Spectroscopic imaging unit adjustment system

Abstract

The objective is to provide a spectroscopic imaging unit adjustment system that facilitates the adjustment of the spectroscopic imaging unit and improves the adjustment accuracy. [Solution] The spectral imaging unit adjustment system 1 adjusts a spectral imaging unit having an adjustment slit member 14 into which light from a light source 2 is incident through a slit 14a, a rotationally asymmetric diffraction unit 30, and a spectral imaging sensor 36 equipped with an image sensor 36a, and uses the adjustment slit member 14 to display at least the rotation angle of the diffraction unit 30 in the imaging area of ​​the spectral imaging sensor 36, wherein the slit 14a is cross-shaped, and the wavelength of the light source 2 is set such that when the spectral range is 450 nm to 1700 nm, the wavelength of the emitted light emitted from the diffraction unit 30 through the cross-shaped slit 14a is 1 / 2 or 1 / 3 of the wavelength of the spectral range.

Description

Technical Field

[0001] The present invention relates to a spectral imaging unit adjustment system, and particularly to a spectral imaging unit adjustment system that performs spectroscopy in a wavelength range of 450 nm to 1700 nm.

Background Art

[0002] A spectral imaging unit is a device that receives light from a plurality of measurement locations and forms an image on a sensor in the spatial axis and wavelength axis.

[0003] As a spectral imaging unit, there is known a spectral imaging unit provided with a slit at the incident side end in the optical axis direction, and successively including a glass plate, a collimator lens, a first prism, a grating, a second prism, a focus lens, and a spectral imaging sensor in the longitudinal direction from the slit (see Patent Document 1 below). The collimator lens, the first prism, the grating, the second prism, and the focus lens form an imaging optical system for using the incident light for imaging. The spectral imaging sensor is installed inclined in a direction away from the slit on the upper side with respect to the optical axis. In the spectral imaging unit of Patent Document 1, the transmission characteristics are calculated based on the imaging result obtained by the spectral imaging sensor by the arithmetic processing unit connected to the spectral imaging unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in recent years, short-wave infrared (SWIR) sensors have become sensitive to wavelengths ranging from the visible range (visible light) to the near-infrared range (near-infrared light). As the number of pixels increases and the pixel size decreases, there is a growing demand for spectroscopic cameras with high wavelength resolution and high resolution. When using a spectral imaging sensor that can cover the visible range to the near-infrared, the spectral imaging unit appropriately adjusts the rotation angle (amount of rotation) of the diffraction unit (spectroscopic element group), which consists of a first prism, a grating, and a second prism, with respect to the optical axis, as well as the tilt (amount of tilt) of the spectral imaging sensor, in order to obtain the desired wavelength resolution and resolution.

[0006] This adjustment method involves incorporating an adjustment slit member, which has a long, narrow slit (linear slit) formed horizontally, into the spectral imaging unit, and adjusting by injecting linear light through the linear slit. Based on the image line formed on the spectral imaging sensor, the rotation angle (amount of rotation) of the diffraction unit (group of spectral elements) with respect to the optical axis and the tilt (amount of tilt) of the spectral imaging sensor are determined. For example, if an adjustment slit member having an elongated hole formed laterally (a slit member having a linear slit) is incorporated into a spectral imaging unit, and it is confirmed that the direction of the image line formed on the spectral imaging sensor through the linear slit is oblique, then adjustment (angle adjustment of the diffraction unit, etc.) becomes necessary. However, if the linear slit is formed horizontally, it is possible to confirm whether the horizontal direction of the image line is horizontal, but it is difficult to confirm whether the vertical direction of the image line is perpendicular. Therefore, it is necessary to rotate the adjustment slit member, which has an elongated hole formed horizontally, by 90 degrees to additionally confirm whether the vertical image line is perpendicular. Consequently, there is a problem that the adjustment is time-consuming and cumbersome.

[0007] In view of the above problems, the present invention aims to provide a spectral imaging unit adjustment system that facilitates the adjustment of a spectral imaging unit, which is performed to enable imaging with high wavelength resolution and high resolution, and improves the accuracy of the adjustment. [Means for solving the problem]

[0008] The spectroscopic imaging unit adjustment system 1 of the present invention comprises an adjustment slit member 14 through which light from a light source 2 is incident via a slit 14a, a rotationally asymmetric diffraction unit 30, and a spectroscopic imaging sensor 36 equipped with an image sensor 36a, wherein the adjustment slit member 14 is used to display at least the amount of rotation of the diffraction unit 30 in the imaging region of the spectroscopic imaging sensor 36, wherein the slit 14a is cross-shaped, and the wavelength of the light source 2 is set such that, when the spectral range is 450 nm to 1700 nm, the wavelength of the emitted light emitted from the diffraction unit 30 via the cross-shaped slit 14a is 1 / 2 or 1 / 3 of the wavelength of the spectral range. [Effects of the Invention]

[0009] The spectroscopic imaging unit adjustment system of the present invention comprises an adjustment slit member through which light from a light source is incident, a rotationally asymmetric diffraction unit, and a spectroscopic imaging sensor equipped with an image sensor, wherein the adjustment slit member is used to display at least the amount of rotation of the diffraction unit in the imaging region of the spectroscopic imaging sensor, the slit is cross-shaped, and the wavelength of the light source is set such that, when the spectral range is 450 nm to 1700 nm, the wavelength of the emitted light emitted from the diffraction unit through the cross-shaped slit is 1 / 2 or 1 / 3 of the wavelength of the spectral range. Therefore, with the spectroscopic imaging unit adjustment system having the above configuration, the amount of adjustment (rotation of the diffraction unit) required to obtain high wavelength resolution and high resolution, i.e., to bring the diffraction unit to the desired rotational fixed position, can be visually confirmed based on the cross-shaped image displayed in the imaging area of ​​the spectroscopic imaging sensor. Thus, it is possible to provide a spectroscopic imaging unit adjustment system that facilitates adjustment (reduces adjustment time) and improves adjustment accuracy. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows the configuration of the spectroscopic imaging unit adjustment system 1 according to the embodiment. [Figure 2] This figure shows the external appearance of the spectral imaging unit 3, the slit member 14, and the fixing jig 60. [Figure 3] This diagram illustrates the non-rotational symmetry of the diffraction unit. [Figure 4] This diagram illustrates the spectral wavelengths of the 0th to 2nd order light. [Figure 5] This is a perspective view showing the external appearance of the spectral imaging camera, including the spectral imaging unit 3. [Figure 6] This diagram shows the imaging region (imaging plane) of the spectral imaging sensor 36. [Figure 7] This figure shows a cross-shaped image target that is imaged in the imaging region of the spectral imaging sensor 36. [Figure 8] This diagram illustrates the adjustment process using the Spectroscopic Imaging Unit Adjustment System 1. [Figure 9] This diagram illustrates the adjustment process using the Spectroscopic Imaging Unit Adjustment System 1. [Modes for carrying out the invention]

[0011] The configuration of the spectroscopic imaging unit adjustment system 1 according to this embodiment will be described below with reference to the drawings.

[0012] <Overall configuration of Spectroscopic Imaging Unit 1> Figure 1 is a diagram showing the configuration of the spectral imaging unit adjustment system 1 according to the embodiment. Figure 2 is a diagram showing the external appearance of the spectral imaging unit 3, slit member 14, and fixing jig 60. Figure 3 is a diagram for explaining the non-rotational symmetry of the diffraction unit. Figure 4 is a diagram for explaining the spectral wavelengths of 0th to 2nd order light. Figure 5 is a perspective view showing the external appearance of the spectral imaging camera including the spectral imaging unit 3. Figure 6 is a diagram showing the imaging region (imaging surface) of the spectral imaging sensor 36. Figure 7 is a diagram showing a cross-shaped imaging target imaged in the imaging region of the spectral imaging sensor 36, where the horizontal axis is the length in the X-axis direction of the imaging surface of the spectral imaging sensor 36 (size: mm), and the vertical axis is the length in the Y-axis direction of the imaging surface of the spectral imaging sensor 36 (size: mm). Figure 8 is a diagram for explaining the adjustment by the spectral imaging unit adjustment system 1. Figure 9 is a diagram for explaining the adjustment by the spectral imaging unit adjustment system 1.

[0013] In Figure 1, the front-to-back direction is the longitudinal direction of the spectral imaging unit 3, and the up-and-down direction is the up-and-down direction of the spectral imaging unit 3. Furthermore, the front-to-back direction of the spectral imaging unit 3 is also the direction of light propagation (optical axis direction). In addition, in each figure used to explain the embodiments, components having the same function are denoted by the same reference numerals, and redundant explanations may be omitted.

[0014] As shown in Fig. 1, the spectroscopic imaging unit adjustment system 1 is composed of a light source 2 and a spectroscopic imaging unit 3. The spectroscopic imaging unit 3 includes a slit member 14 provided at an incident side end for incident light from the light source 2, a collimator lens group (combined convex lenses) 20, a diffraction unit (spectroscopic element group, prism group) 30, a focus lens group (combined convex lenses) 40, and a spectroscopic imaging sensor 36. The collimator lens group 20, the diffraction unit 30, and the focus lens group 40 are imaging optical systems used to image the incident light. An image processing device 39 (see Fig. 5) described later is connected to the spectroscopic imaging sensor 36.

[0015] <Light source> As the light source 2, a laser light source that emits light with a wavelength of 1 / n (n is 2 or 3) of 450 nm to 1700 nm is used so that the spectroscopic wavelength is between the first wavelength and the second wavelength of 450 nm to 1700 nm. The reason for setting the spectroscopic wavelength range, for example, between the first wavelength and the second wavelength of 450 nm to 1700 nm is that if it is outside this range, the imaging target where light from the light source is imaged in the imaging region of the spectroscopic imaging sensor 36 through the slit will be imaged outside the range of the imaging region of the spectroscopic imaging sensor 36, and the imaging target necessary for the adjustment described later will not be visible. As shown in Fig. 4, since the zero-order light is the condensing position for all wavelengths, the zero-order light is not used for imaging on the imaging surface of the spectroscopic imaging sensor 36. That is, the black-painted area in Fig. 4 is the area imaged on the imaging surface of the spectroscopic imaging sensor 36.

[0016] For example, when the wavelength of the emitted light from the light source 2 is set to 1 / 2 of the spectroscopic wavelength to 650 nm, the spectroscopic wavelength is 650 nm for the first order and 1300 nm for the second order, and the first wavelength to the second wavelength is within the range of 450 nm to 1700 nm. Also, when the wavelength of the emitted light from the light source 2 is set to 1 / 3 of the spectroscopic wavelength to 500 nm, the spectroscopic wavelength range is 500 nm for the first order, 1000 nm for the second order, and 1500 nm for the third order, and the first wavelength to the third wavelength is within the range of 450 nm to 1700 nm. In the case where the wavelength of the emitted light is 1 / n of the spectroscopic wavelength, the value of n is preferably 2 or 3.

[0017] <Slit member> The slit member 14 is provided on the front side in the longitudinal direction (optical axis direction) of the spectroscopic imaging unit 3 such that light from an object (light source) enters through an objective lens 38 (see FIG. 5, omitted in FIG. 1) that receives the light. As shown in FIG. 2, a cross-shaped slit (entrance) 14a through which light from the light source 2 enters is formed in the slit member 14. The cross-shaped slit 14a is composed of a vertically elongated hole 14a1 (first elongated hole) and a horizontally elongated hole 14a2 (second elongated hole) that is orthogonal to the vertically elongated hole 14a1. Note that the optical axis direction positions of the objective lens 38 and the slit 14a are determined so that the light emitted from the light source 2 enters the slit 14a. The slit 14a is provided to extend in the left-right direction and the up-down direction (hereinafter referred to as the "horizontal-vertical direction") of the spectroscopic imaging unit 3, and the vertical length is shorter than the horizontal length. Note that the reference numeral 50 in FIG. 2(b) is a slit fixing member disposed on the incident side of the collimator lens group 20.

[0018] As shown in FIG. 8(c), a first imaging line 142a1 corresponding to the vertically elongated hole (first elongated hole) 14a1 of the primary light and a second imaging line 142a2 corresponding to the horizontally elongated hole (second elongated hole) 14a2 are imaged on an imaging region 70 of the spectroscopic imaging sensor 36 through the cross-shaped slit 14a (see FIG. 2). The length of the first imaging line 142a1 and the length of the second imaging line 142a2 need to be 1 / 4 or more of the width direction length (Ha) in the imaging region 70 of the spectroscopic imaging sensor 36 (see FIG. 8(c)). Furthermore, a first imaging line 242a1 corresponding to the vertically elongated hole (first elongated hole) 14a1 of the secondary light and a second imaging line 242a2 corresponding to the horizontally elongated hole (second elongated hole) 14a2 are imaged on an imaging region 70 of the spectroscopic imaging sensor 36 through the cross-shaped slit 14a (see FIG. 2). The length of the first imaging line 142a1 and the length of the second imaging line 142a2 need to be 1 / 4 or more of the width direction length (Ha) in the imaging region 70 of the spectroscopic imaging sensor 36 (see FIG. 8(c)). If the ratio is less than 1 / 4, the imaging target necessary for the adjustment described later becomes difficult to see within the imaging area 70, making it difficult to determine the horizontal orientation in the width direction and the vertical orientation in the height direction of the spectral imaging sensor 36.

[0019] Furthermore, an image processing device 39 (see Figure 5) is connected to the spectral imaging unit 3. The image processing device 39 has an image processing unit (not shown) that performs processing such as converting the information received by the spectral imaging sensor 36 into image information. The image processing unit consists of a macroprocessor such as a CPU (Central Processing Unit) and memory.

[0020] The image processing device 39 may also include a display unit (not shown) to display measurement results, etc. The display unit can be, for example, a liquid crystal display or an organic EL display. The display unit may also be a separate unit. The image processing device 39 may also include an internal storage unit (not shown) to store image data and analysis results from the image processing device 39. As for the storage unit, various types of storage devices may be used as needed, such as an HDD (hard disk drive) or an SSD (solid state drive).

[0021] <Collimator lens group> The collimator lens group 20 is a combination convex lens formed by combining a cemented lens 21 and a convex lens 22, and has positive refractive power. No optical components are placed between the slit member 14 and the collimator lens group 20. Generally, mirrors (optical components) are placed to change the optical path, and aspherical lenses (optical components) or spherical lenses (optical components) are placed to correct aberrations, but in this embodiment, since there is no change in the optical path or correction of aberrations, no optical components are placed between the slit member 14 and the collimator lens group 20.

[0022] <Diffraction Unit (Prism Group)> As shown in Figure 1, the diffraction unit 30 comprises a grating 33, an incident prism 31, and an exit prism 32, and has a rotationally asymmetric structure. In the case of rotational asymmetry, as shown in the upper part of Figure 2, the object to be imaged in the imaging region also rotates and its appearance changes (see imaging lines 150 and 152), so adjustment of the spectral imaging unit described later is necessary. However, in the case of rotational symmetry, as shown in the lower part of Figure 2, the object to be imaged in the imaging region does not rotate and its appearance does not change (see imaging line 150), so adjustment of the spectral imaging unit described later is unnecessary. The incident prism 31 is positioned with its vertical surface facing the grating 33 and its slanted surface facing the collimator lens group 20. The exit prism 32 is positioned with its vertical surface facing the grating 33 and its slanted surface facing the focus lens group 40, which will be described later. The incident prism 31 and the exit prism 32 are angle correction prisms. The grating 33 is for wavelength dispersion.

[0023] (Diffraction unit fixing jig) As shown in Figure 2, the diffraction unit fixing jig 60 is ring-shaped and comprises a narrow plate-shaped member 61 and a wide plate-shaped member 63. The narrow plate-shaped member 61 and the wide plate-shaped member 63 are formed alternately along the circumferential direction and are integrally molded. The inner diameter of the fixing jig 60 is the same as or slightly larger than the outer diameter of the diffraction unit 30. The diffraction unit fixing jig 60 is preferably made of a resin material or metal with a certain degree of flexibility, such as polyethylene or polypropylene, but is not limited to this material as long as it has sufficient flexibility and hardness to perform the function of fixing the diffraction unit 30, which will be described later. Fixing to the diffraction unit 30 is performed by fitting the diffraction unit fixing jig 60 onto the diffraction unit 30 while the rotation (angle) position of the diffraction unit 30 itself and the individual rotation (angle) positions of the prisms 31, 32 and grating 33 that constitute the diffraction unit 30 are set to the desired rotation (angle) position.

[0024] <Focus lens group> As shown in Figure 1, the focusing lens group 40 is a combination lens consisting of a convex lens 41 and a cemented lens 42 made up of a biconvex lens and a concave lens, and has positive refractive power. The focal length f of the focusing lens group 40 is the distance from the main plane of the focusing lens group 40 to the image sensor 36a, which will be described later, and is preferably 30 to 40 mm.

[0025] <Spectroscopic Imaging Sensor> The spectral imaging sensor 36 is a two-dimensional optical sensor (image sensor) and includes an image sensor 36a and a sensor cover 36b (see Figure 1). The spectral imaging sensor 36 is a sensor that can cover visible light to near-infrared light, and can sense, for example, the wavelength range of light from 450 nm to 1700 nm. However, it may also be a sensor that can sense other ranges. The spectral imaging sensor 36 is installed at an angle with respect to the optical axis direction (front-to-back direction), with its upper side tilted away from the slit member 14.

[0026] The image sensor 36a has numerous photodetectors arranged in two dimensions and has a positive or rectangular shape (see Figure 6). Each photodetector converts the light it receives into an electrical signal. When the spectral imaging sensor 36 is installed as shown in Figure 1, the horizontal direction of the image sensor 36a (direction of arrow A in Figure 6) becomes the spatial axis, and the vertical direction of the image sensor 26a (direction of arrow B in Figure 6) becomes the wavelength axis. That is, each piece of light information from the vertically extending slit 14a1 is imaged on the wavelength axis corresponding to the vertical position of the slit 14a (direction of arrow B in Figure 6). Each piece of light information from the horizontally extending slit 14a2 is imaged on the spatial axis corresponding to the horizontal position of the slit 14a (direction of arrow A in Figure 6). When using the spectral imaging unit 3 of the embodiment, the characteristics when the wavelength becomes longer as you go higher in the vertical direction are shown.

[0027] Light from the slit 14a is dispersed through the collimator lens group 20 and the prism group 30, and finally focused onto the spectral imaging sensor 36 via the focus lens group 40, and then imaged onto the image sensor 36a via the sensor cover 36b. As shown in Figure 6, the image of the light on the image sensor 36a is formed by the primary cross-slit imaging and the secondary cross-slit imaging within the dispersion range of Hb on the vertical axis (see Figure 6). In this embodiment, Hb is the wavelength range from 450 nm to 1700 nm, which is the same as or shorter than the effective vertical element distance of the image sensor 36a. Furthermore, in the coupling region of the spectral imaging sensor 36, a cross-shaped imaging target 142a (cross-slit primary imaging) is displayed near the intersection of the cross-slit primary imaging X-axis line and the cross-slit Y-axis line, for example, as shown in Figure 7, and a cross-shaped imaging target 242a (cross-slit secondary imaging) is displayed near the intersection of the cross-slit secondary imaging X-axis line and the cross-slit Y-axis line, for example, as shown in Figure 7.

[0028] <Example of adjustment of the spectroscopic imaging unit> The following describes an example of adjusting the spectral imaging unit based on the imaging target imaged by the spectral imaging sensor 36, assuming that the zeroth order optical wavelength of the emitted light from the light source 2 is 650 nm. (Before adjustment) Before adjustment, as shown in Figure 8(a), light of the primary wavelength is imaged as image target 140a in the imaging region of the spectral imaging sensor 36, and light of the secondary wavelength is imaged as image target 240a. The cross of image targets 140a and 240a is tilted by a predetermined angle clockwise from the horizontal in the horizontal direction, and by a predetermined angle clockwise from the vertical in the vertical direction. This is due to the tilt (rotation angle with the axis of rotation being perpendicular to the optical axis) and rotation angle (angle with the axis of rotation being perpendicular to the optical axis) of the diffraction unit 30 itself, the tilt (rotation angle with the axis of rotation being perpendicular to the optical axis) and rotation angle (angle with the axis of rotation being perpendicular to the optical axis) of each lens constituting the diffraction unit 30, and poor adjustment of the tilt (angle with the axis of rotation being perpendicular to the optical axis) of the spectral imaging sensor 36. Note that the thickness of the vertical and horizontal lines of the imaging target 140a shown in Figure 8(a) is not uniform; this is due to the focal length between the focus lens group 40 and the spectral imaging sensor 36. Figure 8(b) shows the image after the focal length has been corrected and adjusted. Figure 8(c) shows the imaging target after the spectral imaging unit 3, which will be described later, has been adjusted (see Figure 9). Therefore, it is necessary to adjust the rotation of the entire diffraction unit 30 and the rotation of the prisms 31, 32 and grating 33 that make up the diffraction unit 30 (see above) so that the cross of the imaging targets 140a and 240a is horizontal in the horizontal direction and vertical in the vertical direction.

[0029] Furthermore, if it is confirmed that the cross of the imaging targets 140a and 141a is tilted horizontally by a predetermined angle clockwise relative to the vertical direction, and vertically by a predetermined angle clockwise relative to the horizontal direction (see Figures 8(a) and (b)), a control device (not shown) connected to the spectral imaging sensor 36 may emit a warning sound or change the display format (solid line, dashed line, dotted line, etc.) or display color (red, green, blue, etc.) of the imaging targets 141a and 142a according to the amount of tilt detected. This would make it even easier to confirm whether adjustment is necessary. (After adjustment) If, before adjustment, the cross shape of the imaging targets 140a and 240a is tilted by a predetermined angle clockwise in the horizontal direction compared to the vertical direction, or tilted by a predetermined angle clockwise in the vertical direction compared to the horizontal direction, the spectral imaging unit 3 is adjusted according to the following procedure. (1) If the line width of the imaging target 140a is thick rather than thin as shown in Figure 8(a), adjust the focal length. (2) Next, if the horizontal direction of the cross of the imaging targets 140a and 240a is not horizontal and the vertical direction is not vertical, it is necessary to adjust the rotation of the entire diffraction unit 30 and the individual rotations of the prisms 31, 32 and grating 33 that constitute the diffraction unit 30. The rotation adjustment is performed by fitting the diffraction unit fixing jig 60 onto the diffraction unit 30 while the tilt (rotation angle with the rotation axis in the direction perpendicular to the optical axis), rotation angle (angle with the rotation axis in the direction perpendicular to the optical axis), and the tilt (rotation angle with the rotation axis in the direction perpendicular to the optical axis) and rotation angle (angle with the rotation axis in the direction of the optical axis) of each lens that constitutes the diffraction unit 30 are set to the desired angular position. (3) If the horizontal direction of the cross of the imaging target 140a, 240a is horizontal but the vertical direction is not vertical, or if the vertical direction of the cross is vertical but the horizontal direction is not horizontal, the same adjustment as in (1) above will be performed. Figure 9 shows the imaging patterns that require adjustment.

[0030] [1: No adjustment required (OK) pattern] The pattern shown on the far left of Figure 9 is normal and requires no adjustment. The horizontal direction of the cross is horizontal, and the vertical direction is also vertical. [2: Adjustment required (NG) Pattern 1] The pattern shown second from the left in Figure 9 is abnormal and requires adjustment. The horizontal direction of the cross is not horizontal, and the vertical direction is not vertical. [3: Pattern 2 requiring adjustment (NG)] The pattern shown third from the left in Figure 9 is abnormal and requires adjustment. The horizontal direction of the cross is horizontal, but the vertical direction is not vertical. [4: Adjustment required (NG) Pattern 3] The pattern shown fourth from the left in Figure 9 is abnormal and requires adjustment. The vertical direction of the cross is vertical, but the horizontal direction is not horizontal.

[0031] <Effects> [Effects in the Embodiment] According to the spectral imaging unit adjustment system 1 of the embodiment, the spectral imaging unit adjustment system 1 of the embodiment adjusts a spectral imaging unit having an adjustment slit member 14 into which light from a light source 2 is incident through a slit 14a, a rotationally asymmetric diffraction unit 30, and a spectral imaging sensor 36 equipped with an image sensor 36a, and uses the adjustment slit member 14 to display at least the rotation angle of the diffraction unit 30 in the imaging region of the spectral imaging sensor 36, The slit 14a is cross-shaped, and the wavelength of the light source 2 is set such that, when the spectral range is 450 nm to 1700 nm, the wavelength of the emitted light from the diffraction unit 30 through the cross-shaped slit 14a is 1 / 2 or 1 / 3 of the wavelength of the spectral range. Therefore, the amount of adjustment (rotation of the diffraction unit) required to obtain high wavelength resolution and high resolution, i.e., to bring the diffraction unit to the desired rotational fixed position, can be visually confirmed based on the cross-shaped image displayed in the imaging area of ​​the spectral imaging sensor 36. This makes adjustment easier (shorter adjustment time) and improves adjustment accuracy.

[0032] According to the spectral imaging unit adjustment system 1 of the embodiment, the cross-shaped slit 14a is composed of a first elongated hole 14a1 and a second elongated hole 14a2 perpendicular to the first elongated hole 14a1. The first imaging length corresponding to the first elongated hole 14a1 and the second imaging length corresponding to the second elongated hole 14a2, which are imaged in the imaging region of the spectral imaging sensor 36 through the slit, are 1 / 4 or more of the widthwise length (sensor width Ha) in the imaging region of the spectral imaging sensor 36. Therefore, since the imaging position of the light is displayed within the imaging area of ​​the spectral imaging sensor 36, the desired amount of rotation of the diffraction unit 30 (error in rotational position) and the desired tilt of the spectral imaging sensor 36 (error in tilt) can be easily confirmed, thereby ensuring a more accurate adjustment.

[0033] According to the spectral imaging unit 3 of this embodiment, the diffraction unit 30 includes a grating 33 and a pair of prisms 31 and 32 arranged symmetrically on either side of the grating 33 and each having the same wedge angle, and a fixing jig 60 for fixing the grating 33 and the pair of prisms 31 and 32 is attached to the diffraction unit 30. Therefore, since the grating and the pair of prisms are fixed together at the desired rotational position, there is no need to disassemble the grating and the pair of prisms when adjusting the rotation; only the diffraction unit 30 needs to be rotated. As a result, only the rotation of the diffraction unit 30, which consists of the grating and the pair of prisms, needs to be adjusted, thus reducing the time required for rotation adjustment.

[0034] According to the spectral imaging unit 1 of this embodiment, the fixing jig 60 is ring-shaped and comprises a narrow plate-shaped member 61 and a wide plate-shaped member 63. The narrow plate-shaped member 61 and the wide plate-shaped member 63 are formed alternately along the circumferential direction and are integrally molded. The inner diameter of the fixing jig 60 is the same as or slightly larger than the outer diameter of the diffraction unit 30. Therefore, since the fixing jig 60 can be easily attached to and detached from the diffraction unit 30, the time required for rotational adjustment can be reduced.

[0035] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. [Explanation of Symbols]

[0036] 1…Spectroscopic imaging unit adjustment system, 2…Light source, 3…Spectroscopic imaging unit, 14…Adjustment slit member, 14a…Cross-shaped slit, 20…Collimator lens group, 30…Diffraction unit, 33…Grating (diffraction grating), 36…Spectroscopic imaging sensor, 36a…Image sensor, 40…Focus lens group

Claims

1. A spectral imaging unit is adjusted, which includes an adjustment slit member that receives light from a light source through a slit, a rotationally asymmetric diffraction unit, and a spectral imaging sensor equipped with an image sensor. A spectroscopic imaging unit adjustment system that uses the adjustment slit member to display at least the rotation angle of the diffraction unit in the imaging region of the spectroscopic imaging sensor, The slit is cross-shaped, and the wavelength of the light source is set such that, when the spectral range is 450 nm to 1700 nm, the wavelength of the emitted light from the diffraction unit through the cross-shaped slit is 1 / 2 or 1 / 3 of the wavelength of the spectral range. A spectroscopic imaging unit adjustment system characterized by the following features.

2. The cross-shaped slit is composed of a first elongated hole and a second elongated hole perpendicular to the first elongated hole, and the first imaging length corresponding to the first elongated hole and the second imaging length corresponding to the second elongated hole, which are imaged in the imaging region of the spectral imaging sensor through the slit, are 1 / 4 or more of the widthwise length in the imaging region of the spectral imaging sensor. The spectroscopic imaging unit adjustment system according to feature 1.

3. The aforementioned spectroscopic element group comprises a grating and a pair of prisms arranged symmetrically on either side of the grating, each having the same wedge angle. The grating and the fixing fixture for securing the pair of prisms are attached to the diffraction unit. A spectroscopic imaging unit adjustment system according to claim 1 or 2, characterized by the above.

4. The fixing jig is ring-shaped and comprises a narrow plate-shaped member and a wide plate-shaped member, the narrow plate-shaped member and the wide plate-shaped member are formed alternately along the circumferential direction and are integrally molded, and the inner diameter of the fixing jig is the same as or slightly larger than the outer diameter of the diffraction unit. The spectroscopic imaging unit adjustment system according to feature 3.

Images