JP6100408B1 - Optical distance measuring device - Google Patents

Abstract

[PROBLEMS] To provide real-time three-dimensional information of living specimens with a high resolution for height and refractive index distribution in and out of the plane and with a thickness of a cell or the like that cannot be obtained by a normal imaging optical system. An optical distance measuring device can be obtained. A laser light source 21, a collimator lens 22, a pupil transmission lens system 25, a two-dimensional scanning device 26, and a beam splitter 27 are arranged side by side. The pupil transfer lens system 30 is located next to the beam splitter 27, and the objective lens 31 faces the measurement object G1. The beam splitter 10 is located on the left side of the beam splitter 27, and four light receiving element groups 5 to 8 are arranged via the beam splitters 11 and 12 and the polarizers 1 to 4. The light reflected from the measurement object G1 is received by the light receiving element groups 5 to 8, and the signal comparator 33 obtains information based on signals from these lights. [Selection] Figure 1

Description

  The present invention relates to an optical distance measuring device that realizes measurement of a surface state profile of a measurement object by laser light irradiation, measurement and observation of a surface state and internal state of a cell or the like with extremely high resolution, and an optical device such as a microscope. The present invention is suitable for an apparatus for improving the resolution of an instrument and an apparatus for measuring the degree of polarization of a measurement object.

  In addition to the difficulty in three-dimensional measurement with conventional optical microscopes, it has been impossible to observe and measure objects below the diffraction limit. As an alternative, devices such as scanning electron microscopes, probe microscopes (STM, AFM, NFOS, etc.), confocal microscopes, etc. have been developed and used in many fields.

  Since this scanning electron microscope uses a very thin beam as a scanning electron probe, the resolution is high and the depth of focus is significantly larger than that of an optical microscope. However, in order to observe a measurement object with low conductivity such as a cell, it is necessary to coat a sample that is the measurement object with platinum palladium or gold having good conductivity. For this reason, the cells themselves are often damaged, and as a matter of course, it is impossible to observe and measure living cells.

  A probe microscope measures the distance from the measurement object by using an atomic force, tunnel current, optical near field, etc. It is. However, it is difficult to move the probe at high speed, and it is difficult to handle because the distance to the object to be measured is very close, and it takes a lot of time to acquire two-dimensional information. .

  On the other hand, a confocal microscope irradiates a spot on a measurement object, and the objective lens or measurement target is set so that the amount of light received by the light receiving element disposed at the confocal position via the pinhole is maximized. By moving the object, the height information and the path difference information of the measurement object are acquired. However, in the confocal microscope, basically, if there is a phase distribution in the spot, the beam is deformed and becomes erroneous information. In particular, if the object to be measured has a wavefront that changes in phase, such as a change in refractive index of a cell or the like, the reliability of the value must be poor. Moreover, since it is necessary to move the objective lens and the measurement object so that the received light quantity becomes maximum, the real-time property is lacking.

  In response to these circumstances, with the recent development of the micro / nanotechnology field, attention has been focused on a technique for measuring three-dimensional information of fine industrial products and precision parts at high speed. In addition, in biology, medicine, and agriculture, there is an increasing demand for real-time acquisition of three-dimensional profile information of a biological sample having a thickness such as a cell.

On the other hand, heterodyne interferometry is well known as one of means for measuring distances and thicknesses with a microscope and measuring or observing minute objects with high accuracy. . Here, the optical heterodyne method using light is described, but the same concept is applied to other electromagnetic waves. In this optical heterodyne method, two laser beams having different frequencies are caused to interfere with each other, a beat signal having a frequency difference between the two is generated, and a phase change of the beat signal is detected with a resolution of about 1/500 of a wavelength. . In other words, according to this optical heterodyne method, the distance to the measurement object is measured while measuring the change in the height direction of the surface, which is three-dimensional information, and the thickness or the like of the measurement object itself is measured or observed. I can do it.
In addition, a differential interference microscope is known as one means for observing cells and the like without staining. This differential interference microscope is suitable for observing a measurement object having a slightly different refractive index. The optical distance cannot be visualized. In addition, this differential interference microscope obtains a differential image of an object to be measured by using a Wollaston prism in principle and slightly shifting two different polarized lights. For this reason, since the object to be measured has birefringence, for example, a substance containing a protein such as a cell, direction dependency occurs and the polarization plane is disturbed. The obtained information tends to be fake information.

JP 59-214706 A

  In Japanese Patent Application Laid-Open No. 59-214706 of Patent Document 1 described above, two beams having different wavelengths are generated adjacent to each other using an acousto-optic element, a phase change between these two beams is detected, and the phase is detected. A method for accumulating changes to obtain a surface profile is disclosed. However, in this patent document 1, unevenness information is obtained by making two beams close to each other slightly larger than the beam profile, detecting an average phase difference in the two beam profiles by heterodyne detection, and integrating sequentially. It was what you get.

  Therefore, according to this Patent Document 1, the unevenness information can be measured for the measurement object that is assumed to be flat such as a semiconductor wafer, but the information in the beam profile is I couldn't pull it out. For this reason, the resolution in the beam profile that is in-plane cannot be increased.

  From the above, conventional microscopes and other technologies can not only increase the resolution within the in-plane beam profile, but also remain alive without damaging a biological sample with a thickness of cells, etc. It was not possible to observe and measure 3D information in real time. In addition, information related to birefringence possessed by a living body cannot be obtained together with three-dimensional information.

  The present invention has been made in view of the above-mentioned background, and has a high resolution with respect to height and refractive index distribution in and out of the plane, and is a biological sample having a thickness of a cell or the like that cannot be obtained by a normal imaging optical system. It is an object of the present invention to provide an optical distance measuring device that can not only obtain dimensional information in real time in real time but also acquire information related to the birefringence of a measurement object.

An optical distance measuring device according to claim 1 is a light source that emits coherent irradiation light;
A two-dimensional scanning element that scans irradiation light from a light source in two different directions, respectively;
A polarizing optical member that separates the irradiation light that has passed through the measurement object while being polarized along four different polarization axes;
Four light receiving elements that respectively receive and photoelectrically convert the irradiation light separated into four;
While obtaining information of the measurement object from the state between the signals from each light receiving element, a measurement unit for obtaining a measurement value for the measurement object based on this information,
including.

The operation of the optical distance measuring device according to claim 1 will be described below.
In the present invention, coherent irradiation light is irradiated from the light source, and the two-dimensional scanning element scans the irradiation light in two different directions and sends it to the measurement object as a scanning beam. Further, the polarization optical member separates the irradiation light passing through the measurement object while polarizing the light along four different polarization axes, and the four light receiving elements respectively receive the four irradiation lights. To photoelectrically convert. Then, as the measurement unit obtains information on the measurement object from the state between signals photoelectrically converted by each light receiving element, a measurement value such as an optical distance can be obtained based on this information.

  Therefore, according to the present invention, the presence of the above-described polarization state detection system allows not only the measurement of the optical distance in the measurement object such as a cell based on the data from these detection systems, but also the simultaneous irradiation. The change in the polarization state with respect to the irradiation light can be measured. For this reason, it is possible to perform, in real time, a structural analysis in a cell having birefringence and measurement of a three-dimensional orientation of a birefringent object without staining.

As a result of the above, the microscope to which the present invention is applied has a very high in-plane resolution, and further, by performing two-dimensional scanning once, the optical distance such as the height and refractive index distribution of the measurement object can be reduced. It becomes possible to measure. For this reason, it is possible to perform a three-dimensional measurement in real time such as a state change of a living cell or a micromachine. That is, it has a large feature that cannot be compared with a conventional laser scanning confocal microscope that acquires two-dimensional information and integrates it in a three-dimensional direction.
Furthermore, when the present invention is applied to a transmission type microscope, cells, micro-organisms, etc. can be visualized and observed and measured with a simple apparatus at high resolution and high speed without being fluorescently colored. For this reason, it has the big characteristic which the electron microscope which inactivates a cell etc. and measures does not have.

According to a second aspect of the present invention, there is provided a separation element that receives irradiation light from a measurement object and separates it into two parts without polarization, and two sets of polarizing elements including a first polarizing element and a second polarizing element. One polarizing optical member may be configured. Accordingly, one irradiation light separated by the separation element can be transmitted through the first polarizing element while being separated as polarized light orthogonal to each other. In addition, the second polarizing element transmits the other irradiation light separated by the separation element while separating the polarized light orthogonal to each other at a 45 ° angle with respect to the polarized light separated by the first polarizing element. Can be made.
In this way, as a result, there are four polarization axes that are different from each other by an angle of 45 °, and the polarization state of the irradiation light passing through the measurement object can be detected more accurately.

  On the other hand, as in claim 3, the two sets of polarizing elements separate the irradiation light into two beams with no polarization and the irradiation lights separated by the separation beam splitter are different from each other. Alternatively, two polarizers that transmit light in the polarization state may be used. In this way, it is possible to easily obtain necessary data by a simple operation simply by changing the polarization axis of the polarizer.

  According to a fourth aspect of the present invention, the measuring unit processes the signals respectively acquired by the four light receiving elements to obtain the major axis, minor axis, and inclination angle values of the elliptically polarized light, and the measurement object is obtained from these values. It is good also as obtaining the measured value about. In this way, as the state of elliptically polarized light can be grasped specifically as an elliptical shape, the birefringence is calculated from the information of the elliptically polarized light and the optical distance detected on the polarization axis and the information of the elliptically polarized light described above. Can be derived. As described above, the optical distance, the birefringence, the polarization information, and the like can be simultaneously measured by deriving the optical distance with the polarization axes and detecting the elliptical polarization state with at least three polarization axes.

  On the other hand, as in claim 5, a quarter-wave plate that gives a phase difference of π / 2 in the direction of electric field oscillation of the irradiation light from the light source is arranged in front of the measurement object and circularly polarized on the measurement object. It is good also as irradiating irradiation light. In this way, instead of the linearly polarized light irradiated by the light source, circularly polarized light can be created by the quarter wavelength plate, and the elliptically polarized state can be easily created by irradiating the measurement object with this circularly polarized light. become.

  Further, according to the sixth aspect, the light receiving element receives the irradiation light passing through the measurement object while being shifted to any one side with the direction perpendicular to the optical axis direction of the irradiation light as a boundary line. It is also good to do. In this way, even with a single light receiving element, sufficient data can be reliably obtained from the irradiated light. The reason why the light receiving element is shifted to one side of the boundary line is that when the light receiving element is positioned at the center of the optical axis, the phase is reversed across the boundary line. This is because it is difficult to obtain sufficient data from the irradiated light.

  On the other hand, as in claim 7, two light receiving elements may exist with a boundary line interposed therebetween, and the two light receiving elements may receive irradiation light. In this way, the scanning beam can be received as an amount whose phases are mutually reversed by one light receiving element existing in a region on one side of the optical axis and another light receiving element present in a region opposite to this region. Accordingly, the optical distance can be easily detected from the phase difference of the scanning beam by these light receiving elements. For this reason, if the average value is calculated by the measurement unit after the phase difference is detected independently by both light receiving elements, it is possible to reduce the influence of noise and obtain more accurate data.

  Further, as in claim 8, if the measurement object reflects the irradiation light when the irradiation light passes through the measurement object, the light receiving element of claim 1 receives the reflected light and photoelectrically Will be converted. In this case, by arranging a beam splitter in the optical axis between the light source and the measurement object, the irradiation light reflected and returned by the measurement object is further reflected and sent to the light receiving element side. be able to. Further, as in claim 9, when the irradiation light passes through the measurement object when the irradiation light passes through the measurement object, the light receiving element of claim 1 arranged on the optical axis, for example, The transmitted light is received and photoelectrically converted.

  As described above, in the optical distance measuring device of the present invention, the coherent irradiation light is irradiated from the light source, and the irradiation light passing through the measurement object is polarized along four different polarization axes. However, it is separated and received by each of the four light receiving elements to perform photoelectric conversion. Therefore, there is an excellent effect that a quantitative optical distance or the like can be calculated as the measurement unit obtains information on the measurement object from the state between the signals photoelectrically converted by the light receiving element. .

It is a block diagram of the apparatus of the reflective optical system used as Example 1 of the optical distance measuring device which concerns on this invention. It is explanatory drawing showing the light irradiation area | region on the light receiving element of the reflective optical system of FIG. It is a block diagram which shows the apparatus of the reflective optical system which concerns on Example 2 of the optical distance measuring device which concerns on this invention. It is a block diagram which shows the apparatus of the transmission optical system which concerns on Example 3 of the optical distance measuring device which concerns on this invention. It is a figure showing the graph which shows the relationship between the light intensity detected by a light receiving element group, and elliptically polarized light. It is the schematic which shows the structure of Example 4 of the optical distance measuring device which concerns on this invention. It is the schematic which shows the structure of Example 5 of the optical distance measuring device which concerns on this invention. It is the schematic which shows the structure of Example 6 of the optical distance measuring device which concerns on this invention. It is the schematic which shows the structure of Example 7 of the optical distance measuring device which concerns on this invention.

  Embodiments 1 to 7 of the optical distance measuring device according to the present invention will be described below in detail with reference to the drawings.

  A first embodiment of the optical distance measuring device according to the present invention will be described below with reference to FIGS. In this embodiment, the apparatus is a reflection optical system that reflects a scanning beam by a measurement object. FIG. 1 is a block diagram illustrating a configuration of a reflection optical system according to an embodiment.

  As shown in FIG. 1, a laser light source 21 that is a light source that emits (emits) laser light, which is coherent irradiation light, and an acousto-optic device (AOD) 23 that is controlled by an AOD driver 24 connected thereto. A collimator lens 22 whose aberration is corrected so that parallel light can be obtained from the laser light is disposed between the two. Therefore, in the present embodiment, the linearly polarized laser light emitted from the laser light source 21 is converted into parallel light by the collimator lens 22.

  Further, following this acoustooptic element 23, a pupil transmission lens system 25 comprising two groups of lenses, a two-dimensional scanning device 26 which is a two-dimensional scanning element for two-dimensionally scanning the inputted laser light, and the inputted laser light. The non-polarized beam splitter 27 is originally arranged in order to separate and emit the light. As shown in FIG. 1, the optical path of the laser beam toward the pupil transfer lens system 25 is the optical axis L. Further, adjacent to the lower side of the beam splitter 27 is a pupil transmission lens system 30 composed of two groups of lenses, and an objective lens 31 is disposed next to the objective lens 31 so as to face the object G1. That is, these members are also arranged along the optical axis L.

  As described above, the irradiation light emitted from the laser light source 21 is converted into parallel light by the collimator lens 22, and the acoustooptic device 23 modulates the irradiation light by the electric signal from the AOD driver 24. When the modulation at this time is DSB modulation, two beams adjacent to each other in frequency can be created. Along with this, the laser light that has been beam-paired by the acoustooptic device 23 is moved along the optical axis L through the pupil transmission lens system 25, the two-dimensional scanning device 26, the beam splitter 27, the pupil transmission lens system 30, and the objective lens 31. In sequence, the measurement object G1 is irradiated. At this time, due to the operation of the two-dimensional scanning device 26, the laser beam becomes a scanning beam and is scanned two-dimensionally on the measurement object G1.

  Then, linearly polarized irradiation light from the laser light source 21 passes through the objective lens 31 and is irradiated onto the measurement object G1, and the irradiation light is reflected by the measurement object G1. At this time, the scanning beam reflected by the measuring object G1 becomes diffracted light, and returns to the parallel light in the order of the objective lens 31, the pupil transfer lens system 30, and the beam splitter 27.

  On the other hand, a separating element for dividing the diffracted light reflected by the measuring object G1 into two directions is a direction perpendicular to the direction in which the optical axis L passes and is adjacent to the non-polarized beam splitter 27. An unpolarized beam splitter 10 is located. As a result, the light is reflected by the beam splitter 27, and this reflected light is incident on the beam splitter 10 along the optical axis L of the reflected light orthogonal to the original optical axis L.

  Also, a non-polarized beam splitter 11 is located on the left side of the beam splitter 10 in FIG. 1, and a polarizer 1 and a light receiving element group 5 are continuously arranged on the left side of the beam splitter 11. Similarly, the polarizer 2 and the light receiving element group 6 are continuously arranged below the beam splitter 11. However, the polarizer 1 and the polarizer 2 have polarization axes orthogonal to each other. Therefore, the light separated by the beam splitter 11 passes through the polarizer 1 and the polarizer 2 which are two polarizers having mutually orthogonal polarization axes, and the light having the polarization axes orthogonal to the light receiving element group 5. Each is incident on the light receiving element group 6.

  Further, an unpolarized beam splitter 12 is located on the upper side of the beam splitter 10 in FIG. 1, and a polarizer 3 and a light receiving element group 7 are continuously arranged on the left side of the beam splitter 12. Similarly, the polarizer 4 and the light receiving element group 8 are continuously arranged above the beam splitter 12. However, the polarizer 3 and the polarizer 4 have polarization axes orthogonal to each other. Therefore, the light separated by the beam splitter 12 passes through the polarizer 3 and the polarizer 4 which are two polarizers having mutually orthogonal polarization axes, and the light having the polarization axes orthogonal to the light receiving element group 7. Each is incident on the light receiving element group 8.

  As described above, the polarization axis of the polarizer 1 and the polarization axis of the polarizer 2 are in a direction different from each other by 90 degrees, and the polarization axis of the polarizer 3 and the polarization axis of the polarizer 4 are also 90 degrees. The orientation is different. However, these shall be arrange | positioned so that the polarization axis of the polarizer 1 and the polarization axis of the polarizer 3 may have 45 degree | times mutually. Here, the beam splitters 11 and 12 are separation beam splitters, the beam splitter 11 and the polarizers 1 and 2 are first polarization elements, and the beam splitter 12 and the polarizers 3 and 4 are second polarization elements. The

  Specifically, when the measurement object G1 is an object having birefringence or optical rotation, the polarization state of the irradiated light is reflected while being changed by the measurement object G1, and the objective lens 31 and the pupil transfer lens are reflected. It returns to the beam splitter 27 through the system 30 and is reflected by the beam splitter 27 toward the beam splitter 10 side. The reflected light is divided into two directions by the beam splitter 10, and each is further divided into four directions by the beam splitter 11 and the beam splitter 12.

  Accordingly, the light separated by the beam splitter 11 is incident on the light receiving element group 5 and the light receiving element group 6 via the polarizer 1 and the polarizer 2 having mutually orthogonal polarization axes, respectively. The light of intensity I1 is detected by the group 5, and the intensity I2 is detected by the light receiving element group 6. Similarly, the light separated by the beam splitter 12 is incident on the light receiving element group 7 and the light receiving element group 8 through the polarizer 3 and the polarizer 4 having mutually orthogonal polarization axes, respectively. The light having the intensity I3 is detected with the light receiving element group 8, and the light receiving element group 8 detects the intensity I4.

  The light receiving element groups 5 to 8 are not only arranged on the far field (far field) surface of the measurement object G1, but in this embodiment, the light receiving elements 5A to 8A and 5B, which are two optical sensors. ~ 8B. However, if the light receiving element group 5 is given as an example, as shown in FIG. 2, this light is on a plane substantially perpendicular to the direction along the optical axis L which is the center of the spot of the scanning beam LA. The light receiving elements 5A and 5B are arranged with a boundary line S passing through the axis L interposed therebetween. That is, the light receiving element 5A is shifted to one side of the boundary line S, and the light receiving element 5B is shifted to the opposite side of the boundary line S. The scanning beam is reflected by the measurement object G1 and passed therethrough. These light receiving elements 5A and 5B receive LA.

  Further, each of the light receiving elements 5A and 5B has a structure having a photoelectric conversion unit (not shown), and each of the light receiving elements 5A and 5B receives the scanning beam LA and performs photoelectric conversion. Further, as each of the light receiving elements 5A and 5B is connected to the signal comparator 33, the signal comparator 33 uses the signals from the light receiving elements 5A and 5B to determine the intensity information of each polarization axis and the measurement target. The phase information of the object G1 is obtained. The signal comparator 33 is connected to a data processing unit 34 that finally processes data and obtains a measured value such as a profile of the measurement object G1. For this reason, in the present embodiment, the signal comparator 33 and the data processing unit 34 are set as measurement units.

  The laser light source 21 is a semiconductor laser and generates coherent laser light. The laser light is converted into a parallel light beam by the collimator lens 22 and is incident on the pupil transfer lens system 25. At this time, the incident beam diameter of the laser light is optimized using a diaphragm mechanism (not shown) or the like in consideration of the pupil transmission lens system 25.

  On the other hand, a DSB modulation signal such as sin (2πfct) sin (2πfmt) is applied to the acoustooptic device 23 from the AOD driver 24 as a modulation signal. When such modulation is performed, the acoustooptic device 23 to which two frequency modulations of fc + fm and fc-fm have been applied generates an acoustic dense wave corresponding to the pitch d of the Bragg diffraction grating. That is, if the velocity of the ultrasonic wave is Va and the applied frequency is f, d = Va / f. Specifically, the laser light incident on the acoustooptic device 23 is separated into ± first-order diffracted light by the rough wave, and each diffracted light is modulated at a frequency of fc ± fm.

  Here, the pupil transmission lens system 25 disposed between the acoustooptic element 23 and the two-dimensional scanning device 26 transmits the position of the exit surface of the collimator lens 22 to the next two-dimensional scanning device 26 in a conjugate manner. This is an optical system. The laser light that has passed through the pupil transmission lens system 25 is sent to the beam splitter 27 as a scanning beam via the two-dimensional scanning device 26, and the scanning beam from the beam splitter 27 is transmitted to the pupil of the objective lens 31. The light enters the objective lens 31 through the pupil transmission lens system 30 that is conjugated to the position.

Next, the respective light receiving element groups 5 to 8 that receive light polarized through the non-polarized beam splitters 10 to 12 and the polarizers 1 to 4 will be described.
Regarding each of the light receiving element groups 5 to 8, the light receiving elements 5A to 8A and 5B to 8B can receive light and perform photoelectric conversion. However, as described above, the light receiving element group 5 is described as an example, but only the light receiving elements located on one side of the two-divided light receiving region with the boundary line S passing through the optical axis L shown in FIG. One feature of this embodiment is that phase information that is intensity information and phase shift information can be detected.

  As described above, the reason why the intensity information and phase information of each polarization axis can be detected only on one side of the two-divided light receiving region is that the boundary line S is a direction substantially perpendicular to the optical axis L direction of the objective lens 31 shown in FIG. The intensity information and the phase information can be sufficiently detected only by one of the light receiving elements 5A on one side divided by the boundary line S, or the phase information is also sufficiently sufficient only by the other light receiving element 5B on the other side. This is because it can be detected. Of course, information can also be detected simultaneously by both light receiving elements 5A and 5B.

  However, the phase of the light that is diffracted from the measurement object G1 and reaches each of the light receiving elements 5A and 5B is reversed between the light receiving elements 5A and 5B with the optical axis L as a boundary. Accordingly, the signal comparator 33 finally processes the data based on the signals of the phase information of the opposite phases which are photoelectrically converted by the light receiving elements 5A and 5B, and the data processing unit 34 profiles the measurement object G1. A measurement value of the optical distance such as is obtained.

  That is, the signal comparator 33 obtains the intensity information of each polarization axis and the phase information of the measurement object G1 from each of the light receiving element groups 5 to 8 by a signal obtained by photoelectrically converting the scanning beam reflected by the measurement object G1. Thus, the intensity information and the phase information are sent to the data processing unit 34 including a CPU and a memory connected to the signal comparator 33. Along with this, the intensity information and phase information are recorded together with scanning information for the plane by the data processing unit 34, and a measurement value such as profile information about the surface of the measurement object G1 can be easily derived.

  As described above, according to the present embodiment, the in-plane resolution is high, the resolution for the height and the refractive index distribution is high outside the plane, and the thickness of the cell or the like that cannot be obtained by a normal imaging optical system is obtained. An optical distance measuring device that can obtain three-dimensional information of a living sample in real time in a living state is provided.

  Accordingly, if such an optical system is used, three-dimensional measurement data can be acquired every time two-dimensional scanning is performed. For this reason, according to the present optical system, it is possible to observe and measure the state change of the cells and microorganisms, the transient change of the surface state and the internal state accompanying the state change, etc. at high speed. Therefore, by using a commercially available autostereoscopic display or a three-dimensional display using polarized glasses, a three-dimensional stereoscopic image can be displayed, so that the apparatus is useful in education, research, and medicine. Can do.

  On the other hand, in the present embodiment, at least three non-polarized beam splitters 10 to 12 and four polarizers 1 to 4 are used to detect the polarization state, but instead of these, a plurality of different angles are used. By disposing the polarizing beam splitter, the same measurement as when a non-polarizing beam splitter and a polarizer are employed is possible. When the beam splitters 11 and 12 themselves are replaced with polarizing beam splitters, a polarizer is not necessary. In particular, when a polarization beam splitter is employed, two orthogonal polarization beam splitters can be prepared, and one set of polarization beam splitters can be compared to the other set of polarization beam splitters. By rotating 45 °, the polarization state can be measured efficiently.

  In this optical system, the example using one two-dimensional scanning device 26 shown in FIG. 1 has been described. However, if the application requires simple data in only one direction, this two-dimensional scanning device is used. The same effect can be obtained even if it is replaced with a one-dimensional scanning device. As these one-dimensional scanning devices, galvanometer mirrors, resonant mirrors, rotating polygon mirrors, and the like can be employed.

  Also, instead of one two-dimensional scanning device 26, two independent one-dimensional scanning devices are prepared for the X direction and the Y direction orthogonal to each other, and these are arranged before and after the pupil transfer lens system 25. By doing so, the same function as the two-dimensional scanning device 26 can be realized. For example, a micromirror device using a micromachine technique may be used. As this micromirror device, both one-dimensional and two-dimensional devices are known and commercialized. Furthermore, one one-dimensional scanning device and a table (not shown) that supports the measurement object G1 can be used in a form orthogonal to each other.

  In the present embodiment, since DSB modulation using two irradiation lights close to each other is adopted, heterodyne detection is used when detecting with a light receiving element, but single frequency modulation may be used. It becomes detection of two irradiation lights. In the case of the present embodiment, the irradiation light is irradiated to the measurement object G1 with linearly polarized light, and the light reflected by the beam splitter 27 is mainly linearly polarized light. Here, “main body” means that although the polarization plane is rotated by the measurement object G1, the polarization state is slightly changed because the polarization plane is hardly changed.

Next, a second embodiment of the optical distance measuring device according to the present invention will be described below with reference to FIG. This embodiment is also a reflection optical system that reflects a scanning beam by a measurement object.
FIG. 3 is a block diagram illustrating a configuration of the reflection optical system according to the embodiment. Since the main optical system is the same as the above-described apparatus, a description thereof will be omitted. A ¼ wavelength plate 14 is arranged, and the ¼ wavelength plate 14 makes irradiation light, which is laser light from the laser light source 21, circularly polarized light. In this embodiment, the acoustooptic device 23 and the AOD driver 24 are not required.

  Therefore, in this embodiment, the measurement object G1 is irradiated with irradiation light that is circularly polarized laser light. However, when the measurement object G1 is an object having birefringence or optical rotation, the polarization state irradiated by the birefringence or optical rotation of the measurement object G1 is changed and reflected as elliptically polarized light. It returns to the beam splitter 27 through the lens 31 and the pupil transmission lens system 30. Then, the beam splitter 27 reflects the beam splitter 10 side as in the first embodiment.

  As a result, diffracted light is detected as elliptically polarized light in the light receiving element groups 5 to 8 through the beam splitters 11 and 12 and the polarizers 1 to 4 as in the first embodiment. Instead of arranging the quarter-wave plate 14 between the pupil transfer lens system 25 and the two-dimensional scanning device 26, it is a part in front of the objective lens 31 that is a part that becomes a parallel light beam in the middle of the optical system. The quarter-wave plate 14 may be disposed between the pupil transmission lens system 25 and the objective lens 31.

  As described above, the present embodiment also has a high in-plane resolution and a high resolution with respect to height and refractive index distribution outside the surface, as well as the first embodiment, and cells that cannot be obtained by a normal imaging optical system. An optical distance measuring device capable of obtaining three-dimensional information of a biological sample having a thickness of alive in real time is provided.

  In the present embodiment, since the laser light from the laser light source 21 which is a semiconductor laser is directly modulated, it is naturally single frequency modulated. Further, since the quarter-wave plate 14 is disposed between the pupil transmission lens system 25 and the two-dimensional scanning device 26 that are positioned closer to the laser light source 21, the measurement object G1 is irradiated with circularly polarized light, The light reflected by the beam splitter 27 is mainly circularly polarized.

Next, Embodiment 3 of the optical distance measuring device according to the present invention will be described below with reference to FIG. In the present embodiment, the apparatus is a transmission optical system in which a scanning beam passes through a measurement object.
FIG. 4 is a block diagram illustrating the configuration of the transmission optical system according to the present embodiment. Since the main optical system is the same as that of the reflection optical system described above, a description thereof will be omitted. However, in this transmission optical system, the light condensed by the objective lens 31 is compared with the first and second embodiments. It passes through the measurement object G2.

  Further, in this embodiment, since it is a transmission optical system, the beam splitter 27 becomes unnecessary, and in accordance with this, at a position on the extension line of the optical axis L on the side opposite to the objective lens 31 via the measurement object G2, A lens 13 and a beam splitter 10 that make the light transmitted through the measurement object G2 parallel light are sequentially arranged. For this reason, the light condensed by the objective lens 31 passes through the measurement object G2 and becomes a parallel light flux by the lens 13. The beam splitters 11 and 12 and the polarizers 1 to 4 used in the reflection optical system according to the first embodiment are disposed in the same manner after the beam splitter 10 although the positional relationship is different. The operation is the same as that of the reflection optical system.

  Specifically, a beam splitter 11 is positioned below the beam splitter 10, and a polarizer 1 and a light receiving element group 5 are continuously arranged below the beam splitter 11. On the left side of 11, a polarizer 2 and a light receiving element group 6 are arranged in succession. Further, the beam splitter 12 is located on the left side of the beam splitter 10 in FIG. 4, and the polarizer 3 and the light receiving element group 7 are continuously arranged on the left side of the beam splitter 12. The polarizer 4 and the light receiving element group 8 are continuously arranged on the upper side.

  In addition, a quarter-wave plate 14 is disposed between the pupil transmission lens system 25 and the objective lens 31, which are a part in front of the objective lens 31 that is a part that becomes a parallel light beam of the incident system. If it does in this way, the laser beam of a circular polarization state will be irradiated to measurement object G2 like Example 2. Accordingly, the acoustooptic device 23 and the AOD driver 24 are not present in this embodiment.

  In particular, it is conceivable that a port is prepared immediately before the objective lens 31 as in a normal microscope, and a switching mechanism is provided so that the quarter-wave plate 14 can be removably inserted. In this way, by switching the ¼ wavelength plate 14 to / from the port, the linearly polarized laser light and the circularly polarized laser light are incident depending on the polarization state of the measuring object G2. Changes can be analyzed in more detail.

  Similarly, in the apparatus of the reflective optical system of Example 2 shown in FIG. 3, if the quarter wavelength plate 14 is arranged in front of the objective lens 31, this switching mechanism is provided in the same manner, and this 1 / The four-wave plate 14 can be detachable. On the other hand, in this embodiment, as shown in FIG. 3, the quarter-wave plate 14 may be disposed between the two-dimensional scanning device 26 and the pupil transfer lens system 30.

  On the other hand, in this embodiment, at least three non-polarizing beam splitters 10 to 12 and four polarizers 1 to 4 are used in order to detect the polarization state. By arranging a plurality of polarizing beam splitters having different angles, it is possible to perform the same measurement as when a non-polarizing beam splitter and a polarizer are employed. Similarly to the first embodiment, in the present embodiment, the light receiving element groups 5 to 8 are not only arranged on the far field surface of the measurement object G2, but are each constituted by two light receiving elements.

  Accordingly, as in the first embodiment, not only the intensity information of the polarization axis photoelectrically converted by the light receiving elements 5A to 8A and 5B to 8B constituting the light receiving element groups 5 to 8, but also phase information is obtained. Then, the signal comparator 33 obtains the phase information of the measuring object G2 from the phase information signal. Finally, the data is processed, and the data processing unit 34 can obtain the measured value of the optical distance such as the profile of the measurement object G2. As a result, the present embodiment also provides an optical distance measuring device with high effective resolution and no spatial frequency loss.

  In particular, the transmission optical system apparatus as in this embodiment not only has the same effects as those of the first and second embodiments, but also changes the state of cells that remain unstained and non-invasive in real time. Since it can be observed, it can play a major role in testing whether iPS and ES cells are normal, checking for the presence of cancer cells, and the like. This is a feature that is greatly different from a measuring instrument such as an electron microscope that cannot be observed unless the living body is killed even at a high magnification.

  In the present embodiment, since the laser light from the laser light source 21 is directly modulated, the single frequency modulation is naturally performed. Further, since the quarter-wave plate 14 is disposed between the pupil transmission lens system 25 and the objective lens 31 which are the front part of the objective lens 31, the measurement object G2 is irradiated with circularly polarized light, The light transmitted through the lens is mainly circularly polarized.

Next, the reason why the optical distance, the birefringence, the polarization information, etc. can be measured simultaneously in Examples 1 to 3 will be described below.
Laser light that has been linearly polarized or circularly polarized by the quarter-wave plate 14 passes through the beam splitters 11 and 12 and the polarizers 1 to 4 having the respective polarization axes by the measuring objects G1 and G2, and the light receiving element group. Lights of intensities I1, I2, I3, and I4 are obtained at 5-8. The relationship between the light intensity detected by the light receiving element groups 5 to 8 and the elliptically polarized light at this time will be described with reference to the graph shown in FIG.

  The electric field vector of light is set by setting the axis Ex shown in FIG. 5 as the polarization axis of the polarizer 1 and the axis Ey as the polarization axis of the polarizer 2. At this time, the polarized light by the measuring objects G1 and G2 is generally elliptically polarized light. When this elliptically polarized light is an ellipse D shown in FIG. 5, the length of the ellipse D with respect to the axis Ex is set as a is the major axis along the major axis T of the ellipse D and b is the minor axis perpendicular to the major axis T. The inclination angle θ of the axis T can be expressed as the following equation (1).

  Here, the intensity I1 detected by the light receiving element group 5 is a value of 0 in the axis Ey direction, and therefore can be obtained by the following equation (2). Similarly, the intensity I2 detected by the light receiving element group 6 is a value of 0 in the direction of the axis Ex and can be obtained by the following equation (3).

  On the other hand, the values of the intensity I3 detected by the light receiving element group 7 can be obtained by the following equation (4) by simple deformation on the tilted axes Sx and Sy inclined by 45 ° with respect to the axes Ey and Ex. Similarly, the value of the intensity I4 detected by the light receiving element group 8 is obtained by the following equation (5). Here, the polarization axis of the polarizer 3 that is an inclination axis inclined by 45 ° with respect to the axis Ex is Sx, and similarly, the polarization axis of the polarizer 4 that is an inclination axis inclined by 45 ° with respect to the axis Ey is Sy. To do.

  From these expressions, since the value of the left side of the expression (4) + (5) is double the value of the left side of the expression (2) + (3), the expression (2) to (5) There are three independent equations. Therefore, the three variables a, b, and θ are obtained independently from the above formula. The expression of these three variables a, b, and θ is described as follows. Here, β = cos θ. In addition, since two values are obtained from the values of the intensity I1 and the intensity I2, a larger value is defined as the major axis a, and a smaller value is defined as the minor axis b. In the following three variables a, b, and θ, I2> I1 is shown. However, when I2 <I1, b represents the major axis and a represents the minor axis. Become.

Next, consider the case where the quarter wavelength plate 14 is inserted between the pupil transfer lens system 25 and the two-dimensional scanning device 26 in the optical system.
The measurement objects G1 and G2 are irradiated with circularly polarized laser light, but are detected as elliptically polarized light in the same manner as described above on the light receiving element groups 5 to 8 due to the birefringence of the measurement objects G1 and G2. . When the phase in the major axis direction of elliptically polarized light due to birefringence is δa and the phase in the minor axis direction is δb, the phase difference δ is obtained by the following equation.
δ = δa−δb = 2π / λ d (na-nb)
Here, d represents the thickness of the measurement objects G1 and G2, na represents the refractive index in the major axis direction, and nb represents the refractive index in the minor axis direction. If the ratio of the major axis to the minor axis of elliptically polarized light is ε, this ratio ε is generally obtained by the following equation.

Therefore, if the major axis and minor axis of the elliptically polarized light are measured by the procedure described above, the phase difference δ, that is, the refractive index difference can be detected.
Further, when scanning is performed while irradiating the measurement objects G1 and G2 with laser light, a signal comparator is obtained by modulating a light modulation signal obtained by at least one light receiving element sandwiching a boundary line S perpendicular to the optical axis L direction. 33 etc. perform signal processing. As a result, the phase difference θ0 between the amplitude M0 of the 0th-order diffracted light and the amplitude M1 of the 1st-order diffracted light with respect to the 0th-order diffracted light is obtained, and the optical distance nh can be obtained from this phase difference θ0.

Here, γ = M ₁ / M ₀ was set. γ is the ratio of the light of the 0th order diffracted light and the 1st order diffracted light.
Since θo is the phase difference of the first-order diffracted light with respect to the 0th-order diffracted light, Θo is obtained from θo and γ.
Furthermore, the optical distance nh can be obtained from Θo = (2π / λ) nh.

  For example, when measuring with water and cells sandwiched between a preparation (not shown) and a cover glass, the optical distance is determined by the refractive index of water, which is a known medium, and the refractive index of the cells at two polarization axes. It is expressed as the product of the difference and height. Since the inclination angle θ of the ellipse D can be found from the information on the elliptically polarized light, the birefringence can be derived from the optical distance detected on the polarization axis and the information on the elliptically polarized light. Thus, the optical distance, birefringence, polarization information, etc. can be measured simultaneously by deriving the optical distance with two polarization axes and detecting the state of elliptically polarized light with at least three polarization axes.

In addition, according to each embodiment of the present invention described later, such information can be acquired in a region having a high spatial frequency, so that dynamic changes of cells and the like can be followed with extremely high resolution. Furthermore, by detecting the change in polarization state and the birefringence, it is possible to analogize the substances constituting the cells. Further, by extracting and displaying the birefringence, birefringence, etc. within a certain range, the movement of the substance can be expressed visually and three-dimensionally without staining.
In other words, if the incident polarization state is fixed in advance, a polarizer having at least three polarization axes different from each other in the state of elliptically polarized light reflected by the optical rotation and birefringence information of the measurement objects G1 and G2. Can be identified by the amount of light that has passed through.

  The above-described procedure can also be applied to the case where only the intensity information that the cells are stained is included. In this case, even with the data obtained by the light receiving elements 5A to 8A on one side with the optical axis L as a boundary without using both of the two light receiving elements 5A to 8A and 5B to 8B constituting the light receiving element groups 5 to 8. Alternatively, the total data of these two light receiving elements 5A to 8A and 5B to 8B may be used. That is, if it is limited to the use of only this intensity information, only one light receiving element may be used. In this case, however, it cannot be determined whether the stained substance or the substance of the cell has an influence on the refractive index.

  Therefore, the information is acquired by the light receiving elements 5A to 8A or the light receiving elements 5B to 8B on one side with the optical axis L as a boundary, and the optical distance is determined for those having phase information such as unstained cells. It is conceivable to consider both the visualized or measured information and the analysis result of this polarization state. This makes it possible to quantify the birefringence of the measurement objects G1 and G2 and determine the optical axis, which is a major feature of the embodiments of the present invention.

  At this time, the spatial frequency associated with the scanning of the laser light is converted into an electrical signal by the light receiving element, and quantified by signal processing using a direct current component or an alternating current component of the electrical signal. The present invention is particularly effective when there is a structure in G2. That is, since the internal polarization state can be measured together with the optical distances of the measurement objects G1 and G2, the refractive index distribution and the like can be measured in three dimensions in real time. Further, as will be described in the following examples, by using an optical system that interferes with the 0th-order diffracted light and the 1st-order diffracted light having a high spatial frequency, the analysis of the optical distance and the polarization state is higher in resolution than the conventional optical microscope. Can be done with.

A fourth embodiment of the optical distance measuring device according to the present invention will be described below with reference to FIG.
This embodiment is an example in which the present invention is applied to an optical system that combines 0th-order diffracted light and high spatial frequency 1st-order diffracted light, and FIG. 6 is a schematic diagram showing the configuration of this embodiment. In this embodiment, a laser light source 21 that is a light source for irradiating light faces the objective lens 31 through an optical system (not shown) such as a collimator lens 22, a pupil transmission lens system 25, 30, and a two-dimensional scanning device 26. Are arranged. For this reason, the light irradiated by the laser light source 21 is converged and irradiated onto the measurement object G2 that is a transmissive material. A lens 45, which is a convex lens, is positioned on the optical axis L, which is the irradiation optical axis of the convergent irradiation of the laser light source 21, and the lens 45 is parallel to the light beam that has been transmitted through the measuring object G2. Is converted into a luminous flux.

  On the optical axis L below the lens 45, two beam splitters 50 and 53 that divide the parallel light beams emitted from the lens 45 in the left and right directions are continuously arranged. On L, beam splitters 10 to 12, polarizers 1 to 4, and light receiving element groups 5 to 8 are arranged in the same manner as in the third embodiment. For this reason, the light on the optical axis L is converted into intensity information of four polarizations having different polarization axes by the set of these optical elements.

  On the other hand, a lens 46, which is a convex lens, is positioned on the optical axis L1, which is an inclined optical axis having an inclination on the right side of FIG. The light beam emitted from G2 is a parallel light beam. A reflecting mirror 48 for reflecting the parallel light beam downward is disposed on the optical axis L 1, and a beam splitter 51 is positioned below the reflecting mirror 48. For this reason, the reflecting mirror 48 disposed between the lens 46 and the beam splitter 51 reflects the light emitted from the lens 46 toward the beam splitter 51 side. On the other hand, a lens 47, a reflecting mirror 49, and a beam splitter 52 having the same configuration as described above are symmetrically arranged along the optical axis L2 on the left side of FIG.

  A part of the 0th-order diffracted light from the measurement object G <b> 2 converted into parallel light by the lens 45 is sent to the beam splitter 51 via the beam splitter 50. The beam splitter 51 combines the first-order diffracted light that has become a parallel light beam by the lens 46 disposed obliquely with respect to the optical axis L and a part of the zero-order diffracted light.

  Similarly, a part of the 0th-order diffracted light from the measurement object G <b> 2 that is converted into parallel light by the lens 45 is sent to the beam splitter 52 via the beam splitter 53. The beam splitter 52 combines the −1st order diffracted light and a part of the 0th order diffracted light, which are converted into parallel light beams by the lens 47 disposed obliquely opposite to the lens 46 with respect to the optical axis L.

  In this embodiment, the beam splitter 12, the polarizers 3 and 4, and the light receiving element groups 7 and 8 are disposed below the beam splitter 51. A beam splitter 11, polarizers 1 and 2, and light receiving element groups 5 and 6 are arranged below the beam splitter 52.

  In addition to the light receiving element groups 5 to 8 described above, the light receiving element groups 7 and 8 and the light receiving element groups 5 and 6 are connected to a signal comparator 33 for comparing signals from these light receiving element groups, respectively. Yes. The signal comparator 33 is connected to a data processing unit 34 that finally processes the data to obtain a profile of the measurement object G2. For this reason, the signal comparator 33 and the data processing unit 34 receive light receiving element groups 5 to 8 that receive 0th-order diffracted light on the optical axis L, light receiving element groups 7 and 8 that are positioned on the right side of the optical axis L, and Since the polarization intensity information from the light receiving element groups 5 and 6 positioned on the left side with respect to the optical axis L is input and data is processed, the signal comparator 33 and the data processing unit 34 are used as the measurement unit.

  Specifically, the light synthesized by the beam splitter 51 is converted into intensity information of two polarized light beams having different polarization axes by the beam splitter 12, the polarizers 3 and 4, and the light receiving element groups 7 and 8. The light combined by the beam splitter 52 is converted into intensity information of two polarized light beams having different polarization axes by the beam splitter 11, the polarizers 1 and 2, and the light receiving element groups 5 and 6. However, the polarization axes of the polarizers 1 and 2 are inclined by 45 ° with respect to the polarization axes of the polarizers 3 and 4, respectively.

  That is, a part of the 1st-order diffracted light and the 0th-order diffracted light and a part of the −1st-order diffracted light and the 0th-order diffracted light are separated into four polarized lights having different polarization axes, and the light receiving element groups 7 and 8 and the light receiving element groups 5, 6 is converted into intensity information. Since the four pieces of intensity information are independent as described above, the elliptical polarization state can be detected from them. Also, the 0th-order diffracted light on the optical axis L is also separated into four polarized lights having different polarization axes, and is converted into intensity information by the light receiving element groups 5 to 8.

  At this time, if the measurement object G2 is a phase object, the first-order diffracted light and the −1st-order diffracted light are different in phase from each other by 180 °, so that optical distance information can be acquired by two light receiving element groups on one side. . Of course, the optical distance information can be acquired by a total of four light receiving element groups on both sides of the optical axis L. In addition, since the information on the polarization does not depend on the ± first-order diffracted light, the information on the polarization axes different in both light receiving element groups may be acquired.

  As described above, when the measurement object G2 has birefringence or optical rotation, for example, the optical distance and light received by the light receiving element group 5 from the light synthesized by the left beam splitter 52. The optical distance acquired by the element group 6 is measured as different values. In this case, since the two lights received by the light receiving element group 5 and the light receiving element group 6 pass through the same path, different values represent a difference in refractive index of the measurement object G2.

  The refractive index of the measurement object G2 having birefringence can be measured from the information on the optical distance and the information such as the ratio of the major axis to the minor axis of elliptically polarized light. In this case, in particular, the zero-order diffracted light and the first-order diffracted light having a high spatial frequency are modulated by scanning, and this is detected by the light receiving element group, so that high-resolution polarization information is obtained simultaneously with the optical distance information having high resolution. be able to. In this way, optical distance information and polarization information can be obtained at the same time with high resolution without staining cells or the like from information such as birefringence and birefringence. It becomes.

  It should be noted that a set of optical elements composed of the beam splitters 10 to 12 on the optical axis L of the objective lens 31, the polarizers 1 to 4, the light receiving element groups 5 to 8 and the like so that the four polarization states can be acquired simultaneously. The intensity information may be obtained from the light combined by the beam splitter 51 and the light combined by the beam splitter 52. Further, if information with a low spatial frequency is not required, the light receiving element groups 5 to 8 on the optical axis L of the objective lens 31 may be omitted.

  In this embodiment, four types of polarizers are employed, but in general, polarizers having different polarization axes may be used. However, for example, it is conceivable to rotate the polarization axes of the polarizers 2, 3, and 4 at 45, 90, and 135 degrees with the polarizer 1 as a reference. Further, two sets of polarizing beam splitters may be employed instead of the non-polarizing beam splitter, and these polarizing beam splitters may be arranged while rotating with respect to each other. For example, this embodiment may be substituted by a polarizing beam splitter that detects P-polarized light and S-polarized light and a polarizing beam splitter that is inclined 45 degrees with respect to the polarizing beam splitter.

Embodiment 5 of the optical distance measuring device according to the present invention will be described below with reference to FIG.
This embodiment is an example in which the present invention is applied to another optical system having a high resolution by synthesizing zero-order diffracted light and first spatial diffracted light, and FIG. 7 is a schematic diagram showing the configuration of this embodiment. It is.
In this embodiment, the process is the same as that in FIG. 6 until the parallel light beam is incident on the objective lens 31 and converges on the measurement object G2. That is, the tilted optical system shown in this figure is arranged below the transmission optical system of the second embodiment. In FIG. 7, optical systems such as the collimator lens 22, the pupil transmission lens systems 25 and 30, and the two-dimensional scanning device 26 are not shown.

  However, in this embodiment, a part of the 0th-order diffracted light transmitted through the measurement object G2 and diffracted on the optical axis L3 substantially tilted with respect to the optical axis L of the objective lens 31 and the 0th-order diffracted light. A lens 61 is disposed that uses a part of the first-order diffracted light with high spatial frequency not included as parallel light. As a result, a part of the 0th-order diffracted light and a part of the 1st-order diffracted light transmitted through the measuring object G2 are intermediate inclination angles between the optical axis L of the 0th-order diffracted light and the optical axis L1 of the 1st-order diffracted light. Can be incorporated into the lens 61 tilted by the optical axis L3.

  Thus, by installing the lens 61 so as to be inclined with respect to the optical axis L of the 0th-order diffracted light, not only a part of the 0th-order diffracted light but also a higher spatial frequency is obtained compared to the case where the same lens is used. A part of the first-order diffracted light can be taken in, and interference between the zeroth-order diffracted light and the first-order diffracted light is realized.

  Further, a rhomboid prism 62 is disposed on the optical axis L3, and the light converted into a parallel light beam by the lens 61 does not include a part of the above-described 0th order diffracted light and 0th order diffracted light. A part of the first-order diffracted light having a high spatial frequency is synthesized. The rhomboid prism 62 has a light incident surface 62A for incident light and an output surface 62B that is a transparent surface opposite to the light incident surface 62A. A semi-transparent mirror 62C is provided, and a surface opposite to the semi-transparent mirror 62C is provided as a semi-transparent mirror 62D, and optical elements that pass through the rhomboid prism 62 and receive the respective light beams are disposed to face the surfaces 62B to 62D.

  That is, as shown in FIG. 7, a set of the beam splitter 11, the polarizers 1 and 2, and the light receiving element groups 5 and 6 is arranged facing the semi-transparent mirror 62C, and further facing the exit surface 62B. 10 to 12, a set of polarizers 1 to 4 and light receiving element groups 5 to 8 are arranged, and a set of the beam splitter 12, the polarizers 3 and 4 and the light receiving element groups 7 and 8 are opposed to the semi-transparent mirror 62D. Is arranged so that the light beam is guided to the set of these optical elements.

  Further, the light receiving element groups 5 to 8, the light receiving element groups 7 and 8, and the light receiving element groups 5 and 6 are respectively connected to a signal comparator 33 for comparing signals from these light receiving element groups. The signal comparator 33 is connected to a data processing unit 34 that finally processes the data to obtain a profile of the measurement object G2. Therefore, the intensity of polarized light from the light receiving element groups 5 to 8, the light receiving element groups 7 and 8, and the light receiving element groups 5 and 6 that respectively receive part of the 0th order diffracted light and part of the first order diffracted light on the optical axis L3. Since information is input to the signal comparator 33 and the data processing unit 34 to process the data, these are used as the measurement unit.

  Here, the set of the beam splitter 11, the polarizers 1 and 2, and the light receiving element groups 5 and 6 facing the semi-transparent mirror 62 </ b> C interferes with the first-order diffracted light including the 0th-order diffracted light of the lens 61. A spatial frequency comparable to the NA of the lens 31 can be separated. On the other hand, a set of beam splitters 10-12, polarizers 1-4, and light receiving element groups 5-8 facing the exit surface 62B, and a beam splitter 12, polarizers 3, 4, facing the semitransparent mirror 62D, light receiving element group 7 In the set of 8, the first-order diffracted light of NA or higher of the objective lens 31 is combined with the 0th-order diffracted light, so that the spatial frequency of NA or higher of the objective lens 31 can be separated.

  These spatial frequencies are detected by being converted into electrical modulation signals by the respective light receiving element groups by irradiating the measuring object G2 with laser light while scanning. Based on the detected AC signal of the modulation signal, a high-resolution polarization state can be obtained simultaneously with the high-resolution optical distance information.

  Each of the optical elements facing the surfaces 62B to 62D of the rhomboid prism 62 is composed of beam splitters 10 to 12, polarizers 1 to 4, and light receiving element groups 5 to 8 that simultaneously acquire four polarization states. May be. Further, by attaching a polarizing beam splitter to the semi-transparent mirror 62D that is the right slope of the rhomboid prism 62, the optical elements such as the beam splitters 10 to 12 positioned on the lower side and the beam splitter 12 positioned on the right side can be obtained. Instead, only the light receiving element can be directly arranged.

  Furthermore, an optical system such as a rhomboid prism corresponding to the optical system such as the rhomboid prism 62 of the present embodiment is additionally prepared, and the above-described optical system is arranged on the opposite side with the optical axis L of the objective lens 31 as a boundary. It is conceivable that an optical system such as the rhomboid prism is arranged at an angle of 45 ° with respect to the rhomboid prism 62 so that the tilt is symmetrical to the system. The above can be said to be a modification of the fourth embodiment shown in FIG.

  Note that two sets of polarizing beam splitters may be employed instead of the non-polarizing beam splitter, and these polarizing beam splitters may be arranged while rotating. For example, this embodiment may be substituted by a polarizing beam splitter that detects P-polarized light and S-polarized light and a polarizing beam splitter that is inclined 45 degrees with respect to the polarizing beam splitter.

A sixth embodiment of the optical distance measuring device according to the present invention will be described below with reference to FIG.
The present embodiment is an example in which the present invention is applied to still another optical system having high resolution, and FIG. 8 is a schematic diagram showing the configuration of this embodiment.
In the present embodiment, in order to process the scanning beam transmitted through the measuring object G2 while improving the lateral resolution, for example, the inclined optical system shown in this figure is arranged in the lower part of the transmission optical system of the second embodiment. To do. In FIG. 8, optical systems such as the collimator lens 22, the pupil transmission lens systems 25 and 30, and the two-dimensional scanning device 26 are not shown.

  In the present embodiment, a lens 61 that is inclined with respect to the optical axis L of the 0th-order diffracted light that is the optical axis of the objective lens 31 and that collimates the light diffracted from the measurement object G2 is installed. Yes. As a result, a part of the 0th-order diffracted light and a part of the 1st-order diffracted light transmitted through the measuring object G2 are intermediate inclination angles between the optical axis L of the 0th-order diffracted light and the optical axis L1 of the 1st-order diffracted light. Can be incorporated into the lens 61 tilted by the optical axis L3.

  Thus, not only a part of the 0th-order diffracted light but also a part of the 1st-order diffracted light having a higher spatial frequency compared to the case where the same lens is used, Interference is realized. Although not shown, in the present embodiment, a similar optical system is disposed at a target position with respect to the optical axis L.

  Further, as shown in FIG. 8, optical elements that pass through the lens 61 and receive the light beam are arranged to face each other. That is, a set of beam splitters 10 to 12, polarizers 1 to 4, and light receiving element groups 5 to 8 is arranged to face the lens 61. In this way, by tilting the lens 61, a part of the 0th-order diffracted light and a part of the 1st-order diffracted light are acquired, and the diffracted lights converted into parallel light beams by the lens 61 are guided to the set of optical elements. Yes.

  However, in this embodiment, the lens 63 is disposed between the polarizers 1 to 4 and the light receiving element groups 5 to 8, and the light receiving surfaces of the light receiving element groups 5 to 8 are substantially in the focal position of the lens 63. To be. However, it is not always necessary that the light receiving surfaces of the light receiving element groups 5 to 8 are the image forming surface of the measurement object G2, and even in the case of defocusing, the 0th order diffracted light and the 1st order diffracted light sufficiently interfere with each other. Absent. As a result, also in the present embodiment, intensity information on four different polarization axes can be detected by the respective light receiving element groups 5 to 8 as in the above embodiments.

  From the above, this embodiment also has a high in-plane resolution and high resolution with respect to the height and refractive index distribution outside the surface, as in the first to fifth embodiments, and is difficult to obtain with a normal imaging optical system. An optical distance measuring device capable of obtaining in real time three-dimensional information of a biological sample having a thickness such as a possible cell is provided.

  In this way, information can be obtained very easily up to a region with a high spatial frequency, and the MTF characteristics can be improved. This makes it possible to measure a highly reliable optical distance even for the measurement object G2 that requires a high lateral resolution. In this embodiment, since the lens 63 is used, a wavefront aberration that allows the phase difference between the 0th-order diffracted light and the 1st-order diffracted light incident on the lens 63 to be reflected is allowed. For this reason, there is no need to use an expensive lens.

  Each of the optical systems shown in FIGS. 4, 6, and 7 is drawn on the paper surface, but a similar optical system may be additionally arranged in a direction perpendicular to the paper surface. By doing so, the polarization axes to be detected can be arranged in four different directions, and detection without directionality can be performed. In addition, with respect to the orientation of each polarization axis, it is preferable that the axes are different from each other by 45 ° in order to simplify the arrangement and calculation.

Embodiment 7 of the optical distance measuring device according to the present invention will be described below with reference to FIG.
FIG. 9 is a schematic diagram showing the configuration of this embodiment. This embodiment is a modification of the sixth embodiment. For this reason, the content described in the sixth embodiment is omitted below.

  As shown in FIG. 9, in this embodiment, the optical element that passes through the lens 61 and receives the light beam is arranged to face the lens 61. However, in this embodiment, the beam splitter 12, the polarizers 3 and 4, the light reception A set of element groups 7 and 8 is arranged to face the lens 61. As a result, the lens 61 is tilted to acquire a part of the 0th-order diffracted light and a part of the 1st-order diffracted light, and the diffracted lights converted into parallel beams by the lens 61 are guided to the set of optical elements in the same manner as in the sixth embodiment. It has come to be.

  On the other hand, in the present embodiment, the optical axis L2 of the −1st order diffracted light is at a position symmetrical to the optical axis L1 with respect to the optical axis L of the objective lens 31. Then, the measurement object G2 is transmitted through the lens 61 that is disposed in a state where the optical axis L4 having an intermediate inclination angle between the optical axis L of the 0th-order diffracted light and the optical axis L2 of the −1st-order diffracted light is inclined. A part of the 0th order diffracted light and a part of the −1st order diffracted light are taken in. Then, as shown in FIG. 9, sets of optical elements that pass through the lens 61 and receive the light beam are arranged opposite to each other as described above. However, on the optical axis L4, the set of the beam splitter 11, the polarizers 1 and 2, and the light receiving element groups 5 and 6 is disposed to face the lens 61. The tilted lens 61 acquires a part of the 0th-order diffracted light and a part of the −1st-order diffracted light, and the diffracted lights converted into parallel light beams by the lens 61 are guided to the set of optical elements. ing.

  In this embodiment, the lens 63 is disposed between the polarizers 3 and 4 and the light receiving element groups 7 and 8, respectively, and the light receiving surfaces of the light receiving element groups 7 and 8 are approximately the focal position of the lens 63. To be. However, it is not always necessary that the light receiving surfaces of the light receiving element groups 7 and 8 are the imaging surface of the measurement object G2, and even in the case of defocusing, the 0th order diffracted light and the 1st order diffracted light sufficiently interfere with each other. Absent. Similarly, the lens 63 is also inserted between the polarizers 1 and 2 and the light receiving element groups 5 and 6 so that the light receiving surfaces of the light receiving element groups 5 and 6 are substantially at the focal position of the lens 63. However, it is not always necessary that the light receiving surfaces of the light receiving element groups 5 and 6 are the image forming surface of the measurement object G2, and even in the case of defocusing, the 0th order diffracted light and the 1st order diffracted light sufficiently interfere with each other. Absent.

  As a result of the above, also in this embodiment, the light receiving element groups 7 and 8 and the light receiving element groups 5 and 6 can detect intensity information on four different polarization axes as in the above embodiments. For this reason, this embodiment also has a high in-plane resolution and a high resolution with respect to height and refractive index distribution outside the surface, as in the first to sixth embodiments, and is difficult to obtain with a normal imaging optical system. An optical distance measuring device capable of obtaining in real time three-dimensional information of a biological sample having a thickness such as a possible cell is provided.

  However, in this embodiment, the polarization directions of the polarizers 1 and 2 of the optical system set existing on the optical axis L4 with respect to the polarization directions of the polarizers 3 and 4 of the optical system set existing on the optical axis L3. Is tilted 45 degrees. On the other hand, a polarizing beam splitter can be used instead of the beam splitter and the polarizer. In this case, the other polarizing beam splitter may be disposed at an angle of 45 degrees with respect to one polarizing beam splitter.

  In addition, since the information regarding polarization should just detect the intensity | strength of the light via light polarizers, such as a polarizing plate which has three different polarization axes at least, the structure of the set of an optical element is restricted to what was mentioned above. Absent. In addition, the optical system in the drawing paper should be the above optical system that can detect the polarization, and in the direction perpendicular to the drawing paper, the optical system should not detect the polarization just to calculate and observe the optical distance. You can also.

  Further, in the above-described embodiment, each light receiving element constituting each light receiving element group is located on either side divided by the boundary line, but the light receiving element may be arranged across the boundary line. Even in this case, it is only necessary that the light receiving element is positioned so as to be shifted to one side of the boundary line.

  As mentioned above, although each Example concerning this invention was described, this invention is not limited to each above-mentioned Example, A various deformation | transformation can be implemented in the range which does not deviate from the meaning of this invention.

  The optical distance measuring device according to the present invention can be applied not only to the distance to the sample that is the measurement object and the shape of the sample, but also to various types of measuring instruments such as a microscope. The optical distance measuring device of the present invention can be applied not only to a microscope but also to various types of optical devices and measuring devices using electromagnetic waves having waves, and these optical devices and measuring devices using electromagnetic waves having waves. Resolution can be improved.

1-4 Polarizer (polarizing optical member)
5-8 Light receiving element group (polarizing optical member)
5A-8A Light receiving element (polarizing optical member)
5B-8B Light receiving element (polarizing optical member)
10-12 Beam splitter (polarizing optical member)
14 1/4 wavelength plate 21 Laser light source (light source)
22 Collimator lens 25 Pupil transmission lens system 26 Two-dimensional scanning device (two-dimensional scanning element)
27 Beam splitter 30 Pupil transmission lens system 31 Objective lens 33 Signal comparator (measurement unit)
34 Data processing unit (measurement unit)
D Ellipse G1, G2 Measurement object L Optical axis LA Scanning beam S Boundary line T Long axis θ Tilt angle

Claims (9)

A light source that emits coherent illumination light;
A two-dimensional scanning element that scans irradiation light from a light source in two different directions, respectively;
A polarizing optical member that separates the irradiation light that has passed through the measurement object while being polarized along four different polarization axes;
Four light receiving elements that respectively receive and photoelectrically convert the irradiation light separated into four;
While obtaining information of the measurement object from the state between the signals from each light receiving element, a measurement unit for obtaining a measurement value for the measurement object based on this information,
An optical distance measuring device. The polarizing optical member is a separating element that receives irradiation light from a measurement object and separates it into two pieces without polarization, and two sets of polarizing elements by a first polarizing element and a second polarizing element,
The first polarizing element transmits the one irradiation light separated by the separation element while separating it as polarized light orthogonal to each other,
The second polarization element passes the other irradiation light separated by the separation element while separating the polarized light orthogonal to each other at a 45 ° angle with respect to the polarization separated by the first polarization element. The optical distance measuring device according to claim 1.   Two sets of polarizing elements separate the splitting beam splitter into two pieces of non-polarized light, and the two splitting light beams transmitted by the splitting beam splitter in different polarization states. The optical distance measuring device according to claim 2, wherein the optical distance measuring device is a polarizer.   The measurement unit processes signals acquired by four light receiving elements to obtain major axis, minor axis, and inclination angle values of elliptically polarized light, and obtains a measurement value for a measurement object from these values. The optical distance measuring device according to any one of claims 1 to 3.   A quarter-wave plate that gives a phase difference of π / 2 along the direction of electric field vibration of irradiation light from the light source is disposed in front of the measurement object, and the measurement object is irradiated with circularly polarized irradiation light. Item 4. The optical distance measuring device according to Item 1.   6. The light receiving element receives irradiation light passing through a measurement object while being shifted to one of the sides with a direction perpendicular to the optical axis direction of irradiation light as a boundary line. The optical distance measuring device according to any one of the above. There are two light receiving elements across the boundary,
The optical distance measuring device according to claim 1, wherein the two light receiving elements respectively receive irradiation light. A beam splitter is disposed between the light source and the measurement object,
The beam splitter reflects the irradiation light reflected from the measurement object and returned from the measurement object, so that the light receiving element receives the irradiation light passing through the measurement object. An optical distance measuring device according to claim 1.   The optical distance measuring device according to any one of claims 1 to 7, wherein the light receiving element receives irradiation light passing through the measurement object by transmitting the measurement object.

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