JP2981695B2 - Method and apparatus for measuring three-dimensional information of a specimen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring three-dimensional information of a specimen, and more particularly to non-destructively measuring morphological three-dimensional information such as a tomographic image and a three-dimensional image of a specimen by scanning a laser beam. The present invention relates to a method and an apparatus for measuring three-dimensional information of a specimen to be measured.

[0002]

2. Description of the Related Art Conventionally, morphological three-dimensional information of a specimen, that is, not only the external form of the specimen but also the internal form of the specimen, is shown.
It is desired that non-destructive measurement of dimensional information is performed. Particularly, in the field of biology and medicine, since the above-mentioned specimen is a living body, morphological three-dimensional information of the specimen is non-destructively (hereinafter simply referred to as three-dimensional information). Is strongly desired.

[0003] To meet such demands, X-ray CT
And MRI have achieved tomographic images of specimens. However, the tomographic image is strictly two-dimensional information, and research for measuring three-dimensional information of a specimen is being advanced.

[0004] One of them is a multi-tomographic X-ray CT method.
The sample is irradiated with two X-rays, and the X-rays are transmitted through the sample by rotating the X-ray 360 ° on a circumference in a plane perpendicular to the body axis about a virtual axis (hereinafter referred to as a body axis) of the sample. Tomographic image data is calculated from the transmitted X-rays, and the X-rays are moved in the body axis direction, and then tomographic image data is calculated again in the same manner as described above.
The two-dimensional image data is interpolated and calculated from the two tomographic image data to calculate three-dimensional information of the specimen.

The multi-tomographic X-ray CT technique provides helical scan X that gives continuous image data in the body axis direction and moves the X-ray in a spiral shape with the body axis of the specimen as the center axis of rotation. It has evolved into a line CT technique.

However, the above-mentioned X-ray CT technique and MRI
Have not been able to directly measure three-dimensional information.
That is, in the X-ray CT method, since a point-shaped irradiation line irradiates a sample, the detected image is merely line segment information in which a point is displaced. Therefore, a helical scan X-ray CT method using a conical beam, which irradiates the above-mentioned irradiation light in a plane and obtains plane image data, has been proposed ("3D helical scan CT using conical beam projection"). Transactions of the Society D-II vol.J74-D-II No.8 1991 8
), The helical scan X-ray C
Since means for detecting a planar state of an X-ray obtained by the T method, that is, a two-dimensional image, has not been realized, it does not fall outside the range of the proposal.

[0007] On the other hand, since spectroscopic analysis is a useful method for identifying a substance, an attempt has been made to image the internal morphology of a specimen by using light. In the optical field, means for detecting the form of a specimen as a two-dimensional image has already been established. For example, a CCD camera can detect the form of a specimen two-dimensionally.

Therefore, as a method for measuring three-dimensional information using light, a method for measuring three-dimensional information of a specimen using an optical CT microscope is known.

This optical CT microscope irradiates the sample with a laser beam from an oblique direction and moves the light source of the laser beam along the periphery of the bottom surface of the cone whose apex is the sample. The transmitted light image of the laser light transmitted through the specimen from a different angle is recorded in a CCD camera, and the transmitted light image is subjected to image reconstruction processing by a CT method to measure three-dimensional information of the specimen ( “Optical CT Microscope and 3D Observation” Optical Technology Contact Vol.28 No.
11 (1990)).

[0010]

However, in the above measuring apparatus, since the direction in which the laser light irradiates the sample is limited, the data of the cross-sectional image along the transmission direction of the transmitted light image becomes insufficient. The accuracy of the cross-sectional image cannot be improved.

In the above-mentioned image reconstruction process,
Since the approximation method (Born approximation method) for limiting the specimen to a substantially transparent body is used, the specimen contains a light scattering medium, such as a living body, in which scattered light is emitted mixed with transmitted light. In the case of, there is a disadvantage that the above measurement method cannot be applied.

In view of the above circumstances, it is an object of the present invention to provide a method and an apparatus for measuring morphological three-dimensional information of a specimen using a laser beam which are highly accurate and can be applied to a specimen containing a light scattering medium. It is in.

[0013]

Means for Solving the Problems Claim 1 according to the present invention.
The method for measuring three-dimensional information of a specimen described above includes irradiating the specimen with a laser beam formed in a conical beam on the surface thereof, and forming another cone-shaped laser beam having a frequency slightly different from that of the laser beam transmitted two-dimensionally through the specimen. The laser light of the sample is wavefront-matched, the laser light of the cross-section two-dimensionally aligned with the wavefront is optically heterodyne-detected two-dimensionally, and the intensity of the laser light transmitted through the sample is measured from the detected beat signal. The laser beam and the sample are relatively displaced so that the laser beam scans the sample in a spiral manner, and the morphological three-dimensional information of the sample is obtained from the intensity of the transmitted laser beam by a CT method. Is measured.

According to a third aspect of the present invention, in the method for measuring three-dimensional information of a specimen, the first laser beam is wavefront-matched with a second laser beam having a frequency slightly different from that of the laser beam. The light is formed into a conical beam, and the laser light formed into the conical beam is converted into a laser light having the same frequency as the first laser light and a laser light having the same frequency as the second laser light. The optical path is divided, and one of the two laser lights having the divided optical path is irradiated onto the specimen, and the laser light transmitted through the specimen and the other cone obtained by dividing the optical path. Wavefront matching with the laser light in a cross section, two-dimensional optical heterodyne detection of the laser light having a two-dimensional cross section with the wavefront matched, and measuring the intensity of the laser light transmitted through the specimen from the detected beat signal. And the laser light is applied to the specimen. The laser light and the specimen are relatively displaced so as to scan in a spiral manner, and the morphological three-dimensional information of the specimen is measured from the intensity of the transmitted laser light by a CT method. .

Further, a three-dimensional information measuring apparatus for a specimen according to a third aspect is an apparatus for implementing the three-dimensional information measuring method for a specimen according to the first aspect. Optical path splitting means for splitting the optical path of the laser light, which is arranged in the optical path of the laser light emitted from the laser light source, into two, and a laser light traveling along one of the two optical paths obtained by splitting Frequency conversion means for converting the frequency of at least one laser light to another frequency so that the frequency of the laser light traveling on the other optical path is slightly different from the frequency of the laser light traveling on the other optical path, and the two optical paths obtained by the division. An optical means for forming the traveling laser light into a conical beam, and applying one of the two laser lights formed on the conical beam to the sample and irradiating the sample with the laser light. Scanning means for relatively displacing the laser light and the sample so that the light scans the sample in a spiral shape; a laser beam irradiated on the sample and transmitted through the sample; and the conical beam A wavefront matching means for wavefront matching the other laser light formed on the surface thereof, and a wavefront-matched cross section 2 arranged on a plane which intersects substantially perpendicularly to the traveling direction of the laser light wavefront matched by the wavefront matching means. Two-dimensional intensity detecting means for two-dimensionally detecting light intensity that repeats intensity according to the difference frequency of the two-dimensional laser light, and a laser light transmitted through the specimen based on the intensity of the laser light detected by the detecting means. Measurement processing means for detecting intensity and measuring and processing three-dimensional information of the sample by a CT method.

A three-dimensional information measuring apparatus for a specimen according to a fourth aspect is an apparatus for performing the three-dimensional information measuring method for a specimen according to the second aspect, comprising: a single-frequency laser light source; First optical path splitting means for splitting the optical path of the laser light, which is arranged in the optical path of the laser light emitted from the laser light source, into two, and one of the two optical paths obtained by the splitting; Frequency conversion means for converting the frequency of at least one laser beam to another frequency so that the frequency of the traveling laser beam and the frequency of the laser beam traveling on the other optical path are slightly different, and a laser having the frequency converted First wavefront matching means for wavefront matching the light and the laser light traveling in one optical path obtained by the division, and optical means for forming the wavefront matched laser light into a conical beam; The cone Second optical path splitting means for splitting the optical path of the laser light formed into the two beams into two laser lights having slightly different frequencies, and any one of two optical paths obtained by splitting by the optical path splitting means. A scanning unit that relatively displaces the laser light and the sample so that the sample scans the sample in a spiral shape while irradiating the sample with laser light that travels in one of the optical paths. Second wavefront matching means for wavefront matching the laser light irradiated on the sample and transmitted through the sample and the laser light traveling on the other optical path obtained by splitting by the second optical path splitting means; The intensity of light that repeats intensities due to the difference frequency between the two-dimensionally cross-sectionally two-dimensional laser light, which is arranged on a plane that intersects substantially perpendicularly to the traveling direction of the laser light that has been wavefront-aligned by the wavefront matching means, The original to detect 2
Dimensional intensity detection means, and measurement processing means for detecting the intensity of the laser light transmitted through the specimen based on the intensity of the laser light detected by the detection means, and measuring and processing the three-dimensional information of the specimen by a CT method. It is characterized by comprising.

Further, the apparatus for measuring three-dimensional information of a specimen according to claim 5 is an apparatus for performing the method for measuring three-dimensional information of a specimen according to claim 2, and the apparatus for measuring three-dimensional information of specimen according to claim 4. In the dimensional information measuring device, the second optical path splitting means also serves as the second wavefront matching means, and the reflecting means arranged at a position for causing the laser light transmitted through the sample to travel to the second optical path splitting means. It is characterized by having.

The above-mentioned helix is a locus of displacement obtained by a vector sum of a rotational displacement about an arbitrary virtual axis (hereinafter referred to as a body axis) of the specimen and a linear displacement in the body axis direction. Means

Therefore, the above-mentioned laser beam scans the specimen in a spiral manner when, for example, the laser light source is displaced along the spiral spiral and the laser beam from the laser light source is applied to the specimen. Means

The single-frequency laser light source is
It does not mean a laser light source that can emit only a single-frequency laser beam, but a laser light source that can emit a single-frequency laser beam for a predetermined period of time.
Means a laser light source capable of emitting the above laser light.

Further, the frequency converting means may be means for converting one of the two laser lights divided into two optical paths by the optical path dividing means into another frequency having a slightly different frequency. A means for frequency-converting the two laser lights so that the frequency of one laser light is slightly different from the frequency of the other laser light may be used.

[0022]

The method for measuring three-dimensional information of a specimen according to the present invention comprises:
The laser light formed on the conical beam surface irradiation in the sample, the laser beam is emitted from the outer surface and internal scattered by material or absorbed by the specimen of the portion of the specimen as well as transmitted through the specimen and, by the laser beam and the frequency be WFM other conical laser beam slightly different to the emitted laser beam, only the transmitted light goes straight through the sample out of the laser beam the emission By interfering with the other laser light to form an interfering laser light that repeats the intensity with the interference of the frequency of the difference between the two laser lights, the other laser light proceeds as it is, and the intensity of the interference laser light is detected by optical heterodyne detection. The two-dimensional intensity distribution of the transmitted light is detected.

Further, the laser beam formed into the conical beam is spirally scanned with respect to the specimen, and the two-dimensional intensity distribution of the transmitted light at each scanning position is continuously detected. The two-dimensional intensity distribution of the transmitted light can be measured by the CT method, that is, the reconstruction algorithm for the conical beam projection helical scan, to measure the three-dimensional information of the specimen.

According to a second aspect of the present invention, there is provided a method for measuring three-dimensional information of a specimen, wherein the method according to the first aspect irradiates the specimen with one of two laser lights having slightly different frequencies on the surface of the specimen. In contrast to the above, the two laser lights having slightly different frequencies are subjected to wavefront matching before one of the two laser lights is incident on the specimen, and the wavefront-matched laser light is conically shaped. After being formed into a beam, it is again divided into two laser beams having different frequencies, and one of the two divided laser beams is irradiated onto the surface of the specimen, and then the two interfere with each other. It is.

[0025]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram showing an embodiment of an apparatus for measuring three-dimensional information of a specimen according to the present invention. The illustrated three-dimensional information measuring apparatus for a specimen uses a laser beam a having a single frequency ν _0.
1 a laser light source 1 for emitting a half mirror 9 for dividing the laser beam a ₁ into two optical paths in the optical path of the emitted laser beam a ₁ from the laser light source 1 is disposed.

Further, wherein the one optical path of the two light paths obtained by the half mirror 9, the laser beam a ₁ the frequency of the laser beam a ₃ traveling through the optical path frequency [nu ₀ and slightly different from the the frequency shifter 3 as a frequency conversion means for converting the laser beam a ₄ frequency [nu ₀ + .DELTA..nu are arranged in the optical path of the laser beam a _3.

Furthermore, in the optical path of the laser beam a ₄ in after being frequency converted by the frequency shifter 3 (after being reflected by the reflecting mirror 10 in the figure) forming the laser beam a ₄ to conical beam a ₆ A lens 5 is provided.

On the other hand, in the optical path of the laser beam a ₂ traveling on the other optical path split by the half mirror 9 (after being reflected by the reflection mirror 10 ′ in the figure), the laser beam a ₂ is conical. Is formed, and a laser beam a after being formed into this conical beam is provided.
₅ is a scanning unit 6 to which the laser beam a ₅ displaces the sample 2 so as to scan the sample 2 in the helical spiral is arranged with the sample 2 surface irradiation.

Further, a beam splitter 7 as a wavefront matching means is provided at a position where the laser beam a ₆ formed into the conical beam and the laser beam a ₇ emitted from the sample 2 after irradiating the sample 2 are wavefront matched. Are arranged.

[0031] Furthermore, two-dimensional intensity distribution detecting a two-dimensional parallel operation type image sensor 8 of the laser beam a ₈ to a plane perpendicular direction of travel of the wavefront-matched laser beam a ₈ is disposed, the image A measurement processing unit 11 for calculating a transmitted light projection image of the sample 2 based on the intensity of the laser beam a ₈ detected by the sensor 8 and measuring three-dimensional information of the sample by a CT method; Reconstructing means 12 for outputting a stereoscopic image of the specimen 2 and the like. Here, the sample 2 is a sample containing a light scattering medium, for example, a liquid containing dispersed particles.

Next, the operation of this embodiment will be described.

The laser beam a ₁ emitted from the laser light source 1 having a single frequency [nu ₀ is divided by a half mirror 9 into two laser beams a ₂ and a _3, one of the laser beam a ₃ by frequency shifter 3 is converted to the laser beam a ₄ slightly different other frequency [nu ₀ + .DELTA..nu the original frequency [nu _0.

The laser beam a ₂ becomes a laser beam a ₅ formed into a conical beam by the lens 4 and irradiates the surface of the specimen 2.

[0035] Here, the sample 2 is displaced by the scanning means 6 in a helical spiral are scanned with the laser beam a ₅ to helical spiral along the entire circumference.

[0036] The laser beam a ₅ is partially the specimen 2
Scattered by the outer surface or inside of the light scattering medium is emitted into the indefinite direction and another portion is absorbed by the outer surface and internal material of the specimen 2, the remainder is the laser beam a ₅ specimen of The light is transmitted through the specimen while maintaining the direction of incidence on the sample 2, and is emitted. Therefore, the transmitted light the emitted light a ₇ the laser beam a ₅ is emitted from the specimen 2 is traveling with the scattered light traveling in the direction of the indefinite is the scattered in a certain direction are mixed.

On the other hand, the laser beam a _{4 having the} frequency ν ₀ + Δν
Is formed in a conical beam by the lens 5 in the same manner as the laser beam a ₅ of the frequency [nu ₀ to laser light a _6, and the
The transmitted light and the laser light a _{6 of the} emitted light a ₇ are wavefront-aligned by the beam splitter 7 to generate the interference laser light a ₈ .

Next, the interference laser beam a ₈ projects a two-dimensional intensity distribution image of the interference laser beam a ₈ on the two-dimensional surface of the two-dimensional parallel operation type image sensor 8.
Said two-dimensional intensity distribution image is photoelectrically converted by, is optical heterodyne detection processing by the measurement processing means 11, two-dimensional intensity distribution data (transmitted light projected from the two-dimensional intensity distribution image of the light transmitted through the interference laser beam a ₈ Image) is calculated, and two-dimensional intensity distribution data of the transmitted light corresponding to each scanning position of the specimen 2 is subjected to a CT process (a reconstruction algorithm for a cone beam projection helical scan) to obtain three-dimensional information of the specimen 2. Measured. Further, the reconstruction means 12 outputs a three-dimensional image of the specimen or a tomographic image along an arbitrary cross section from the three-dimensional information.

The apparatus for measuring three-dimensional information of a specimen according to the present embodiment
Since the laser beam scans the sample in a spiral shape, the transmitted light projection image obtained through the sample has continuity over the entire circumference of the sample, and the accuracy of the cross-sectional image along the transmission direction is high. improves.

Further, by subjecting the emitted light emitted from the specimen to optical heterodyne detection processing, it is possible to detect only transmitted light for obtaining the component distribution of the specimen, and therefore, the specimen contains a light scattering medium. It is possible to measure the three-dimensional information of the sample even if it is a sample.

In this embodiment, the specimen 2 is displaced. However, the specimen 2 is stopped, and the lens 4 and the lens 5 are displaced.
The beam splitter 7 and the image sensor 8 may be integrally displaced in a spiral shape around the specimen 2 substantially, or the specimen 2 and the lens or the like may be relatively displaced. .

FIG. 2 is a block diagram showing another embodiment of the apparatus for measuring three-dimensional information of a specimen according to the present invention.

The three-dimensional information measuring apparatus for a specimen shown in the figure has a laser light source 21 which emits a laser beam a ₂₁ having a single frequency ν _0.
When, and a the laser light source two half-wave plate 28 to be divided into the optical path 21 polarization plane of the laser beam a ₂₁ emitted from the orthogonal polarization beam splitter 25.

[0044] The frequency [nu ₀ of the polarizing beam splitter 25 the laser beam a ₂₃ in the optical path of the laser beam a ₂₃ traveling one optical path of the two light paths obtained divided by
Frequency shifter 23 for converting the laser beam a ₂₄ slightly different frequency [nu ₀ + .DELTA..nu this frequency [nu ₀ is arranged to.

Further, the frequency-converted laser light a_{twenty four}
And the other split laser beam a _{twenty two}And wavefront matching
A polarization beam splitter 45 is disposed at a position where the polarization beam splitter 45 is located.

A lens for forming the laser beam a ₂₅ into a conical beam in the optical path of the laser beam a ₂₅ whose wavefront has been matched.
24, and further converts the laser beam a ₂₆ formed into this conical beam into a laser beam a having a frequency ν ₀ whose polarization planes are orthogonal to each other.
A polarizing beam splitter 26 for splitting an optical path into ₂₇ and a laser beam a ₂₈ having a frequency ν ₀ + Δν is provided.

Further, the laser beam a with the optical path of one divided by the polarization beam splitter 26 is the divided one laser beam a ₂₇ faces irradiation to the specimen 22
_{27 so} that the sample 22 spirally scans the sample 22.
Scanning means 27 for displacing 22 is provided.

Further, after irradiating the sample 22, the sample 22
The laser beam a ₂₉ emitted from 22 and the polarizing beam splitter
Laser light a ₂₈ traveling on the other optical path divided by 26
A polarization beam splitter 38 to a wavefront matching the door, and a polarizing plate 30 to interfere with the same polarization plane components between the two laser beams obtained by wavefront matching, the two-dimensional intensity distribution of the interference laser beam a ₃₀ Detection A two-dimensional parallel operation type image sensor 35 for converting the transmitted light into an electric signal, and a transmitted light projected image of the specimen 22 are calculated based on the intensity of the laser beam a ₃₀ detected by the image sensor 35. From the specimen
Measurement processing means 36 for measuring three-dimensional information of the sample 22; and reconstructing means 37 for outputting a three-dimensional image of the sample 22 from the three-dimensional information.
Is provided.

Next, the operation of this embodiment will be described.

The laser light a ₂₁ emitted from the laser light source 21 having a single frequency ν ₀ is split by the half-wave plate 28 and the polarizing beam splitter 25 into laser lights a ₂₂ and a ₂₃ whose polarization planes are orthogonal to each other. one laser beam a ₂₃ frequency shifter
The laser light is converted into a laser beam a ₂₄ of another frequency ν ₀ + Δν slightly different from the original frequency ν ₀ by 23.

The two laser beams a ₂₂ and a ₂₄ whose polarization planes are orthogonal to each other and have slightly different frequencies form a laser beam a ₂₅ whose wavefront has been matched by the second polarization beam splitter 45, and are further conical by the lens 24. Shaped beam.

The laser beam a formed into the conical beam
₂₆ is divided by the polarization beam splitter 26 into a laser beam a ₂₇ and the frequency [nu ₀ + .DELTA..nu laser beam a ₂₈ of the frequency [nu _0.

At this time, the laser beam a ₂₇ is reflected by the polarizing beam splitter 26, and the laser beam a ₂₈ transmits through the polarizing beam splitter.

The reflected laser beam a ₂₇ irradiates the surface of the sample 22, and the laser beam transmitted and emitted through the sample 22 is reflected by the polarizing beam splitter 38.
The frequency [nu ₀ is transmitted light of the laser beam a ₂₉ emitted from the
Wavefront matching with + Δν laser light a ₂₈ . Next, in the wavefront-matched laser light, the same polarization direction components of the transmitted light and the laser light a ₂₈ having the frequency ν ₀ + Δν interfere with each other by the polarizing plate 30, and the two-dimensional intensity of the interfered laser light a ₃₀ The distribution image is projected on the two-dimensional parallel operation type image sensor 35.

[0055] Further, the sample 22 is scanned with the laser beam a ₂₇ is displaced in a helical spiral by scanning means 27 to the helical spiral along the entire circumference.

Hereinafter, the image sensor 35 and the measurement processing means 36
The operation of the reconfiguration means 37 is the same as the operation of the image sensor 8, the measurement processing means 11, and the reconfiguration means 12 in the first embodiment.

The three-dimensional information measuring apparatus for a specimen according to the present embodiment
When the laser beam a ₂₄ immediately after the frequency conversion and the laser beam a ₂₂ not frequency-converted are incident on the optical system 100 for wavefront matching before scanning the sample, even if the incident direction shifts, the sample 22 The laser beam a ₂₉ transmitted through the polarization beam splitter 26 and the laser beam a ₂₈ transmitted through the polarization beam splitter 26 can be wavefront-matched by the polarization beam splitter 38 without causing a shift.

The scanning means 27 does not necessarily scan the specimen 22, but scans the specimen 22 in an spiral manner with an optical system 101 for irradiating the specimen 22 with a laser beam as shown in FIG. Things can also be adopted.

FIG. 4 is a block diagram showing another embodiment of the apparatus for measuring three-dimensional information of a specimen according to the present invention. In the illustrated sample three-dimensional information measuring apparatus, in the embodiment shown in FIG. 2, the polarizing beam splitter 26 as the second optical path splitting unit also serves as the polarizing beam splitter 38 as the second wavefront matching unit, and the sample 22 is The optical disk device further includes concave mirrors 33 and 34 as reflection means disposed at positions where the transmitted laser light travels to the polarization beam splitter 26 as the second optical path splitting means, and further the laser light reflects or reflects the polarization beam splitter 26. A quarter-wave plate 29 for controlling the transmission of the laser light and rotating the polarization plane of the laser light is provided.

Next, the operation of this embodiment will be described.

The laser light a ₂₁ emitted from the laser light source 21 having a single frequency ν ₀ is split by a half-wave plate 28 and a polarizing beam splitter 25 into laser lights a ₂₂ and a ₂₃ whose polarization planes are orthogonal to each other. one laser beam a ₂₃ frequency shifter
The laser light is converted into a laser beam a ₂₄ of another frequency ν ₀ + Δν slightly different from the original frequency ν ₀ by 23.

The two laser beams a ₂₂ and a ₂₄ whose polarization planes are orthogonal to each other and have slightly different frequencies form a laser beam a ₂₅ whose wavefront has been matched by the second polarization beam splitter 45, and are further conical by the lens 24. Shaped beam.

The laser beam a formed into the conical beam
₂₆ is divided by the polarization beam splitter 26 into a laser beam a ₂₇ and the frequency [nu ₀ + .DELTA..nu laser beam a ₂₈ of the frequency [nu _0.

At this time, the laser beam a ₂₇ is reflected by the reflection surface P ₁ of the polarization beam splitter 26, and the laser beam a ₂₈ passes through the polarization beam splitter.

The reflected laser beam a ₂₇ transmits through the quarter-wave plate 29, is reflected by the concave mirror 33 having the radius of curvature R, and transmits through the quarter-wave plate 29 again. At this time, since the laser beam a ₂₇ transmits through the quarter-wave plate twice, the polarization plane is 90 °.
Is rotated passes through the reflecting surface P ₁ of the polarization beam splitter 26.

Further, the laser beam a ₂₇ transmitted through the polarizing beam splitter 26 passes through the quarter-wave plate 29, irradiates the surface of the specimen 22, and the laser beam transmitted through the specimen 22 and exits the concave mirror. The reflected light is reflected by the concave mirror 34 having a curvature radius 2R disposed at a position where the center of curvature coincides with the concave mirror 33 and is opposed to the concave mirror 33, and irradiates the specimen 22 again.

The laser beam a ₂₉ irradiating the specimen 22 and passing through the specimen 22 and emitted again passes through the quarter-wave plate, so that the polarization plane is rotated by 90 ° and the polarization beam splitter 26
The transmitted light is WFM laser light a ₂₈ in the frequency [nu ₀ + .DELTA..nu in the laser beam a ₂₉ emitted the specimen 22 reflected at this time by the reflecting surface P ₂ of the. Next, this wavefront-matched laser light is transmitted by the polarizing plate 30 to the transmitted light at a frequency ν ₀ + Δν.
The same polarization direction components of the laser light a ₂₈
The two-dimensional intensity distribution image of the interfering laser beam a ₃₀ is projected onto the two-dimensional parallel operation type image sensor 35.

[0068] Further, the sample 22 is scanned with the laser beam a ₂₇ is displaced in a helical spiral by scanning means 27 to the helical spiral along the entire circumference.

Hereinafter, the image sensor 35 and the measurement processing means 36
The reconstructing means 37 operates in the same manner as in the first embodiment to measure three-dimensional information of the specimen and output a stereoscopic image or the like. By the above-described operation, the apparatus for measuring three-dimensional information of a specimen according to the present embodiment obtains the same effects as those of the embodiment shown in FIG.

However, in this embodiment, the laser beam is
In order to irradiate the specimen twice, when the specimen advances from the concave mirror 34 to the concave mirror 34 and when the specimen advances from the concave mirror 34 to the polarization beam splitter 26, the measurement processing means 36 measures the transmitted light projection image in consideration of the above-described operation. Needless to say, it is set to be performed.

[0071]

As described above in detail, the method and apparatus for measuring three-dimensional information of a specimen according to the present invention irradiate the specimen with a laser beam formed in a conical beam in a spiral helix. The transmitted light projection image of the specimen can be continuously detected from the entire circumferential direction, and high-precision three-dimensional information can be measured in a cross section along any direction from the detected transmitted light projection image.

Further, only the transmitted light can be detected from the specimen containing the light scattering medium by the optical heterodyne detection method, and the morphological three-dimensional information of the specimen containing the light scattering medium such as a living body can be detected with high accuracy. It is possible to measure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus for measuring three-dimensional information of a specimen according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the apparatus for measuring three-dimensional information of a specimen according to the present invention;

FIG. 3 is a block diagram showing a third embodiment of the sample three-dimensional information measuring apparatus according to the present invention;

FIG. 4 is a block diagram showing a fourth embodiment of the sample three-dimensional information measuring apparatus according to the present invention;

[Explanation of symbols]

 1,21 Single frequency laser light source 2,22 Sample 3,23 Frequency shifter 4,5,24 Lens 6,27 Scanning means 7 Beam splitter 8,35 Two-dimensional parallel operation type image sensor 9 Half mirror 10,10 ', 32 , 39 mirror 11, 36 measurement processing means 12, 37 reconstruction means 25, 26, 38, 45 polarizing beam splitter 28 1/2 wavelength plate 29 1/4 wavelength plate 30 polarizing plate 31 intensity correction means 33 concave mirror (radius of curvature) R) 34 concave mirror (curvature radius 2R)

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/17 A61B 10/00 G01B 11/24 A61B 6/03

Claims (5)

(57) [Claims] 1. A sample is irradiated with a laser beam formed in a conical beam onto a sample, and a laser beam transmitted two-dimensionally through the sample and another conical laser beam having a slightly different frequency are wavefronted. Aligned, two-dimensionally optically heterodyne-detects the laser light having a two-dimensional cross section subjected to the wavefront alignment, measures the intensity of the laser light transmitted through the specimen from the detected beat signal, and determines that the laser light is The method is characterized in that the laser light and the sample are relatively displaced so as to scan the sample in a spiral shape, and the morphological three-dimensional information of the sample is measured by a CT method from the intensity of the transmitted laser light. 3D information measurement method for the specimen to be determined. 2. A second laser light having a frequency slightly different from that of the laser light is wavefront-matched to the first laser light, and the wavefront-matched laser light is formed into a conical beam. The optical path of the laser beam formed into the beam is divided into a laser beam having the same frequency as the first laser beam and a laser beam having the same frequency as the second laser beam, and the optical path is divided into a specimen. One of the two laser lights is irradiated on the surface, and the laser light transmitted through the specimen and the other conical laser light obtained by dividing the optical path are wavefront-matched, and the wavefront matching is performed. Laser light with a two-dimensional cross section
Dimensionally detect optical heterodyne, measure the intensity of laser light transmitted through the sample from the detected beat signal, and scan the sample with the laser light so that the laser beam scans the sample in a spiral shape. And measuring the morphological three-dimensional information of the sample from the intensity of the transmitted laser light by a CT method. 3. A laser light source having a single frequency, an optical path splitting means for splitting an optical path of the laser light, which is disposed in an optical path of the laser light emitted from the laser light source, into two, and obtained by splitting. Frequency conversion for converting the frequency of at least one laser beam to another frequency such that the frequency of the laser beam traveling on one of the two optical paths is slightly different from the frequency of the laser beam traveling on the other optical path. Means, optical means for forming the laser light traveling along the two optical paths obtained by the division into a conical beam, and one of the two laser lights formed on the conical beam. Scanning means for irradiating the surface of the sample with one laser beam and relatively displacing the laser beam and the sample so that the laser beam scans the sample in a spiral shape; and irradiates the sample. Wavefront matching means for wavefront matching the laser light transmitted through the sample and the other laser light formed into the conical beam, and substantially perpendicular to the traveling direction of the laser light wavefront matched by the wavefront matching means. Two-dimensional intensity detection means for two-dimensionally detecting light intensity which repeats intensities depending on the difference frequency of the laser light having a cross-section two-dimensional shape and arranged on the intersecting surface, and a laser detected by the detection means Measuring means for detecting the intensity of the laser beam transmitted through the sample based on the intensity of the light, and measuring and processing the morphological three-dimensional information of the sample by a CT method. Information measuring device. 4. A single-frequency laser light source, and first optical path splitting means for splitting an optical path of the laser light disposed in an optical path of the laser light emitted from the laser light source into two, The frequency of at least one laser beam is converted to another frequency such that the frequency of the laser beam traveling on one optical path of the two optical paths obtained is slightly different from the frequency of the laser beam traveling on the other optical path. Frequency-converting means, a first wavefront matching means for wavefront-matching the laser light whose frequency has been converted and the laser light traveling on one of the divided optical paths, and a laser light having the wavefront matched. Optical means for forming a laser beam into a conical beam; second optical path dividing means for dividing the optical path of the laser beam formed into the conical beam into two laser beams having slightly different frequencies; Optical path split 2 obtained by dividing by means
And irradiating the surface of the specimen with laser light traveling along one of the two optical paths, and displacing the laser light and the specimen relatively so that the laser light scans the specimen in a spiral manner. Scanning means, and second wavefront matching means for wavefront matching the laser light irradiated on the specimen and transmitted through the specimen and the laser light traveling on the other optical path obtained by division by the second optical path dividing means. And the second
The light intensity which repeats intensities depending on the difference frequency of the two-dimensionally cross-sectioned laser light, which is arranged on a plane substantially perpendicular to the traveling direction of the laser light wave-aligned by the wave front matching means, is two-dimensionally. Two-dimensional intensity detection means for detecting
Measurement processing means for detecting the intensity of the laser light transmitted through the specimen based on the intensity of the laser light detected by the detection means, and measuring the three-dimensional information of the specimen by a CT method. A three-dimensional information measuring device for a specimen. 5. The second optical path splitting means also serves as the second wavefront matching means, and a reflecting means disposed at a position for causing the laser light transmitted through the sample to travel to the second optical path splitting means. The apparatus for measuring three-dimensional information of a specimen according to claim 4, wherein the apparatus is provided.