JP2001304966A - Fourier spectrometric image measuring equipment and artificial satellite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem where, with the images of objects 100 by n-pieces equal to the number of lenses of a lens array 111 imaged on a 2-dimension detector 160, only a spectrometric image of division number of nx×ny/n is acquired even if the 2-dimension detector 160 of such multiple pixels as nx×ny is used, resulting in the spectrometric image of low space resolution. SOLUTION: A Fourier spectrometric image measuring means is moved while a distance from an object is kept constant so that an optical path difference corresponding to a distance taken when a measurement light vertically incident on a flat end surface of a double refraction means reaches a slope end surface is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fourier spectroscopic image measurement apparatus used in the field of manufacturing industry such as product inspection and monitoring of a production line, and in the field of environmental measurement including earth observation from satellites such as ocean monitoring and air pollution monitoring. It relates to an artificial satellite using this.

[0002]

2. Description of the Related Art Fourier spectroscopy is a method of obtaining a spectrum by Fourier transforming an interference signal of an interferometer that causes two light beams to interfere with each other. In recent years, a Fourier spectroscopic image measurement device using this Fourier spectroscopy for image measurement has been used in various fields. FIG. 10 shows, for example, Japanese Patent Application Laid-Open No. 6-347324.
FIG. 1 is a diagram illustrating a configuration of a conventional Fourier spectroscopic image measurement device as described above disclosed in Japanese Unexamined Patent Publication. In the figure, 100
Is a measurement object to be image-measured, 110 is a collimating optical system that collimates light emitted from the measurement object 100 to be parallel light, 111 is a lens array composed of lenses arranged in a lattice, and 120 and 120. Reference numeral 130 denotes polarizers arranged so that their polarization planes are orthogonal to each other, and these are referred to as a polarizer and an analyzer, respectively. Reference numeral 140 denotes a liquid crystal cell in which a wedge-shaped birefringent liquid crystal cell is joined, and separates incident light into two linearly orthogonally polarized ordinary lights and extraordinary lights. Reference numeral 150 denotes a relay optical system that condenses the light transmitted through the analyzer 130 onto the two-dimensional detector 160, and reference numeral 160 denotes a two-dimensional detector that detects the interference light transmitted through the relay optical system 150. The polarizer 120, the liquid crystal cell 140, and the analyzer 130 constitute a polarization interferometer.

FIG. 11 is a block diagram showing the polarization interferometer in FIG. In the figure, 140a and 140b are wedge-shaped birefringent liquid crystal cells constituting the liquid crystal cell 140, and the liquid crystal inside is represented by an ellipse painted black. Note that the same components as those in FIG. 10 are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 12 is a view showing a spectral image obtained by the above-mentioned conventional Fourier spectral image measuring apparatus, and FIG.
Indicates a multiplexed image matrix when a 4 × 4 lens array is used, and (b) indicates an interferogram image.
In the figure, reference numeral 200 denotes a multiplex image matrix which is an interference image corresponding to a 4 × 4 lens array, and 300 denotes an interferogram image, in which the interference images arranged in the multiplex image matrix 200 are arranged for each optical path difference.

Next, the operation will be described. Measurement object 1
The light emitted from 00 is converted into collimated light by the collimating optical system 110, and is then split by the lens array 111 into light having a number of images corresponding to the number of lenses. A predetermined polarization component is extracted from the light passing through the lens array 111 by the polarizer 120, and a multiple image of the measurement target 100 is formed in the liquid crystal cell 140. In the liquid crystal cell 140, the light of each image of the multiplex image is separated into ordinary light and extraordinary light, and an optical path difference is given. These lights are caused to interfere by the analyzer 130, collected by the relay optical system 150, and detected by the two-dimensional detector 160 as an interference image.

Here, the liquid crystal cell 140 of the polarization interferometer is
The wedge-shaped birefringent liquid crystal cells 140a, 14 constituting the same
The directions in which the thickness changes are reversed so that the ridge lines of Ob are parallel to each other. The first birefringent liquid crystal cell 140a is composed of the optical axis of the liquid crystal molecules and the cell 140.
The liquid crystal molecules are aligned so that the ridge line of a is parallel. The second birefringent liquid crystal cell 140b is oriented so that the optical axis of the liquid crystal molecules and the ridgeline of the cell 140b are orthogonal. As shown in FIG. 11, the x-axis and the y-axis are defined, the apex angle of the birefringent liquid crystal cells 140a and 140b is φ, and the two birefringent liquid crystal cells 140a and 140b are placed on the x-axis in a plane perpendicular to the optical axis. It is rotated around the rotation angle θ. The optical path difference l (x, y, ν) between the ordinary light and the extraordinary light generated by propagating through the two birefringent liquid crystal cells 140a and 140b is expressed by the following equation. l (x, y, ν) = Δn (ν) ｛2 (xsinθ−ycosθ)｝ tanφ (1) where, ν = 1 / λ, the light wave number, and Δn (ν) is the liquid crystal with respect to the wave number ν. (The difference between the extraordinary light refractive index and the ordinary light refractive index).

In FIG. 10, light emitted from a point on the measurement object 100 interferes at different detection elements on the two-dimensional detector 160 with different optical path differences according to the optical path difference represented by the above equation. The image of each measurement object 100 in the multiplex image formed on the two-dimensional detector 160 has an interference intensity distribution according to the optical path difference. As shown in FIG. 12, an individual image that has interfered is defined as an interference image, and the entire image in which the interference images of the number of lenses constituting the lens array 111 are arranged in a lattice is defined as an interference image matrix 200. An interferogram image 300 is obtained by cutting out each interference image from the interference image matrix 200 and stacking the images in ascending order of the optical path difference. At a certain spatial position in the interferogram image 300, the one-dimensional intensity distribution extracted in the optical path difference direction corresponds to a sampled interferogram in normal Fourier spectroscopy. The spectral image can be reproduced by performing the inverse Fourier transform on.

[0008]

Since the conventional Fourier spectroscopic image measuring apparatus is configured as described above, an image of the measuring object 100 having the number n of lenses of the lens array 111 is formed on the two-dimensional detector 160. It is imaged. Therefore, even if the two-dimensional detector 160 having a large number of pixels nx × ny is used, only a spectral image having a division number nx × ny / n can be obtained.
There is a problem that only a spectral image with low spatial resolution can be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and omits a lens array. The distance from the plane end face of the wedge-shaped birefringent means to the slope end face is reduced. By moving the Fourier spectral image measurement means or the measurement object so as to have a corresponding optical path difference,
An object of the present invention is to obtain a Fourier spectroscopic image measurement device capable of obtaining a two-dimensional spectral image with high spatial resolution.

Another object of the present invention is to provide an artificial satellite capable of obtaining a two-dimensional spectral image of the ground surface with high spatial resolution while orbiting the earth with the object to be measured as the ground surface.

[0011]

A Fourier spectroscopic image measuring apparatus according to the present invention comprises a planar end face on which measurement light, which is light emitted from an object to be measured, is vertically incident, and a sloped end face opposed thereto. Birefringent means having a wedge shape and separating measurement light into two linearly polarized lights orthogonal to each other, and polarized light for extracting a predetermined polarization component so that the two linearly polarized lights separated by the birefringent means interfere with each other. Fourier spectroscopic image measurement means comprising interference means, two-dimensional detection means for detecting two linearly polarized interference lights transmitted through the polarization interference means, and processing the interference light detected by the two-dimensional detection means. Signal processing means for obtaining a spectral image, wherein the Fourier spectral image measuring means has an optical path difference according to the distance until the measuring light perpendicularly incident on the planar end face of the birefringent means reaches the inclined end face. It is intended to dynamic.

The Fourier spectroscopic image measuring apparatus according to the present invention has a wedge shape having a flat end face on which measurement light, which is light emitted from an object to be measured, is perpendicularly incident, and a slope end face opposed thereto. Birefringent means for separating the measurement light into two linearly polarized light beams orthogonal to each other; polarization interfering means for extracting a predetermined polarized component so that the two linearly polarized light beams separated by the birefringent means interfere with each other; Fourier spectroscopic image measurement means comprising two-dimensional detection means for detecting two linearly polarized interference lights transmitted through the interference means, and signal processing for processing the interference light detected by the two-dimensional detection means to obtain a two-dimensional spectral image The measurement object moves so as to have an optical path difference corresponding to the distance until the measurement light perpendicularly incident on the planar end face of the birefringent means reaches the inclined end face.

A Fourier spectroscopic image measuring apparatus according to the present invention has a first light condensing means for converging a measuring light beam and passing it through a birefringent means and then focusing, and has a predetermined imaging magnification, And a second light condensing means for condensing the light coupled to the two-dimensional detection means.

The Fourier spectroscopic image measuring apparatus according to the present invention is characterized in that a birefringent material constituting the birefringent means has a wedge-shaped birefringent material having a stepped end face.

The Fourier spectroscopic image measuring apparatus according to the present invention is characterized in that the birefringent means is formed by joining two wedge-shaped birefringent materials such that their inclined end faces face each other.

The Fourier spectroscopic image measuring apparatus according to the present invention is characterized in that two birefringent materials are joined so that their ridges are parallel and the directions in which the thickness changes are opposite. is there.

In the Fourier spectral image measuring apparatus according to the present invention, the signal processing means includes first error detecting means for detecting an error due to movement or swing of the Fourier spectral image measuring means,
The detection of the interference light by the two-dimensional detection means is corrected based on the error information detected by the first error detection means.

The Fourier spectroscopic image measuring apparatus according to the present invention has a second function of detecting an error due to movement or swing of the object to be measured.
The signal processing means is provided with the error detecting means, and the detection of the interference light by the two-dimensional detecting means is corrected based on the error information detected by the second error detecting means.

An artificial satellite according to the present invention is characterized in that the object to be measured is a ground surface, the apparatus has the Fourier spectral image measuring means according to any one of claims 1 to 8, and the birefringent means has a planar shape. The measurement light that is perpendicularly incident on the end face orbits so as to have an optical path difference corresponding to the distance until reaching the inclined end face.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a Fourier spectral image measurement apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a measurement target object which is an object of image measurement, 2 denotes a collimating optical system (first condensing unit), which collimates light (measurement light) emitted from the measurement target 1 into parallel light, and 3 Is a polarizer for extracting a predetermined polarization component from the light collimated by the collimating optical system 2, and 4 is the same as the polarizer 3 from the two linearly polarized lights separated by the birefringent unit 5 so that they interfere with each other. It is an analyzer (polarized light interference means) for extracting a polarized light component. The polarizer 3 and the analyzer 4 are composed of polarizers arranged so that their polarization planes are orthogonal to each other. 5 is a birefringent portion (birefringent means) made of a wedge-shaped birefringent material,
The incident light is separated into two linearly orthogonally polarized ordinary lights and extraordinary lights. Reference numeral 6 denotes a two-dimensional detector (two-dimensional detecting means), which detects interference light transmitted through the analyzer 4.
Reference numeral 7 denotes a Fourier spectroscopic image measurement unit (Fourier spectroscopic image measurement means) including a collimating optical system 2, a polarizer 3, a birefringent unit 5, and an analyzer 4, and 8 denotes an interference light detected by the two-dimensional detector 6. Determine an interferogram image based on the
A signal processing unit (signal processing means) that obtains a two-dimensional spectral image by performing Fourier transform on the interferogram image with respect to the optical path difference.

Next, the operation will be described. Light (measurement light) emitted from the measurement target 1 is condensed by the collimating optical system 2 to become parallel light, and a predetermined polarization component is extracted by the polarizer 3. The light transmitted through the polarizer 3 is perpendicularly incident on the wedge-shaped planar end face of the birefringent part 5, and is separated into two linearly-polarized ordinary lights and extraordinary lights orthogonal to each other from the wedge-shaped inclined end face. Each of them emits light with an optical path difference.
At this time, the Fourier spectroscopic image measurement unit 7 is moved so that the light perpendicularly incident on the planar end surface of the birefringent unit 5 has an optical path difference according to the distance until reaching the inclined end surface.

Next, the analyzer 4 extracts the same polarization component as that of the polarizer 3 from the ordinary light and the extraordinary light emitted from the birefringent portion 5 and causes them to interfere. Interfering light that has passed through the analyzer 4 and interfered is detected by the two-dimensional detector 6. The signal processing unit 8 obtains an interferogram image based on the interference light detected by the two-dimensional detector 6, and obtains a two-dimensional spectral image by performing a Fourier transform on the interferogram image with respect to an optical path difference.

Next, the movement of the Fourier spectral image measurement unit 7 will be described in detail. FIG. 2 is a side view showing a birefringent part and a two-dimensional detector of the Fourier spectral image measurement device according to the first embodiment. In the drawing, l1 (i, j) indicates the thickness of the birefringent material corresponding to the detection element at the position (i, j) of the two-dimensional detector 6. That is, the light vertically incident on the wedge-shaped planar end face of the birefringent part 5 propagates inside the birefringent part 5 by a distance l1 (i, j), and after being emitted, the position (i, It is detected by the detection element in j). Assuming that the refractive index for ordinary light is no and the refractive index for extraordinary light is ne, the position (i, j) of the two-dimensional detector 6
The optical path difference τ between the ordinary light and the extraordinary light at the position corresponding to the detection element is expressed by the following equation. τ = l1 (i, j) (no-ne) (2)

Here, the inclination of the wedge-shaped birefringent portion 5 at the inclined end surface is in the j-column direction of the two-dimensional detector 6, and the Fourier spectral image measuring unit 7 is moved in the j-column direction with respect to the object 1 to be measured. When moved, each detection element in the i-th row of the two-dimensional detector 6 observes an interference signal from the same place of the measurement object 1 due to an optical path difference according to the thickness of the birefringent part 5 at that position. Will be. In other words, the light passes through the wedge-shaped birefringent portion 5 and is separated into ordinary light and extraordinary light having an optical path difference, and these lights interfere with each other by extracting a polarization component by the analyzer 4, thereby generating an interference signal. I do. These interference signals are further moved by moving the Fourier spectral image measurement unit 7 in the j-column direction with respect to the measurement object 1 to further increase the thickness of the wedge-shaped birefringent unit 5 (that is, the thickness of the wedge-shaped birefringent unit 5). An optical path difference according to the distance from the flat end surface to the inclined end surface) can be given.

FIG. 3 is a diagram for explaining signal processing in the signal processing section of the Fourier spectral image measurement apparatus according to the first embodiment. The case where the detection signal detected by the detection element on the i-th row of the two-dimensional detector 6 is processed is shown. In the figure, there are measurement objects □, Δ, and * corresponding to different points of the measurement object 1. These measurement objects □, △, *
Controls the Fourier spectroscopic image measurement unit 7 with respect to the measurement object 1 in the j-th column while controlling so that the detection element in the i-th row of the two-dimensional detector 6 detects the time-series signal as shown below. Move in the direction.

At time t = 0 (that is, when the Fourier spectral image measurement unit 7 is at the movement start position), an interference signal due to light emitted from the measurement object □ is detected at the position (i, 1) of the two-dimensional detector 6. It shall be detected by the detecting element. Time t
= T, an interference signal due to light emitted from the measurement target □ due to the movement of the Fourier spectral image measurement unit 7 in the j-column direction is detected by the detection element at the position (i, 2) of the two-dimensional detector 6, and the measurement target △ It is assumed that an interference signal due to the light emitted from the detector is detected by the detection element at the position (i, 1) of the two-dimensional detector 6. At time t = 2T, the Fourier spectral image measurement unit 7 moves in the j-column direction, and an interference signal due to light emitted from the measurement target □ is detected by the detection element at the position (i, 3) of the two-dimensional detector 6, An interference signal due to light emitted from the measurement target △ is detected by the detection element at the position (i, 2) of the two-dimensional detector 6, and further the measurement target *
It is assumed that an interference signal due to the light emitted from the detector is detected by the detection element at the position (i, 1) of the two-dimensional detector 6.
At time t = 3T, the Fourier spectroscopic image measurement unit 7 further moves in the j-column direction, and an interference signal due to light emitted from the measurement target □ is detected by the detection element at the position (i, 4) of the two-dimensional detector 6. , An interference signal due to light emitted from the measurement target △ is detected by the detection element at the position (i, 3) of the two-dimensional detector 6, and an interference signal due to light emitted from the measurement target * is detected by the two-dimensional detector 6.
At the position (i, 2).
In this manner, the movement of the Fourier spectral image measurement unit 7 in the direction of the j-th column causes the interference signal of each measurement target to be detected by the two-dimensional detector 6.
Is detected by each detection element in the i-th row.

Here, the signal processing unit 8 detects the position of the detection element at the position (i, 1) of the two-dimensional detector 6 at time t = 0, the time t
= Detection element at position (i, 2) of two-dimensional detector 6 at T, position (i, 2) of two-dimensional detector 6 at time t = 2T
3) Detection element, two-dimensional detector 6 at time t = 3T
By sampling the output of the detection element at the position (i, 4), the interferogram based on the light emitted from the measurement target □ can be obtained.
Interferogram based on the emitted light from the light source.

Thereafter, the signal processing section 8 performs a Fourier transform on the interferogram based on the light emitted from each of the measurement objects obtained as described above, and obtains a spectral intensity distribution of each of the measurement objects. Thus, when the spectral intensity of each measurement target at the same wavelength is sampled, a one-dimensional spectral image in the moving direction of the Fourier spectral image measurement unit 7 at that wavelength can be obtained. Here, in the two-dimensional detector 6, the detection elements are arranged in the i-th row, the i + 1-th row, and the i + 2-th row in the direction perpendicular to the movement direction, so that the Fourier spectral image measurement unit 7 is moved with respect to the measurement object 1. By performing the measurement while performing the measurement, a two-dimensional spectral image of the measurement object 1 can be obtained.

As described above, according to the first embodiment, the wedge-shaped portion is formed by the flat end face on which the measuring light, which is the light emitted from the measuring object 1, is perpendicularly incident, and the inclined end face facing the flat end face. A birefringent unit 5 for separating the measurement light into two linearly polarized light beams orthogonal to each other, and a detection unit for extracting a predetermined polarization component so that the two linearly polarized light beams separated by the birefringent unit 5 interfere with each other. Photon 4 and 2 transmitted through this analyzer 4
A Fourier spectroscopic image measuring unit 7 including a two-dimensional detector 6 for detecting two linearly polarized interference lights, and a signal processing unit 8 for processing the interference light detected by the two-dimensional detector 6 to obtain a two-dimensional spectral image. And the Fourier spectral image measurement unit 7 is moved so that the measurement light perpendicularly incident on the planar end surface of the birefringent unit 5 has an optical path difference corresponding to the distance until reaching the inclined end surface. High two-dimensional spectral image can be obtained.

Embodiment 2 FIG. The Fourier spectroscopic image measurement device according to the second embodiment includes a first light condensing unit that condenses light emitted from the object to be measured 1 and a second light condensing unit that condenses light focused by the first light condensing unit on the two-dimensional detection unit. 2 light collecting means.

FIG. 4 is a block diagram showing a Fourier spectroscopic image measuring apparatus according to a second embodiment of the present invention. In the drawing, reference numeral 3a denotes a polarizer for extracting a predetermined polarization component from light collimated by the collimating optical system 2, and 4a denotes the same as the polarizer 3 so that two linearly polarized lights separated by the birefringent unit 5 interfere with each other. 5a is a birefringent portion (birefringent means) made of a wedge-shaped birefringent material, which extracts two polarized components of ordinary light, which are two linearly polarized lights orthogonal to each other. , Separated into extraordinary light. Polarizer 3
The a, the analyzer 4a, and the birefringent part 5a are made large enough to allow the light collected by the collimating optical system 2 to pass. Reference numeral 9 denotes a relay optical system (second condensing unit) having an imaging magnification of M. The same components as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

Next, the operation will be described. The light (measuring light) emitted from the measurement object 1 by the collimating optical system 2 is focused immediately after the wedge-shaped birefringent portion 5a. The focused measurement light passes through the analyzer 4a and is collected on the two-dimensional detector 6 by the relay optical system 9. Thereafter, the interference signal detected by the two-dimensional detector 6 is converted to the signal of the first embodiment.
The two-dimensional spectral image can be obtained by performing the processing in the signal processing unit 8 in the same manner as described above. As described above, in the Fourier spectroscopic image measurement apparatus according to the second embodiment, the image of the measurement target 1 formed immediately after the birefringent portion 5a is formed by using the relay optical system 9 having an imaging magnification of M times. An image is formed on the dimension detector 6. Thereby, the size of the image formed immediately after the birefringent part 5a may be 1 / M times that of the two-dimensional detector 6, and even if the small birefringent part 5a, the polarizer 3a, and the analyzer 4a are used. In addition, the size and weight of the device can be reduced.

As described above, according to the second embodiment, the collimating optical system 2 that focuses the measuring light and focuses the light after passing through the birefringent portion 5a, and has a predetermined imaging magnification. And a relay optical system 9 for condensing the focused light on the two-dimensional detector 6. Therefore, the birefringent portion 5 a, the polarizer 3 a, and the analyzer have a size corresponding to the imaging magnification of the relay optical system 9. 4
Since a may be used, these sizes can be reduced, and the size and weight of the device can be reduced. In particular, since it is difficult to obtain a large birefringent material, cost reduction can be achieved.

Embodiment 3 In the third embodiment, birefringent means in which two inclined end faces of two wedge-shaped birefringent materials are joined to each other is used.

FIG. 5 is a diagram showing a birefringent portion used in the Fourier spectroscopic image measuring device according to the third embodiment of the present invention. In the drawing, 5b1 and 5b2 are birefringent materials in the form of two wedges, and the birefringent portions (birefringent means) 5b are formed by joining mutually inclined oblique end faces. Further, the thickness of the birefringent material 5b1 corresponding to the detection element at the position (i, j) of the two-dimensional detector 6 is set to 11
(I, j), the thickness of the birefringent material 5b2 is l2 (i, j).
And The components other than the above are the same as those of the first embodiment.
This is the same as that shown in FIG.

Next, the outline will be described. Assuming that no is the refractive index for ordinary light and ne is the refractive index for extraordinary light in the same manner as in the second embodiment, the ordinary ray at the position (i, j) of the two-dimensional detector 6 corresponding to the detection element The optical path difference τ between the light beam and the extraordinary ray is expressed by the following equation. τ = (no−ne) {l1 (i, j) −12 (i, j)} (3) The inclination of each inclined end face of the birefringent materials 5b1 and 5b2 having a wedge shape is in the j-column direction. When the Fourier spectroscopic image measurement unit 7 moves in the j-column direction with respect to the measurement target 1, each detection element in the i-th column of the two-dimensional detector 6 becomes the birefringent unit 5 at that position.
An interference signal from the same place on the measurement object 1 due to the optical path difference according to the thickness of b will be observed. This allows
A two-dimensional spectral image can be obtained by processing the interference signal detected by the two-dimensional detector 6 in the signal processing unit 8 as in the first embodiment.

At this time, where the thickness of the birefringent material 5b1 is equal to the thickness of the birefringent material 5b2, the optical path difference of the interference light becomes zero. Further, even when the detection element does not always correspond to such a position, the optical path difference becomes zero.
The phase shift of the interferogram can be calculated from nearby sampling data, and the phase can be compensated.

As described above, according to the third embodiment, the birefringent portion 5b has the birefringent material 5 having two wedge shapes.
The birefringent materials 5b1 and 5b2 are characterized in that the birefringent materials 5b1 and 5b2 are characterized in that they are joined with their inclined end faces facing each other.
Where the optical path difference of the interference light becomes 0, the phase shift of the interferogram can be calculated from the sampling data where the optical path difference is around 0, and the phase can be compensated. . As a result, an accurate two-dimensional spectral image can be obtained.

Embodiment 4 In the fourth embodiment, the sloped end surface of the wedge-shaped birefringent material constituting the birefringent means is stepped.

FIG. 6 is a diagram showing a birefringent portion used in the Fourier spectroscopic image measuring device according to the fourth embodiment of the present invention. In the figure, reference numeral 5c denotes a birefringent portion (birefringent means) made of a birefringent material having a stepped sloped end surface. Also,
Although not shown, the thickness of the birefringent portion 5c corresponding to the detecting element at the position (i, j) of the two-dimensional detector 6 is set to 11
(I, j). The other components are the same as those described in the first embodiment with reference to FIG.

Next, the outline will be described. The optical path difference τ between the ordinary light and the extraordinary light at the position corresponding to the detection element at the position (i, j) of the two-dimensional detector 6 is the same as the equation (2). When the slope of the inclined end surface of the birefringent portion 5c having a wedge shape is in the j-column direction, and the Fourier spectral image measurement unit 7 moves in the j-column direction with respect to the measurement target 1, the i-th column of the two-dimensional detector 6 Each detection element of the eye observes an interference signal from the same part of the measurement object 1 due to an optical path difference according to the thickness of the birefringent part 5c at that position. Thus, by processing the interference signal detected by the two-dimensional detector 6 in the signal processing unit 8 in the same manner as in the first embodiment, a two-dimensional spectral image can be obtained.

As described above, since the ordinary light and the extraordinary light are emitted at different refraction angles due to the difference in the refractive index at the inclined end surface, the image forming distances of the two lights are different, and the image may be blurred due to the interference. However, in the fourth embodiment, the principal rays of the incident light incident on the birefringent material portion 5c and the outgoing light emitted from the birefringent material portion 5c are shifted with respect to the incident surface and the emission surface of the birefringent portion 5c. Be vertical. For this reason, the blur of the image as described above can be avoided.

Further, two birefringent materials having a stepped end surface in a stepped shape are joined with the stepped inclined surface end surfaces facing each other, or a direction in which the ridge lines are parallel to each other and the thickness changes. Are bonded in the opposite directions, it is possible to not only prevent the blurring of the image due to the emergence of the inclined end face at a different refraction angle due to the difference in the refractive index between the ordinary light and the extraordinary light, as described above, but also to the third embodiment. By using the fact that the optical path difference of the interference light passing through the place where the thicknesses of the two birefringent materials are equal becomes 0 as shown in the above, the phase shift of the interferogram is obtained from the sampling data where the optical path difference is around 0. It can be calculated and phase compensated.

As described above, according to Embodiment 4, the birefringent material 5c constituting the birefringent portion 5c is incident on the birefringent material portion 5c because the sloped end face of the birefringent material has a stepped shape. Since the principal rays of the incident light and the outgoing light emitted from the birefringent material portion 5c are perpendicular to the incident surface and the outgoing surface of the birefringent portion 5c, the ordinary light and the extraordinary light have different refraction angles at the inclined end surface. Blurring of an image generated due to emission can be avoided.

According to the fourth embodiment, in addition to the above-described structure, the birefringent part is formed by joining the two wedge-shaped birefringent materials with their respective inclined end faces facing each other and joining them. The same effect as described above is obtained, and at the place where the thicknesses of the two birefringent materials are equal, utilizing the fact that the optical path difference of the interference light becomes 0, the interferogram of the interferogram is obtained from the sampling data where the optical path difference is around 0. The phase shift can be calculated and the phase can be compensated. Thus, highly accurate image measurement can be performed.

Embodiment 5 FIG. The fifth embodiment includes first error detecting means for detecting an error due to movement or swing of the Fourier spectral image measuring means, and a two-dimensional detecting means based on the error information detected by the first error detecting means. This is for correcting the detection of the interference light.

FIG. 7 is a diagram showing a Fourier spectral image measuring apparatus according to a fifth embodiment of the present invention. In the figure, 8
a is a signal processing for selecting a detection element on the two-dimensional detector 6 that performs sampling of interference light based on the information on the movement and swing of the Fourier spectral image measurement unit 7 detected by the detection unit 10. A unit (first error detecting unit, signal processing unit) 10 detects an error due to movement or swing of the Fourier spectral image measurement unit 7 and transmits information about the movement or swing to the signal processing unit 8 ( First error detecting means)
It is. The same components as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

Next, the operation will be described. Measurement object 1
The operation until the light emitted from the detector passes through the analyzer 4 and is detected by the two-dimensional detector 6 is the same as that described in the above-described embodiment, and thus the duplicated description is omitted here. Similarly to the first embodiment, the signal processing unit 8a also obtains an interferogram image based on the interference light detected as a time-series signal from the two-dimensional detector 6, and Fourier transforms the interferogram image with respect to the optical path difference. To obtain a two-dimensional spectral image. At this time, if the Fourier spectral image measurement unit 7 moves or swings, the imaging point of the measurement object 1 due to the radiated light from the measurement target is detected, for example, at the position (i, 1) of the two-dimensional detector 6. The detection element in the i-th row such as the element → the detection element at the position (i, 2) → the detection element at the position (i, 3) → the detection element at the position (i, 4) is sequentially moved without moving the detection element in the i-th row. , 1) → detection element at position (i, 2) →
The detection element at the predetermined position in the i-th row is skipped, such as the detection element at the position (i, 3) → position (i, 5), or i
There is a possibility that an error of moving to the detection element located in the (+1) th row may occur.

Therefore, in the fifth embodiment, information relating to the movement and swing of the Fourier spectral image measurement unit 7 is detected by the detection unit 10.
, And information on the movement and the swing is transmitted to the signal processing unit 8.
Send to a. Specifically, the detection unit 10 detects an error due to the movement or swing of the Fourier spectral image measurement unit 7 described above from the interference signal detected by the two-dimensional detector 6. The detected error information is transmitted to the signal processing unit 8a, and based on the error information, the signal processing unit 8a selects a detection element on the secondary detector 6 that samples the interference signal. Thereby, even if there is an error due to the movement or swing of the Fourier spectral image measurement unit 7, an interference signal detected at an incorrect position can be removed.

As described above, according to the fifth embodiment, the signal processing unit 8a includes the detection unit 10 for detecting the movement or the swing of the Fourier spectral image measurement unit 7, and the error information detected by the detection unit 10 , The detection of the interference light by the two-dimensional detector 6 is corrected based on the above, so that even if the Fourier spectroscopic image measurement unit 7 has moved or fluctuated from a predetermined position, the emitted light from the measurement object 1 can be accurately measured. The resulting interferogram can be obtained. Thus, highly accurate image measurement can be performed.

Embodiment 6 FIG. In the sixth embodiment, second error detecting means for detecting an error due to movement or swing of the measuring object is provided, and the interference light by the two-dimensional detecting means based on the error information detected by the second error detecting means. Is corrected.

FIG. 8 is a diagram showing a Fourier spectroscopic image measuring device according to a sixth embodiment of the present invention. In the figure, 8
b is a signal processing unit that selects a detection element on the two-dimensional detector 6 that performs sampling of interference light based on the information on the movement and swing of the measurement target 1 detected by the detection unit 11. 2 error detection means, signal processing means),
Reference numeral 11 denotes an error (image blur) due to movement or swing of the measurement object 1 and information about the movement or swing is transmitted to the signal processing unit 8.
b is a detection unit (second error detection unit) for transmitting the signal to the control unit b. The same components as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

Next, the operation will be described. Measurement object 1
The operation until the light emitted from the detector passes through the analyzer 4 and is detected by the two-dimensional detector 6 is the same as that described in the above-described embodiment, and thus the duplicated description is omitted here. Similarly to the first embodiment, the signal processing unit 8b also obtains an interferogram image based on the interference light detected as a time-series signal from the two-dimensional detector 6, and Fourier transforms the interferogram image with respect to the optical path difference. To obtain a two-dimensional spectral image. At this time, if the measurement object 1 moves or swings, the image is blurred, and the imaging point of the measurement object is, for example, the detection element at the position (i, 1) of the two-dimensional detector 6 → the position (i). , 2) → the detection element at the position (i, 3) → the detection element at the position (i, 4) without detecting the detection element in the i-th row in sequence, and detecting the position (i, 1). A detection element at a predetermined position in the i-th row is skipped, such as an element → a detection element at a position (i, 2) → a detection element at a position (i, 3) → a position at the (i + 1) th row. May cause an error to move to the detecting element.

Therefore, in the sixth embodiment, the detecting unit 11
Detects information on the movement and swing of the measuring object 1
, And information on the movement and the swing is transmitted to the signal processing unit 8.
Send to a. Specifically, the detection unit 11 uses the interference signal detected by the two-dimensional detector 6 to detect the measurement target 1 as described above.
Image blur, which is an error due to movement or swing of the image, is detected. The detected error information is transmitted to the signal processing unit 8b, and based on the error information, the signal processing unit 8b selects a detection element on the secondary detector 6 for sampling the interference signal. As a result, even if there is an error due to the movement or swing of the measurement target 1, an interference signal detected at an erroneous position can be removed. You can get grams.

As described above, according to the sixth embodiment, the signal processing unit 8b includes the detection unit 11 for detecting an error due to the movement or swing of the measurement object 1, and the error information detected by the detection unit 11 Is used to correct the detection of interference light by the two-dimensional detector 6 on the basis of the interferogram obtained from the radiation light from the measurement target 1 accurately even if there is an error due to the movement or swing of the measurement target 1. Can be obtained.

In the first to sixth embodiments, the Fourier spectroscopic image measuring unit 7 is moved with respect to the measuring object 1, but the measuring object 1 corresponds to the processing of the Fourier spectroscopic image measuring apparatus of the present invention. By providing moving means for moving the object 1, the measurement object 1 is moved as described above to the birefringent portions 5, 5a, 5
The measurement light may be moved so as to have an optical path difference corresponding to the distance until the measurement light vertically incident on the planar end faces b1, 5b2, and 5c reaches the inclined end face. Thereby, effects similar to those of the first to sixth embodiments can be obtained. As a result, it is possible to improve the inspection accuracy of continuously moving products such as steel and pipes flowing on a production line of a production factory.

Embodiment 7 FIG. In the seventh embodiment, the Fourier spectroscopic image measuring means is mounted on an artificial satellite orbiting the earth without moving the Fourier spectroscopic image measuring means with respect to the object to be measured as described in the above embodiment. A two-dimensional spectral image of the surface can be measured.

FIG. 9 is an explanatory view showing a case where an artificial satellite equipped with a Fourier spectral image measurement unit images the Japanese archipelago as an object to be measured. FIG. 9A shows a Fourier spectrum disclosed in JP-A-6-347324. (B) shows a case where an image of the Japanese archipelago is taken from an artificial satellite equipped with a spectral image measurement means, and (b) shows a case where an image of the Japanese archipelago is taken from an artificial satellite according to the seventh embodiment. In the figure, reference numeral 1 denotes an object to be measured, which indicates the Japanese archipelago, which is the ground surface as viewed from the Fourier spectral image measurement unit 7. 12
Is a two-dimensional spectral image centered on Hokkaido, 13 is a two-dimensional spectral image centered on the Tohoku region, and 14 is a two-dimensional spectral image 1
2 shows a non-imaging portion generated between 2 and 13. Reference numeral 15 denotes a two-dimensional spectral image of the entire Japanese archipelago.

Next, the outline will be described. First, for comparison with the satellite according to the seventh embodiment, FIG.
Let us consider an artificial satellite equipped with a Fourier spectral image measuring means disclosed in JP-A-6-347324 shown in FIG. To obtain, for example, a two-dimensional spectral image of the entire Japanese archipelago with the Fourier spectral image measuring means disclosed in JP-A-6-347324, first obtain a two-dimensional spectral image 12 centered on Hokkaido, and subsequently Sequential photographing must be performed as described above to acquire the two-dimensional spectral image 13 centered on the Tohoku region. In order to realize this, it is necessary to take an image synchronously every time the artificial satellite travels by the size of the measurement range of the Fourier spectral image measurement means. However, in this case, if the time control of the image acquisition is not performed with high accuracy, the imaging impossible unit 14 occurs,
A continuous two-dimensional spectral image of the entire Japanese archipelago cannot be obtained.

Therefore, when the Fourier spectral image measuring unit 7 according to the present invention is mounted on an artificial satellite orbiting the earth, the Fourier spectral image measuring unit 7 is moved as the satellite moves (the artificial satellite moves with respect to the earth). It moves with respect to the ground surface (measurement target) which is the measurement target 1. As a result, FIG.
As shown in (b), by performing the processing described in the first embodiment on the light from the Japanese archipelago, which is the measurement object 1, a continuous two-dimensional spectral image 15 of the Japanese archipelago can be obtained. .

As described above, according to the seventh embodiment, the measuring object 1 is the ground surface, includes the Fourier spectral image measuring unit 7 of the present invention, and is perpendicularly incident on the plane end face of the birefringent unit. Since the measured light orbits so as to have an optical path difference corresponding to the distance until reaching the inclined end face, a two-dimensional spectral image with high spatial resolution with respect to the ground surface can be obtained.

[0062]

As described above, according to the Fourier spectroscopic image measuring apparatus of the present invention, the flat end face on which the measuring light, which is the light emitted from the object to be measured, is vertically incident, and the inclined end face facing the flat end face. And a birefringent means for separating the measurement light into two linearly polarized lights orthogonal to each other, and extracting a predetermined polarization component such that the two linearly polarized lights separated by the birefringent means interfere with each other. Polarization interference means, and a Fourier spectral image measurement means comprising two-dimensional detection means for detecting interference light of two linearly polarized lights transmitted through the polarization interference means, and processing the interference light detected by the two-dimensional detection means, Signal processing means for obtaining a two-dimensional spectral image, the Fourier spectral image measuring means having an optical path difference according to the distance until the measuring light perpendicularly incident on the planar end face of the birefringent means reaches the inclined end face Like Since moving, there is an effect that it is possible to obtain a high spatial resolution two-dimensional spectral image.

According to the Fourier spectroscopic image measuring apparatus of the present invention, it has a wedge shape composed of a flat end face on which measurement light, which is light emitted from an object to be measured, is perpendicularly incident, and an inclined end face opposed thereto. A birefringent means for separating the measurement light into two linearly polarized lights orthogonal to each other, a polarization interference means for extracting a predetermined polarized component so that the two linearly polarized lights separated by the birefringent means interfere with each other, Fourier spectral image measuring means comprising two-dimensional detecting means for detecting two linearly polarized interference lights transmitted through the polarization interfering means, and a signal for processing the interference light detected by the two-dimensional detecting means to obtain a two-dimensional spectral image Processing means, the object to be measured moves so that the measurement light perpendicularly incident on the planar end face of the birefringent means has an optical path difference according to the distance until reaching the inclined end face, so that the spatial resolution is high. High There is an effect that it is possible to obtain a two-dimensional spectral image. As a result, it is possible to improve the inspection accuracy of continuously moving products such as steel and pipes flowing on a production line of a production factory.

According to the Fourier spectroscopic image measuring apparatus of the present invention, the first light condensing means for converging the measuring light and focusing after passing through the birefringent means, and having a predetermined imaging magnification,
A second condensing means for condensing the focused light on the two-dimensional detecting means, so that a birefringent means or a polarizing interference means having a size corresponding to the imaging magnification of the second condensing means is used. Therefore, these sizes can be reduced in size, and the device can be reduced in size and weight. In particular, since it is difficult to obtain a large birefringent material, there is an effect that the cost can be reduced.

According to the Fourier spectroscopic image measuring apparatus of the present invention, the birefringent means constituting the birefringent means is characterized in that the sloped end surface of the wedge-shaped birefringent material is stepped, so that the light enters the birefringent means. Since the principal ray of the incident light and the outgoing light emitted from the birefringent means is perpendicular to the incident surface and the outgoing surface of the birefringent means, the ordinary light and the extraordinary light are emitted at different refraction angles at the inclined end face. This has the effect of avoiding image bleeding occurring in the image.

According to the Fourier spectroscopic image measuring apparatus of the present invention, the birefringent means is formed by joining two wedge-shaped birefringent materials with their respective inclined end faces facing each other. Where the thickness of the two birefringent materials is equal, utilizing the fact that the optical path difference of the interference light becomes 0, the phase shift of the interferogram is calculated from the sampling data where the optical path difference is around 0, and the phase compensation is performed. can do. Thereby, there is an effect that accurate image measurement can be performed.

According to the Fourier spectroscopic image measuring apparatus of the present invention, the two birefringent materials are joined so that their ridge lines are parallel and the direction in which the thickness changes is opposite. Thus, the same effect as in paragraph 0066 can be obtained.

According to the Fourier spectral image measuring apparatus of the present invention, the signal processing means includes first error detecting means for detecting an error due to movement or swing of the Fourier spectral image measuring means. Corrects the detection of interference light by the two-dimensional detection means based on the error information detected by
Even if the Fourier spectroscopic image measurement means moves or fluctuates from a predetermined position, an interferogram obtained by the emitted light from the measurement object can be obtained accurately. Thereby, there is an effect that accurate image measurement can be performed.

According to the Fourier spectroscopic image measuring apparatus of the present invention, the signal processing means includes the second error detecting means for detecting an error due to the movement or swing of the object to be measured, and the second error detecting means detects the error. The detection of the interference light by the two-dimensional detection means is corrected based on the obtained error information.
The same effect as described above can be obtained.

According to the artificial satellite of the present invention, the object to be measured is the ground surface, the apparatus is provided with the Fourier spectral image measuring means according to any one of claims 1 to 8, and the plane of the birefringent means is provided. The measurement light, which is perpendicularly incident on the end surface, orbits so as to have an optical path difference according to the distance until it reaches the inclined end surface, and it has the effect of obtaining a two-dimensional spectral image with high spatial resolution on the ground surface. is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a Fourier spectral image measurement device according to a first embodiment of the present invention.

FIG. 2 is a side view showing a birefringent part and a two-dimensional detector of the Fourier spectral image measurement device according to the first embodiment.

FIG. 3 is a diagram illustrating signal processing in a signal processing unit of the Fourier spectral image measurement device according to the first embodiment.

FIG. 4 is a configuration diagram illustrating a Fourier spectral image measurement device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a birefringent portion used in a Fourier spectral image measurement device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a birefringent unit used in a Fourier spectral image measurement device according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a Fourier spectral image measurement device according to a fifth embodiment of the present invention.

FIG. 8 is a diagram showing a Fourier spectral image measurement device according to a sixth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a case where an artificial satellite equipped with a Fourier spectral image measurement unit images the Japanese archipelago as an object to be measured.

FIG. 10 is a diagram showing a configuration of a conventional Fourier spectral image measurement device.

11 is a configuration diagram showing a polarization interferometer in FIG.

FIG. 12 is a diagram showing a spectral image obtained by a conventional Fourier spectral image measurement device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Object to be measured, 2 Collimating optical system (first condensing means), 3, 3a polarizer, 4, 4a Analyzer (polarizing interference means), 5, 5a, 5b, 5c Birefringent part (birefringent means) 5b1, 5b2 birefringent material, 6 two-dimensional detector (two-dimensional detecting means), 7 Fourier spectral image measuring section (Fourier spectral image measuring means), 8 signal processing section (signal processing means), 8a signal processing section ( 1b, a signal processing unit (second error detecting unit,
Signal processing means), 9 relay optical system (second light condensing means), 10 detection units (first error detection means), 11 detection units (second error detection means).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tohru Tajime 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Yasuhisa Tamagawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Rishi Electric Co., Ltd. (72) Inventor Takataka Nakano 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2G020 BA19 CA12 CB05 CC22 CC24 CC29 CC63 CD15 CD16 CD22 CD35 2H088 EA45 EA46 EA47 HA18 JA05

Claims (9)

[Claims] 1. A wedge shape having a planar end face on which measurement light, which is light emitted from an object to be measured, is perpendicularly incident, and a sloped end face opposed thereto, and the measurement light is orthogonal to each other.
Birefringent means for separating two linearly polarized lights, polarization interfering means for extracting a predetermined polarization component so that the two linearly polarized lights separated by the birefringent means interfere with each other, A Fourier spectral image measuring means comprising a two-dimensional detecting means for detecting linearly polarized interference light, and a signal processing means for processing the interference light detected by the two-dimensional detecting means to obtain a two-dimensional spectral image, The Fourier spectroscopic image measuring device is a Fourier spectroscopic image measuring device that moves so that the measurement light perpendicularly incident on the planar end face of the birefringent means has an optical path difference according to a distance until reaching the inclined end face. . 2. A wedge shape comprising a planar end face on which measurement light, which is light emitted from an object to be measured, is perpendicularly incident, and a sloped end face opposed thereto, and the measurement lights are orthogonal to each other.
Birefringent means for separating two linearly polarized lights, polarization interfering means for extracting a predetermined polarization component so that the two linearly polarized lights separated by the birefringent means interfere with each other, A Fourier spectral image measuring means comprising a two-dimensional detecting means for detecting linearly polarized interference light, and a signal processing means for processing the interference light detected by the two-dimensional detecting means to obtain a two-dimensional spectral image, A Fourier spectroscopic image measurement apparatus in which a measurement object moves so that the measurement light perpendicularly incident on the planar end face of the birefringent means has an optical path difference according to a distance until reaching the inclined end face. 3. A first light condensing means for converging a measuring light and passing the light through a birefringent means to form a focal point, and having a predetermined image forming magnification, and two-dimensionally detecting the focused light. 3. The Fourier spectroscopic image measuring apparatus according to claim 1, further comprising a second condensing means for condensing the light. 4. The Fourier according to claim 1, wherein the birefringent material having a wedge shape constituting the birefringent means has a stepped end face. Spectral image measurement device. 5. The birefringent means according to claim 1, wherein two birefringent materials having a wedge shape are joined with their respective inclined end faces facing each other. 4. The Fourier spectroscopic image measurement device according to claim 1. 6. The Fourier spectroscopic image measurement apparatus according to claim 5, wherein the two birefringent materials are joined so that their ridge lines are parallel and the directions in which the thickness changes are opposite. . 7. The signal processing means includes first error detection means for detecting error information due to movement or swing of the Fourier spectral image measurement means, and based on the error information detected by the first error detection means. The Fourier spectral image measurement apparatus according to any one of claims 1 to 6, wherein the detection of interference light by the two-dimensional detection means is corrected. 8. The signal processing means includes second error detection means for detecting an error due to movement or swing of the measurement object, and performs two-dimensional detection based on error information detected by the second error detection means. 7. The Fourier spectroscopic image measurement apparatus according to claim 1, wherein the detection of the interference light by the means is corrected. 9. An artificial satellite orbiting around the earth while maintaining a constant distance from the ground surface, wherein the object to be measured is the ground surface.
And a circuit for circulating the birefringent means so as to have an optical path difference corresponding to a distance until the measuring light perpendicularly incident on the planar end face of the birefringent means reaches the inclined end face. An artificial satellite characterized by: