JPH10132530A - Optical information processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract the sectional image information of the part existing at the optional depth of a three dimensional object by high space resolving power. SOLUTION: A laser beam whose wave length varies with the passage of time is emitted from a semiconductor laser 24, and branched into a measured object 36 and the side of the whole reflection mirror 34 by a beam splitter 30. The interference light image of a light path length decided by the characteristics of variation of the wave length of a laser beam is formed of the reflection beam of the measured subject 36 and light phase modulated by a phase modulater 32 on the beam splitter 30. After the interference light image is converted into an electric charge distribution through a space light modulating tube 44, light read out from an other laser generating device 48 is irradiated onto the space light modulating tube 44 to read out the interference light image corresponding to the electric charge distribution for photographing it by a video camera 58. The characteristics of variation of the wave length of the laser beam is varied to change the light path length for extracting the sectional image information of the optional part in the direction of depth of the measured object 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical information processing apparatus capable of extracting cross-sectional image information of a portion at an arbitrary depth of a three-dimensional object by synthesizing a light wave coherence function.

[0002]

2. Description of the Related Art Conventionally, holographic technology has been used to extract features of the shape and the like of a three-dimensional object.
Proceedings of the Annual Meeting of the Japan Society for Lightwave Sensing Technology, May 1995
Moon, pp. 75-82, "Photonic Sensing by Synthesis of Lightwave Coherence Function" is known.

FIG. 8 shows the configuration of the system disclosed in this document. The laser light emitted from the semiconductor laser 2 is expanded into a parallel beam light having an appropriate diameter by a lens system, and this beam light is branched by a half mirror 4. One of the branched light beams is reflected by reflection mirrors 6 and 8. Input to the detector 10,
The other light beam irradiates the measured object 14 through the half mirror 12. Here, by changing the current amplitude of the drive current i (t) supplied to the semiconductor laser 2 with time, the laser light whose wavelength (frequency) f changes with time is emitted, so that the light wave coherence function is changed. Controlling.

When such a laser beam is used, on the detector 10, the one beam light (reference light from the reflecting mirror 6) and the reflected light reflected by the measured object 14 have an optical path length determined by a light wave coherence function. Interference only for Z ₀ . The components of this interference image are recorded using holography, and the holography is further irradiated with a reading laser beam from another laser light source 16 to obtain a cross-sectional image of a portion corresponding to the optical path length Z ₀ of the measured object 14. The feature information is projected on the screen 18 and visualized.

Further, by changing the current amplitude of the drive current i (t) supplied to the semiconductor laser 2 to change the light wave coherent function, a cross-sectional image of a portion corresponding to another optical path length Z _i is extracted. Then, a cross-sectional image of the measured object 14 in the depth direction is obtained.

[0006]

However, in such a holographic system, in order to form an interference image on the detector, the reference light is obliquely reflected with respect to the reflected light from the measured object. It is necessary to enter from. Setting the incident angle in this manner has a problem that the spatial resolution (resolution) in the depth direction of the measured object is limited. That is, if the incident angles of the reflected light and the reference light are θ ₁ and θ _2, and the beam diameter of each light is D, the spatial resolution of the optical path length is ΔZ = D | sin θ ₁ −sin θ ₂ |
Thus, the feature extraction of the measured object could not be performed with a higher spatial resolution.

Further, the conventional system shown in FIG. 1 has a problem that it is difficult to process the feature extraction of the measured object in real time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has an optical information processing method capable of improving the spatial resolution in the depth direction of an object to be measured and realizing its feature extraction processing in real time. It is intended to provide a device.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a semiconductor laser which emits laser light whose wavelength changes with time according to the current amplitude of a supplied drive current, A beam splitter for irradiating one branch light to an optical path having a total reflection mirror and a phase modulator, and irradiating the other branch light to an object to be measured; and a splitter for phase modulation by the phase modulator. Means having a lock-in amplifier function for exposing an interference light image generated by interference with reflected light from the measurement object, and emitting laser light having different wavelength change characteristics by changing the current amplitude of the drive current. Thus, an interference light image of a cross-sectional image of an arbitrary part in the depth direction of the measured object is generated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an optical information processing apparatus will be described with reference to the drawings. FIG. 1 is a block diagram showing the entire configuration of the optical information processing apparatus. In the figure, a central control unit 20 composed of a computer system is provided, and controls the operation of the present apparatus by executing a program created based on a predetermined algorithm.

As shown in FIGS. 2A, 3A and 3B, the drive current generating circuit 22 has a drive whose current amplitude changes with time based on waveform parameters specified by the central control unit 20. By supplying the current i (t) to the semiconductor laser 24, laser light whose wavelength (frequency) f (t) changes with time according to the current amplitude of the drive current i (t) is emitted. That is, data of various waveform parameters is stored in the central control unit 20 in advance, and when one of the waveform parameters is input to the drive current generation circuit 22, the drive current generation circuit 22 To output a drive current i (t) having a specific waveform whose current amplitude changes with time, and the semiconductor laser 24 emits a laser beam having a wavelength f (t) corresponding to the current value of the drive current i (t). .

At the laser beam emitting end of the semiconductor laser 24,
A magnifying lens system 28 is provided through an optical isolator 26 for preventing the emitted laser light from returning. The magnifying lens system 28 expands the laser light into parallel light having a predetermined beam diameter and irradiates the laser light to the beam splitter 30.

A beam splitter 30 splits the parallel light, and one of the split parallel lights (hereinafter, referred to as a first light beam) is incident on a total reflection mirror 34 through a phase modulator 32, and the other split light is split. Parallel light (hereinafter, referred to as a second light beam) irradiates the measured object 36. Further, the first light beam reflected by the total reflection mirror 34 returns to the beam splitter 30 again through the phase modulator 32, and the second light beam (ie, reflected light) reflected by the measured object 36 is also reflected. The light beam returns to the half mirror 30, and the returned light beam and the reflected light interfere with each other, so that an interference light image is generated on the half mirror 30. That is, a configuration equivalent to a so-called Michelson interferometer is realized by the total reflection mirror 34 and the measured object 36.

Here, by modulating the frequency of the semiconductor laser with the waveform shown in FIG.
, The optical path lengths Z ₀ , 2Z ₀ , 3Z ₀ ,.
Only the reflected light from the optical path interferes with the first light beam, and the reflected light of another optical path length cannot interfere with the first light beam. In depth of the object to be measured 36, the peak of one of the coherence function in FIG. 2 (b) (e.g., the peak of the optical path length Z ₀₎
If only one exists, only one piece of cross-sectional information corresponding to the optical path length Z ₀ in the measured object 36 forms an interference light image.

The phase modulator 32 has 0 ° and 18 ° according to the binary level of the drive voltage V _PH supplied from the drive circuit 38.
The phase of the first light beam is shifted to 0 ° and 18 °.
Perform phase modulation to 0 °. The switching data D _SW output from the central control unit 20 is converted by the D / A converter 40 into a binary analog signal S _PH , and this analog signal S _PH is
8 amplifies the power to form the drive voltage V _PH in the state “H” and the state “L” determined to be the predetermined voltage, respectively.

More specifically, as shown in FIG.
A period longer than the period τ of the laser beam (for example, 1/10
Second) At T, a predetermined voltage V _PH (π) corresponding to the state “H” is set in the first half T / 2 period, and a predetermined voltage V _PH (0) corresponding to the state “L” is set in the second half T / 2 period. And the period T
Is continuously repeated a plurality of times.

Among the first light beam and the reflected light from the measured object 36, only the reflected light having the optical path length Z ₀ interferes. However, by performing the above voltage control, the voltage V _PH (π) is applied. During this period, the first light beam phase-modulated by 180 ° by the phase modulator 32 and the reflected light interfere with each other at the same phase, and show the brightest state. On the other hand, the voltage V
_In the period during which _PH (0) is applied, the first light beam that has been phase-modulated by 0 ° by the phase modulator 32 and the above-mentioned reflected light interfere with each other, indicating the darkest state.

As described above, when the first light beam is phase-modulated by the phase modulator 32, only the reflected light having the optical path length Z ₀ is caused to interfere with the first light beam to change the light and dark states to the period T. , While the reflected light of other optical path lengths is the first
Since it does not interfere with the beam light of
It does not show changes synchronized with the phase modulator and remains constant. Therefore, if the amplitude of the AC component that alternates between light and dark in the cycle T can be converted to DC brightness, and the background light with constant brightness can be removed, the reflected light image from the optical path length Z ₀ can be formed. Can be obtained selectively. The two-dimensional lock-in amplifier described below performs this processing.

The light image generated in the beam splitter 30 is formed on the light receiving surface of the two-dimensional lock-in amplifier 44 by the image forming lens 42. In this embodiment, a spatial light modulator (MSLM) is used as the two-dimensional lock-in amplifier 44, and the binary write control voltage Vb output from the voltage control circuit 46 is applied to the phase modulator of the spatial light modulator 44. (Described later) to convert the light image into its charge distribution, thereby realizing exposure. Note that the switching data S _SW output from the central control unit 20 is transmitted to the D / A converter 4.
0 is converted into a binary analog signal Sb, and the voltage control circuit 4
6 amplifies and boosts the analog signal Sb to form a write control voltage Vb of a state “H” and a state “L”, each of which is determined to be a predetermined voltage.

The spatial light modulation tube 44 is provided with an optical reading section for obtaining a light image by optically reading a charge distribution formed on a dielectric mirror described later. That is, the optical reading unit includes a laser generator 48 for emitting a laser beam of a predetermined wavelength in accordance with a command signal S _RD from the central control unit 20, and a magnifying lens system 50 for expanding the laser beam into a parallel beam of a predetermined beam diameter. And a polarizer element 52 that polarizes the parallel light, and irradiates the polarized parallel light (hereinafter, referred to as reading light) to the phase modulation unit of the spatial light modulation tube 44 and returns light returning from the phase modulation unit. A half mirror 54 for making an image incident on the analyzer element 56, and a video camera 58 for obtaining the interference light image of the measured object 36 by two-dimensionally capturing a return light image passing through the analyzer element 56, The image signal _SVDO of the interference light image obtained at 58 is transferred to the frame memory of the central control unit 20.

As shown in FIG. 4, the spatial light modulation tube 44 has a photocathode 60, a grid electrode 62, an anode electrode 64, a microchannel plate 66, a mesh electrode 68, and a phase modulation unit 70 arranged in series, and is arranged in a vacuum tube. It has a sealed structure. Further, the phase modulating unit 70 is configured as shown in FIG.
(A) has an electro-optic crystal 72 made of LiNbO ₃ having a cut plane of 55 ° with respect to the crystal,
A dielectric mirror 74 is stacked on the surface of the electro-optic crystal 72 on the mesh electrode 68 side, and a transparent electrode 76 is stacked on the back surface of the electro-optic crystal 72. The components of the spatial light modulation tube 44 are set to a predetermined potential.

When the two-dimensional light image from the imaging lens 42 is incident on the photoelectric surface 60, the spatial light modulating tube 44
A two-dimensional photoelectron image is emitted by the external photoelectric effect of 0, and this two-dimensional photoelectron image is
4 accelerates and converges to form an image on the input surface of the microchannel plate 66, multiplies the electrons by the microchannel plate 66, reaches the dielectric mirror 74 via the mesh electrode 68, Due to the secondary electron emission characteristics set by the applied voltage Vc and the write control voltage Vb of the transparent electrode 76, the surface of the dielectric mirror 74 is charged with a charge distribution corresponding to the incident energy distribution of the two-dimensional photoelectron image. doing.

In this embodiment, the dielectric mirror 74 is controlled by controlling the voltage Vc applied to the mesh electrode 68 and the write control voltage Vb of the transparent electrode 76 provided on the back of the electro-optic crystal 72 as follows. A writing mode in which the charge distribution is charged and the charge distribution is integrated and emphasized, and an erase mode in which the charged charge distribution is erased are set.

The principle of setting each mode will be described with reference to FIGS. FIG. 4B shows the mesh electrode 6.
FIG. 9 is an explanatory diagram showing secondary electron emission characteristics of the dielectric mirror 74 when the voltage Vc and the write control voltage Vb of 8 are set to 0 <Vc <Vb.

The secondary electron emission characteristic means that the dielectric mirror 74
When primary electrons e ₁ are incident on the secondary electron e _2, secondary electrons e ₂ are emitted. When the number of secondary electrons emitted is large relative to the number of primary electrons, the dielectric mirror 74 is charged with a positive charge, and When the number of secondary electrons emitted is small, the dielectric mirror 74 is charged with negative charges. The ratio of the number of secondary electrons to the number of primary electrons is called a secondary electron emission ratio δ. The secondary electron emission ratio δ, as shown in FIG. (B), and has a characteristic that varies depending on the incident energy E of the incident electron e _1.

In general, an equilibrium state in which the number of primary electrons and the number of secondary electrons are equal, that is, 2 in which the secondary electron emission ratio is δ = 1
There point (called crossover point), the incident energy E of the primary electrons e ₁ is when the first crossover point E1 is smaller than the, or when greater than the second crossover point E2, the secondary electron The emission ratio becomes δ <1. On the other hand, when the energy E of the incident primary electrons is between the first and second crossover points E1 and E2, the secondary electron emission ratio is δ> 1.

When the voltage Vc applied to the mesh electrode 68 is set to a voltage Vc (E2 ') corresponding to the energy E2' between the first and second crossover points E1 and E2, the voltage in FIG. As shown by the dotted line, the second crossover point has a characteristic of changing from E2 to E2 '. Thus the second crossover point E2 'reason phenomenon changes to occur, the incident energy of the primary electrons e ₁ incident on the dielectric mirror 74 is a cross-over point E2' and E2
If the energy is between 2 and 3, the number of secondary electrons should be larger than the number of primary electrons in a state of 1 <δ shown by a solid line. However, the potential Vc (E2 ′) of the mesh electrode 68 becomes higher than the voltage V.
For lower than b (E2), emitted secondary electrons e ₂ becomes to be returned to the dielectric mirror 74, as a result [delta] <1
Because it becomes.

Therefore, in the present embodiment, the mesh electrode 68 is held at the predetermined voltage Vc (E2 '), and the secondary electron emission characteristic of the dielectric mirror 74 is variably controlled by the write control voltage Vb. The electric charge distribution corresponding to the interference light image of the measured object 36 is charged on the dielectric mirror 74.

More specifically, as shown in FIG.
In synchronization with the cycle T of the drive voltage V _PH of the phase modulator 32, the write control voltage Vb is controlled to be switched at a binary level, and when the state is “L”, the first write mode and the state “H” are set. Is the second write mode. In the first write mode, the write control voltage Vb changes the voltage corresponding to the state “L” (the voltage in the first half T / 2 period) to the first and second crossover points E1 and E2 ′ in FIG. By setting the voltage Vb (E ') corresponding to the energy E' between
A state of 1 <δ is set, whereby the dielectric mirror 74 is charged with a positive charge. On the other hand, in the second write mode,
When the applied voltage Vb is a voltage corresponding to the state “H” (second half T / 2)
Is set to a voltage Vb (E ") corresponding to the energy E" higher than the second crossover point E2 ', thereby setting the state of δ <1.
To a negative charge.

Then, by synchronizing the drive voltage V _PH of the phase modulator 32 and the write control voltage Vb with a period T,
In the first writing mode, many positive charges are charged on the surface of the dielectric mirror 74 in the interference light image generated by the reflected light from Z ₀ in the measured object 36. On the other hand, in the second writing mode, the interference light image is dark as described above, so that a small amount of negative charges are charged, and as a result, positive charges corresponding to the interference structure remain. On the other hand, since the background light image is invariable in the first and second writing modes, the same amount of positive and negative charges is generated, and as a result, no charge remains in the background light image. That is, only the characteristic information of the portion of the measured object 36 corresponding to the optical path length determined according to the wavelength characteristic of the laser light can be obtained as the positive charge distribution.

After the surface of the dielectric mirror 74 is charged with a positive charge distribution corresponding to the interference light image of the measured object 36 by the first and second writing modes, coherent read light is applied to the transparent electrode 76 side. By irradiation, a light image corresponding to the charge distribution is optically read. When the reading light is irradiated in this manner, the reading light is reflected by the dielectric mirror 74 and passes through the electro-optic crystal 72 phase-modulated according to the charge distribution, thereby returning to an optical image corresponding to the charge distribution. The interference light image can be obtained by photographing this light image with the video camera 58 via the half mirror 54 and the analyzer element 56.

Further, an erasing mode for erasing the charge distribution of the dielectric mirror 74 can be set. In this erase mode, the semiconductor laser 24 emits laser light of a constant wavelength to irradiate a uniform light beam to the photoelectric surface 60 of the spatial light modulation tube 44. In this state, the write control voltage Vb is applied to the mesh electrode 68. By setting a voltage Vb (E ') corresponding to the same energy E', that is, Vb (E ') = Vc (E'), an equilibrium state of δ = 1 is established and the charge distribution is erased.

Next, the operation of the optical information processing apparatus having such a configuration will be described with reference to the control flowchart of the central control unit 20 shown in FIG.

When the apparatus is started, in step S100, the period T of the drive voltage V _PH supplied to the phase modulator 32 and the period T of the write control voltage Vb applied to the spatial light modulator 44 are determined.
Is set internally, and steps S102 and S104
, The number of repetitions M and N are set internally. here,
The number of repetitions N is the number of times of generation of the drive voltage V _PH and the write control voltage Vb synchronized with the cycle T.
Is set for one exposure period N × T. The number of repetitions M is
This is because the number of exposures is set at the same time as the number of waveform parameters is set. With this number of times M, the waveform parameters are sequentially changed each time each exposure period N × T is completed, and laser light is emitted in accordance with M kinds of drive currents i (t) supplied in order, and M pieces of laser light are emitted. By setting the optical path lengths Z _{1 to} Z _M , information on the depth direction of the measured
Extract at the stage.

Next, in step S106, the spatial light modulator 44 is set to the erasing mode. That is, the write control voltage Vb is made equal to the potential Vc of the mesh electrode, and the spatial light modulation tube 44 is irradiated by the semiconductor laser 24 with uniform laser light having a constant light intensity. As a result, the entire surface of the dielectric mirror 74 has the potential Vs corresponding to the energy E2 '(see FIG. 13B), and the state is equilibrium with δ = 1, whereby the reset is achieved.

Next, in step S108, a first waveform parameter is set.

Next, at step S110, the driving current i set based on the first waveform parameter
(t) is supplied to the semiconductor laser 24, and a laser beam whose wavelength (frequency) changes with time according to the current amplitude of the drive current i (t) is emitted.

Next, in steps S112 and S114, the drive voltage V whose state changes to "H" or "L"
_{The PH} and the write control voltage Vb are supplied to the phase modulator 32 and the spatial light modulator 44. As a result, in the first half T / 2 of the period T, as shown in FIG. 7A, the positive charge of the interference light image of the portion of the measured object 36 corresponding to the optical path length Z ₁ determined by the wavelength change characteristic of the laser light. The distribution G (+ Q) and the positive charge distribution H (+ Q) of the background light image are charged on the surface of the dielectric mirror 74. In the latter half T / 2 period, as shown in FIG. 7B, since the interference light image of the portion of the measured object 36 corresponding to the optical path length Z ₀ is dark, almost no negative charges are generated, while the background Since the light image is unchanged, the same amount of negative charges as in the first half is generated. As a result, the negative charge distribution H (-Q) and the positive charge distribution H (+
Q) and the positive charge distribution G of the interference light image
Only (+ Q) remains.

In step S116, it is determined whether or not N exposures have been completed, and if not, the processes in steps S110 to S114 are repeated. When the process is repeated N times in this manner, as shown in FIG.
The positive charge distribution G (+ Q) of the interference light image corresponding to ₀ is added and emphasized N times. Then, when the N-time exposure is completed, the process proceeds to step S118.

In step S118, the semiconductor laser 24 is once stopped, and the laser generator 48 is started, so that the electro-optic crystal 7
2 is irradiated with readout light. Then, a return light image returning from the electro-optic crystal 72 is captured by the video camera 58.

Next, in step S120, the image signal S _{VB O} the central control unit 20 obtained by the video camera 58
Is transferred to and stored in the frame memory provided in. Accordingly, among the object to be measured, the frame image of the cross-sectional image of the object to be measured 36 impinges on the light path length Z ₁ is obtained.

Next, in step S122, it is determined whether or not M photographings have been completed. If not, the process returns to step S106 to erase the charges on the dielectric mirror 74 in the erase mode.

In the second steps S108 and S110, a second waveform parameter is set,
By emitting a laser beam having a different wavelength variation characteristic and the first laser beam, to generate interference light image portion of the object to be measured 36 corresponding to the next optical path length Z _2, further steps S110~S116 Is repeated N times to charge the emphasized positive charge image corresponding to the interference light image on the dielectric mirror 74, and then the step S11 is performed.
8 and S120, a second frame image is obtained.

Thereafter, similarly, in step S106, the spatial light modulator tube 44 is reset, and in step S108, parameters for sequentially changing the optical path length are set. By repeating the processes in steps S110 to S120, the measured object is measured. An M frame image is obtained for M portions of the object 36 in the depth direction.

If it is determined in step S122 that the M frame image has been obtained, step S124
In the above, the data of these M frame images are subjected to computer graphic processing, so that the measured object 36
Is formed and displayed on a display means such as a monitor television.

As described above, in the conventional holography technique, it is necessary to incline the incident angle between the return light from the object to be measured and the reference light, so that the resolution of the object to be measured in the depth direction is improved. Although there is a limit, according to this embodiment, the reflected light from the measured object 36 and the reference light generated by the phase modulator 32 and the total reflection mirror 34 are parallel to each other, so that the spatial resolution can be improved. Can be planned.

Further, by controlling the writing mode of the spatial light modulator tube 44, a cross-sectional image of the measured object 36 can be clearly exposed, and furthermore, real-time measurement is possible.

In this embodiment, a positive charge image distribution corresponding to the interference light image of the measured object 36 is formed in the first writing mode, and the charge of the background light image is removed in the second writing mode. Is canceled out to form only the positive charge distribution corresponding to the measured object 36. Conversely, the first writing mode is set to a mode for charging the negative charge distribution of the interference light image, By setting the second writing mode to a mode for charging a positive charge distribution, a negative charge distribution corresponding to the measured object 36 is formed, and reading is performed to the electro-optic crystal 72 phase-shifted by the negative charge distribution. Imaging may be performed by irradiating light. In this case, the drive voltage V _PH and the write control voltage V shown in FIGS.
Make b the same phase. That is, in each cycle T, the driving voltage V
_{Both the PH} and the write control voltage Vb are set to the state “H” during the first half T / 2 period, and set to the state “L” during the second half T / 2 period. Further, in each cycle T, both the drive voltage V _PH and the write control voltage Vb may be in the state “L” in the first half T / 2 period, and may be in the state “H” in the second half T / 2 period.

[0049]

As described above, according to the present invention, the spatial resolution in the depth direction of the measured object can be improved, so that the feature of the measured object can be extracted with high accuracy.

This feature extraction processing can be performed in real time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical information processing apparatus.

FIG. 2 is a characteristic diagram showing a relationship between a wavelength change characteristic of a laser beam and a change in an interference characteristic due to an optical path length.

FIG. 3 is a timing chart showing a drive current i (t), a wavelength f (t) of a laser beam, a drive voltage V _PH, and a write control voltage Vb.

FIG. 4 is an exploded view for explaining the structure and characteristics of the spatial light modulator.

FIG. 5 is an explanatory diagram for explaining secondary electron emission characteristics of the spatial light modulator.

FIG. 6 is a flowchart illustrating an operation of the optical information processing apparatus.

FIG. 7 is an explanatory diagram showing a principle of forming a positive charge distribution in a spatial light modulation tube.

FIG. 8 is a block diagram illustrating a configuration of a conventional optical information processing apparatus.

[Explanation of symbols]

Reference numeral 20: central control unit, 22: drive current generating circuit, 24: semiconductor laser, 26: optical isolator, 28: magnifying lens system, 30: beam splitter, 32: phase modulator, 34
... total reflection mirror, 36 ... measured object, 38 ... drive circuit,
40 D / A converter, 42 imaging lens, 44 two-dimensional lock-in amplifier (spatial light modulator), 46 voltage control circuit, 48 laser generator, 50 magnifying lens system, 52
Polarizer element, 54: Half mirror, 56: Analyzer element, 58: Video camera, 60: Photocathode, 62
.. Grid electrode, 64 anode electrode, 66 microchannel plate, 68 mesh electrode, 70 phase modulator, 72 electro-optic crystal, 74 dielectric mirror, 7
6 ... Transparent electrode 76.

Continued on the front page (72) Inventor Naohisa Kosaka 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture 1 Hamamatsu Photonics Co., Ltd.

Claims (1)

[Claims] 1. A semiconductor laser that emits a laser beam whose wavelength changes with time according to a current amplitude of a supplied drive current, a laser beam that branches, and one of the branch lights is phase-modulated by a total reflection mirror. A beam splitter for irradiating the object to be measured with the other branch light to an optical path having a light source, and an interference light image generated by interference between the branch light phase-modulated by the phase modulator and the reflected light from the object to be measured. A means having a lock-in amplifier function for exposing, by changing the current amplitude of the drive current to emit laser light having different wavelength change characteristics, a cross-sectional image of an arbitrary portion in the depth direction of the measured object is obtained. An optical information processing apparatus for generating an interference light image.