Microscopic analysis device

Abstract

Microscopic analysis apparatus, comprising: a) an optical concentration system (5) which concentrates the measuring light emitted by a sample (2) in a measuring area or measuring surface onto a first concentration point; b) a passage plate with an opening (6) located at the first concentration point; c) an elliptical concave mirror (8) that reflects measuring light passing through the opening (6) and concentrates the reflected measuring light onto a second concentration point; d) a shielding plate arranged in front of the second concentration point, wherein a through-hole (9a) is formed in the shielding plate with an incident-side edge or end surface whose shape corresponds to a cross-sectional shape of a luminous flux of measuring light at a position of the shielding plate; and e) a photodetector (9) provided at the second concentration point, wherein the luminous flux of measuring light between the elliptical concave mirror (8) and the photodetector (9) has a deformed conical shape which is distorted with respect to an optical axis (C) of the luminous flux of measuring light, and wherein the shielding plate is arranged so that it is perpendicular to the optical axis (C) of the luminous flux of the measuring light, wherein the incident-side edge or end surface of the through-hole (9a) has the same shape as that of the cross-section on which the shielding plate crosses the light flux of measuring light with the deformed conical shape.

Description

[Technical field]

[0001] The present invention relates to a microscopic analysis device that collects light emitted from a small measuring area of ​​a sample, concentrates the collected light on a photodetector using an elliptical concave mirror and performs an analysis, and it relates in particular to an infrared microscope. [State of the art]

[0002] A microscopic analysis device is used to analyze a small measurement area on a sample surface. In an infrared microscope, which is a type of microscopic analysis device, a sample is analyzed by irradiating the sample with infrared light and obtaining a spectrum of transmitted or reflected infrared light (see, for example, patent document 1).

[0003] The Fig. Figure 1 shows the construction of a main part of a transmission-type infrared microscope, a conventionally used infrared microscope. Infrared light (measuring light) emitted from an infrared light source 101 to penetrate a sample 102 is concentrated on a small-diameter aperture (passage) 106 of a pass-through plate by a Cassegrain mirror 105, which comprises a set of a concave mirror 103 and a convex mirror 104, each with through-holes in its center. The measuring light passing through the aperture 106 spreads out as it re-disperses, is reflected by a half-mirror (also called a hot mirror) 107, which transmits visible light and reflects infrared light, and is subsequently re-concentrated on an infrared detector 109 by an elliptical concave mirror 108.The infrared detector 109 subjects the measuring light to wavelength separation and measures the measuring light.

[0004] The elliptical concave mirror 108 has an elliptical arc-shaped cross-section, the focal points of which correspond to the aperture 106 and a concentration position within the infrared detector 109 within a plane that includes an optical axis of the incident measuring light and an optical axis of the reflected measuring light. Furthermore, a spherical surface is formed outside this plane by rotating the arc around a straight line connecting both focal points. In this way, the elliptical concave mirror 108 concentrates the light propagating from one focal point (the aperture 106) onto the other focal point (the interior of the infrared detector 109).In general, a light-concentrating optical element requires that (1) the penetrating wavelength band is broad and that no wavelength band has high absorption within any part of it, (2) the refractive index is not too high, (3) a material that is easy to process and manufacture is used, (4) the price is low, and (5) the resistance to the environment is excellent. However, no lens meets all these requirements in a wavelength band of infrared light, and consequently, an elliptical concave mirror is used to concentrate infrared light in many cases. An imaging lens 110 and an imaging unit 111, positioned above the sample 102, are used to irradiate a surface of the sample 102 with visible light from a visible light source (not shown) and to inspect its condition.

[0005] US 2002 / 0033452A1 describes an infrared imaging microscope, particularly for performing FT-IR measurements, with a detector in the form of a small detector array consisting of individual detector elements. The outputs of the detector elements are fed in parallel to processing means that process the output signals. The use of a small array means that the outputs can be processed without the need for complex multiplexing, or perhaps no multiplexing at all, thus avoiding the reduction in the signal-to-noise ratio associated with large-scale multiplexing. The small detector array generally has between 3 and 100 detector elements. Typically, the upper limit is 64, and a preferred arrangement has 16 detector elements. CN 101900604A describes a bidirectional fiber optic probe for use in spectroscopy with an optical input and output coupler. [State of the art document][Patent document]

[0006] [Patent Document 1] JP 7-63994 A [Summary of the invention][Technical problem]

[0007] The Fig. Figure 2 shows an enlarged view of an optical path of measuring light from the half-mirror 107 to the infrared detector 109. If infrared light from outside the measuring area falls on the infrared detector 109 in the infrared microscope, the accuracy of the measurement decreases. For this reason, as described in the Fig. Figure 2 shows a shielding plate (cold-pass plate) provided with a cylindrical through-hole (cold pass) 109a, placed on an incident surface of the infrared detector 109, so that only light falling on the cold pass 109a can enter the interior of the infrared detector 109 and light from outside the measuring surface is blocked.

[0008] As described above, measuring light passing through aperture 106 spreads out, is reflected by the elliptical concave mirror 108, and is concentrated on the inside of the infrared detector 109. In this case, the flux of the measuring light reflected by the elliptical concave mirror 108 has an essentially conical shape and is concentrated on the inside of the infrared detector 109. However, the flux corresponds exactly to a conical shape that is distorted with respect to a principal axis (optical axis) (hereinafter referred to as the "distorted conical shape").In particular, when an angle of a beam of measuring light passing through a left end with respect to an optical axis of measuring light (a vertical line passing through the apex of a cone) is set to θa and an angle of a beam of measuring light passing through a right end is set to θb on a paper surface that is in the . Fig. Figure 2 shows that an asymmetric cross-section which satisfies θb > θa is included.

[0009] As described above, the cold aperture 109a has a cylindrical shape, and an incident-side edge or end surface thereof has a circular shape. Therefore, in the case of an experiment where all measurement light fluxes are allowed to enter a light-receiving section, light from outside the measurement area enters the light-receiving section from the left side of the optical axis, as shown in the Fig. 3(a) is shown. Furthermore, in the case of an attempt to block light outside the measuring area, there is a problem in that part of the measuring light is blocked, as shown in the Fig. 3(b) is shown.

[0010] Here, the infrared microscope, which is a typical device, has been described as an example. However, the problem is not limited to infrared light, and the same problem as described above exists in any device that has a setup in which light emitted from a measuring surface of a sample is concentrated onto a aperture, and light passing through the aperture is refocused onto a photodetector by means of an elliptical concave mirror.

[0011] One problem that the invention aims to solve is that more measuring light can enter a photodetector without allowing light from outside a measuring surface to enter the photodetector in a microscopic analysis device that concentrates measuring light emitted from a measuring surface of a sample onto a photodetector by means of an elliptical concave mirror. [Solution to the problem]

[0012] The problem underlying the invention is solved by a microscopic analysis device according to one of independent claims 1 and 2. A further embodiment is defined in dependent claim 3.

[0013] For example, a Cassegrain mirror can be used for the optical concentration system.

[0014] Furthermore, the elliptical concave mirror is a concave mirror with a spherical surface, whose two focal points correspond to the first concentration point and the second concentration point.

[0015] The light flux of the measuring light reflected by the elliptical concave mirror has a conical shape (deformed conical shape) that is distorted with respect to a principal axis (optical axis). For example, a conventionally used shielding plate with a cylindrical through-hole arranged so that its cross-section is circular can be used as a shielding plate in which the through-hole can be formed with an edge or end surface whose shape matches the cross-sectional shape of the measuring light flux. In this case, only the arrangement of a conventionally used photodetector and a shielding plate needs to be modified, and a setup can be obtained at low cost.

[0016] Furthermore, the shielding plate can be designed as a shielding plate arranged perpendicular to an optical axis of a luminous flux of measuring light and in which a through-hole with an incident-side end surface whose shape corresponds to the shape of the cross-section can be formed. In this case, more measuring light than before can enter without allowing light to enter from outside a measuring area, while maintaining the same arrangement as before.

[0017] In the microscopic analysis device according to the invention, a cross-section of a measuring light flux with a deformed conical shape coincides with a shape of an incident-side end surface of a through hole and consequently more measuring light can enter a photodetector without allowing light outside a measuring area to enter the photodetector. [Advantageous effects of the invention]

[0018] When a microscopic analysis device according to the invention is used, more measuring light can enter a photodetector without allowing light from outside a measuring area to enter the photodetector: [Brief description of the drawings] Fig. Figure 1 is a main part configuration diagram of an infrared microscope; Fig. Figure 2 is an enlarged view of an optical path of measuring light from a half-mirror to an infrared detector in a conventional infrared microscope; Fig. Figure 3 is a diagram showing conditions in which light from outside a measuring area enters the infrared detector and part of the measuring light is blocked by a shielding plate in the conventional infrared microscope; Fig. Figure 4 is a main part configuration diagram of an infrared microscope, which is an embodiment of a microscopic analysis device according to the invention; Fig. Figure 5 is an enlarged view of part of an optical path of measuring light in the infrared microscope of the present embodiment; Fig. Figure 6 is a diagram describing an arrangement of an infrared detector and a shape of a cold pass-through in the infrared microscope of the present embodiment; and Fig. Figure 7 is a diagram describing an arrangement of an infrared detector and a shape of a cold pass in an infrared microscope modification. [Description of embodiments]

[0019] Below, an infrared microscope, which is an embodiment of a microscopic analysis device according to the invention, is described with reference to the Fig. 4, Fig. 5 to Fig. 6 described. Fig. Figure 4 is a main part configuration diagram of the infrared microscope of the present embodiment.

[0020] The infrared microscope of the present embodiment has a setup in which both transmitted and reflected light from a sample 2 can be measured. In the case of transmittance measurement, infrared light from a transmission infrared light source 1a, which is a ceramic light source such as SiC, SiN, etc., is shone through a mirror 20 from below the sample 2. The infrared light (transmission light) passing through the sample 2 is concentrated at a first concentration point by a Cassegrain mirror 5, which comprises a set of a concave mirror 3 and a convex mirror 4, each with through-holes in its center.The measuring light passing through the opening 6 spreads out as it is redistributed, is reflected by a half-mirror (hot mirror) 7 which transmits visible light and reflects infrared light, and is subsequently concentrated again at a second concentration point within an infrared detector 9 by an elliptical concave mirror 8.

[0021] The infrared detector 9 is a highly sensitive mercury-cadmium telluride (MCT) detector and is cooled by liquid nitrogen together with a cold transmittance plate, which is described below. The elliptical concave mirror 8 is a concave mirror with a spherical surface whose focal points correspond to a concentration point of transmittance measurement light within the aperture 6 and a concentration point of transmittance measurement light within the infrared detector 9. The infrared detector 9 performs wavelength separation of the measurement light and measures it.

[0022] In the case of measuring reflected light, infrared light from a reflection measurement infrared light source 1b, which is a ceramic light source similar to the light source described above, is shone through a half-mirror 21 and the Cassegrain mirror 5 from above the sample 2. The infrared light (reflection measurement light) reflected from a surface of the sample 2 is concentrated at the first concentration point of the aperture 6 as described above, reflected through each of the half-mirror 7 and the elliptical concave mirror 8, and concentrated at the second concentration point within the infrared detector 9.

[0023] The imaging lens 10 and the imaging unit 11, which are provided above the sample 2, are used to irradiate the surface of the sample 2 with visible light from a visible light source (not shown) and to check its condition.

[0024] The Fig. Figure 5 is an enlarged view of an optical path of the (transmitted or reflected) measuring light from the half-mirror 7 to the infrared detector 9 in the infrared microscope of the present embodiment. A shielding plate (cold-pass plate) in which a cylindrical through-hole (cold pass-through) 9a is provided as in the Fig. 2 is provided on an incidence surface of the infrared detector 9 of the present embodiment.

[0025] As stated with reference to the Fig. As described in Figure 3, a luminous flux of measuring light reflected by the elliptical concave mirror 8 has a conical shape (deformed conical shape) that is distorted with respect to an optical axis C. If an angle of a ray of measuring light passing through a left end with respect to the optical axis C is set to θa, and an angle of a ray of measuring light passing through a right end is set to θb within a plane on a paper surface of Fig. When set to 5, the deformed conical shape has an asymmetrical cross-section that satisfies θb > θa. Although θb > θa is satisfied in the present embodiment, θb < θa may be satisfied depending on the arrangement of each section.

[0026] In this embodiment, as described in the Fig. 6(a) shows the cold transmitting plate of the infrared detector 9 inclined at an angle such that a surface on which the transmitting plate crosses a light flux of the deformed conical shape has essentially the same shape as a shape of an incident-side edge or end surface of the through-hole (i.e., a circular shape, cf. the Fig. 6(b)). In particular, within a plane on a paper surface of Fig. 6(a) a central axis P of a field of view of the infrared detector 9 inclined at an angle θc = (θb - θa) / 2 with respect to the optical axis C, and the arrangement is carried out such that an angle of the beam of measuring light passing through the left end with respect to the optical axis C is equal with respect to the center to an angle of the beam of measuring light passing through the right end.

[0027] As described above, in the infrared microscope of the present invention, a cross-section of a measurement light flux with a deformed conical shape through the transmission plate can coincide with the incident-side end surface of the cold passage 9a using the infrared detector 9. This coincides with the cold passage plate in which the cylindrical cold passage 9a is configured as before. Therefore, all measurement light rays can be allowed to enter the infrared detector 9. Furthermore, light outside the measurement area can be reliably blocked by the cold passage plate, and consequently, there is no concern that this light will enter the infrared detector 9. Therefore, the sample can be analyzed with a high signal-to-noise ratio.

[0028] Next, an infrared microscope will be modified with reference to the Fig. 7 described. Since every component element of this infrared microscope is identical to that of the preceding embodiment, a description and illustration of each section are omitted and the differences from the preceding embodiment are described.

[0029] In the modified infrared microscope, an infrared detector 9' (and a cold transmission plate) is arranged such that a perpendicular of a detection surface of the infrared detector 9' (= a perpendicular of the cold transmission plate) coincides with an optical axis C of the measuring light, as described in the Fig. 7(a) is shown. Furthermore, as shown in the Fig. Figure 7(b) shows a cold aperture 9a' having an incident-side end surface with substantially the same shape as that of a cross-section on which the cold aperture plate crosses a measuring luminous flux with a deformed conical shape.

[0030] In the infrared microscope of this modification, the cross-section of the measurement light flux coincides with the shape of the cold aperture 9a' as in the preceding embodiment, and consequently, all measurement light rays can be allowed to enter the infrared detector 9 and reliably block light outside a measurement area through the cold aperture plate. Therefore, the sample can be analyzed with a high signal-to-noise ratio.

[0031] If a Cassegrain mirror other than the elliptical concave mirror of the preceding embodiment and modification is used, a conical light flux can be directed into the infrared detector. However, since the Cassegrain mirror is expensive, the infrared microscope becomes expensive if two Cassegrain mirrors are used. That is, the infrared microscope of the preceding embodiment and modification has the advantage that the infrared microscope can be manufactured at a lower cost compared to an infrared microscope using two Cassegrain mirrors.

[0032] Each of the foregoing embodiments and modifications is an example and can be modified in a suitable manner according to the essence of the invention. The arrangement of each section shown in the main part configuration diagram of Fig.Figure 4 is merely an example, and the configuration can be modified as appropriate. For instance, the transmission infrared light source 1a and the transmission infrared light source 1b can be defined as a single infrared light source, and an optical element, such as a mirror, can be arranged to allow infrared light to be directed onto the sample from both an upper and a lower direction. Furthermore, in the foregoing embodiment, the arrangement is configured such that the optical axis C of the measurement light reflected by the elliptical concave mirror 8 is oriented vertically. However, the arrangement is configured so that the optical axis is oriented horizontally.

[0033] Furthermore, although the foregoing embodiment corresponds to the infrared microscope, the invention can be used in various microscopic analysis devices in which measuring light in a wavelength band of light that is different from infrared light, such as visible light, ultraviolet light, etc., is concentrated on an inside of a photodetector by an elliptical concave mirror. [List of reference symbols] 1a Transmittance measurement infrared light source 1b Reflection measurement infrared light source 2 Sample 20 mirrors 21 Semi-mirrors 3 Concave Mirrors 4 Convex mirrors 5 Cassegrain mirrors 6 passage 7 Semi-mirrors 8 Elliptical concave mirror 9.9' Infrared detector 9a, 9a' Cold passage 10 Imaging lens 11 Imaging Unit

Claims

[1] Microscopic analysis apparatus comprising: a) an optical concentration system (5) which concentrates the measuring light emitted by a sample (2) in a measuring area or measuring surface onto a first concentration point; b) a passage plate with an opening (6) located at the first concentration point; c) an elliptical concave mirror (8) that reflects measuring light passing through the opening (6) and concentrates the reflected measuring light onto a second concentration point; d) a shielding plate arranged in front of the second concentration point, wherein a through-hole (9a) is formed in the shielding plate with an incident-side edge or end surface whose shape corresponds to a cross-sectional shape of a luminous flux of measuring light at a position of the shielding plate; and e) a photodetector (9) provided at the second concentration point, wherein the luminous flux of measuring light between the elliptical concave mirror (8) and the photodetector (9) has a deformed conical shape which is distorted with respect to an optical axis (C) of the luminous flux of measuring light, and wherein the shielding plate is arranged so that it is perpendicular to the optical axis (C) of the luminous flux of the measuring light, wherein the incident-side edge or end surface of the through-hole (9a) has the same shape as that of the cross-section on which the shielding plate crosses the light flux of measuring light with the deformed conical shape. [2] Microscopic analysis apparatus comprising: a) an optical concentration system (5) which concentrates the measuring light emitted by a sample (2) in a measuring area or measuring surface onto a first concentration point; b) a passage plate with an opening (6) located at the first concentration point; c) an elliptical concave mirror (8) that reflects measuring light passing through the opening (6) and concentrates the reflected measuring light onto a second concentration point; d) a shielding plate arranged in front of the second concentration point, wherein a through-hole (9a) with a cross-section having a circular shape is formed in the shielding plate; and e) a photodetector (9) provided at the second concentration point, wherein the shielding plate is arranged such that a central axis (P) of a viewing field of the infrared detector (9) is inclined at an angle (θb - θa) / 2 with respect to an optical axis (C) of a luminous flux of measuring light, wherein the luminous flux of measuring light between the elliptical concave mirror (8) and the photodetector (9) has a deformed conical shape which is distorted with respect to the optical axis (C) of the luminous flux of measuring light, where θa is an angle of a beam of measuring light passing through a left end with respect to the optical axis (C), where θb is an angle of a beam of measuring light passing through a right end with respect to the optical axis (C), and wherein a shape of an incident-side end face of the through hole (9a) corresponds to a shape of a cross-sectional area of ​​the luminous flux of measuring light at a position of the shielding plate. [3] Microscopic analysis device according to claim 1 or 2, wherein the measuring light is infrared light.

Images