurement device of FIG. 1. FIG. 2 is a diagram illustrating an example of interference fringes. FIG. 3 is a diagram illustrating an example of interference fringes compressed by a cylindrical lens. FIG. 4 is a top view and a side view showing a configuration example of a spectroscopic measurement device when a single member realizes the functions of generating parallel light and dividing and refracting parallel light. FIG. 5 is a top view and a side view showing a configuration example of a spectroscopic measurement device when a single member realizes the functions of dividing, refracting, and focusing parallel light. FIG. 6 is a diagram illustrating an example of a slit. FIG. 7 is a diagram illustrating an example of an arrangement of a slit member. FIG. 8 is a diagram illustrating the appearance of a lens member. FIG. 9 is a diagram for explaining a lens member. FIG. 10 is a top view and a side view showing a configuration example of a spectroscopic measurement device when a lens member is provided. FIG. 11 is a diagram illustrating the appearance of a lens member. FIG. 12 is a top view and a side view of a spectroscopic measurement device 1 when a lens member and a cylindrical lens are integrated. FIG. 13 is a top view and a side view of a spectroscopic measurement device when a lens and a lens member are integrated. FIG. 14 is a diagram illustrating a configuration example of a spectroscopic measurement device according to a third embodiment of the present technology. FIG. 15 is a diagram illustrating the appearance of a prism member. 16 is a top view and a side view of the spectroscopic measurement device of FIG. 15. It is a diagram showing an example of a light distribution on a plane on which a light receiving sensor is arranged. It is a diagram showing an example of a detection result of a light distribution by a light receiving sensor. It is a block diagram showing an example of the configuration of a calculation unit. It is a diagram showing another example of the appearance of a prism member. It is a diagram showing the appearance of a lens member. It is a diagram for explaining a lens member. It is a top view and a side view showing an example of the configuration of a spectroscopic measurement device when a lens member is provided. It is a top view and a side view of a spectroscopic measurement device when a lens member and a cylindrical lens are integrated. It is a diagram showing an example of the configuration of a spectroscopic measurement device used in thermal gradient spectroscopy. It is a diagram showing an example of the configuration of a spectroscopic measurement device when the surface temperature of an object to be measured is changed by laser light. It is a diagram showing another example of the configuration of a spectroscopic measurement device when the surface temperature of an object to be measured is changed by laser light.

[0012] Hereinafter, embodiments for carrying out the present technology will be described in the following order: 1. First embodiment 2. Second embodiment 3. Third embodiment 4. Fourth embodiment 5. Modification

[0013] 1. First Embodiment FIG. 1 is a diagram illustrating an example of the configuration of a spectroscopic measurement device 1 according to a first embodiment of the present technology.

[0014] As shown in FIG. 1, a spectroscopic measurement device 1 according to a first embodiment of the present technology is configured with a slit member 11, a lens 12, a biprism 13, a cylindrical lens 14, a light receiving sensor 15, and a calculation unit (not shown).

[0015] In the following description, the x-axis indicates the lateral direction (horizontal direction) when viewing the spectroscopic measurement device 1 from the light incident surface side, the y-axis indicates the height direction, and the z-axis indicates the depth direction. The z-axis corresponds to the optical axis of the spectroscopic measurement device 1, and the optical axis indicates the direction of travel of the approximately parallel light beams traveling within the spectroscopic measurement device 1. The yz-plane indicates a plane (first reference plane) that includes the optical axis, and the zx-plane indicates a plane (second reference plane) that includes the optical axis and is perpendicular to the yz-plane.

[0016] The slit member 11 is configured by arranging one slit, for example, in the shape of a strip, through which measurement light passes.

[0017] The lens 12, like the other optical components (biprism 13 and cylindrical lens 14) described below, is made of a material that is transparent to the measurement light. When the measurement light is visible light, examples of materials for the lens 12 include glass and plastic, and when the measurement light is in the mid-infrared range, examples of materials for the lens 12 include silicon and germanium. Like the other optical components, the lens 12 is desirably treated with an anti-reflection coating to improve light utilization efficiency and prevent stray light. Because anti-reflection coating increases costs, it may not be necessary to apply the anti-reflection coating depending on the design.

[0018] Various processing methods can be applied to optical components made of transparent materials such as the lens 12. For example, glass molding is used for glass (optical glass for visible light and chalcogenide glass for the mid-infrared region), injection molding is used for plastic, and cutting is used for germanium and silicon. The processing method for optical components is determined at the discretion of the designer, taking into account factors such as mass productivity and cost.

[0019] The biprism 13 is an optical element formed by joining two prisms together. The two prisms are joined together along the yz plane, for example.

[0020] The cylindrical lens 14 is an optical element having, for example, a semi-cylindrical curved surface as the light incident surface extending in the x-axis direction, and a flat light exit surface.

[0021] The light receiving sensor 15 is a sensor that measures the light distribution. The light receiving sensor 15 is configured, for example, as a line sensor in which pixels are arranged in the x-axis direction (linearly), and detects the intensity of light incident on each pixel.

[0022] The calculation unit calculates the spectrum of the measurement light based on the detection result by the light receiving sensor 15.

[0023] Fig. 2 is a top view and a side view of the spectroscopic measurement device 1 of Fig. 1. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 2, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 2.

[0024] For example, measurement light reflected from the object to be measured enters the slit member 11 from the left side of Fig. 2, and the light that passes through the slit is converted into a substantially parallel beam by the lens 12. The lens 12 functions as a beam generator that converts the light that passes through the slit into a substantially parallel beam. The substantially parallel beam is guided to the biprism 13.

[0025] 2, the biprism 13 has a shape symmetrical with respect to the yz plane, and the light incident surface of the biprism 13 is composed of planes SF1 and SF2 inclined by an angle θ about the y axis with respect to the incident light wavefront (a plane parallel to the xy plane). In other words, the biprism 13 has two planes, the light incident surface or light exit surface of which is inclined symmetrically with respect to the yz plane. In other words, the biprism 13 is composed of a prism including the plane SF1 and a prism including the plane SF2 joined along the yz plane.

[0026] The angle θ contributes to the pitch of the interference fringes generated on the light-receiving sensor 15, and if the pitch of the interference fringes is d and the wavelength of the measurement light is λ, the relationship between the angle θ, the pitch d, and the wavelength λ is λ = 2d sin θ. Therefore, the angle θ is set based on the wavelength range for which a spectrum is desired to be obtained and the pixel pitch of the light-receiving sensor 15. Normally, as the wavelength increases, the pixel pitch of the light-receiving sensor also increases proportionally, so it is considered preferable to set the angle θ to 1 degree or less regardless of the wavelength, but this depends on the design.

[0027] The substantially parallel beam (measurement light) incident on the biprism 13 is split into two beams: one refracted by the prism including the plane SF1 and the other refracted by the prism including the plane SF2. The wavefronts of the two beams are tilted toward the optical axis, and they are superimposed on the plane where the light-receiving sensor 15 is disposed.

[0028] That is, the biprism 13 functions as a beam splitter that splits a substantially parallel beam into a first beam (a beam incident on the prism including the plane SF1) and a second beam (a beam incident on the prism including the plane SF2), refracts and emits the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam with respect to the yz plane, thereby causing interference between the first beam and the second beam.

[0029] Such a configuration of a biprism and a light-receiving sensor is the configuration of a classic biprism interferometer, and interference fringes (interferogram) are observed on the light-receiving sensor.

[0030] Fig. 3 is a diagram showing an example of interference fringes, which are generated when two light beams split by the biprism 13 are superimposed on the light receiving sensor 15 without passing through the cylindrical lens 14.

[0031] The light that has passed through the prism including the plane SF1 and the light that has passed through the prism including the plane SF2 intersect on the light receiving sensor 15. If the area on the light receiving sensor onto which the light that has passed through the prism including the plane SF1 is incident is designated as A1 and the area on the light receiving sensor onto which the light that has passed through the prism including the plane SF2 is incident is designated as A2, interference fringes occur in area A11 where area A1 and area A2 overlap, as shown in FIG.

[0032] Unlike the phase shifter described in Patent Document 2, the biprism 13 of the present technology has a structure that is symmetrical with respect to the yz plane, and therefore the interference fringes observed on the light receiving sensor are also perpendicular to the yz plane, making it suitable for measuring spectra.

[0033] If a light-receiving sensor with pixels arranged in a two-dimensional array is placed behind the biprism, the light-receiving sensor can detect interference fringes (interference light between light transmitted through a prism including a plane SF1 and light transmitted through a prism including a plane SF2) as shown in Fig. 3, and the calculation unit can measure the spectrum of the measurement light based on the detection results of the interference fringes. However, since the vertical direction in Fig. 3 does not contain any information useful from the perspective of spectrum measurement, there is no problem with compressing (concentrating) the light in the vertical direction.

[0034] In terms of size and cost, it is preferable to use a line sensor in which pixels are arranged in a straight line as a light receiving sensor rather than a sensor in which pixels are arranged in a two-dimensional array. Therefore, in this technology, the light beam transmitted through the biprism 13 is focused on the zx plane by the cylindrical lens 14 (compressing the light in the y-axis direction). The cylindrical lens 14 functions as a focusing unit that focuses the light beam transmitted through the biprism 13 on the zx plane. Because the lens 12 and the biprism 13 are each symmetrical with respect to the yz plane, the pitch of the interference fringes does not change even when the light is focused on the zx plane by the cylindrical lens 14.

[0035] FIG. 4 is a diagram showing an example of interference fringes compressed by the cylindrical lens 14. In FIG.

[0036] As shown in the upper part of FIG. 4, linearly compressed interference fringes are observed on the light receiving sensor 15.

[0037] For example, when a phase shifter is used instead of the biprism 13 as in the technology described in Patent Document 2, the two light beams are asymmetric with respect to the yz plane, and therefore oblique interference fringes are formed on the light-receiving surface (focal position). If the distance between the cylindrical lens and the light-receiving surface deviates from the state in which oblique interference fringes are formed, the interference fringes will have a complex shape. Therefore, in the technology described in Patent Document 2, the distance between the cylindrical lens and the light-receiving surface must be set precisely.

[0038] In this technology, the interference fringes are formed parallel to the y-axis direction, so even if the distance between the cylindrical lens 14 and the light-receiving sensor 15 changes slightly, the image blurs in the y-axis direction, but the pitch of the interference fringes is not affected. Therefore, the spectroscopic measurement device 1 can be said to be a stable and easily adjustable device.

[0039] As described above, because interference fringes occur linearly, using a line sensor as the light-receiving sensor 15 is preferable from a cost perspective. The photoelectric conversion method of the light-receiving sensor 15 is preferably determined by the designer based on various factors, such as the wavelength range for which the spectrum is to be obtained and cost. When the measurement light is in the visible or near-infrared range, a CMOS (Complementary Metal Oxide Semiconductor) line sensor using Si, GaAs, or the like is preferable as the light-receiving sensor 15. When the measurement light is in the mid-infrared range, a bolometer, a thermopile, an MCT (Mercury Cadmium Telluride) sensor, a pyroelectric sensor, or the like is preferable as the light-receiving sensor 15. However, the sensors used as the light-receiving sensor 15 are not limited to these.

[0040] 4 shows the detection results of (the light distribution of) interference fringes by the light receiving sensor 15. The horizontal axis indicates the pixel position, and the vertical axis indicates the light intensity.

[0041] When the measurement light is monochromatic, simple interference fringes such as those shown in Fig. 4 are observed, but when the measurement light contains light of multiple wavelengths, interference fringes of various pitches corresponding to the intensity of each wavelength are observed as superimposed fringes. Therefore, the calculation unit converts the detection results by the light-receiving sensor 15 into intensities for each wavelength using calculation processing such as Fourier transform, thereby calculating the spectrum of the measurement light.

[0042] The order of each component in the spectroscopic measurement device 1 can be interchanged; for example, the order of the biprism 13 and the cylindrical lens 14 may be reversed. The order of each component can be determined at the discretion of the designer. If the incident light is parallel, the slit member 11 and the lens 12 are not necessary. For example, when used for astronomical observation or when parallel light is obtained by another optical component, the spectroscopic measurement device 1 can be configured without the slit member 11 and the lens 12.

[0043] In the above, the functions of generating (converting) parallel light, splitting and refracting parallel light, and focusing light are each realized by separate components, but at least two of these functions may also be realized by a single component.

[0044] 5 is a top view and a side view showing an example of the configuration of a spectroscopic measurement device 1 in which the functions of generating parallel light and splitting and refracting the parallel light are realized by a single component. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 5, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 5.

[0045] In Fig. 5, the same components as those in Fig. 2 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 5 differs from the spectroscopic measurement device 1 in Fig. 2 in that a composite member 31 is provided instead of the lens 12 and the biprism 13.

[0046] The composite member 31 is a member in which the lens 12 and the biprism 13 are integrated, and is a member that realizes the function of generating parallel light realized by the lens 12 ( FIG. 2 ) and the function of dividing and refracting parallel light realized by the biprism 13. The composite member 31 is an optical member, for example, in which the light incident surface has a semi-cylindrical curved surface extending in the y-axis direction, and the light exit surface has two flat surfaces that are each inclined by an angle θ around the y-axis with respect to the wavefront of the incident light.

[0047] 6 is a top view and a side view showing an example of the configuration of a spectroscopic measurement device 1 in which the functions of splitting, refracting, and focusing parallel light are realized by a single component. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 6, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 6.

[0048] In Fig. 6, the same components as those in Fig. 2 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 6 differs from the spectroscopic measurement device 1 in Fig. 2 in that a composite member 35 is provided instead of the biprism 13 and the cylindrical lens 14.

[0049] The composite member 35 is a member in which the biprism 13 and the cylindrical lens 14 are integrated, and is a member that realizes the function of dividing and refracting parallel light realized by the biprism 13 ( FIG. 2 ) and the function of focusing realized by the cylindrical lens 14. The composite member 35 is an optical member, for example, in which the light incident surface has two flat surfaces that are each inclined by an angle θ about the y-axis with respect to the wavefront of the incident light, and the light exit surface has a semi-cylindrical curved surface that extends in the x-axis direction.

[0050] FIG. 7 is a diagram showing an example of a slit.

[0051] In the present technology, basically, only one slit is arranged in the slit member 11, as shown by the slit member 11A in FIG. 7 . As the slit width (length in the x-axis direction) increases, the contrast of the interference fringes decreases, so a small width is desirable. On the other hand, there are fewer restrictions on the slit length (length in the y-axis direction), and it is sufficient to design it so that light reaches the light-receiving sensor 15. The width and length of the slit are determined by the magnification of the optical system and the sensitivity characteristics of the light-receiving sensor 15, and are therefore up to individual design.

[0052] 7, a plurality of slits may be arranged side by side in the slit member 11. Since the amount of light passing through the slit member 11 increases, the effect of increasing the intensity of light reaching the light receiving sensor 15 is expected.

[0053] However, at a certain wavelength, the interference fringes caused by light transmitted through one slit and the interference fringes caused by light transmitted through the adjacent slit have the same pitch, so that the interference fringes reinforce each other, but at a different wavelength, the interference fringes may weaken each other. Therefore, when the wavelength range for which a spectrum is desired to be obtained is limited, it is desirable to place multiple slits.

[0054] The slit member 11 does not need to be placed at a position on the upstream side of the optical system, and the position of the slit member 11 can be determined by the design. For example, as shown in Fig. 8, the slit member 11 may be placed at the focal position of the lens 12 between the lens 12 and the biprism 13. In this case, light reflected from the object to be measured Obj1 is collected by the lens 12, and the collected light passes through the slit and is guided to the biprism 13.

[0055] When the slit member 11 is disposed at a position subsequent to the lens 12, the entire optical system becomes longer, but it is possible to prevent the slit member 11 from being damaged because the slit member 11 is not exposed on the surface of the spectroscopic measurement device 1. Furthermore, when the surface of the object to be measured is not flat or when an area for installing the slit member 11 cannot be secured, it is effective to dispose the slit member 11 at the middle stage of the optical system.

[0056] 2. Second Embodiment The biprism 13 is a component that realizes the function of generating two light beams traveling in two directions. This function is not contradictory to the light-condensing function (function of generating parallel light) of the lens 12, and therefore it is possible to integrate the function of the lens 12 and the function of the biprism 13.

[0057] FIG. 9 is a diagram showing the appearance of the lens member 51. As shown in FIG.

[0058] 9, the lens member 51 has a shape symmetrical with respect to the yz plane. The lens member 51 is formed by, for example, joining a portion of a lens (lens piece) having a flat surface on one side and a curved surface on the other side with another lens piece similar to the lens piece. The lens member 51 realizes the functions of the lens 12 and the biprism 13 in an integrated manner.

[0059] FIG. 10 is a diagram for explaining the lens member 51. As shown in FIG.

[0060] Light emitted from a focal point on the optical axis is converted into a light beam parallel to the optical axis (the central axis of the lens 52) when it passes through a certain lens 52. On the other hand, as shown in A of Fig. 10, light emitted from a position P1 offset from the optical axis is converted into a light beam tilted with respect to the optical axis when it passes through the lens 52.

[0061] The lens element 51 utilizes the fact that light emitted from a position offset from the central axis is converted by the lens into a light beam tilted with respect to the optical axis, thereby realizing both a light-condensing function and a function of generating two light beams traveling in two directions. Note that, hereinafter, the central axis of the lens piece is assumed to be the same as the central axis of the original lens.

[0062] 10B, one surface of lens member 51 (e.g., the light entrance surface) is flat, and the other surface (e.g., the light exit surface) has lens surfaces SF5 and SF6. In other words, lens member 51 is formed by cementing together a lens piece including lens surface SF5 and a lens piece including lens surface SF6.

[0063] The lens piece including lens surface SF5 is formed so that its central axis C1 is located on the opposite side of the yz plane (the joint surface of the lens piece) in the zx plane. The lens piece including lens surface SF6 is formed so that its central axis C2 is located on the opposite side of the yz plane (the joint surface of the lens piece) in the zx plane. In other words, lens member 51 can also be considered an optical member having two lens surfaces SF5 and SF6, whose light entrance and exit surfaces have central axes located on opposite sides of the yz plane.

[0064] 11 is a top view and a side view showing a configuration example of the spectroscopic measurement device 1 when the lens member 51 is provided. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 11, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 11.

[0065] In Fig. 11, the same components as those in Fig. 2 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 11 differs from the spectroscopic measurement device 1 in Fig. 2 in that a lens member 51 is provided instead of the lens 12 and biprism 13.

[0066] Since the lens piece including lens surface SF5 and the lens piece including lens surface SF6 are each formed so that their central axes are located on opposite sides of the yz plane, light incident on lens member 51 is refracted by lens surfaces SF5 and SF6, and converted into two light beams (parallel light) whose wavefronts are tilted toward the optical axis.

[0067] In this way, it is possible to integrate the light-collecting function and the function of generating two light beams traveling in two directions using only one of the light entrance and exit surfaces (the surface formed by lens surfaces SF5 and SF6) of lens member 51. Compared to when lens 12 and biprism 13 are formed separately, the number of parts is reduced, and the reduced number of interfaces is expected to improve efficiency and reduce stray light.

[0068] When two lens pieces are joined together, the outer shape of the lens member 51 may not be a perfect circle but may be approximately almond-shaped, as shown in Figure 9. To make it easier to handle, it is possible to modify the outer shape of the lens member 51 or provide a flange on the outer periphery.

[0069] It should be noted that instead of integrating the functions of the lens 12 and the biprism 13, it is also possible to integrate the functions of the biprism 13 and the cylindrical lens 14.

[0070] FIG. 12 is a diagram showing the appearance of the lens member 55. As shown in FIG.

[0071] 12 has a shape symmetrical with respect to the yz plane. When viewed from above, lens member 55 is configured with two surfaces, for example, one surface SF7 having a flat surface and the other surface SF8 tilted by an angle θ about the y axis with respect to the wavefront of the incident light (a surface parallel to the xy plane), and is formed to have a semi-cylindrical curved surface when viewed from the side.

[0072] The lens element 55 combines the function of generating two light beams in two directions using the biprism 13 and the function of focusing light in a straight line using the cylindrical lens 14, and can be realized using only the light exit surface (surface SF8).

[0073] 13 is a top view and a side view of the spectroscopic measurement device 1 when the lens member 51 and the cylindrical lens 14 are integrated together. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 13, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 13.

[0074] In Fig. 13, the same components as those in Fig. 2 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 13 differs from the spectroscopic measurement device 1 in Fig. 2 in that a composite member 61 is provided instead of the lens 12, the biprism 13, and the cylindrical lens 14.

[0075] The composite member 61 is a member in which the lens member 51 and the cylindrical lens 14 are integrated. The light incident surface of the composite member 61 has a lens surface SF11 corresponding to the lens surface SF5 of the lens member 51, and a lens surface SF12 of the lens member 51. The light exit surface of the composite member 61 has a semi-cylindrical curved surface SF13 extending in the x-axis direction.

[0076] In this case, lens surfaces SF11 and SF12 convert the light incident on composite member 61 into two beams traveling in two directions, and curved surface SF13 focuses the two beams in the y-axis direction.

[0077] 14 is a top view and a side view of the spectroscopic measurement device 1 when the lens 12 and the lens member 55 are integrated together. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 14, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 14.

[0078] In Fig. 14, the same components as those in Fig. 2 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 14 differs from the spectroscopic measurement device 1 in Fig. 2 in that a composite member 62 is provided instead of the lens 12, the biprism 13, and the cylindrical lens 14.

[0079] The composite member 62 is a member in which the lens 12 and the lens member 55 are integrated. The light incident surface of the composite member 62 has a lens surface SF21 corresponding to the lens surface of the lens 12, and the light exit surface of the composite member 62 has a surface SF22 corresponding to the surface SF8 of the lens member 55.

[0080] In this case, the lens surface SF21 converts the light incident on the composite member 61 into an approximately parallel beam of light, and the surface SF22 converts the approximately parallel beam of light into two beams of light traveling in two directions, and the two beams of light are focused on the zx plane.

[0081] As described above, it is possible to assign functions to the light entrance surface and the light exit surface of the optical member. When forming an optical member such as composite member 61 or composite member 62, it is more difficult to process the material, but all optical functions can be concentrated in one member, which is expected to have effects such as improved light utilization efficiency, miniaturization, and reduction of stray light.

[0082] 15 is a diagram showing a configuration example of a spectroscopic measurement device 1 according to a third embodiment of the present technology. In Fig. 15, the same components as those in Fig. 1 are denoted by the same reference numerals. Duplicate descriptions will be omitted as appropriate.

[0083] The spectroscopic measurement device 1 of Figure 15 differs from the spectroscopic measurement device 1 of Figure 1 in that a prism member 101 is provided instead of the biprism 13, and that light receiving sensors 111 and 112 are provided instead of the light receiving sensor 15.

[0084] The prism member 101 is configured by joining three prisms together, where two of the three prisms are joined together along the yz plane, for example, and one of the three prisms is joined together along the zx plane, for example, with the two prisms joined together along the yz plane.

[0085] The light receiving sensors 111 and 112 are each configured, for example, by a line sensor in which pixels are arranged in the x-axis direction. The light receiving sensor 111 (second line sensor) detects a light beam in which no interference fringes are generated, and the light receiving sensor 112 (first line sensor) detects interference fringes (interfering light). The light receiving sensors 111 and 112 are arranged in the y-axis direction. In other words, the light receiving sensors are configured by a plurality of pixels arranged in an array of two rows and multiple columns.

[0086] The calculation unit calculates the spectrum of the measurement light based on the detection results from the light receiving sensors 111 and 112. The method of calculating the spectrum by the calculation unit will be described later.

[0087] FIG. 16 is a diagram showing the appearance of the prism member 101. As shown in FIG.

[0088] While the light incident surface of the biprism 13 is composed of two planes SF1 and SF2 tilted symmetrically about the y-axis with respect to the wavefront of the incident light, the light incident surface of the prism member 101 is composed of planes SF51 and SF52 corresponding to the planes SF1 and SF2 of the biprism 13, and a plane SF53 tilted with respect to the wavefront of the incident light. The plane SF53 is a plane tilted with respect to the x-axis with respect to the wavefront of the incident light. In other words, the prism member 101 can be said to be an optical member whose light incident or exit surface has two planes tilted symmetrically with respect to the yz-plane and one plane tilted with respect to the zx-plane.

[0089] It is desirable that the prism member 101 have a shape that is symmetrical with respect to the yz plane in order to ensure the symmetry of the interference fringes observed on the light receiving sensors 111 and 112. In other words, it is desirable that the prism member 101 be formed so that the planes SF51 and SF52 are arranged symmetrically with respect to the yz plane, and the plane SF53 is symmetrical with respect to the yz plane.

[0090] Fig. 17 is a top view and a side view of the spectrometer 1 of Fig. 15. The top view of the spectrometer 1 is shown in the upper part of Fig. 17, and the side view of the spectrometer 1 is shown in the lower part of Fig. 17.

[0091] For example, measurement light reflected from the object to be measured enters the slit member 11 from the left side of FIG. 17, and the light transmitted through the slit is converted into a substantially parallel beam by the lens 12. The substantially parallel beam is guided to the prism member 101.

[0092] The approximately parallel light beam incident on the prism member 101 is split into three light beams: a light beam (first light beam) refracted by the prism including the plane SF51, a light beam (second light beam) refracted by the prism including the plane SF52, and a light beam (third light beam) refracted by the prism including the plane SF53.

[0093] As described in the first embodiment, the wavefronts of the light beam refracted by the prism including the flat surface SF51 and the light beam refracted by the prism including the flat surface SF52 are tilted toward the optical axis (x-axis direction), and are collected by the cylindrical lens 14 onto the light-receiving sensor 112 and overlapped on the light-receiving sensor 112. Therefore, interference fringes are observed on the light-receiving sensor 112.

[0094] The light beam refracted by the prism including the plane SF51 and the light beam refracted by the prism including the plane SF52 are used to measure the spectrum.

[0095] On the other hand, the light beam refracted by the prism including the plane SF53 has its wavefront tilted toward the optical axis (y-axis direction), and is focused by the cylindrical lens 14 onto the light receiving sensor 111, which is located at a different position from the light receiving sensor 112.

[0096] FIG. 18 is a diagram showing an example of a light distribution on a plane on which the light receiving sensors 111 and 112 are arranged.

[0097] 18, interference fringes occur in the lower portion of the plane (the portion where the light receiving sensor 112 is located) where the light receiving sensors 111 and 112 are located. On the other hand, no interference fringes occur in the upper portion of the plane (the portion where the light receiving sensor 111 is located) because only the light beam refracted by the prism including the plane SF53 is collected.

[0098] By placing the light receiving sensor 112 in the lower part where interference fringes occur and the light receiving sensor 111 in the upper part where interference fringes do not occur, it is possible to detect the light distribution without interference fringes and the light distribution with interference fringes, respectively.

[0099] 18 shows the light distribution when the slit is infinitesimally small, and light does not reach the middle portion of the plane where the light receiving sensors 111 and 112 are arranged. In reality, the length of the slit in the y-axis direction is finite, and as the length of the slit in the y-axis direction increases, the upper and lower portions where light reaches become wider, and the dark band in the middle portion is eroded. The length of this dark band in the y-axis direction is determined by the inclination angle of the plane SF53 of the prism member 101, and therefore the inclination angle of the plane SF53 is appropriately designed based on the length of the slit in the y-axis direction and the distance between the light receiving sensors 111 and 112.

[0100] 18, the light beam refracted by the prism including the flat surface SF53 and the interference light resulting from the superposition of the light beam refracted by the prism including the flat surface SF51 and the light beam refracted by the prism including the flat surface SF52 are not focused on a single line. This phenomenon occurs due to aberrations of the lens 12 and the cylindrical lens 14, etc.

[0101] In reality, noise (stray light) is generated due to the uneven distribution of light either locally or globally due to reflection, scattering, and diffraction at each component. Furthermore, light receiving sensors generate noise caused by devices such as dark current and fixed pattern noise. Because signals resulting from various factors that differ from ideal conditions are input to the light receiving sensor, the detection results from the light receiving sensor contain a significant amount of bias component.

[0102] Since the detection results by the light receiving sensors 111 and 112 are considered to contain similar bias components, the calculation unit of the spectroscopic measurement device 1 can use the detection results by the light receiving sensors 111 to remove the bias components contained in the detection results by the light receiving sensors 112.

[0103] Fig. 19 is a diagram showing an example of the detection results of the light distribution by the light receiving sensors 111 and 112. In Fig. 19, the horizontal axis indicates the pixel position, and the vertical axis indicates the light intensity.

[0104] 19, the detection result by the light receiving sensor 111 is indicated by a dotted line, and the detection result by the light receiving sensor 112 is indicated by a solid line. Because the combined area of ​​the planes SF51 and SF52 is different from the area of ​​the plane SF53, the intensities of light detected by the light receiving sensors 111 and 112 are different. However, in the example at the top of FIG. 19, the detection results by the light receiving sensors 111 and 112 are adjusted so that their integral values ​​match.

[0105] For example, assuming that the maximum sensitivity of the light receiving sensor is 1, a bias component of about 0.2 is included in the entire detection result, so the maximum value of the detection result by the light receiving sensor 111 is about 0.33. Therefore, the detection result by the light receiving sensor 111 can only be applied with a gain of about 3 times at most.

[0106] 19 shows the difference between the detection result by the light receiving sensor 111 and the detection result by the light receiving sensor 112. Because the maximum value of the difference between the detection result by the light receiving sensor 111 and the detection result by the light receiving sensor 112 is about 0.1, a gain of about 10 times can be applied to this difference. Therefore, by differentially amplifying the detection results by the light receiving sensors 111 and 112, a large gain can be applied to the detection result of the optical distribution of interference fringes, making it possible to measure the spectrum with high accuracy.

[0107] As mentioned above, there are various types of light receiving sensors, but since photoelectric conversion alone does not provide sufficient output, many types of light receiving sensors are provided with an amplifier circuit in the subsequent stage. The amplifier circuit is provided as part of the calculation unit, for example.

[0108] If the amount of light flux incident on the plane SF51 and the plane SF52 is expected to be equal to the amount of light flux incident on the plane SF53, the bias component can be removed without being affected by noise generated during amplification by the amplifier circuit by subtracting the output of the light receiving sensor 111 from the output of the light receiving sensor 112 before amplifying them. For example, if a sensor with polarity such as a pyroelectric sensor is used as the light receiving sensor, the bias component can be effectively removed by reversing the polarity of the light receiving sensor 111 and the light receiving sensor 112 and connecting each pixel by column.

[0109] The ratio of the amount of light flux incident on the planes SF51 and SF52 to the amount of light flux incident on the plane SF53 is preferably determined based on design conditions and noise conditions. For example, if the bias component due to stray light is relatively small, it is preferable to reduce the relative area of ​​the plane SF53 and increase the amount of light flux collected on the light-receiving sensor 112. In an optical system with no bias component at all, it is preferable to use the biprism 13 instead of the prism member 101.

[0110] For example, when a sensor such as a Si sensor or a bolometer, which does not have polarity and whose output changes depending on the amount of light received, is used as a light receiving sensor, an amplifier circuit is provided for each light receiving sensor (light receiving sensor 111 and light receiving sensor 112).

[0111] FIG. 20 is a block diagram showing an example of the configuration of the calculation unit.

[0112] As shown in FIG. 20, the calculation section is made up of, for example, amplifier circuits 151 and 152, a gain calculation section 153, a differential amplifier circuit 154, and a spectrum calculation section 155.

[0113] The amplifier circuit 151 applies a gain (first gain) to the output (detection result) of the light receiving sensor 111 and supplies the result to a differential amplifier circuit 154 .

[0114] The amplifier circuit 152 applies a gain (second gain) to the output (detection result) of the light receiving sensor 112 and supplies the result to a differential amplifier circuit 154 .

[0115] The gain calculation unit 153 calculates the value of the gain to be applied to the output of the light receiving sensor in each of the amplifier circuits 151 and 152 , and controls the amplifier circuits 151 and 152 .

[0116] The differential amplifier circuit 154 amplifies the difference between the output of the light receiving sensor 111 to which the gain has been applied by the amplifier circuit 151 and the output of the light receiving sensor 112 to which the gain has been applied by the amplifier circuit 152 , and supplies the amplified difference to the spectrum calculation section 155 .

[0117] The spectrum calculation section 155 performs calculation processing such as Fourier transform based on the difference supplied from the differential amplifier circuit 154 to calculate the spectrum of the measurement light.

[0118] In this way, the gain calculation unit 153 of the calculation unit can balance the outputs of the light receiving sensors 111 and 112 by appropriately adjusting the amounts of amplification by the amplifier circuits 151 and 152 .

[0119] For example, the gains of the amplifier circuits 151 and 152 are adjusted so that the integrated value or average value of the pixel values ​​of all pixels of the light receiving sensor 111 and the integrated value or average value of the pixel values ​​of all pixels of the light receiving sensor 112 become the same.

[0120] Furthermore, for example, since the difference between the outputs of the light-receiving sensors 111 and 112 includes positive and negative values, the gains of the amplifier circuits 151 and 152 are adjusted so that the integrated value of the difference between the outputs of the light-receiving sensors 111 and 112 is minimized. Here, the output from the light-receiving sensor may contain both bias components that are independent of the amount of incident light flux, such as fixed noise and dark current, and bias components that are dependent on the amount of incident light flux, such as stray light. Furthermore, the sensitivity of each pixel of the light-receiving sensor may vary. In such cases, it is desirable to remove the bias components that are independent of the amount of incident light flux, and then adjust the gains of the amplifier circuits 151 and 152, taking into account only the bias components that are dependent on the amount of incident light flux. In this case, the integrated value of the difference between the outputs of the light-receiving sensors 111 and 112 is not necessarily minimized.

[0121] The gain values ​​in the amplifier circuits 151 and 152 may be recorded in a recording unit provided in the spectroscopic measurement device 1 during the adjustment process when creating the spectroscopic measurement device 1, or may be dynamically adjusted when measuring the spectrum.

[0122] When the differential amplifier circuit 154 outputs positive and negative voltages, it is necessary to supply a negative voltage to the differential amplifier circuit 154, which may complicate the circuitry of the arithmetic unit. In this case, adding a predetermined bias voltage so that the voltage output from the differential amplifier circuit 154 becomes a positive voltage can prevent the circuitry of the arithmetic unit from becoming complicated.

[0123] The specific shape of the prism member is determined as appropriate by the designer, and is not limited to the shape described with reference to Figure 16, as long as it is possible to generate at least two light beams that form interference fringes and at least one light beam that does not form interference fringes from one substantially parallel light beam.

[0124] FIG. 21 is a diagram showing another example of the appearance of the prism member.

[0125] 21A, the light incidence surface of the prism member 102 has planes SF51 and SF52 corresponding to planes SF1 and SF2 of the biprism 13, a plane SF53 tilted with respect to the wavefront of the incident light, and a plane SF54 tilted with respect to the wavefront of the incident light at an angle different from that of plane SF53. The planes SF53 and SF54 are planes tilted about the x-axis with respect to the wavefront of the incident light.

[0126] On the plane on which the light receiving sensors 111 and 112 are arranged, the light is not actually focused in a straight line, but spreads out above and below the bright linear portion, due to the influence of, for example, the aberration of the cylindrical lens 14. When the light incident surface is viewed from the front, by arranging the planes SF51 and SF52 in the middle and the planes SF53 and SF54 in the upper and lower stages, as in the prism member 102, only the light beam refracted by the planes SF53 and SF54 is strongly affected by the aberration of the cylindrical lens 14, and the light beam refracted by the planes SF51 and SF52 is not greatly affected by the aberration.

[0127] Therefore, the light beam that is strongly affected by the aberration of the cylindrical lens 14 can be used for bias removal, and the light beam that is not so affected by the aberration can be used for detecting interference fringes.

[0128] In the prism member 102, the inclination angles of the planes SF53 and SF54 are different, so that the light beam used for bias removal is focused at two locations. For example, as shown in the prism member 103 in FIG. 21B, the inclination angles of the planes SF53 and SF54 may be adjusted so that the light beam refracted by the planes SF53 and SF54 is focused at one location.

[0129] 21C, when the light incident surface is viewed from the front, planes SF51 and SF52 may be disposed in the center, and plane SF55, which is tilted about the x-axis with respect to the wavefront of the incident light, may be disposed so as to surround planes SF51 and SF52. In this case, the light beam that is strongly affected by the aberration of lens 12 can be used for bias removal.

[0130] 4. Fourth Embodiment As in the second embodiment, it is also possible to integrate the function of the lens 12 and the function of the prism member 101.

[0131] FIG. 22 is a diagram showing the appearance of the lens member 201. As shown in FIG.

[0132] 22, the lens member 201 has a shape that is symmetrical with respect to the yz plane. The lens member 201 is formed by, for example, cementing together three lens portions (lens pieces) each having a flat light exit surface and a curved light entrance surface.

[0133] The light incidence surface of lens member 201 has lens surfaces SF101, SF102, and SF103. In lens member 201, a lens piece including lens surface SF101 and a lens piece including lens surface SF102 are cemented together along the yz plane. Lens surface SF101 corresponds to lens surface SF5 ( FIG. 10 ) of lens member 51, and lens surface SF102 corresponds to lens surface SF6 of lens member 51. In lens member 201, lens surface SF103 is cemented to each of the lens pieces including lens surface SF101 and lens surface SF102, and corresponds to plane SF53 of prism member 101.

[0134] The lens member 201 realizes the functions of the lens 12 and the prism member 101 in an integrated manner.

[0135] FIG. 23 is a diagram for explaining the lens member 201. As shown in FIG.

[0136] The lens piece including lens surface SF101 is formed so that its central axis C101 (center point P51) is located on the opposite side of the yz plane (the joint surface of the lens piece) on a plane parallel to the zx plane. Also, the lens piece including lens surface SF102 is formed so that its central axis C102 (center point P52) is located on the opposite side of the yz plane (the joint surface of the lens piece) on a plane parallel to the zx plane.

[0137] Furthermore, the lens piece including the lens surface SF103 is formed so that its central axis (center point P53) is located on the opposite side of the zx plane in the yz plane. In other words, the lens member 201 can be said to be an optical member having two lens surfaces, each with its central axis located on the opposite side of the yz plane, as the light entrance or exit surface, and one lens surface with its central axis located on the opposite side of the zx plane. The central axis of the lens piece including the lens surface SF103 can be located anywhere on the yz plane, as long as it does not coincide with the optical axis. The position of the central axis of the lens piece including the lens surface SF103 can be designed based on the desired position at which the light beam used for bias removal is focused.

[0138] Fig. 24 is a top view and a side view showing a configuration example of the spectroscopic measurement device 1 when the lens member 201 is provided. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 24, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 24.

[0139] In Fig. 24, the same components as those in Fig. 17 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 24 differs from the spectroscopic measurement device 1 in Fig. 17 in that a lens member 201 is provided instead of the lens 12 and the prism member 101.

[0140] Since the lens piece including the lens surface SF101 and the lens piece including the lens surface SF102 are each formed so that their central axes are located on opposite sides of the yz plane, light incident on the lens member 201 is refracted by the lens surfaces SF101 and SF102, and converted into two light beams whose wavefronts are tilted toward the optical axis (y-axis direction).

[0141] The light beam refracted by the lens piece including the lens surface SF101 and the light beam refracted by the lens piece including the lens surface SF102 are focused onto the light receiving sensor 112 by the cylindrical lens 14 and overlapped on the light receiving sensor 112.

[0142] Furthermore, since the lens piece including the lens surface SF103 is formed so that its central axis is located on the opposite side of the zx plane, light incident on the lens member 201 is refracted by the lens surface SF103 and converted into a light beam whose wavefront is tilted toward the optical axis (x-axis direction).

[0143] The light beam refracted by the lens piece including the lens surface SF103 is condensed onto the light receiving sensor 111 by the cylindrical lens 14.

[0144] In this way, it is possible to integrate and realize the light-collecting function and the function of generating three light beams traveling in three directions using only one of the light entrance surface and exit surface (the surface formed by lens surfaces SF101, SF102, and SF103) of lens member 201. Compared to when lens 12 and prism member 101 are formed separately, the number of parts is reduced, and the reduced number of interfaces is expected to improve efficiency and reduce stray light.

[0145] 25 is a top view and a side view of the spectroscopic measurement device 1 when the lens member 201 and the cylindrical lens 14 are integrated together. The top view of the spectroscopic measurement device 1 is shown in the upper part of Fig. 25, and the side view of the spectroscopic measurement device 1 is shown in the lower part of Fig. 25.

[0146] In Fig. 25, the same components as those in Fig. 17 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in Fig. 25 differs from the spectroscopic measurement device 1 in Fig. 17 in that a composite member 211 is provided instead of the lens 12, the prism member 101, and the cylindrical lens 14.

[0147] The composite member 211 is a member in which the lens member 201 and the cylindrical lens 14 are integrated. The light incident surface of the composite member 211 has a lens surface SF111 corresponding to the lens surface SF101 of the lens member 201, a lens surface SF112 corresponding to the lens surface SF102 of the lens member 201, and a lens surface SF113 corresponding to the lens surface SF103 of the lens member 201. The light exit surface of the composite member 211 has a semi-cylindrical curved surface SF121 extending in the x-axis direction.

[0148] In this case, the lens surfaces SF111, SF112, and SF113 convert the light incident on the composite member 211 into three light beams traveling in three directions, and the curved surface SF121 focuses the three light beams in the y-axis direction.

[0149] As described above, it is possible to assign functions to the light entrance surface and the light exit surface of the optical element. When forming the composite element 211, it is more difficult to process the material, but since all optical functions can be concentrated in one element, it is expected to have effects such as improved light utilization efficiency, miniaturization, and reduction of stray light.

[0150] 5. Modifications In the spectroscopic measurement device 1 of the present technology, there is no limitation on the wavelength of the measurement light. Currently, many small-sized devices are commercially available as spectroscopes for the visible light range to the near-infrared range, and therefore it is expected that the spectroscopic measurement device 1 of the present technology will be applied to a spectroscope for the mid-infrared range.

[0151] Currently, spectrometers using a Michelson interferometer are widely used as mid-infrared spectrometers. However, because a spectrometer using a Michelson interferometer has moving parts, it is not very robust and is not very portable. Furthermore, because a spectrometer using a Michelson interferometer requires a certain amount of time for the mirror to scan in order to obtain a single spectrum, it is not suitable for applications such as measuring moving samples or observing the time response to some kind of stimulus.

[0152] The spectroscopic measurement device 1 of the present technology can be used for transmission measurement, reflection measurement, ATR (Attenuated Total Reflection), and the like, similar to a spectrometer using a Michelson interferometer.

[0153] Since the optical members are arranged on a substantially uniaxial line, the spectroscopic measurement device 1 of the present technology is smaller than a spectrometer using a Michelson interferometer, and since there are no moving parts, the spectroscopic measurement device 1 of the present technology is highly robust. Furthermore, since a line sensor is used as the light-receiving sensor 15, it is possible to measure the spectrum at high speed.

[0154] Because the spectroscopic measurement device 1 of the present technology can measure spectra at high speed, it can suitably measure the spectroscopic response of an object to be measured to some kind of stimulus that would be difficult to measure with a spectrometer using a Michelson interferometer.

[0155] The spectroscopic measurement device 1 of the present technology can be used, for example, in thermal gradient spectroscopy, in which the surface of an object to be measured is heated with a heater, and the increase in radiant light emitted from the heated surface of the object to be measured is observed while being dispersed, thereby allowing the absorption spectrum of the object to be calculated.

[0156] FIG. 26 is a diagram showing an example of the configuration of a spectroscopic measurement device 1 used in thermal gradient spectroscopy.

[0157] The spectrometer 1 in FIG. 26 is configured by arranging a slit member 301, a lens 12, a prism member 101, a cylindrical lens 14, and a light receiving sensor 112 (light receiving sensor 111) substantially on one axis.

[0158] At least one slit is arranged in the slit member 301. The slit member 301 is arranged in close contact with the object to be measured Obj11, and also functions as a temperature change section that changes the surface of the object to be measured Obj11.

[0159] The slit member 301 is formed by patterning a heater circuit on a transparent material such as germanium. The slit member 301 is formed so that the opening of the heater circuit also functions as a slit. Because the heater is provided in the slit member 301, the surface of the object to be measured Obj11 around the slit can be suitably heated without having to provide a heater and a slit member separately.

[0160] The spectroscopic measurement device 1 of the present technology can measure spectra at high speed, and therefore can continuously measure spectra in synchronization with the heating of the heater (changes in the surface temperature of the object being measured), and by measuring the response of each wavelength of radiant light to changes in surface temperature, it is possible to ultimately measure the absorption spectrum of the object being measured.

[0161] Instead of a heater, for example, a laser beam may be used to change the surface temperature of the object to be measured.

[0162] FIG. 27 is a diagram showing an example of the configuration of the spectroscopic measurement device 1 when the surface temperature of the object to be measured is changed by laser light.

[0163] For example, if the wavelength of the radiant light from the object to be measured is assumed to be 6 to 13 μm, the surface of the object to be measured is heated with laser light having a wavelength of, for example, 3 μm. In this case, the spectroscopic measurement device 1 shown in Fig. 27 is configured by arranging the lens 12, long-pass filter 311, slit member 11, prism member 101, cylindrical lens 14, and light-receiving sensor (not shown) approximately on one axis.

[0164] 27, laser light is introduced from the side of the optical axis of the spectroscopic measurement device 1, reflected by the long-pass filter 311, and irradiated onto the surface of the object to be measured Obj21. The radiated light emitted from the object to be measured Obj21 passes through the lens 12, the long-pass filter 311, the slit member 11, the prism member 101, and the cylindrical lens 14, and is collected on the light-receiving sensor.

[0165] The laser light is reflected by the object to be measured Obj21 side of the long-pass filter 311 and does not pass through to the light receiving sensor side, so that only the radiant light from the object to be measured Obj21 can be detected by the light receiving sensor.

[0166] FIG. 28 is a diagram showing another example of the configuration of the spectroscopic measurement device 1 when the surface temperature of the object to be measured is changed by laser light.

[0167] The spectrometer 1 in FIG. 28 is composed of a lens 12, a parabolic mirror 321, a slit member 11, a prism member 101, a cylindrical lens 14, a light receiving sensor (not shown), and a laser light source.

[0168] A through-hole is formed in the mirror surface of the parabolic mirror 321. As shown by the arrow in Fig. 28, laser light emitted from the light source of the laser light passes through the through-hole of the parabolic mirror 321 and is irradiated onto the surface of the object to be measured Obj31 from the top to the bottom in Fig. 28. The light source of the laser light functions as a temperature changing unit that changes the surface temperature of the object to be measured by irradiating the surface of the object to be measured with laser light.

[0169] The mirror surface of the parabolic mirror 321 is disposed at an angle to the right in Fig. 28 with respect to the object to be measured Obj31. Radiant light emitted in the upward direction in Fig. 28 from the object to be measured Obj31 is converted into a parallel beam by the lens 12, and the parallel beam is condensed to the right in Fig. 28 by the mirror surface of the parabolic mirror 321 and passes through the slit member 11, the prism member 101, and the cylindrical lens 14.

[0170] The spectroscopic measurement device 1 of the present technology can measure the absorption spectrum of a measurement object in the mid-infrared range regardless of the thickness of the measurement object, and can therefore be used, for example, to measure the absorption spectrum of a living body. In this case, reflected light, transmitted light, scattered light, etc. incident on the living body are converted into parallel beams of light by the lens 12, and then split into at least two beams of light by a prism member 101 or the like, and used to measure the absorption spectrum of the living body. For example, the spectroscopic measurement device 1 of the present technology can be used to measure the moisture content of skin, subcutaneous blood glucose levels, cholesterol levels, etc.

[0171] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0172] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology.

[0173] <Examples of Combinations of Configurations> The present technology can also have the following configurations.

[0174] (1) A measurement device comprising: a beam splitter that splits a substantially parallel beam into a first beam and a second beam, refracts the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam with respect to a first reference plane that includes the traveling direction of the substantially parallel beam, thereby causing the first beam and the second beam to interfere with each other, a focusing unit that focuses the first beam and the second beam on a second reference plane that includes the traveling direction of the substantially parallel beam and is orthogonal to the first reference plane, a sensor unit that detects interference light between the first beam and the second beam, and a calculation unit that calculates a spectrum of the substantially parallel beam based on a detection result by the sensor unit. (2) The measurement device according to (1), wherein the beam splitter is configured by an optical member whose light entrance surface or exit surface has two flat surfaces that are inclined symmetrically with respect to the first reference plane. (3) The measurement device according to (1), wherein the beam splitter is configured by an optical element having an entrance surface or exit surface of light with two lens surfaces whose central axes are located on opposite sides of the first reference plane. (4) The measurement device according to any of (1) to (3), wherein the sensor unit is configured by a line sensor with pixels arranged in a straight line. (5) The measurement device according to (4), wherein the beam splitter further splits the approximately parallel beam into a third beam. (6) The measurement device according to (5), wherein the beam splitter is configured by an optical element having an entrance surface or exit surface of light with two planes tilted symmetrically with respect to the first reference plane and one plane tilted with respect to the second reference plane. (7) The measurement device according to (5), wherein the light beam splitter is configured by an optical member having an incident surface or an exit surface of light, and the incident surface or exit surface of light has two lens surfaces whose central axes are located on opposite sides of the first reference plane, and one lens surface whose central axis is located on the opposite side of the second reference plane. (8) The measurement device according to any of (5) to (7), wherein the sensor unit is configured by a first line sensor that detects the interference light and a second line sensor that detects the third light beam.(9) The measurement device according to (8), wherein the calculation unit calculates the spectrum based on the detection result by the first line sensor and the detection result by the second line sensor. (10) The measurement device according to (9), wherein the calculation unit amplifies the difference between the detection result by the first line sensor and the detection result by the second line sensor, and calculates the spectrum based on the amplified difference. (11) The measurement device according to (10), wherein the calculation unit multiplies the detection result by the first line sensor by a first gain and the detection result by the second line sensor by a second gain, and then amplifies the difference between the detection result by the first line sensor and the detection result by the second line sensor. (12) The measurement device according to (11), wherein the calculation unit adjusts the first gain and the second gain. (13) The measurement device according to (8), wherein each pixel of the first line sensor and each pixel of the second line sensor are connected by a column. (14) The measurement device according to any one of (1) to (13), further comprising: a slit member having a slit arranged therein; and a light beam generating unit that converts light transmitted through the slit into the approximately parallel light beam. (15) The measurement device according to (14), further comprising a temperature changing unit that changes the surface temperature of the object to be measured, wherein the light transmitted through the slit is radiant light emitted from the surface of the object to be measured. (16) The measurement device according to (15), wherein the calculation unit calculates the spectrum in synchronization with a change in the surface temperature of the object to be measured caused by the temperature changing unit. (17) The measurement device according to (15) or (16), wherein the temperature changing unit is constituted by a heater provided in the slit member. (18) The measurement device according to (15) or (16), wherein the temperature changing unit changes the surface temperature of the object to be measured by irradiating light onto the surface of the object to be measured. (19) The measurement device according to any one of (14) to (18), wherein the light beam generating unit and the light beam dividing unit, or the light beam dividing unit and the light collecting unit, are configured by a single optical member.(20) The measurement device according to any one of (1) to (19), wherein the beam splitter splits light incident from a living body into the first beam and the second beam.

[0175] REFERENCE SIGNS LIST 1 Spectroscopic measurement device, 11 Slit member, 12 Lens, 13 Biprism, 14 Cylindrical lens 14 Light receiving sensor, 31, 35 Composite member, 51, 55 Lens member, 61, 62 Composite member, 101 to 104 Prism member, 111, 112 Light receiving sensor, 151, 152 Amplification circuit, 153 Gain calculation unit, 154 Differential amplification circuit, 155 Spectrum calculation unit, 201 Lens member, 211 Composite member, 301 Slit member, 311 Long pass filter, 321 Parabolic mirror

Claims

1. A measuring device comprising: a beam splitting unit that splits a substantially parallel beam into a first beam and a second beam, refracts and emits the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam with respect to a first reference plane including the traveling direction of the substantially parallel beam, thereby causing interference between the first beam and the second beam; a focusing unit that focuses the first beam and the second beam on a second reference plane that includes the traveling direction of the substantially parallel beam and is perpendicular to the first reference plane; a sensor unit that detects interference light between the first beam and the second beam; and a calculation unit that calculates the spectrum of the substantially parallel beam based on a detection result by the sensor unit.

2. The measuring device according to claim 1, wherein the light beam splitting section is constituted by an optical member having a light entrance surface or exit surface that has two flat surfaces inclined symmetrically with respect to the first reference plane.

3. The measurement device according to claim 1, wherein the light beam splitting section is configured with an optical member having two lens surfaces whose light entrance surface or exit surface has a central axis located on opposite sides of the first reference plane.

4. The measuring device according to claim 1, wherein the sensor section is composed of a line sensor in which pixels are arranged in a straight line.

5. The measuring device according to claim 4, wherein the beam splitter further splits the substantially parallel beam into a third beam.

6. The measuring device according to claim 5, wherein the light beam splitting section is constituted by an optical member having a light entrance surface or exit surface that has two planes inclined symmetrically with respect to the first reference plane and one plane inclined with respect to the second reference plane.

7. The measuring device according to claim 5, wherein the light beam splitting section is constituted by an optical member having a light entrance surface or exit surface, two lens surfaces each having a central axis located on opposite sides of the first reference plane, and one lens surface having a central axis located on the opposite side of the second reference plane.

8. The measuring device according to claim 5, wherein the sensor section comprises a first line sensor that detects the interference light, and a second line sensor that detects the third light beam.

9. The measurement device according to claim 8, wherein the calculation unit calculates the spectrum based on a detection result by the first line sensor and a detection result by the second line sensor.

10. The measurement device according to claim 9, wherein the calculation unit amplifies a difference between a detection result by the first line sensor and a detection result by the second line sensor, and calculates the spectrum based on the amplified difference.

11. The measuring device of claim 10, wherein the calculation unit multiplies the detection result by the first line sensor by a first gain and the detection result by the second line sensor by a second gain, and then amplifies the difference between the detection result by the first line sensor and the detection result by the second line sensor.

12. The measuring device according to claim 11, wherein the calculation unit adjusts the first gain and the second gain.

13. The measuring device according to claim 8, wherein each pixel of the first line sensor and each pixel of the second line sensor are connected for each column.

14. The measuring device according to claim 1, further comprising: a slit member in which a slit is arranged; and a light beam generating unit that converts the light transmitted through the slit into the approximately parallel light beam.

15. The measuring device according to claim 14, further comprising a temperature change section for changing the surface temperature of the object to be measured, wherein the light transmitted through the slit is radiant light emitted from the surface of the object to be measured.

16. The measurement device according to claim 15, wherein the calculation section calculates the spectrum in synchronization with a change in the surface temperature of the object to be measured caused by the temperature change section.

17. The measuring device according to claim 15, wherein the temperature change section is constituted by a heater provided in the slit member.

18. The measuring device according to claim 15, wherein the temperature change unit changes the surface temperature of the object to be measured by irradiating the surface of the object to be measured with light.

19. The measuring device according to claim 14, wherein the light beam generating section and the light beam splitting section, or the light beam splitting section and the light collecting section, are configured from a single optical member.

20. The measuring device according to claim 1, wherein the light beam splitting section splits the light incident from the living body into the first light beam and the second light beam.

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