JP2011226876A - Spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectrometer capable of obtaining accurate and stable spectral characteristics.SOLUTION: A spectrometer (100) comprises: an objective optical system (11) capable of telecentrically imaging a target object without vignetting; a first transmission wavelength selective filter (12) formed to have a different transmission wavelength along a predetermined direction; a driving member for driving the first transmission wavelength selective filter; a projection optical system (15) for projecting a conjugate image of the target object image without vignetting; an aperture stop (153) provided in the objective optical system or the projection optical system (15), for allowing a telecentric transmission of a component used for image pickup without vignetting, out of the light flux that creates an object image onto the first transmission wavelength selective filter and transmits the filter; a two-dimensional image pickup device (16) for picking up the conjugate image; a storage for storing the conjugate image; and a measuring member for measuring the spectral characteristics of the target object.

Description

  The present invention relates to a spectroscopic measurement apparatus that measures reflection spectral characteristics and transmission spectral characteristics of an object using a spectral image obtained through a wavelength selection filter.

  In the spectroscopic measurement apparatus disclosed in Patent Document 1, a focusing screen is installed at an image image formation position of a photographing lens of the spectroscopic measurement apparatus, and a light receiving element in the spectroscopic measurement apparatus captures an image projected on the focusing screen. A wavelength selection filter whose transmission wavelength continuously changes is disposed between the photographing lens and the focusing screen, and the drive device can be moved so that the wavelength selection filter can be moved in the direction in which the transmission wavelength of the wavelength selection filter changes. Is attached through. The wavelength selection filter is moved in the direction in which the transmission wavelength changes at a movement distance corresponding to an arbitrary wavelength interval, and a light receiving element in the spectroscopic measurement apparatus captures a plurality of images at each movement position of the wavelength selection filter. obtain. These multiple image files are processed by a computer to extract image signals corresponding to each measurement wavelength of the part of the target object corresponding to the same position of each image and combine them to obtain spectral reflectance or spectral transmittance at a predetermined wavelength interval. The spectral characteristic of the object is measured by calculating.

JP 2005-300509 A

However, in the spectroscopic measurement apparatus disclosed in Patent Document 1, there is a possibility that vignetting is present in the light flux that passes through the wavelength selection filter, or the light is not telecentric. In such a case, the wavelength selection filter transmission angle of the light component varies depending on the image height, so that the spectral transmission characteristics change even at the same location on the wavelength selection filter, and accurate spectral characteristics cannot be obtained. There is also.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a spectroscopic measurement apparatus capable of obtaining accurate and stable spectral characteristics.

  The spectroscopic measurement apparatus according to this aspect includes an objective optical system capable of forming a target object image telecentricly without vignetting, and an imaging surface of the target object image formed by the objective optical system. A first transmission wavelength selection filter configured to transmit light up to a second wavelength of a long wavelength and have a transmission wavelength different along a predetermined direction; and a first transmission wavelength selection filter in a predetermined direction within an imaging plane. A drive unit that moves at predetermined pitches, a projection optical system that projects a conjugate image of an image of a target object without vignetting only with a light beam component telecentrically transmitted through a first transmission wavelength selection filter, and an objective optical system or projection optical system The component used for imaging out of the luminous flux that is installed in the system and forms the target object image on the first transmission wavelength selection filter and passes through is telecentric without vignetting. A two-dimensional imaging device that captures a conjugate image projected by a projection optical system in two dimensions, and a plurality of pixels arranged in a predetermined direction and in an orthogonal direction orthogonal to the predetermined direction; When the first transmission wavelength selection filter moves with a predetermined pitch, the storage unit that stores the conjugate image captured by the two-dimensional imaging device captures the conjugate image with the two-dimensional imaging device for each movement, and stores the conjugate image in the storage unit. A measurement unit that measures the spectral characteristics of the target object.

  In the spectroscopic measurement apparatus of the present invention, the objective optical system forms the target object image on the wavelength selection filter without vignetting and telecentrically, so that accurate and stable spectral characteristics can be obtained.

1 is a schematic configuration diagram of a spectrometer 100. FIG. 1 is a schematic optical path diagram of a spectrometer 100. FIG. It is a figure for demonstrating the vignetting phenomenon. It is explanatory drawing of the characteristic of 12 A of 1st transmission wavelength selection filters from which a transmission wavelength changes. FIG. 4 is a diagram illustrating a relative relationship between a first transmission wavelength selection filter 12A and a light receiving surface 161 of a two-dimensional image sensor 16 for each pitch. FIG. 4 is a diagram illustrating a relative relationship between a first transmission wavelength selection filter 12A and a light receiving surface 161 of a two-dimensional image sensor 16 for each pitch. 3 is a schematic diagram illustrating a control unit 17 and an image processing unit 18. FIG. 3 is an explanatory diagram showing a correspondence relationship between a transmission wavelength and a light receiving surface 161 of the two-dimensional imaging device 16. FIG. 6 is a graph showing spectral characteristics obtained by photographing six times of F1, F2, F3, F4, F5, and F6 while shifting the first transmission wavelength selection filter 12A with a pitch S. It is a top view of 12 A of 1st transmission wavelength selection filters of 1st Embodiment. FIG. 6 is a diagram illustrating an example of spectral characteristics displayed on a monitor by the image processing unit 18. It is a figure which shows the relative relationship between the 2nd filter holding | maintenance part 13B of 2nd Embodiment, and the light-receiving surface 161 of the two-dimensional image sensor 16. FIG. It is a figure which shows the relative relationship between the 3rd filter holding | maintenance part 13C of 3rd Embodiment, and the light-receiving surface 161 of the two-dimensional image sensor 16. FIG. It is a figure which shows the relative relationship between 4th filter holding | maintenance part 13D of 4th Embodiment, and the light-receiving surface 161 of the two-dimensional image sensor 16. FIG.

(First embodiment)
<Outline of Spectrometer 100>
FIG. 1 is a schematic configuration diagram of a spectroscopic measurement apparatus 100. FIG. 2 is a schematic optical path diagram of the spectrometer 100. As shown in FIG. 1, in the spectroscopic measurement apparatus 100, the objective optical system 11, the first transmission wavelength selection filter 12A, the projection optical system 15, and the two-dimensional imaging device 16 are arranged in this order along the optical axis Ax. The first transmission wavelength selection filter 12A is held by the first filter holding unit 13A. The first filter holding unit 13A is mounted on a drive stage 14 having a one-dimensional linear drive mechanism, and can move along an arrow AR1 (perpendicular to the optical axis Ax). The control unit 17 controls the drive stage 14 and the two-dimensional image sensor 16. The control unit 17 is connected to the image processing unit 18. The control unit 17 and the image processing unit 18 store the captured image and measure the spectral characteristics of the target object.

  The objective optical system 11 includes objective lenses 111 and 112 arranged along the optical axis Ax as shown in FIG. Here, although the objective lenses 111 and 112 are depicted as convex lenses, they are a lens group composed of a plurality of lenses. The objective optical system 11 may be exchangeable in order to adjust the magnification. Further, the objective optical system 11 can image the object image Im1 on the imaging plane Mi without vignetting and telecentric. The target object is not shown. Here, vignetting is a phenomenon in which a part of the light beam forming the image periphery is removed by a lens frame or the like, and is one cause of the difference in brightness between the center of the image and the image periphery. It becomes.

  The effect of vignetting on the wavelength selective filter transmission spectral characteristics will be described with reference to FIGS. FIG. 3 is a diagram for explaining the vignetting phenomenon. An on-axis light beam FL without vignetting and an off-axis light beam FL 'with vignetting generated are depicted. It is assumed that telecentric imaging is performed on the wavelength selection filter 12A. In FIG. 3A, the off-axis light beam FL 'passes through the point H on the wavelength selection filter 12A. The wavelength selective filter 12A is moved from this state in FIG. 3B, and the axial light beam FL passes through the point H. In the off-axis light beam FL ′, a part of the light beam end is lost due to vignetting, so that the light beam component that passes through the wavelength selection filter 12A at an inclined angle is relatively smaller than the on-axis light beam FL. The spectral characteristic of the interference filter film 122 on the wavelength selection filter 12A varies depending on the light beam passing angle. Usually, the transmission band is widened to the short wavelength side as the light beam becomes oblique. Therefore, it is desirable that the spectral transmission characteristics indicated by the point H be equal in the case of FIG. 3A and FIG. 3B, but in reality, a difference will occur. As a result, the spectral characteristics obtained by the spectroscopic measurement apparatus 100 are affected.

  The objective optical system 11 of the spectrometer 100 forms the object image Im1 on the first transmission wavelength selection filter 12A, and the projection optical system 15 forms the conjugate image Im2 of the object image Im1 on the two-dimensional image sensor 16. The component reaching the two-dimensional imaging element 16 in the object image Im1 imaged light beam transmitted through the first transmission wavelength selection filter 12A by the action of the aperture stop 153 is transmitted through the first transmission wavelength selection filter 12A without vignetting and telecentrically. To do. For this reason, the spectroscopic measurement apparatus 100 can obtain accurate spectral characteristics.

  Further, as shown in FIG. 1, the first transmission wavelength selection filter 12A is held by the first filter holding unit 13A, and is mounted on the drive stage 14 that drives one-dimensional linearly along the arrow AR1 (X-axis direction). Can move. Here, the first filter holding portion 13A is configured such that a window is opened only in the light transmission region of the first transmission wavelength selection filter 12A, and the other portions are shielded from light. The drive stage 14 can move the first transmission wavelength selection filter 12A in the arrow AR1 (X-axis direction) by a predetermined pitch S (see FIG. 5).

  The first transmission wavelength selection filter 12A is a multilayer optical element having a multilayer interference filter layer 122 on one side of the plane parallel plate 121, and can selectively transmit light in a predetermined wavelength band. it can. The transmission wavelength of the first transmission wavelength selection filter 12A changes linearly in the X-axis direction at a predetermined position in the Y-axis direction (see FIG. 4).

  FIG. 4 is an explanatory diagram of the characteristics of the first transmission wavelength selection filter 12A in which the transmission wavelength changes. More specifically, for example, when the first transmission wavelength selection filter 12A has transmission regions A to G in its moving direction, the wavelength band of the transmission region A is λ1 to λ2, and the wavelength band of the transmission region B is λ2 to λ3. ..., the wavelength band of the transmission region G is λ7 to λ8. Further, the transmission wavelengths λ1 to λ8 change linearly as shown in FIG. For example, if the transmission wavelengths λ1 to λ8 correspond to the wavelength band of visible light 400 nm to 750 nm, the transmission region A corresponds to the shortest transmission wavelength band 400 nm to 450 nm, and the transmission region G has the longest transmission wavelength band 700 nm to 750 nm. It corresponds to.

That is, the thickness of the interference filter layer 122 changes along the moving direction of the first transmission wavelength selection filter 12A (the direction of the arrow AR1 in FIG. 1), thereby transmitting light that passes through the first transmission wavelength selection filter 12A. The wavelength changes linearly along the moving direction of the first transmission wavelength selection filter 12A. The first transmission wavelength selection filter 12A is formed such that light of all wavelengths included in the transmission wavelength band is surely transmitted through any interference filter layer 122 in the direction of the arrow AR1.
For ease of understanding, the interference filter layer 122 of the first transmission wavelength selection filter 12A extends the transmission wavelength band in the Y-axis direction and extends in the X-axis direction as shown in FIGS. It is drawn as a divided area.

  Returning to FIG. 2, the first transmission wavelength selection filter 12 </ b> A is disposed so that the interference filter layer 122 matches the imaging plane Mi of the target object. Thereby, the object image Im1 is formed by the objective lens 11 on the interference filter layer 122 of the first transmission wavelength selection filter 12A.

  The projection optical system 15 includes a pair of projection lenses 151 and 152 arranged along the optical axis Ax as shown in FIG. Here, although the projection lenses 151 and 152 are depicted as convex lenses, they are a lens group composed of a plurality of lenses. The projection optical system 15 has an aperture stop 153 between the projection lens 151 and the projection lens 152. The projection optical system 15 can project the conjugate image Im2 of the object image Im1 formed by the objective lens 11 onto the light receiving surface 161 of the two-dimensional image sensor 16 without vignetting. The aperture stop 153 may be provided between the objective lens 111 and the objective 112 of the objective optical system 11.

  The two-dimensional image sensor 16 is a monochrome image sensor, and may be a two-dimensional CCD (Charge Coupled Device) image sensor or a two-dimensional CMOS image sensor, for example.

  The conjugate image Im2 formed by the projection optical system 15 is not only the object image of the target object but also the conjugate image of the first transmission wavelength selection filter 12A. For this reason, the wavelength of the light that forms the conjugate image Im2 on the light receiving surface 161 of the two-dimensional image sensor 16 differs depending on the position in the X-axis direction. That is, when attention is paid to any part of the conjugate image Im2, the corresponding part of the conjugate image Im2 is formed by the light in the wavelength band that transmits the part on the first transmission wavelength selection filter 12A conjugate to this part. Further, when the first transmission wavelength selection filter 12A is moved in the X-axis direction by the drive stage 14, the image of the first transmission wavelength selection filter 12A imaged on the light receiving surface 161 also moves. For this reason, the wavelength of the light received by the two-dimensional image sensor 16 also changes.

  The spectral transmission characteristics of the first transmission wavelength selection filter 12A described above vary depending on the angle of the transmitted light beam. That is, when a light beam is incident on the first transmission wavelength selection filter 12A from an oblique direction, the transmission wavelength is changed. On the other hand, when the first transmission wavelength selection filter 12A is moved in the arrow direction AR1 (FIG. 1: X-axis direction) by the drive stage 14, the relative position (Z-axis direction) between the first transmission wavelength selection filter 12A and the object image Im1. ) May change. As described above, since the objective optical system 11 telecentricly forms the object image Im1 of the target object on the imaging plane Mi, even when the interference filter layer 122 changes in the Z-axis direction, the same XY plane is used. The transmission wavelength band of the light beam passing through the position hardly changes.

  Since the objective optical system 11 is telecentric, the light beam forming the object image Im1 has a converging angle almost at half angle θ at any condensing point, and passes through the principal ray LL1, that is, the main beam O passing through the center O of the aperture stop 153. All of the light beams LL1 are transmitted vertically to the first transmission wavelength selection filter 12A. For this reason, the angular characteristics of the light beams transmitted through the first transmission wavelength selection filter 12A are all equivalent. Therefore, more accurate spectral characteristics can be obtained as compared with the case where the chief ray is transmitted obliquely with respect to the first transmission wavelength selection filter 12A.

  The shape of the spectral characteristic of the transmission wavelength band of the first transmission wavelength selection filter 12A is determined by the design of the first transmission wavelength selection filter 12A and the diameter R of the aperture stop 153. In general, the larger the diameter R of the aperture stop 153, the wider the condensing angle and the transmission wavelength band spread to the short wavelength side, so the diameter is set according to the required specifications.

  The objective optical system 11 and the projection optical system 15 used in the spectroscopic measurement apparatus 100 collect and project a light beam having a wide wavelength band, so that the wavelength band of the first transmission wavelength selection filter 12A, for example, 400 nm to 800 nm. On the other hand, it is preferable to use an optical system in which chromatic aberration is corrected.

<Imaging Process of Spectrometer 100>
5 and 6 are explanatory views of the imaging process by the spectroscopic measurement device 100, and are plan views viewed from the optical axis Ax direction (Z-axis direction). FIGS. 5A to 5G and FIGS. 6H to 6M show the first transmission wavelength for each pitch S when the first transmission wavelength selection filter 12A is moved at the predetermined pitch S by the drive stage 14. 3 is a diagram illustrating a relationship between a selection filter 12A and a light receiving surface 161 of a two-dimensional image sensor 16. FIG.

  The first transmission wavelength selection filter 12A linearly changes its transmission wavelength as shown in FIG. 4, but in FIGS. 5 and 6, the first transmission wavelength selection filter 12A has seven transmission regions A having different transmission wavelengths. The explanation will be divided into ~ G. The transmission wavelength band of the transmission region A is, for example, 400 nm to 450 nm, the transmission wavelength band of the transmission region B is, for example, 450 nm to 500 nm,..., And the transmission wavelength band of the transmission region G is, for example, 700 nm to 750 nm. The first filter holding unit 13A is a light shielding unit except for the window where the first transmission wavelength selection filter 12A is disposed.

In the following description, attention is focused on the pixel region P and the pixel region Q that are marked with a square mark on the light receiving surface 161 depicted in FIG.
In FIG. 5A, the first transmission wavelength selection filter 12A starts to move in the + X-axis direction, and only the light beam that has passed through the transmission region A enters the light receiving surface 161 of the two-dimensional image sensor 16, and a conjugate image Im2 is formed. The Therefore, light having a wavelength band of 400 nm to 450 nm is incident on the pixel region P of the light receiving surface 161.

  In FIG. 5B, the first transmission wavelength selection filter 12A moves by a pitch S in the + X axis direction from the state of FIG. Then, only the light that has passed through the transmission regions A and B enters the light receiving surface 161 of the two-dimensional image sensor 16, and a conjugate image Im2 is formed. The pixel region P of the light receiving surface 161 corresponds to the transmission region B, and light having a wavelength band of 450 nm to 500 nm is incident on the pixel region P of the light receiving surface 161.

  In FIG. 5C, the first transmission wavelength selection filter 12A moves from the state of FIG. 5B by the pitch S in the + X axis direction. Then, only the light that has passed through the transmission regions A to C enters the light receiving surface 161 of the two-dimensional image sensor 16, and a conjugate image Im2 is formed. The pixel region P of the light receiving surface 161 corresponds to the transmission region C, and light having a wavelength band of 500 nm to 550 nm is incident on the pixel region P of the light receiving surface 161.

  The first transmission wavelength selection filter 12A continues to move by a pitch S in the + X axis direction. Therefore, in FIG. 5D, the pixel region P of the light receiving surface 161 corresponds to the transmission region D, and light having a wavelength band of 550 nm to 600 nm is incident on the pixel region P of the light receiving surface 161. 5E, the pixel region P of the light receiving surface 161 corresponds to the transmission region E, and light having a wavelength band of 600 nm to 650 nm is incident on the pixel region P of the light receiving surface 161. In FIG. 5F, the pixel region P of the light receiving surface 161 corresponds to the transmission region F, and light having a wavelength band of 650 nm to 700 nm is incident on the pixel region P of the light receiving surface 161.

  In FIG. 5G, the first transmission wavelength selection filter 12A moves from the state of FIG. 5F by the pitch S in the + X axis direction. The pixel region P of the light receiving surface 161 corresponds to the transmission region G, and light having a wavelength band of 700 nm to 750 nm is incident on the pixel region P of the light receiving surface 161. The pixel region Q of the light receiving surface 161 corresponds to the transmission region A, and light having a wavelength band of 400 nm to 450 nm is incident on the pixel region Q of the light receiving surface 161. In the relationship between the first transmission wavelength selection filter 12A and the light receiving surface 161 depicted in FIG. 5G, the light transmitted through all the transmission regions A to G of the first transmission wavelength selection filter 12A is a two-dimensional imaging device. It is formed as a conjugate image Im2 on 16 light receiving surfaces 161.

  As described above, the first transmission wavelength selection filter 12A moves by one pitch in the + X-axis direction as shown in FIGS. 5A to 5G, so that the pixel region P of the light receiving surface 161 is changed. The imaging with all the wavelength regions 400 nm to 750 nm of the first transmission wavelength selection filter 12A is completed.

  Thereafter, when the first transmission wavelength selection filter 12A is further moved by 6 pitches along the + X axis direction from the state of FIG. 5 (g), the state depicted in FIGS. 6 (h) to 6 (m). become. That is, light in the wavelength band 450 nm to 500 nm... Light in the wavelength band 700 nm to 750 nm is incident on the pixel region Q of the light receiving surface 161. Thereby, the imaging in all the wavelength regions 400 nm to 750 nm of the first transmission wavelength selection filter 12A is completed on the entire light receiving surface 161.

  5 and 6, when the first transmission wavelength selection filter 12A moves every pitch S (for example, 10 mm), the wavelength band changes by 50 nm. However, when measuring the spectral characteristics more accurately, it is preferable to make the pitch S at which the first transmission wavelength selection filter 12A moves finer. That is, for example, when the first transmission wavelength selection filter 12A moves every small pitch S (for example, 2 mm), the wavelength band changes by 10 nm. Therefore, finer spectral characteristics can be measured. On the other hand, in FIG. 5 and FIG. 6, the two-dimensional image sensor 16 has taken 13 shots. However, if the pitch S is set to 1/5, 60 or more shots are required. For this reason, the measurement time of spectral characteristics becomes long.

<Outline of Control Unit 17 and Image Processing Unit 18>
FIG. 7 is a schematic diagram showing the control unit 17 and the image processing unit 18.
As shown in FIG. 7, the control unit 17 includes a drive unit 171 and a storage unit 172. The drive unit 171 is connected to the drive stage 14. The drive unit 171 controls the drive stage 14 so that the first filter holding unit 13A holding the first transmission wavelength selection filter 12A moves along the arrow AR1 (see FIG. 1) by a predetermined pitch S. . The storage unit 172 is connected to the two-dimensional image sensor 16. The storage unit 172 stores a conjugate image Im2 of the target object imaged by the two-dimensional imaging device 16.

  The control unit 17 further includes a first correction unit 173. When the predetermined pitch S exceeds one pixel pi of the two-dimensional image sensor 16 arranged along the arrow AR1 (see FIG. 1), the first correction unit 173 moves in the direction of the arrow AR1 corresponding to the predetermined pitch S. The transmission wavelength shift is corrected for the conjugate image Im2 picked up by a plurality of pixels pi.

  FIG. 8A is an explanatory diagram showing the above-described shift in transmission wavelength, and is a diagram illustrating the transmission region D of the first transmission wavelength selection filter 12A. The wavelength band in the transmission region D of the first transmission wavelength selection filter 12A is λ4 to λ5 (see FIG. 4). The wavelength bands λ4 to λ5 are, for example, wavelength bands 550 nm to 600 nm.

  As shown in FIG. 8A, the predetermined pitch S (10 mm) corresponds to the width of 5 pixels pi (one pixel width 2 mm) of the two-dimensional image sensor 16. That is, the light receiving surface 161 of the two-dimensional image sensor 16 corresponding to the transmission region D has five pixel columns P1 to P5. Note that the actual width of the pixel column of the two-dimensional imaging device 16 is several μm to several tens of μm.

  The pixel column P1 is in the wavelength band λ4 to λ41 (550 nm to 560 nm), the pixel column P2 is in the wavelength band λ41 to λ42 (560 nm to 570 nm), and the pixel column P3 is in the wavelength band λ42 to λ43 (570 nm to 580 nm). P4 corresponds to the wavelength band λ44 to λ44 (580 nm to 590 nm), and the pixel column P5 corresponds to the wavelength band λ44 to λ5 (590 nm to 600 nm). Here, the transmission wavelength varies linearly even between the wavelengths λ4 to λ41, λ41 to λ42... Λ44 to λ5 (see FIG. 4).

  That is, in the state of FIG. 8A, light fluxes in the wavelength bands λ4 to λ41 are incident on the pixels pi in the pixel row P1. Similarly, light fluxes in the wavelength bands λ41 to λ42 are incident on the pixel row P2, light fluxes in the wavelength bands λ42 to λ43 are incident on the pixel row P3, and light fluxes in the wavelength bands λ43 to λ44 are incident on the pixel row P4. In P5, the light flux in the wavelength band λ44 to λ5 enters. Therefore, when the first transmission wavelength selection filter 12A moves from the state of FIG. 8A by a predetermined pitch S, the light flux that has passed through the wavelength band λ41 to λ5 (560 nm to 600 nm) of the first transmission wavelength selection filter 12A into the pixel row P1. Does not enter. Similarly, in the pixel column P2, the light flux that has passed through the wavelength bands λ4 to λ41 (550 nm to 560 nm) and λ42 to λ5 (570 nm to 600 nm) of the first transmission wavelength selection filter 12A does not enter. In the pixel row P3, the light beam that has passed through the wavelength bands λ4 to λ42 (550 nm to 570 nm) and λ43 to λ5 (580 nm to 600 nm) of the first transmission wavelength selection filter 12A does not enter. In the pixel row P4, the light beam that has passed through the wavelength bands λ4 to λ43 (550 nm to 580 nm) and λ44 to λ5 (590 nm to 600 nm) of the first transmission wavelength selection filter 12A does not enter. In the pixel column P5, the light beam that has passed through the wavelength band λ4 to λ44 (550 nm to 590 nm) of the first transmission wavelength selection filter 12A does not enter.

  The spectral lines obtained by the six imagings F1, F2, F3, F4, F5, and F6 with the pixel columns P1, P2, P3, P4, and P5 shown in FIG. 8A shifting the first transmission wavelength selection filter 12A with the pitch S. A characteristic example is shown in FIG. 8B. In FIG. 8B, actually obtained data is indicated by black circles. The wavelength value on the horizontal axis is the center wavelength of the transmission wavelength band of the first transmission wavelength selection filter 12A. As shown in FIG. 8B, the center wavelength of the transmission wavelength band of the first transmission wavelength selection filter 12A corresponding to one imaging is shifted according to the pixel column. By interpolating a discrete data sequence obtained by a plurality of times of imaging, a continuous spectral characteristic measurement result can be obtained for each pixel. In the interpolation calculation, the first graph on the horizontal axis of the graph corresponding to the pixel sequence is obtained. The shift of the center wavelength of the transmission wavelength selection filter 12A transmission wavelength band is taken into account. The first correction unit 173 performs the spectral characteristic interpolation calculation in consideration of the shift of the center wavelength of the transmission wavelength band of the first transmission wavelength selection filter 12A.

  Based on the width of the pixel pi of the two-dimensional image sensor 16 and the wavelength distribution of the first transmission wavelength selection filter 12A shown in FIG. 4, the first correction unit 173 transmits the transmission wavelength of the first transmission wavelength selection filter 12A for the pixel pi. The band center wavelength shift amount is calculated. Alternatively, the wavelength calibration target object may be photographed and the correction amount for the pixel pi may be stored in a lookup table.

  If the predetermined pitch S does not match the width of one pixel pi of the two-dimensional image sensor 16, it is necessary to correct the above-described wavelength shift by the first correction unit 173. The above-described correction is not necessary when it coincides with 16 one pixel pi.

  Returning to FIG. 7 again, the controller 17 will be described. The control unit 17 further includes a second correction unit 174, and the second correction unit 174 corrects the wavelength shift caused by the first transmission wavelength selection filter 12A itself. In the description up to FIG. 8B, the first transmission wavelength selection filter 12A has been described on the assumption that the transmission wavelength linearly changes in the X-axis direction and does not change in the Y-axis direction. However, when the interference filter layer 122 is formed on the first transmission wavelength selection filter 12A, the transmission wavelength may change in the Y-axis direction.

  FIG. 9 is a plan view of the first transmission wavelength selection filter 12A. The first transmission wavelength selection filter 12 </ b> A is a multilayer optical element having a multilayer interference filter layer 122 on one surface of a rectangular parallel flat plate 121. In general, when the interference filter layer 122 is formed on the plane parallel plate 121, a region having the same transmission wavelength as shown in FIG. 9 is a distribution indicated by a dotted line that swells toward the X side, for example. There may be. For this reason, for example, at the same position M1 in the X-axis direction, the transmission wavelengths are different at different points in the Y-axis direction, for example, the points T1 and T2. The second correction unit 174 corrects such a wavelength shift that occurs in the first transmission wavelength selection filter 12A itself.

  In order to correct the wavelength shift of the first transmission wavelength selection filter 12A itself, the wavelength calibration target object is photographed, the wavelength shift of the first transmission wavelength selection filter 12A is measured in advance, and the wavelength shift amount is calculated. Store in a lookup table. For example, the second correction unit 174 performs wavelength correction of 3 nm for the point T1 with reference to the Y0 axis, and performs wavelength correction of 9 nm for the point T2.

  Of course, the first transmission wavelength selection filter 12A may be produced with a large parallel flat plate 121, and for example, the filter 12Z as shown by the broken line in FIG. 9 may be cut out. Then, the wavelength shift of the filter 12Z itself is considerably reduced. In such a case, the second correction unit 174 does not necessarily need to perform wavelength correction of the filter itself.

  In FIG. 7, the first correction unit 173 corrects the wavelength and then the second correction unit 174 corrects the wavelength. The second correction unit 174 first performs wavelength correction, and then the second correction. The one correction unit 173 may perform wavelength correction.

  The control unit 17 has a measurement unit 175. When the first transmission wavelength selection filter 12A moves for each predetermined pitch S, the measurement unit 175 acquires image data of the conjugate image Im2 imaged by the two-dimensional imaging device 16 for each pitch S. The measurement unit 175 measures the spectral characteristics of the target object based on the image data.

  The spectroscopic measurement apparatus 100 further includes an image processing unit 18 that can process the spectral intensity distribution for each image element based on the image data acquired by the measurement unit 175. Here, the image element is image data from the pixel region of the two-dimensional imaging device 16 corresponding to the pitch S when the first transmission wavelength selection filter 12A moves for each pitch S. The control unit 17 and the image processing unit 18 may be a personal computer or the like. The image processing unit 18 displays measurement results such as image data on the connected monitor CRT.

  FIG. 10 is a diagram showing an example of spectral characteristics processed by the image processing unit 18 and displayed on the monitor CRT. For example, the spectroscopic measurement apparatus 100 is used in the medical field, and FIG. 10 shows spectral characteristics when an organ is observed. The observer can determine whether or not the organ is ill with a graph showing the spectral characteristics. For example, when this organ is normal, the spectral characteristic graph in each of the wavelength bands A to G is as shown by the solid line in FIG. However, when this organ is ill, the spectral characteristics I1 to I4, I6, and I7 in the wavelength bands A to D, F, and G hardly change, but the spectral characteristic I5 in the wavelength band E greatly decreases. The spectral characteristic is I5 ′. There is a possibility that the color of a normal organ and the color of a diseased organ cannot be clearly distinguished by the observer's eyes only by changing the wavelength band E. By displaying the spectral characteristics of the organ on the monitor CRT, the observer can determine whether or not the organ has a disease.

(Second Embodiment)
The spectroscopic measurement apparatus 100 of the second embodiment uses a second filter holding unit 13B having a transparent parallel plate 121a and a light-shielding parallel plate 121b in addition to the first transmission wavelength selection filter 12A. Hereinafter, the second filter holding unit 13B will be described with reference to FIG.

  FIG. 11 is a diagram illustrating a relative relationship between the second filter holding unit 13 </ b> B and the light receiving surface 161 of the two-dimensional image sensor 16. As shown in FIG. 11, the second filter holding unit 13B is provided with the first transmission wavelength selection filter 12A described in the first embodiment at the center thereof. Further, on both sides of the first transmission wavelength selection filter 12A in the direction of the arrow AR1, a transparent parallel plate 121a and a light shielding parallel plate 121b having the same material and the same thickness as the parallel plate 121 of the first transmission wavelength selection filter 12A are transmitted through the first transmission wavelength selection filter 12A. Each is provided so as to adhere to the wavelength selection filter 12A. Nothing is formed on the surface of the transparent parallel plate 121a and it is transparent. The surface of the light shielding parallel plate 121b is, for example, chrome plated to shield the light beam from the objective lens 11.

  As shown in FIG. 11A, the transparent parallel plate 121a stops at a position covering the entire light receiving surface 161. Therefore, the two-dimensional image sensor 16 can capture an object image that does not pass through the first transmission wavelength selection filter 12A. In this state, since the object image is captured as a monochrome image, it is used for determining the imaging composition and focusing. Since the transparent parallel plate 121a has the same refractive index and the same thickness as the first transmission wavelength selection filter 12A, the focal position does not change even if the second filter holding portion 13B moves after focusing.

  Next, when the second filter holding unit 13B is imaged by the two-dimensional image sensor 16 while moving in the direction of the arrow AR1 for each pitch S, the spectroscopic measurement can be performed as described with reference to FIGS. As the movement for each pitch S is performed, the light receiving surface 161 is covered with the light-shielding parallel plate 121b. The light shielding parallel plate 121b functions as a light shielding frame of the first filter holding portion 13A (FIG. 1).

(Third embodiment)
The spectroscopic measurement apparatus 100 of the third embodiment uses a third filter holding unit 13C having two first transmission wavelength selection filters 12A. Hereinafter, the third filter holding unit 13C will be described with reference to FIG.

  FIG. 12 is a diagram illustrating a relative relationship between the third filter holding unit 13 </ b> C and the light receiving surface 161 of the two-dimensional imaging element 16. As shown in FIG. 12, the third filter holding unit 13C has the two first transmission wavelength selection filters 12A described in the first embodiment. That is, the two first transmission wavelength selection filters 12A are formed so as to adhere along the moving direction of the third filter holding portion 13C (the direction of the arrow AR1).

  First, as described in the second embodiment, focusing is performed using the transparent parallel flat plate 121a. Next, the third filter holding portion 13C is moved to the position shown in FIG. The amount of movement is 7 pitches, and the first first transmission wavelength selection filter 12A moves to a position covering the entire light receiving surface 161. In this state, the first imaging is performed by the two-dimensional imaging device 16. Imaging is performed simultaneously from the wavelength band A to the wavelength band G on the entire light receiving surface 161 of the two-dimensional imaging device 16. Thereafter, the third filter holding unit 13C moves for each pitch S.

  FIG. 12B is a diagram illustrating a state in which the third filter holding unit 13C has moved by three pitches from the state of FIG. The light receiving surface 161 of the two-dimensional imaging device 16 includes wavelength bands A, B, and C in one first transmission wavelength selection filter 12A and wavelength bands D, E, F, and G in another first transmission wavelength selection filter 12A. I'm shooting at the same time.

  FIG. 12C is a diagram illustrating a state in which the third filter holding unit 13C has moved from the state of FIG. The wavelength band G in one first transmission wavelength selection filter 12A and the wavelength bands A to F in another first transmission wavelength selection filter 12A cover the light receiving surface 161. The light receiving surface 161 of the two-dimensional image sensor 16 captures images from the wavelength band A to the wavelength band G simultaneously. That is, by moving the third filter holding unit 13C six times for every pitch from FIG. 12A to FIG. 12C, the entire wavelength of the light receiving surface 161 of the two-dimensional imaging device 16 is changed from the wavelength band A to the wavelength band. Images up to G can be captured.

  In the first embodiment, as shown in FIGS. 5 and 6, the two-dimensional image pickup device 16 has taken 13 times. According to the third embodiment, the two-dimensional image sensor 16 may perform shooting seven times. For this reason, the imaging time can also be shortened.

(Fourth embodiment)
The spectroscopic measurement apparatus 100 according to the fourth embodiment uses a fourth filter holding unit 13D having a first transmission wavelength selection filter 12A and a second transmission wavelength selection filter 12B having a different wavelength range. Hereinafter, the fourth filter holding unit 13D will be described with reference to FIG.

  FIG. 13 is a diagram illustrating a relative relationship between the fourth filter holding unit 13 </ b> D and the light receiving surface 161 of the two-dimensional image sensor 16. As shown in FIG. 13, the fourth filter holding unit 13D includes a transparent parallel plate 121a, a first transmission wavelength selection filter 12A, a second transmission wavelength selection filter 12B, and a light shielding parallel plate 121b in order from the right side of the drawing. Yes.

  Here, the second transmission wavelength selection filter 12B is the same type of optical element as the first transmission wavelength selection filter 12A described in the first embodiment, but the wavelength band of the transmission wavelength is different. For example, the first transmission wavelength selection filter 12A transmits visible light in the wavelength band 400 nm to 750 nm, while the second transmission wavelength selection filter 12B transmits infrared light in the wavelength band 750 nm to 1100 nm. For example, when the second transmission wavelength selection filter 12B includes transmission regions H to N in its moving direction, the wavelength region of the transmission region H is 750 to 800 nm, the wavelength region of the transmission region I is 800 to 850 nm, and the wavelength region of the transmission region J. Is 850 nm to 900 nm, the wavelength band of the transmission region K is 900 nm to 950 nm, the wavelength band of the transmission region L is 950 nm to 1000 nm, the wavelength band of the transmission region M is 1000 nm to 1050 nm, and the wavelength band of the transmission region N is 1050 nm to 1100 nm. .

  With such a configuration, for example, in the state shown in FIG. 13B, the entire light receiving surface 161 of the two-dimensional image sensor 16 has the wavelength bands D, E, F, and G in the first transmission wavelength selection filter 12A and the second transmission. It is possible to simultaneously cope with the wavelength bands H, I, and J in the wavelength selection filter 12B.

  For example, in the state of FIG. 13C, the light receiving surface 161 of the two-dimensional image sensor 16 captures images from the wavelength band H to the wavelength band N simultaneously. As described above, the spectroscopic measurement apparatus 100 according to the fourth embodiment can obtain spectral characteristics over a wider wavelength band than those of the first to third embodiments. Although the second transmission wavelength selection filter 12B has been described in the infrared light region, the second transmission wavelength selection filter 12B may be in the ultraviolet light region.

  The optimum embodiment of the present invention has been described above, but as will be apparent to those skilled in the art, the present invention can be implemented with various modifications within the technical scope thereof. For example, the transparent parallel flat plate 121a, the light shielding parallel flat plate 121b, and the first transmission wavelength selection filter 12A in the second embodiment may be configured by dividing one transparent parallel flat plate into three parts. Further, the two first transmission wavelength selection filters 12A in the third embodiment may be formed on one transparent parallel plate. Furthermore, in the fourth embodiment, the first transmission wavelength selection filter 12A and the second transmission wavelength selection filter 12B may be configured as a single transparent parallel plate.

  Further, for example, in the second to fourth embodiments, the first transmission wavelength selection filter 12A, the second transmission wavelength selection filter 12B, the transparent parallel plate 121a, and the light-shielding parallel plate 121b are directly bonded to each other and held in the filter holding unit. It had been. However, it is good also as a structure comprised with the filter holding | maintenance part which consists of a sheet | seat one sheet | seat one by one, and has several windows.

DESCRIPTION OF SYMBOLS 11 ... Objective optical system 12A, 12B ... 1st transmission wavelength selection filter 13A, 13B, 13C, 13D ... Filter holding | maintenance part 14 ... Drive stage 15 ... Projection optical system 16 ... Two-dimensional image sensor 17 ... Control part 18 ... Image processing part 19a, 19b ... Parallel plane plate 100 ... Spectrometer 111, 112, 151, 152 ... Lens 121, 121a, 121b ... Parallel plane plate 122 ... Interference filter layer 153 ... Aperture stop 161 ... Light receiving surface 171 ... Drive unit 172 ... Memory Unit 173 ... first correction unit, 174 ... second correction unit 175 ... measurement unit Ax ... optical axis Im1 ... object image, Im2 ... conjugate image CRT ... monitor

Claims (11)

An objective optical system capable of forming a target object image telecentricly without vignetting;
It is arranged on the imaging surface of the target object image by the objective optical system, and transmits light from the first wavelength to the second wavelength longer than the first wavelength so that the transmission wavelength is different along a predetermined direction. A first transmitted wavelength selection filter,
A drive unit that moves the first transmission wavelength selection filter in the predetermined direction within the imaging plane by a predetermined pitch;
A projection optical system that projects a conjugate image of the image of the target object without vignetting only with a light beam component telecentrically transmitted through the first transmission wavelength selection filter;
An aperture stop that is installed in the objective optical system or the projection optical system and forms a target object image on the first transmission wavelength selection filter and transmits a component used for imaging without vignetting and telecentric. When,
A two-dimensional imaging element that includes a plurality of pixels arranged in the predetermined direction and in an orthogonal direction orthogonal to the predetermined direction, and that captures the conjugate image projected by the projection optical system in two dimensions;
A storage unit for storing the conjugate image captured by the two-dimensional image sensor;
When the first transmission wavelength selection filter moves by the predetermined pitch, a measurement unit that captures a conjugate image with the two-dimensional image sensor and stores the conjugate image in the storage unit for each movement, and measures the spectral characteristics of the target object When,
A spectroscopic measurement apparatus.   The first transmission wavelength selection filter has a multilayer interference filter layer on one side of a plane parallel plate, and the thickness of the multilayer film changes along the predetermined direction, whereby the first transmission wavelength selection filter The spectroscopic measurement apparatus according to claim 1, wherein the transmission wavelength of the light passing through the laser beam linearly changes from the first wavelength to the second wavelength along the predetermined direction.   When the predetermined pitch moves beyond one pixel of the two-dimensional image sensor arranged in the predetermined direction, the conjugate image captured by a plurality of pixels in the predetermined direction corresponding to the predetermined pitch is The spectroscopic measurement apparatus according to claim 1, further comprising a first correction unit configured to correct a transmission wavelength shift.   The spectroscopic measurement device according to any one of claims 1 to 3, wherein the transmission wavelengths are different at different positions in the orthogonal direction of the first transmission wavelength selection filter.   5. The apparatus according to claim 1, further comprising: a second correction unit configured to correct a shift in the transmission wavelength with respect to the conjugate image captured by the pixels corresponding to different positions in the orthogonal direction. Spectroscopic measurement device. Furthermore, the interference filter layer of the multilayer film is not formed, and includes a reference plane plate of the same material and thickness as the parallel plane plate,
The spectroscopic measurement apparatus according to claim 2, wherein the driving unit moves the reference plane plate to the imaging plane. At least two of the first transmission wavelength selection filters are disposed along the predetermined direction;
The said measurement part moves two said 1st transmission wavelength selection filters for every said predetermined pitch, and captures the said conjugate image with the said two-dimensional image sensor for every movement, It memorize | stores in the said memory | storage part. The spectroscopic measurement device according to claim 5. The first transmission wavelength selection filter is disposed along the predetermined direction, transmits light from the second wavelength to a third wavelength longer than the second wavelength, and has a different transmission wavelength along the predetermined direction. A second transmission wavelength selection filter formed as follows:
The measurement unit moves the first transmission wavelength selection filter and the second transmission wavelength selection filter at the predetermined pitch, captures the conjugate image with the two-dimensional imaging element for each movement, and stores the conjugate image in the storage unit. The spectroscopic measurement device according to any one of claims 1 to 5.   The second transmission wavelength selection filter has a multilayer interference filter layer on one side of a plane parallel plate, and the thickness of the multilayer film changes along the predetermined direction, whereby the second transmission wavelength selection filter The spectroscopic measurement apparatus according to claim 8, wherein the transmission wavelength of the light passing through the laser beam linearly changes from the second wavelength to the third wavelength along the predetermined direction.   The spectroscopic measurement device according to claim 8 or 9, wherein the transmission wavelength is different at different positions in the orthogonal direction of the second transmission wavelength selection filter.   Image processing for displaying a spectral intensity distribution for each image element after converting the conjugate image to an image element for each predetermined pitch based on image data of the conjugate image stored in the storage unit for each predetermined pitch The spectroscopic measurement apparatus according to claim 1, further comprising a portion.