JPH11237333A - Light image measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and stably measure a light image with a high sensitivity by performing translation - rotary action using light beams. SOLUTION: A pair of parabola reflection mirrors 11 and 12 being arranged at positions that are symmetrical with respect to a point for a focal point F are moved along a light axis AA', at the same time, light beams in parallel with the light axis AA' are moved in a direction that orthogonally crosses the light axis AA' and are guided to the parabolic reflection mirror 11. Therefore, while a light source 10, a measurement object 13, and a photo detector 16 are being fixed, light beams can be subjected to translation - rotary operation for the measurement object 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical image measuring apparatus for irradiating a measurement object with a light beam such as a laser beam instead of an X-ray source to form a two-dimensional or three-dimensional image of the object.

[0002]

2. Description of the Related Art A so-called optical CT, which irradiates a sharp light beam from a laser or the like onto a measurement object, converts light transmitted through the object into an electric signal, and measures the optical tomographic image using a computer, is used. An optical image measurement device called (computed tomography) has been developed. In this apparatus, it is required to reliably capture projection data of a light beam that has passed straight through the object.

FIG. 24 shows a schematic configuration for taking in projection data. The measurement operation basically required to capture the projection data is a translation-rotation method. In this method, as shown in FIG. 1A, a light beam from a light source is applied to a measurement object at appropriate intervals, and light transmitted through the measurement object is detected by a photodetector. As shown in b), a combination of a rotation operation of rotating the light beam by a predetermined angle with respect to the measurement object and sequentially measuring the transmitted light is provided. This method is a method originally used in X-ray CT. In the case of X-rays, a method of arranging a large number of X-ray sources in parallel with the measurement object and performing the same arrangement for the X-ray detector, or forming a circular X-ray source and detector around the measurement object The translation-rotation operation is realized by a configuration in which a large number are arranged and measured sequentially by combining them in accordance with a program.

[0004]

However, in the case of a light beam, it is difficult to perform a translation-rotation operation due to the above-described configuration. That is, for example, a living body or a part of a measurement object thereof for obtaining an optical CT image is an extremely strong light scattering diffusion medium. That is, when a light beam is applied to a dense fog or thick cloud, the reflected light spreads in all directions, and not only can you see the state of being transmitted straight, but also the transmitted light is similarly widely diffused, and the entire field of view It is similar to the fact that it spreads out dimly and that the transmitted light cannot be determined. As shown in FIG. 24A, a single light source and a photodetector are moved with respect to the measurement object in such a situation, and light beams from this light source are made to travel straight and one after another. It is difficult to perform the translation-rotation operation by detecting the light source and the light detector while rotating the light source and the light detector with respect to the measurement object by a predetermined angle as shown in FIG.

That is, in the case of optical CT, the phenomenon is almost completely different from that in the case of the above-mentioned X-ray source which almost goes straight through the living body and enters the detector. It is impossible to apply a method of performing translation-rotation operation by arranging a large number in parallel. The reason is described below in detail.

(1) Since each incident light beam spreads in all directions while traveling inside the object to be measured, each photodetector detects an extremely weak linear light component from a light source combined with the light detector. As the number of scattered lights increases, all of those scattered lights are added to generate noise light, and high sensitivity detection with a good signal-to-noise ratio cannot be realized.

(2) With the current optoelectronic technology, it is extremely difficult to operate a large number of light sources at the same time in terms of uniform performance, life, and price. In particular, it is practically impossible to use many expensive lasers simultaneously. The same applies to the photodetector. In particular, in the case of X-rays, it may be sufficient to simply use the detectors in parallel, but as described above, the noise components of the scattered light rushing from all directions are reduced. Exclude and select only the weakest straight light component,
When using devices and systems for detection in combination, such parallel operation requires a great deal of cost for research and development as well as practical use in terms of design, manufacture, adjustment, maintenance, operation, etc. Less value.

For the above two main reasons, a plurality of light sources and photodetectors have been used in an optical CT apparatus in accordance with the case of X-rays so far to receive transmitted straight light with high sensitivity, and an object to be measured has been obtained. Development that performed translation-rotation motion without moving,
There can be no reports of experiments. In other words, in the case of development and experiments that have been performed in various countries around the world, a single light source and a single photodetector are fixed, and the measurement object is moved to obtain the required transmitted straight light component with the highest possible sensitivity. The focus is on detecting and reconstructing the image. For this reason, at present, only the simplest operation of fixing the measurement object to the sample stage for performing the translation-rotation operation, rotating it by 360 ° or a required angle, and adding the translation operation is performed. .

In view of the problems described in (1) and (2) above, it is almost practical to perform a required operation with extremely high accuracy and high sensitivity by combining a plurality of light sources and photodetectors. Is not considered to have. As an alternative, fixing the measurement object itself to a sample stage capable of translation-rotation and performing translation and rotation is impractical for a living body or a part of a living body to be measured. It is a target.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to perform a translation-rotation operation in a state where a light source, a photodetector, and a measurement object are all spatially fixed. It is an object of the present invention to provide an optical image measurement device capable of realizing, stabilizing measurement accuracy and data, and performing highly sensitive measurement.

[0011]

Means for solving the problems of the present invention are as follows.

(1) Basically, one light source and one photodetector are used, and all high-performance devices and subsystems attached to them are fixed spatially (however, as a development of the present invention, a plurality of The use of a plurality of light sources of the same wavelength or light sources of different wavelengths and a plurality of photodetectors and equivalently the same configuration is sufficiently possible).

(2) All the measurement samples are arranged at required spatial positions and fixed to stabilize, and operations such as movement and rotation are not performed.

(3) In consideration of the above two conditions,
The traveling direction of the light beam from the light source is changed optically to realize the required translation and rotation operations. Therefore, optical means such as a reflecting mirror and a parabolic reflecting mirror are mechanically and precisely driven to scan the light beam with respect to the measurement object. All of this mechanical movement is digitally and precisely controlled by a computer.

That is, the optical image measuring apparatus of the present invention has a half paraboloid, is arranged point-symmetrically with respect to the focal point, and is movable in the optical axis direction. A parabolic reflector, a light source for generating a light beam, first optical means for guiding the light beam generated from the light source to the first parabolic reflector in parallel with the optical axis, and the first parabolic mirror. A second light beam reflected by the reflecting mirror, transmitted through the measurement object disposed about the focal point on the optical axis, reflected by the second parabolic reflecting mirror, and received in parallel with the optical axis; Optical means, a detecting means for detecting a light beam from the second optical means, and a focal point of the first and second parabolic reflecting mirrors for causing the light beam to be translated and incident on a measurement object. Move the first and second parabolic reflectors along the axis. And a first driving means that.

Further, the optical image measuring apparatus of the present invention has first and second parabolas having a half paraboloid, arranged symmetrically with respect to the focal point, and movable in the optical axis direction. A reflecting mirror, a light source for generating a light beam, first optical means for receiving the light beam generated from the light source, and a light beam from the first optical means for converting the light beam into a first light beam and a second light beam. A first semi-transparent mirror that divides the first light beam into beams in parallel with the optical axis to the first parabolic reflector, and is reflected by the first parabolic reflector and is disposed on the optical axis. Second optical means for transmitting the first light beam transmitted through the measured object, reflected by the second parabolic reflector, and guided parallel to the optical axis; and the first translucent mirror. Frequency shift means for shifting the frequency of the second light beam from A second translucent mirror that combines the second light beam whose frequency has been shifted by the scanning means and the first light beam from the second optical means to generate a light beam including a beat signal; Detecting means for heterodyne-detecting the light beam from the second translucent mirror, and the first and second parabolic reflecting mirrors are focused on the optical axis so that the light beam is translated and incident on the measurement object. So that
First driving means for moving the first and second parabolic reflecting mirrors.

Further, the optical image measuring apparatus of the present invention has first and second parabolas having a half paraboloid, arranged symmetrically with respect to the focal point, and movable in the optical axis direction. A reflecting mirror, a light source that generates a light beam, a beam expanding unit that expands the light beam from the light source in a one-dimensional direction and introduces the light beam into the first parabolic reflecting mirror, and reflects the light onto the first parabolic reflecting mirror. Detection means for detecting a light beam transmitted through a measurement object arranged on the optical axis, reflected by the second parabolic reflector, and expanded in a one-dimensional direction parallel to the optical axis; First driving means for moving the first and second parabolic reflecting mirrors so that the focal points of the first and second parabolic reflecting mirrors are along the optical axis in order to cause the light beam to enter the object to be translated. And

Further, the optical image measuring apparatus of the present invention has first and second parabolas having a half paraboloid, arranged point-symmetrically with respect to the focal point, and movable in the optical axis direction. A reflecting mirror, a light source that generates a light beam, a first translucent mirror that divides the light beam from the light source into a first light beam and a second light beam, and the light source from the first translucent mirror. A first beam expanding means for expanding the first light beam in a one-dimensional direction and introducing the first light beam into the first parabolic reflector; and a first beam expanding means which is reflected by the first parabolic reflector and arranged on the optical axis. Transmitted through the measurement object, reflected by the second parabolic reflector,
Optical means for receiving the first light beam parallel to the optical axis and expanded in a one-dimensional direction; frequency shifting means for shifting the frequency of the second light beam from the first translucent mirror; A second light beam for expanding the second light beam whose frequency has been shifted by the frequency shift means in a one-dimensional direction;
And a second light beam generating means for combining the second light beam expanded by the second beam expanding means and the first light beam from the optical means to generate a light beam including a beat signal. A translucent mirror, detection means for heterodyne-detecting the light beam from the second translucent mirror, and the first and second parabolic reflecting mirrors for causing the light beam to translate and enter the measurement object. So that the focus is along the optical axis,
First driving means for moving the first and second parabolic reflecting mirrors.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

First, the principle of the present invention will be described. The basic configuration of the present invention comprises a parabolic reflector. Considering that the measurement object is three-dimensional, a parabolic cylindrical surface generally called a parabolic cylindrical reflecting mirror is preferable.

[Characteristics of Parabolic Reflector] FIG. 2 shows a one-dimensional parabolic reflector P for simplicity.

The focal point of the parabolic reflecting mirror P is F.
All the rays incident parallel to the optical axis (center line) AA ′ of the surface P are reflected by the parabolic reflector P, then gather at the focal point F, pass through that point and spread again.

If the focal length is defined as f and the coordinates are defined as (r, θ) (r: moving radius, θ: tilt angle) as shown in FIG. 3, the design equation is expressed by the following equation.

R = 2f / (1 + cos θ) (If θ = 0, r = f) Therefore, in order to construct a two-dimensional parabolic cylinder surface, the shape of this parabola must be changed vertically as shown in FIG. Just stretch it.

In the manufacture of this parabolic reflector, the most important point is the accuracy of the inner mirror surface, and it is desirable that the accuracy be on the order of λ / 8 to λ / 16, as in the case of a normal optical reflector. Also, the reflectivity should be 10
It is required to be close to 0%.

[Realization of Translation Operation (T Operation)] As shown in FIG. 5, an upper half (lower half) of a semi-cylindrical parabolic reflecting mirror (hereinafter simply referred to as a parabolic reflecting mirror) with respect to an optical axis AA '. Department).

It is assumed that the incident light beam is incident parallel to the optical axis AA 'from the right. When the parabolic reflector P ₀ is located at x ₀ on the optical axis, the incident light beam passes through the focal point F ₀ after reflection.

Next, assuming that the parabolic reflecting mirror has moved to the position of x ₁ (x ₀ → x ₁ ) on the optical axis by digitally precisely controlling it like P ₁ , the focus is on the optical axis AA. F ₁ on '
Move on to Therefore, the incident light beam after reflection by P _1, passes through the focal point F _1.

Similarly, if the parabolic reflecting mirror is moved to P ₂ , its position moves to x ₂ on the optical axis AA ′, and the focal point moves to F ₂ . Therefore, the incident light beam after reflection by the parabolic reflector P _2, proceeds toward the focal point F _2.

As described above, when the parabolic reflecting mirror P ₀ is precisely controlled and moved on the optical axis AA ′ by a predetermined distance, the focal point F ₀ moves sequentially by that distance. Therefore, all the incident light beams travel to each focal point after being reflected by the parabolic reflector. If this operation is performed digitally and sufficiently accurately by computer control, the desired translation operation can be realized.

FIG. 6 shows the relationship between the parabolic reflector and the object to be measured in the translation operation.

The horizontal movement range Δx of the parabolic reflector is determined in advance depending on the shape and size of the object. The configuration and scale of the detection of the light beam after passing through the object differ depending on the detection method, and will be described in an embodiment described later.

[Realization of Rotation Operation (R Operation)] Next, the rotation operation of the light beam will be described.

FIG. 7 shows the upper half (or lower half) of the parabolic reflector with respect to the optical axis.

The incident light beams B ₁ , B ₂ , B ₃ correspond to the optical axis A
It is assumed that they are all parallel to A ′, but have different heights y from the optical axis AA ′. Incident light beam B ₁ ,
After B ₂ and B ₃ are reflected by the parabolic reflector P, they all gather at the focal point F and pass through. However, the directions of incidence on the focal point F all have different angles. That is, with respect to the optical axis AA ′, the incident light beam B ₁ passes through the focal point F at an angle θ ₁ , the incident light beam B ₂ at θ ₂ , and the incident light beam B ₃ at an inclination of θ ₃ .

Therefore, if the distance y of the incident light beam from the optical axis AA 'is precisely controlled, the angle θ can be precisely controlled accordingly.

FIG. 8 shows an example in which the distance y of the incident light beam from the optical axis AA ', that is, the angle θ is precisely controlled. This example is a method in which the position of the light source of the incident light beam is fixed and precise control is performed using the _two reflecting mirrors M ₁ and M ₂ , and various other methods are conceivable.

As shown in FIG. 8, if the angle range Δθ of the rotating operation is determined in advance, the reflecting mirror M
The horizontal movement range Δy of ₂ is uniquely determined.

Therefore, every change angle (step) δθ of θ
May be determined in advance, and the moving distance of M ₂ may be precisely controlled digitally by a computer. Thus, for example, if the incident direction y of the incident light beam is determined so as to have a predetermined angle θ before performing the translation operation, the rotation operation is set.

[Repeated Implementation of Translation-Rotation (TR) Operation] As described above, in order to realize an optical CT image, translation and rotation are alternately repeated in principle. is necessary. It is assumed that the measurement object is fixedly installed at a predetermined position.

The method of implementation may be performed by combining the above-described translation operation and rotation operation. The method of implementation will be described again for reference.

(1) First, in order to perform the translation operation, the inclination of the light beam, specifically, the angle of the incident light on the focal point F with respect to the optical axis AA 'of the parabolic reflecting mirror, for example, θ ₁ is determined.

This can be achieved by determining and fixing the position y ₁ of the movable reflecting mirror M ₂ for the rotating operation. That is, (a) determination of θ ₁ → determination of y ₁ → control / setting of M ₂ (2) A translation operation is performed by setting θ ₁ (y ₁ ). Horizontal movement range of parabolic reflector in translation
x and the movement interval (step) δx of x therebetween are determined, and all controls are performed digitally and precisely.

(B) Determination of Δx, δx → Translation operation (digitally precise control) (3) In the state where the above-mentioned translation operation has been completed and the capture of projection data has been completed, a predetermined θ ₂ (y ₂ ) Is performed.

Also in the case of the rotation operation, the operation range Δθ of θ and the change interval (step) δθ of θ between them, that is, Δy and δy
Is determined in advance. All of the control is performed digitally and precisely.

(C) Determination of Δθ and δθ in advance → θ
₁ (y ₁ ) → Rotation operation to move from θ ₂ (y ₂ ) (digitally precise control) (d) Starting from (a), the operations of (b) and (c) are performed and (a) is performed again. ) May be repeated to perform the translational operation and the rotational operation at predetermined intervals of δx and δθ, and capture the projection data in the entire range of Δx and Δθ determined in advance.

(Examples) Next, specific examples will be described.

FIG. 1 shows a first embodiment of the present invention, and shows a basic configuration of an inner translation operation of a translation-rotation operation at an angle of 90 °. In this embodiment, a case where light detection is performed by a direct detection method will be described.

The first and second parabolic reflecting mirrors 11 and 12 have a structure in which the parabolic cylinder surface is divided into half. 1st, 2nd
Parabolic reflectors 11 and 12 have a focal point F ₀ on the optical axis AA ′.
Are disposed at positions P ₀ and P ₀ ′ that are point-symmetric with respect to.
These first and second parabolic reflecting mirrors 11 and 12 are driven by a driving device 14 using, for example, a linear motor to form an optical axis A.
It can be precisely moved digitally in the same direction along A '. Therefore, the focal point also moves on the optical axis AA 'with the movement of the first and second parabolic reflecting mirrors 11, 12. The measuring object 13 is arranged on the optical axis AA ′ within a range where the focal point passes.

The light source 10 is, for example, a laser light generator. A sharp light beam generated from the light source 10 passes through a fixed mirror M ₁ and a movable mirror M ₂ (for use in a later rotating operation), and Are incident on the first parabolic reflecting mirror 11. Light reflected by the first parabolic reflector 11 passes through the focal point F _0. The transmitted straight light component that has passed through the focal point F ₀ is reflected by the second parabolic reflecting mirror 12, and is again reflected on the optical axis A.
The light travels along an optical path parallel to A ′ and is incident on a movable mirror M ₂ ′.
The light reflected by the movable mirror M ₂ ′ passes through the fixed mirror M ₁ ′ and enters the sorting optical system 15. The sorting optical system 15 is an optical system that selects a transmitted straight light component with high sensitivity from light transmitted through a measurement object having strong light scattering, and the transmitted straight traveling light sorted by the sorting optical system 15 is subjected to light detection. Incident on the detector 16 and detected. The output signal of the photodetector 16 is supplied to an image processing device 17 constituted by a computer, for example. The control device 18
The driving device 14, the sorting optical system 15, the photodetector 1
6. It is connected to the image processing device 17 and controls these operations.

In the above configuration, the fixed mirror M ₁ and the movable mirror M ₂ and the movable mirror M ₂ ′ and the fixed mirror M ₁ ′ are used. However, the present invention is not limited to this. Receiving first
Light can be incident on the parabolic reflector 11 in parallel with the optical axis, and can receive light parallel to the optical axis from the second parabolic reflector 12 and can be guided to the subsequent sorting optical system. Any optical means can be used. Therefore, for example, an optical fiber or the like can be used.

[Translation Operation] The translation operation is performed as follows. First, the drive unit 14 moves the position of the first parabolic reflecting mirror 11 from P _{0 to} P ₁ by a moving interval (step) δ.
with x ₁ moves, it causes the position of the second parabolic reflector 12 P ₀ is the same movement moving distance .delta.x ₁ to '→ P _1'.
'After being reflected by the second parabolic reflector 12 in the optical axis AA' The light passing through the focal point F ₁ from the first parabolic reflector 11 at the position P ₁ is located P ₁ parallel to, and The light passes through the same optical path as the light passing through the focal point F ₀ and sequentially enters the selection optical system 15 and the photodetector 16.

Similarly, the positions of the first and second parabolic reflecting mirrors 11 and 12 are set at the same distance δx in the same direction on the optical axis AA ′ as P ₁ → P ₂ and P ₁ ′ → P ₂ ′. if it caused to ₂ moves, the position P ₂ and P ₂ 'first in, through the common focus F ₂ of the second parabolic reflector 11, 12 P _2'
As described above, the light reflected by the optical path is incident on the sorting optical system 15 and the photodetector 16 sequentially through the same optical path as the optical path.

That is, with the configuration shown in FIG. 1, the translation operation can be performed without moving the measurement object 13, the light source 10, and the photodetector 16 at all.

The photodetector 16 is composed of a well-known photoelectric converter such as a photodiode or a photomultiplier. When the direct detection method is used as in this embodiment, the sorting optical system 15 has the following functions.

(A) When a continuous light beam is used as a light source (system based on a spatial selection method) For example, there are a spatially highly directional light receiving method, a transmitted polarization component detection method, and the like. Spatial high directivity light receiving method, lens, collimator,
This is a method of performing spatial collimation using an aperture, an optical fiber, or the like alone or in combination. This method is based on a configuration in which only a 0th-order diffraction pattern is detected by a pinhole corresponding to a diffraction image of a collimated signal light component by a light condensing system. The transmitted polarized light component detection method is a method of detecting a transmitted straight light component based on the correlation between the polarization directions of an incident light beam and a transmitted straight light component.

(B) In the case of using a pulsed light beam as a light source (a system based on a temporal selection method) For example, a light pulse transmitted through a measurement object with remarkable light scattering has a wider pulse time width. The head portion is considered to be the component that has traveled straight through the object in the shortest time, that is, almost straight. Therefore, in order to quickly cut out and detect the top part, a temporal sorting system equipped with an ultra-high-speed time gate (ultra-high-speed optical switch such as an optical car shutter) is applied, and only the top part is selected. It is a method of taking out.

It is to be noted that a sorting optical system having a similar function can be applied in addition to the above.

[90 ° Rotation Operation] Next, with reference to FIG. 9, the rotation operation by the combination of the two parabolic reflectors shown in FIG. 1 will be described. However, in this configuration, the angle is 9
Operation is possible only in the range of 0 ° or less. In FIG. 9, the same parts as those in FIG.

In this case, the first and second parabolic reflecting mirrors 1
1 and 12 are arranged point-symmetrically with respect to a common focal point F, but need not be moved.

In this rotation operation, the distance y of the light beam output from the light source 10 parallel to the optical axis AA 'from the optical axis AA' is precisely controlled, so that the movable mirrors M ₂ and M ₂ ' Scanning angle range Δθ can be realized with respect to the moving distance range Δy. Therefore, after the predetermined angle change (step) δθ, after the translation operation, the movable mirror M ₂ ,
The movement distance δy of M ₂ ′ may be precisely controlled. The movable mirrors M ₂ , M ₂ ′ are moved precisely by, for example, the same distance by driving devices 14 a, 14 b constituted by, for example, linear motors. The driving devices 14a and 14b are controlled by the control device 18.

Also in this case, as described above, when the fixed mirror M ₁ and the movable mirror M ₂ , and the movable mirror M ₂ ′ and the fixed mirror M ₁ ′ are formed of, for example, optical fibers, the driving devices 14 a and 14 b
Thus, for example, the ends of the optical fibers facing the first and second parabolic reflecting mirrors 11 and 12 may be driven.

Thus, the light beam output from the light source 10 is divided into the fixed mirror M ₁ , the movable mirror M ₂ , and the first parabolic reflector 1
The light reflected at 1 and passing through the focal point F is then reflected at the second parabolic reflector 12 and takes an optical path parallel to the optical axis AA '. The light reflected by the second parabolic reflector 12 is
The movable mirror M ₂ ′, which is moved in synchronization with the movable mirror M ₂ , is guided to the sorting optical system 15 via the fixed mirror M ₁ ′. The subsequent light guide to the photodetector 16 and the detection of the optical signal are as described in FIG.

However, in the rotation operation shown in FIG. 9, the angle range Δθ is 90 ° or less, depending on the size of the object. In order to increase Δθ as much as possible, it is necessary to design and operate in consideration of the dimensions of the measurement object and the dimensions and arrangement of the two semi-parabolic reflectors.

As described above, the light beam is translated / rotated to detect the straight light transmitted through the measuring object 13 and image-processed by the image processing device 17 to obtain the light CT.
Images can be obtained.

[Translation-rotation operation at an angle of 180 °]
With reference to FIG. 10, a method for performing a rotation operation over an angle of 180 ° will be described. This rotation operation is basically based on a combination of the configurations shown in FIG. The configuration of the light detection system is the same as that of FIG.

FIG. 10 (a) has the same configuration as that of FIG. 9. First, a rotation operation of 90 ° (Δθ <90 °) at the upper left of the measurement object 13 and a translation operation similar to FIG. 1 are performed.

FIG. 10B shows a case where the next 90 ° operation, that is, the rotation operation and the translation operation of the measurement object 13 at the lower left 90 ° are performed. If this operation is performed subsequently to FIG. 10A, a total rotation operation of 180 ° (Δθ <180 °) will be performed.

The main point of this translation-rotation operation is that the object to be measured, the light source and the photodetector do not move at all, as in the case of FIGS. Therefore, FIG.
In addition to the first and second parabolic reflecting mirrors 11 and 12 shown in FIG. 10A, third and fourth parabolic reflecting mirrors 21 and 22 shown in FIG. Mirror 11, 1
It is arranged point-symmetrically at a position sharing the focal point F with 2. Third,
The fourth parabolic reflecting mirrors 21 and 22 can be used by moving the first and second parabolic reflecting mirrors 11 and 12 to this position. However, in this example, they are separately provided and, as described later, First to fourth parabolic reflecting mirrors 11, 12, 21,
22 is a direction perpendicular to the optical axis AA ′ (perpendicular to the paper surface)
And the first to fourth parabolic reflecting mirrors 11,
12, 21 and 22 can be inserted into and retracted from the optical path of the light beam.

Further, in this example, the movable mirror M ₂ and the movable mirror M ₂ ′ can be moved beyond the optical axis AA ′. That is, as shown in FIG. 10A, after the translation-rotation operation in the upper left 90 ° range of the measurement object 13 is completed, the first and second parabolic reflecting mirrors 11 and 12 are moved in the optical path of the light beam. And the third and fourth parabolic reflecting mirrors 21 and 2
2 into the optical path of the light beam and the movable mirror M ₂
And the movable mirror M ₂ ′ are moved to the opposite sides beyond the optical axis AA ′. By doing so, the configuration shown in FIG. In this state, the lower left 90 ° of the measurement object 13
In the range of (1) to (4). The translation operation at each predetermined θ is the same as in FIG.

FIG. 11 shows an arrangement of the first to fourth parabolic reflecting mirrors 11, 12, 21, and 22. FIG.
At 0 (a) and (b), in order to perform a rotation operation in a range close to 180 °, as described above, the positions of a pair of parabolic reflectors may be replaced. Although various methods are conceivable, FIG. 11 shows a specific example in which mechanical control is easy and replacement does not require time.

In FIG. 11, first to fourth parabolic reflecting mirrors 11, 12, 21, and 22 having the same structure are arranged.
FIG. 11A shows that the first and second parabolic reflecting mirrors 11 and 12 therein are inserted into the optical path of the light beam LB.
(B) shows a state where the third and fourth parabolic reflecting mirrors 21 and 22 are inserted into the optical path of the light beam LB. In this way, the positions of the first to fourth parabolic reflecting mirrors 11 to 22 may be precisely controlled mechanically and fixed at predetermined positions. The movement of the first to fourth parabolic reflecting mirrors 11 to 22 in the direction perpendicular (vertical) to the optical axis AA ′ can also be digitally and precisely controlled by using, for example, a driving device 23 using a linear motor. The operation of the driving devices 23 and 24 is controlled by the control device 18.

[Rotation-translation operation at an angle of 360 °] Angle 3
To perform the rotation-translation operation over 60 °, the operation shown in FIGS.
May be carried out for the range as well.

FIG. 12 (a) shows a configuration in which the arrangement of the components shown in FIG. 10 (a) is replaced symmetrically, and in FIG. 10 (b), the incident light beam enters from the detection light side. FIG. 12B shows a configuration in which the arrangement of each component shown in FIG. 10B is replaced symmetrically, and in FIG. 10A, the incident light beam is input from the detection light side. Has become. That is, the fixed mirror M ₁ and the movable mirror M ₂ can be moved along the optical axis AA ′ by the driving device 25, and the fixed mirror M ₁ ′ and the movable mirror M ₂ ′ are moved by the driving device 26 to the optical axis AA.
Along A ′, the fixed mirror M ₁ and the movable mirror M ₂ are movable in opposite directions. These driving devices 25 and 26 also
For example, the controller 18 includes a linear motor.
Is controlled by

In the case of the configuration shown in FIG. 12 (a), the translation-rotation operation is performed in an angle range of 90 ° to the upper right of the measurement object 13, and in the case of the configuration shown in FIG.
It translates and rotates through an angle range of 0 °.

By combining the operations shown in FIGS. 1, 9, 10, and 12, a translation-rotation operation of 360 ° can be performed. Therefore, an operation program for the control device 18 may be created in consideration of the entire operation.

According to the first embodiment, first to fourth
Only the parabolic reflector and the optical systems such as fixed mirrors M ₁ and M ₁ ′ and movable mirrors M ₂ and M ₂ ′ for changing the optical path are mechanically moved under precise computer control. . Therefore, it is possible to perform the translation-rotation operation without moving the measurement object 13, the light source 10, and the detection system at all.

In FIGS. 12 (a) and 12 (b), fixed mirrors M ₁ and M ₁ ′ and movable mirrors M ₂ and M ₂ ′ are moved. ) (B), FIG.
(A) Prepared at the positions shown in (b), and mechanically controlled and placed in the optical path according to the operation as shown in FIGS. 10 (a) and (b) and FIGS. 12 (a) and (b). They may be inserted sequentially.

FIG. 13 shows first to fourth parabolic reflecting mirrors 11 and 12 for performing a 360 ° translation-rotation operation.
21 and 22 show the switching operation. These four parabolic reflectors are all arranged to share a common focal point F. In FIG. 13, one set of parabolic reflectors indicated by a thick line is located in the optical path, and one set of parabolic reflectors indicated by a thin line is moved out of the optical path, for example, as shown in FIG. Are arranged so that they do not come. The arrow in the figure indicates the moving direction of the parabolic reflector for performing the translation operation as shown in FIG.

Next, a second embodiment of the present invention will be described. The first embodiment has described the case where the direct detection method is used, but the second embodiment shows a configuration in the case where the optical heterodyne detection method is used. An optical CT apparatus based on an optical heterodyne detection method is a technique described in Japanese Patent Application Laid-Open No. 2-150747 (Japanese Patent Application No. 63-304691) by the inventors of the present application. Therefore, in the following embodiments, description of the operation of the optical heterodyne detection method is omitted.

[Translation-Rotation Operation at an Angle of 90 °] A translation-rotation operation at an angle of 90 ° using the optical heterodyne detection method will be described. This operation is basically the same as the operation in FIG. 1, and is a combination of the operation and the optical heterodyne detection method.

First, the translation operation will be described with reference to FIG.

When the optical heterodyne detection method is used, it is necessary to always introduce a local light beam. For this reason, the light beam from the light source 10 is divided and used by using a translucent mirror (beam splitter).

[0084] That is, output from the light source 10, the light beam LB reflected by the fixed mirror M ₁₁ is incident on the half mirror M ₁₂ movable which can be moved a range of [Delta] y. The light beam reflected by the semitransparent mirror M ₁₂ is guided to the first parabolic reflector 11, the measurement object 13, the movable mirror M ₁₃ successively through the second parabolic reflector 12. Further, the light beam transmitted through the semi-transparent mirror M ₁₂ is introduced to the frequency shifter 31. This frequency shifter 31 outputs a local light beam LLB shifted by a predetermined frequency from the light beam LB. The local light beam LLB is reflected by the fixed mirror M _14, is guided to the half mirror M _15, which is fixed with the light beam reflected by the movable mirror M ₁₃ is synthesized and WFM. The light beam combined by the half mirror M ₁₅ is guided to the photodetector 32 is photoelectrically converted to generate a beat signal (intermediate frequency signal). The output signal of the photodetector 32 is supplied to the IF receiver 33, and the intermediate frequency signal is detected. This detection output signal is supplied to an image processing device 34 composed of, for example, a computer. This image processing device 3
4 is stored in the storage device 35 and supplied to the display device 36 for display.

In FIG. 14, the driving devices of the first and second parabolic reflecting mirrors 11 and 12 and the control device thereof are the same as those of the first embodiment, and therefore are omitted. With such a configuration, the translation operation is performed by moving the first and second parabolic reflecting mirrors 11 and 12 along the optical axis AA ′ and detecting a beat signal at that time.

In principle, if there is a stability that makes the optical heterodyne detection method practicable, a light beam generated by another light source having a predetermined frequency shift from the light beam generated from the light source is locally transmitted. It may be used as an emission beam.

FIG. 15 shows a 90 ° rotation operation.
This operation is basically the same as in FIG. In this case, the semi-transparent mirror M ₁₂ and the movable mirror M ₁₃ is a pre Ji fit-determined movement range [Delta] y (determined by [Delta] [theta]), is moved in conjunction by a predetermined moving distance .delta.y. The value of the moving distance δy is determined by the change δθ of the rotation angle.

[Translation-Rotation Operation at an Angle of 180 °] FIG.
1 shows a translation-rotation operation at an angle of 180 °, and FIG.
The same parts as in FIG. In this case as well, similarly to the configuration shown in FIG.
Selectively is inserted in the optical path of the light beam 1,12,21,22, as shown in FIG. 16 (a), a semi-transparent mirror M ₁₂ and the movable mirror M ₁₃ beyond the optical axis AA 'movement Make it possible.

[0089] That is, as shown in FIG. 16 (b), third, fourth is inserted into the optical beam in the optical path of the parabolic reflector 21, the light semi-transmitting mirror M ₁₂ and the movable mirror M ₁₃ It moves beyond the axis AA '. The light beam from the light source 10 is reflected by the fixed mirror M _11, it is guided to the half mirror M _12.
The light beam reflected by the semitransparent mirror M ₁₂ is led to the fourth parabolic reflector 22. Fourth parabolic reflector 22
Is reflected by the light beam passing through the focal point F is reflected by the third parabolic reflector 21, it is guided via the movable mirror M ₁₃ translucent mirror M _15. Further, the light beam transmitted through the semi-transparent mirror M ₁₂ is directed to frequency shifter 31, through the fixed mirror M ₁₄ semitransparent mirror M _15, is combined with the light beam from said movable mirror M _13.

According to the above configuration, the measuring object 13 and the light source 1
0 and remains totally fixed photodetector further local light beam LLB also refined by computer control without the first through fourth parabolic reflector and the semi-transparent mirror M ₁₂ and the movable mirror M ₁₃ to move the optical path By moving to the angle of 180 °
Can be performed.

[Translation-Rotation Operation at an Angle of 360 °] FIG.
Shows the translation-rotation operation of the remaining angle of 180 °, and this operation is almost the same as that of FIG. In this example,
Since the optical path of the local light needs to be changed, the frequency shifter is also moved.

[0092] That is, as shown in FIG. 17 (a), the fixed mirror M ₁₁ and the semi-transparent mirror M ₁₂ together with is moved along the optical axis AA ', the frequency shifter 31 is also moved. The movable mirror M ₁₃ is a fixed mirror M ₁₁ along the optical axis AA 'half mirror M
Moved in the opposite direction to ₁₂ . Therefore, the light beam from the light source 10 is reflected by the fixed mirror M _11, it is guided to the half mirror M _12. The light beam reflected by the semitransparent mirror M ₁₂ is
The light is guided to the third parabolic reflecting mirror 21. The light beam reflected by the third parabolic reflector 21 and having passed through the focal point F is reflected by the fourth parabolic reflector 22 and is movable M
_The light is guided to the fixed mirror M ₁₄ via the line ₁₃ . Further, the transmitted local light beam semitransparent mirror M ₁₂ is guided to the half mirror M ₁₅ through the frequency shifter 31, is combined with the light beam from the fixed mirror M _14.

In FIG. 17B, first and second parabolic reflecting mirrors 11 and 12 are inserted in the optical path of the light beam instead of the third and fourth parabolic reflecting mirrors 21 and 22, and
Semitransparent mirror M ₁₂ and the movable mirror M ₁₃ is moved past the optical axis AA '. Therefore, the light beam from the light source 10 fixed mirror M ₁₁
It is reflected by and guided to the semi-transparent mirror M _12. Translucent mirror M
_The light beam reflected by 12 is guided to the second parabolic reflector 12. Is reflected by the second parabolic reflector 12, the light beam passing through the focal point F is reflected by the first parabolic reflector 11, fixed mirror M ₁₄ via a movable mirror M ₁₃
It is led to. Further, the transmitted local light beam semitransparent mirror M ₁₂ is guided to the half mirror M ₁₅ through the frequency shifter 31, is combined with the light beam from the fixed mirror M _14.

In the configuration shown in FIGS. 17A and 17B,
First to fourth parabolic reflecting mirrors 11, 12, 21, 22
The or move along the optical axis, by moving the semi-transparent mirror M ₁₂ and the movable mirror M ₁₃ in the direction perpendicular to the optical axis, translation -
A rotation operation is realized.

FIGS. 16 (a) and (b) and FIG. 17 (a)
A translation-rotation operation at an angle of 360 ° is realized as a whole in (b).

In the photoheterodyne detection method,
Depending on the purpose of use, it may be required that the entire optical path length (from the light source) of both the signal light and the local light beam be equal. At that time, it is necessary to arrange all the optical systems so that both are precisely equal.

Next, a third embodiment of the present invention will be described. The first embodiment has described the case where the direct detection method is used as the light detection method, and the second embodiment has described the case where the light heterodyne detection method is used.

In these operations, it is assumed that the light beam from the light source is a single sharp beam. Therefore, the photodetector also considered using a single high-sensitivity detector. Therefore, in order to perform a rotation operation, the light beam emitted from the light source needs to be scanned in a manner such that the light beam moves in a direction orthogonal to the optical axis while keeping parallel to the optical axis AA ′.

In the third embodiment, in order to improve this point and shorten the light detection (measurement) time, for example, the width of the light beam emitted from the light source is expanded to convert it into a one-dimensional parallel beam. A one-dimensional photodetector array in which photodetector elements are arranged one-dimensionally is used as a photodetector. Therefore, the light beam has a thin strip shape. The one-dimensional photodetector array is composed of, for example, a known semiconductor element.

FIG. 18 shows a third embodiment, and the same parts as those in FIG. 1 are denoted by the same reference numerals. First, the light beam from the light source 10 is converted into a parallel beam by the beam expander 41, for example, expanded only in the horizontal direction of the drawing.
The beam expander 41 is configured by a combination of, for example, a lens or a reflecting mirror, an aperture, and a spatial filter. This beam expander 41 adjusts the horizontal width of the incident light beam when reflected by the parabolic reflector used.
Spatial expansion and conversion are performed so that the range of the predetermined angle Δθ can be covered.

When such a parallel beam is incident on the first parabolic reflector 11, the entire beam converges on its focal point F and then expands again, is reflected by the second parabolic reflector 12, and is again reflected on the optical axis AA. It becomes a light beam that is parallel to 'and spread in the horizontal direction. That is, Δ shown by an arrow in FIG.
The entire range of θ will be covered at once by the incidence of this horizontal beam. The light beam reflected by the second parabolic reflector 12 passes through the sorting optical system 42
The light is guided to and detected by the one-dimensional light detection array 43.

Next, the first and second parabolic reflecting mirrors 11,
12 are mechanically and precisely linked as described above, and are sequentially moved to positions indicated by broken lines along the optical axis AA '. Therefore, while the one-dimensional photodetector array 43 remains completely fixed, each element simultaneously receives light intensity for each predetermined angle change (step) δθ within the angle of Δθ. Therefore, focusing on one element of the photodetector array 43, this element is δ
When the θ, the first and second parabolic reflecting mirrors 11 and 12 sequentially move by the moving distance δx, the light intensity sequentially obtained by the translational motion is detected.

That is, as is apparent from FIG. 18, each element of the photodetector array 43 has δ obtained by dividing Δθ by the number of elements.
At an interval corresponding to θ, a series of light intensities in a translation operation corresponding to each rotation angle can be sequentially detected. This means, for example, that the movable mirror M ₂ shown in FIG.
And M ₂ ′ can be omitted in the range of Δy. Therefore, an apparatus for moving the movable mirror in the direction orthogonal to the optical axis can be omitted, so that the apparatus configuration can be simplified and the translation-rotation operation can be performed simultaneously, so that there is an advantage that the measurement time can be reduced. .

An important point in the configuration using the direct detection method shown in FIG. 18 is that each element of the photodetector array 43 must be able to operate completely independently. That is, it is necessary to prevent background noise light from being mixed and to eliminate crosstalk as much as possible. For this purpose, the sorting optical system 42 is provided with a sorting optical system for sorting the transmitted straight light with high sensitivity required in the case of a single photodetector as described in FIG. It is necessary to be.

It should be noted that, based on the configuration shown in FIG.
Extending to a 60-degree translation-rotation operation is the first, second
Since this embodiment is the same as the embodiment described above, a specific description is omitted.
In this case, the light beam expanded by the beam expander 41 is guided to the first to fourth parabolas 11, 12, 21, 22 or the first to fourth parabolas 11, 12, 21, 21, 2
In order to guide the light beam reflected by the light source 2 to the sorting optical system 42, for example, as shown in FIG.
₁ , M ₁ ′, M ₂ , M ₂ ′ are provided, and these reflected lights are inserted into the optical path according to a required translation-rotation operation.

For example, in the translation-rotation operation of 180 °, as shown in FIG. 10B, the first and second parabolic reflecting mirrors 11 and 12 are replaced with third and fourth parabolic reflecting mirrors 21 and
22 is inserted into the optical path, and the light beam from the beam expander 41 is guided to the fourth parabolic reflecting mirror 22 by using _two reflecting mirrors M ₁ and M ₂ . The light beam reflected by the fourth parabolic reflector 22 and transmitted through the measurement object is sequentially guided to the third parabolic reflector 21. This third parabolic reflector 2
The light beam reflected by 1 is divided into two reflecting mirrors M ₂ ′ and M _2
It is guided to the sorting optical system 42 via ₁ '.

In the 360 ° translation-rotation operation, as shown in FIG. 10, the first to fourth parabolic reflecting mirrors 1 are used.
₁ , 12, 21, 22 and reflecting mirrors M ₁ , M ₁ ′, M ₂ ,
M ₂ ′ may be arranged and the light beam from the beam expander 41 may be introduced into the sorting optical system 42.

Next, a fourth embodiment of the present invention will be described. In this embodiment, an optical heterodyne detection method is performed using a photodetector array.

In the optical heterodyne detection method, if the local light beam is sufficiently controlled to perform the detection operation, mixing of background noise and crosstalk as in the case of the direct detection method are avoided in principle. be able to. Therefore, in this case, it is not necessary to use a specially designed sorting optical system as in the third embodiment, but care must be taken so that each element can always operate at high performance without such obstacles. It is required.

FIG. 19 shows a fourth embodiment of the present invention, and the same parts as those in FIGS. 18 and 14 are denoted by the same reference numerals. The configuration basically required in this embodiment is:
This is the local light of the expanded parallel beam. The expanded width of this beam should be the same as or slightly larger than the expanded width of the signal light beam, so that both can cover the entire used width of the photodetector array. In addition, when the signal light beam and the local light beam that enter the measurement object are expanded into parallel beams, it is necessary to maintain the intensity uniformity within the beam width with sufficient control.

[0111] That is, the light beam LB from the light source 10 is incident on the semi-transparent mirror M ₂₁ as a beam splitter.
The beam width of the light beam transmitted through the translucent mirror M ₂₁ is expanded by the beam expander 41 and guided to the first parabolic reflecting mirror 11. The light beam reflected by the first parabolic reflector 11 is guided to the second parabolic reflector 12 through the focal point F. This second parabolic reflector 12
Light beam spreads again reflected by and guided to the fixed mirror M _22. On the other hand, the light beam reflected by the translucent mirror M ₂₁ is transmitted through the frequency shifter 31 to the local light beam LLB.
Is a, the local light beam is reflected by the fixed mirror M _23, it is guided to a beam expander 41a. The beam expander 41a by the signal light beam and the enlarged local light beam to the same width, the with signal light beam from the fixed mirror M ₂₂ is guided to the half mirror M ₂₄ is synthesized and WFM.
The combined light beam is guided to the photodetector array 43 and is subjected to photoelectric conversion.

The translation-rotation operation is basically the same as that of the second embodiment. As shown in FIGS. 16 and 17, first to fourth parabolas 11, 12, 21, 22 and The reflecting mirrors M ₁₁ , M ₁₂ , M ₁₃ and M ₁₄ may be arranged, and the light beams from the beam expanders 41 and 41 a may be introduced into the translucent mirror M ₂₄ .

According to the fourth embodiment, as in the third embodiment, a device for moving the movable mirror in the direction orthogonal to the optical axis can be omitted, so that the configuration of the device can be simplified. In addition, since the translation and rotation operations can be performed simultaneously, the measurement time can be reduced.

In the third and fourth embodiments, the beam from the light source is expanded by the beam expander. However, the present invention is not limited to this. For example, a plurality of light sources for generating light beams having the same wavelength and the same output may be used. It is also possible to generate a light beam that is spread in one dimension by these light sources.

Next, a fifth embodiment of the present invention will be described. In the first to fourth embodiments, when the measurement object is translated and rotated by the light beam, a part of the light beam is masked by the size of the measured object itself, and some projection data of the measured object is lost. Would. That is, a shadow portion remains in the projection data. The fifth embodiment solves this.

FIG. 20 shows the principle of the fifth embodiment. In this embodiment, the inclination angle θ of the parabolic reflecting mirror P is 90 ° or more (θ> 90 °), and the terminal position (upper part in the figure) of the parabolic reflecting mirror P is located on the right side of the focus F in the drawing. doing. The method for determining the angle will be described later.
It is assumed that the measurement object 13 is arranged around the focal point F of the parabolic reflector P. Specifically, it is arranged so that the center of gravity of the measurement object 13 is located at the focal point F.

[0117] In this case, the light beam B _m incident at distance y _m from the optical axis AA 'will reach the parabolic reflector P in contact with the measurement object 13. Therefore, the light beam in the range of the distance y _m from the optical axis AA 'is prevented in the measurement object y
_In the range of the inclination angle θ _m or less (θ <θ _m ) corresponding to _m , the rotation operation is not performed and the rotation remains as a shadow portion. That is,
Since the incident light beam passes through the measuring object 13 before reaching the parabolic reflector P, it does not correspond to the rotating operation of the present invention.

Therefore, if a parabolic reflector having a shape that reflects the incident light beam Bp such that θ = 90 ° is used, the tilt angle range in which the rotating operation can be performed is Δθ = 90 °.
90 ° −θ _m <90 °.

When a CT image is reconstructed using a computer, projection data in an angle range of at least 0 ° to 180 ° is required. However, as will be described later, a configuration in which a set of parabolic reflecting mirrors is arranged so as to be point-symmetric with respect to the focal point, and it is impossible to cover this 180 ° angle range due to its shape, 11
As described above, for example, two sets of parabolic reflecting mirrors are moved up and down one set at a time, and sequentially inserted into the optical path, so that the angle range is 0 ° to 180 °, and further, 180 ° to 3 °.
An angle range of 60 ° can be covered.

Alternatively, a configuration is considered in which a set of parabolic reflecting mirrors arranged in a point-symmetric manner with a common focal point is rotated, for example, by 90 ° around the focal point. In this case, for example, after a rotation operation is first performed in an angle range of 0 ° to 90 ° (Δθ = 90 °), a set of parabolic reflectors is rotated 90 ° around a shared focal point, and a new 90 ° rotation is performed. A rotation operation in an angle range of up to 180 ° is performed. Further, by sequentially rotating a set of parabolic reflectors by 90 °, 180 °
An angle range of 360 ° can be covered. With this configuration, the total number of steps of the translation-rotation operation can be minimized. Therefore, in FIG. 20, it is most desirable to employ a parabolic reflector having a shape such that Δθ = 90 °. In order to realize this shape, as shown in FIG. 20, a distance y from the optical axis AA ′ corresponding to the inclination angle θ _M such that Δθ = θ _M −θ _m = 90 ° is obtained.
A parabolic reflector having a maximum inclination angle θ _M = θ _m + 90 ° that can reflect the light beam B _M incident at _M may be used.

In the above equation, θ _m is determined from the value of y _m , and y _m may be considered as the maximum radius of the measurement object. Therefore, the value of θ _M is also determined from this y _m . In addition, if the rotation operation is set so that Δθ = 90 °, 0 ° to 360 ° as described above is set.
In the rotation operation over the range, the shadow portion where the rotation operation is not performed can be excluded. This is the basic reason for setting the maximum inclination angle θ of the parabolic reflector to 90 ° or more, that is, θ> 90 °.

With the above configuration, the portion of the parabolic reflector P below θ _m (θ <
θ _m ) is not related to the translation-rotation operation. For this reason,
By removing this portion, a parabolic reflecting mirror having θ in the angle range of θ _m to θ _M may be manufactured and used.

FIG. 21 shows the focal length f of the parabolic reflecting mirror P.
Is relatively shown. The change in the x-axis direction along the optical axis AA 'and the y-axis direction perpendicular thereto is within the focal length f, that is, when x <f, the value of y is larger than x, but the value of x is As the value becomes larger, the value of x and y gradually disappears, and eventually x> y. Here, assuming that the angle range of the rotational operation is Δθ = 90 °, the minimum incident angle θ _m of the light beam for minimizing the length of the parabolic reflecting mirror P in the y-axis direction shown in FIG. 21 is studied. Then 45
°. Accordingly, the maximum inclination angle θ _M is θ _M = 90 ° + 45 ° = 135 °, and in this case, Δθ may be designed and manufactured so that the rotation operation is performed in the angle range of 45 ° to 135 °. . However, when the maximum tilt angle is set as described above, the overall size of the parabolic reflector becomes large as is clear from FIG. Therefore, it is not always necessary to select the angular range limiting restrictions and weight and the like in manufacturing, defines a theta _m based on the maximum radius of the measurement object, and then design decide the required theta _M, and manufactured Is also good. Therefore, θ _M = 135 ° is a degree considered as one guide in design, and is not limited to this.

In the fifth embodiment, the angle range from 0 ° to 9
0 °, 90 ° -180 °, 180 ° -270 °, 270
The rotation operation at an angle of from 360 ° to 360 ° is the same as that described with reference to FIGS. 10 to 12 in the first embodiment and that described with reference to FIGS. 15 to 17 in the second embodiment. Omitted. Therefore, in the fifth embodiment, operations not included in the first and second embodiments will be described.

The structure for performing the rotation operation shown in FIG. 22 is the same as the structure shown in FIG. 9 except for the shape of the parabolic reflector, and the light detection system is omitted in FIG.

In FIG. 22, first, a rotation operation of 90 ° (Δθ = θ _M −θ _m = 90 °) at the upper left of the measurement object 13 and a translation operation similar to FIG. 1 are performed.

FIG. 23 shows a case where the next 90 ° operation, that is, the rotation operation and the translation operation of the lower left 90 ° of the measuring object 13 are performed. Performing this operation following FIG.
In total, a rotation operation of 180 ° (Δθ = 90 ° × 2 = 180 °) is performed.

The main point of this translation / rotation operation is that the object to be measured, the light source and the photodetector do not move at all, as in the case of FIGS. For this reason, for example, the third and fourth parabolic reflectors 2 shown in FIG. 23 are different from the first and second parabolic reflectors 11 and 12 shown in FIG.
The first and second parabolic reflecting mirrors 11 and 12 are point-symmetrically positioned at a position sharing the focal point F with the first and second parabolic reflecting mirrors 11 and 12, and the optical axes A of the first and second parabolic reflecting mirrors 11 and 12 are mutually opposite.
A ′ is arranged so as to be orthogonal. First to fourth
As in the embodiment, the first to fourth parabolic reflecting mirrors 1
23, after the translation-rotation operation of 90 ° is completed based on the arrangement of FIG. 22, the optical axes 1, 12, 21, and 22 can be moved in the direction orthogonal to the optical axis AA ′ (the direction perpendicular to the paper surface). The parabolic reflectors 11 and 12 are retracted from the optical path extending in the vertical direction of the measurement object so as to be arranged, and instead, the parabolic reflectors 21 and 22 are precisely controlled in the vertical direction so that they can be inserted into the optical path. Move mechanically and fix it.

Alternatively, the first and second parabolic reflecting mirrors 1
By rotating the mirrors 1 and 12 by 90 ° about the common focal point F and arranging them at the positions of the third and fourth parabolic reflecting mirrors 21 and 22, the optical axes AA ′ of each other in FIGS. Are orthogonal to each other. At this time, the movable mirrors M ₂ and M ₂ ′ are also rotated together with the parabolic reflector.

In FIGS. 22 and 23, the movable mirrors M ₂ and M
_Since the moving directions of ₂ ′ are orthogonal to the optical axis AA ′, they are orthogonal to each other. Also, FIG.
In FIG. 23, since the light source 10 and the photodetector are fixed at the same position, the fixed mirrors M ₁ and M ₁ ′ in FIG.
Becomes unnecessary. For this reason, these fixed mirrors M ₁ and M ₁ ′ are configured so as to easily come out of the optical path by rotating. With such a configuration, in FIG. 22, the data of the angle theta _m the range that is a shadow, can be 23, obtained by rotating operation.

[Rotation-Translation Operation at an Angle of 360 °] Further, when it is required to perform a translation-rotation operation over an angle of 360 ° on a measurement object, for example, in FIG. 23, and the parabolic reflector 11 is arranged on the detection system side, so that in FIG. 23, 90 ° at the lower right of the measurement object including the range of the angle θ _m which is shadowed, that is,
A translation-rotation operation of 70 ° can be realized. After this, FIG.
In the above, if the directions of the incident light beam and the signal light beam are switched, 90 ° at the upper right part of the measurement object, that is, 270 °
A 360 ° translation-rotation operation can be performed.

However, these fixed mirrors and movable mirrors are provided with a moving rail and a rotating mechanism so that they can be sequentially moved to the measurement positions in the respective angle ranges and can be precisely controlled in order to minimize the number of used mirrors. The gantry is designed and manufactured, and its operation is controlled according to a program by a computer and moved.
What is necessary is just to arrange.

According to the fifth embodiment, the arrangement of the two types of parabolic reflectors shown in FIGS. 22 and 23 is changed while the object to be measured is fixed without moving at all, and the light source 10 and the detection system are further changed. Is fixed, and the fixed mirror and the movable mirror are arranged corresponding to the respective four 90 ° rotation ranges, so that a rotation-translation operation at an angle of 360 ° with respect to the measurement object 13 can be performed.

In addition, the maximum inclination angle θ of the parabolic reflector is 9
Since the angle is set to 0 ° or more, with respect to the measurement object 13,
Since there is no shadowed portion, projection data can be obtained from all directions of the measurement object 13 without loss.

In the parabolic reflector, the size of the parabolic reflector can be reduced in size and weight by eliminating the range of θ <θm which is not related to the rotation-translation operation.

Although the fifth embodiment has described the direct detection method, the present invention is not limited to this. The optical heterodyne detection method can be applied as in the second embodiment. The configuration and operation related to the optical heterodyne detection method are the same as those in the second embodiment, and thus description thereof is omitted.

Further, in the fifth embodiment, the case where the incident beam diameter is small has been described. However, as in the third embodiment, for example, the width of the light beam emitted from the light source is increased and the one-dimensional parallel beam is increased. In other words, a direct detection method using a one-dimensional photodetector array in which light beams are converted into a thin strip-shaped light beam and photodetectors are arranged one-dimensionally as photodetectors, or as described in the fourth embodiment, It is also possible to apply the configuration in the case of using the optical heterodyne detection method to the third embodiment.

Further, in the fifth embodiment, the laser light source is not limited to a single wavelength, but a laser capable of changing a plurality of wavelengths, and further, an oscillation wavelength can be used. . In this case, if one laser oscillator is not enough, use a plurality of laser oscillators, arrange and fix them, and appropriately arrange a fixed mirror and a movable mirror or an optical fiber or the like that can replace them, and The light beam may be introduced into the measurement object through the parabolic reflector, and the light beam transmitted through the measurement object and reflected by the parabolic reflector may be guided to the photodetector.

Further, translation by light beams of a plurality of wavelengths
In order to shorten the time of the rotation operation, instead of performing this operation sequentially for each wavelength, by including a plurality of wavelengths in one signal light beam, or by controlling the optical paths of light beams of different wavelengths according to a program, These can be simultaneously translated and rotated.

Of course, various modifications can be made without departing from the spirit of the present invention.

[0141]

As described above in detail, according to the present invention, a pair of parabolic reflectors disposed at point-symmetric positions with respect to the focal point are moved along the optical axis, The light beam is moved in a direction perpendicular to the optical axis, or the beam width is expanded and introduced into a parabolic reflector. Accordingly, an optical image measurement device capable of performing a translation-rotation operation of a light beam with respect to a measurement object with the light source, the measurement object, and the light detection system fixed, and capable of performing stable, high-precision measurement. Can be provided.

[Brief description of the drawings]

FIG. 1, showing a first embodiment of the present invention, is a configuration diagram showing a translation operation.

FIG. 2 is a view for explaining characteristics of a parabolic reflector;

FIG. 3 is a diagram illustrating characteristics of a parabolic reflector;

FIG. 4 is a perspective view showing a cylindrical parabolic reflecting mirror.

FIG. 5 is a view for explaining a translation operation of the present invention.

FIG. 6 is a diagram illustrating a translation operation of the present invention.

FIG. 7 is a view for explaining a rotation operation of the present invention.

FIG. 8 is a diagram specifically showing a rotation operation of the present invention.

FIG. 9 shows the first embodiment of the present invention, and is a configuration diagram showing a rotation operation.

FIG. 10 shows the first embodiment of the present invention, and is a configuration diagram showing a translation-rotation operation at an angle of 180 °.

FIG. 11 is a perspective view showing a driving example of a parabolic reflecting mirror.

FIG. 12 shows the first embodiment of the present invention, and is a configuration diagram showing a translation-rotation operation at an angle of 360 °.

FIG. 13 is a diagram showing a driving example of a parabolic reflecting mirror.

FIG. 14 shows the second embodiment of the present invention, and is a configuration diagram showing a translation operation.

FIG. 15 shows a second embodiment of the present invention, and is a configuration diagram showing a rotation operation.

FIG. 16 shows the second embodiment of the present invention, and is a configuration diagram showing a translation-rotation operation at an angle of 180 °.

FIG. 17 shows a second embodiment of the present invention, and is a configuration diagram showing a translation-rotation operation at an angle of 360 °.

FIG. 18 is a view showing a third embodiment of the present invention, and is a configuration diagram showing a translation-rotation operation.

FIG. 19 is a view showing a fourth embodiment of the present invention, and is a configuration diagram showing a translation-rotation operation.

FIG. 20 shows a fifth embodiment of the present invention, and is a configuration diagram illustrating a modification of the parabolic reflector.

FIG. 21 shows the fifth embodiment of the present invention, and is a view for explaining the angle of the parabolic reflector.

FIG. 22 shows a fifth embodiment of the present invention, and is a configuration diagram showing a rotation operation.

FIG. 23 shows a fifth embodiment of the present invention, and is a configuration diagram showing a rotation operation.

FIG. 24 is a diagram showing a general translation-rotation operation.

[Explanation of symbols]

Reference Signs List 10: light source 11, 12, 21, 22: first to fourth parabolic reflecting mirrors, 13: measuring object, 14, 14a, 14b, 23, 24, 25, 26: driving device, 15, 42: sorting optics System 16, 32 ... Photodetector 17, 34 ... Image processing device, 18 ... Control device, 31 ... Frequency shifter, 33 ... IF receiver, 41, 41a ... Beam expander, 43 ... Photodetector array, F ... _{focus, M 1, M 1 ',} M 11, M 14, M 22, M 23 ... fixed _{mirror, M 2, M 2',} M 13 ... movable _{mirror, M 12, M 15, M} 21, M 24 ... Translucent mirror, LB: Light beam, LLB: Local light beam.

Claims (18)

[Claims] 1. A first and a second parabolic reflecting mirror having a half paraboloid, arranged point-symmetrically with respect to a focal point, and movable in an optical axis direction, and generating a light beam. A light source that guides a light beam generated from the light source to the first parabolic reflector in parallel with the optical axis; and a light source that is reflected by the first parabolic reflector and receives the optical axis. Second optical means for transmitting a light beam transmitted through a measurement object disposed about the upper focal point, reflected by the second parabolic reflector, and guided in parallel with the optical axis; Detecting means for detecting a light beam from the optical means; and
An optical image measuring apparatus, comprising: first driving means for moving the first and second parabolic reflectors so that the focal points of the first and second parabolic reflectors are along the optical axis. . 2. The apparatus according to claim 1, further comprising a second driving unit that drives the first and second optical units in a direction orthogonal to the optical axis to rotate the light beam with respect to the measurement object. The optical image measurement device according to claim 1. 3. A third and a third parabolic reflector near the first and second parabolic reflectors, which share a focal point with the first and second parabolic reflectors and are arranged point-symmetrically with respect to the focal point. And a parabolic reflector 4 for translating the light beam onto the measurement object,
3. The apparatus according to claim 1, further comprising: third driving means for moving the third and fourth parabolic reflectors such that the focal points of the third and fourth parabolic reflectors are along the optical axis.
The optical image measurement device as described in the above. 4. The method according to claim 1, wherein the second driving means is configured to control the first and second driving means.
The optical image measuring apparatus according to claim 2, wherein the optical unit is moved in a direction orthogonal to the optical axis and beyond the optical axis. 5. The apparatus according to claim 1, further comprising: fourth driving means for alternately inserting the first and second parabolic reflecting mirrors and the third and fourth parabolic reflecting mirrors into the optical path of the light beam. The optical image measurement device according to claim 3, wherein: 6. The first optical means is moved along the optical axis to a position facing the third parabolic reflector,
The optical image measurement device according to claim 1, further comprising: a fifth driving unit that moves the second optical unit to a position facing the fourth parabolic reflector along the optical axis. . 7. A first, half-parabolic surface, arranged point-symmetrically with respect to the focal point, and movable in the optical axis direction.
A second parabolic reflector, a light source for generating a light beam, first optical means for receiving the light beam generated from the light source, and a light beam from the first optical means as a first light beam. Dividing the first light beam into the first light beam;
A first translucent mirror that guides the parabolic reflector parallel to the optical axis, and a second parabolic reflection, which is reflected by the first parabolic reflector and transmits a measurement object arranged on the optical axis. The first reflected by a mirror and guided parallel to the optical axis
A second optical means for receiving the light beam of the second light beam; a frequency shift means for shifting a frequency of the second light beam from the first translucent mirror; and a second frequency light frequency shifted by the frequency shift means. A second translucent mirror that combines a light beam and the first light beam from the second optical means to generate a light beam including a beat signal; and a light beam from the second translucent mirror. Detection means for heterodyne detection of, for causing the light beam to translate incident on the measurement object,
An optical image measuring apparatus, comprising: first driving means for moving the first and second parabolic reflectors so that the focal points of the first and second parabolic reflectors are along the optical axis. . 8. A second driving means for driving the first translucent mirror and the second optical means in a direction orthogonal to the optical axis to rotate the light beam with respect to the measurement object. The optical image measurement device according to claim 7, comprising: 9. Near the first and second parabolic reflectors, the third and third parabolic reflectors share a focal point with the first and second parabolic reflectors and are arranged point-symmetrically with respect to the focal point. And a parabolic reflector 4 for translating the light beam onto the measurement object,
8. The apparatus according to claim 7, further comprising: third driving means for moving the third and fourth parabolic reflecting mirrors such that the focal points of the third and fourth parabolic reflecting mirrors are along the optical axis.
The optical image measurement device as described in the above. 10. The apparatus according to claim 1, wherein the second driving means moves the first translucent mirror and the second optical means in a direction orthogonal to the optical axis and beyond the optical axis. The optical image measurement device according to claim 8. 11. The first and second parabolic reflectors,
10. The optical image measurement device according to claim 9, further comprising a fourth driving unit for alternately inserting the third and fourth parabolic reflecting mirrors into the optical path of the light beam. 12. The first optical means and the first translucent mirror are moved along the optical axis to a position facing the third parabolic reflector, and the second optical means and the second translucent mirror are moved. The optical image measurement device according to claim 7, further comprising a fifth driving unit that moves the translucent mirror along the optical axis to a position facing the fourth parabolic reflecting mirror. 13. A first and a second parabolic reflector having a half paraboloid, arranged point-symmetrically with respect to a focal point, and movable in an optical axis direction, and generating a light beam. A light source; a beam expanding unit that expands a light beam from the light source in a one-dimensional direction and introduces the light beam into the first parabolic reflecting mirror; and a beam expanding unit that is reflected by the first parabolic reflecting mirror and disposed on the optical axis. Detecting means for detecting a light beam transmitted through the measured object, reflected by the second parabolic reflector, and expanded in a one-dimensional direction parallel to the optical axis; and translating the light beam with respect to the measured object. To make it incident,
An optical image measuring apparatus, comprising: first driving means for moving the first and second parabolic reflectors so that the focal points of the first and second parabolic reflectors are along the optical axis. . 14. A first and a second parabolic reflecting mirror having a half paraboloid, arranged point-symmetrically with respect to a focal point, and movable in an optical axis direction, and generating a light beam. A light source; a first translucent mirror for dividing a light beam from the light source into a first light beam and a second light beam; and a one-dimensional direction of the first light beam from the first translucent mirror. A first beam expanding means for expanding the light into the first parabolic reflector; and reflecting the first parabolic reflector, transmitting a measurement object disposed on the optical axis, and Optical means for receiving the first light beam reflected by the parabolic reflecting mirror and expanded in a one-dimensional direction parallel to the optical axis; and a frequency of the second light beam from the first translucent mirror Frequency shifting means for shifting the frequency, Second beam expanding means for expanding the shifted second light beam in a one-dimensional direction; and a second light beam expanded by the second beam expanding means and the first light beam from the optical means. A second translucent mirror that combines a light beam and generates a light beam including a beat signal; detection means for heterodyne detecting the light beam from the second translucent mirror; and applying the light beam to a measurement object. For translational incidence,
An optical image measuring apparatus, comprising: first driving means for moving the first and second parabolic reflectors so that the focal points of the first and second parabolic reflectors are along the optical axis. . 15. The optical image measurement device according to claim 3, wherein a maximum inclination angle of each of the first to fourth parabolic reflecting mirrors is set to 90 ° or more. 16. The optical image measurement device according to claim 13, wherein a maximum inclination angle of each of the first and second parabolic reflecting mirrors is set to 90 ° or more. 17. The first and second parabolic reflectors,
17. The optical image measurement device according to claim 1, further comprising a device that rotates by 90 [deg.] About a common focus. 18. The apparatus according to claim 15, wherein the first to fourth parabolic reflecting mirrors have a range of an inclination angle corresponding to a maximum radius of the measurement object removed from an optical axis.
The optical image measurement device according to any one of claims 6 and 17.