JP7000176B2 - Optical image measuring device - Google Patents

Description

The present invention relates to an optical image measuring device for observing a measurement target using light interference.

Optical Coherence Tomography (OCT) is a technique for acquiring tomographic images of objects to be measured using light interference. It has been put into practical use since 1996 in the field of fundus examination, and in recent years, cardiology, dentistry, etc. Application to various fields such as oncology, food industry and regenerative medicine is being considered.

In OCT, the light from the light source is divided into two, a measurement light that irradiates the measurement target and a reference light that is reflected by the reference light mirror without irradiating the measurement target, and the signal light reflected from the measurement target is referred to. A measurement signal is obtained by combining with light and interfering with it.

The OCT is roughly divided into a time domain OCT and a Fourier domain OCT according to a method of scanning the measurement position in the optical axis direction (hereinafter referred to as z scan). In the time domain OCT, a low coherence light source is used as a light source, and z-scan is performed by scanning the reference optical mirror at the time of measurement. As a result, only the components having the same optical path length as the reference light contained in the signal light interfere with each other, and the envelope detection is performed on the obtained interference signal to demodulate the desired signal. The Fourier domain OCT is further divided into a wavelength scanning OCT and a spectral domain OCT. In the wavelength scanning OCT, a wavelength sweeping light source capable of scanning the wavelength of the emitted light is used, and z-scanning is performed by scanning the wavelength at the time of measurement, and the wavelength dependence (interference) of the detected interference light intensity is performed. The desired signal is obtained by Fourier transforming the spectrum). In the spectrum domain OCT, a wide band light source is used as a light source, the generated interference light is separated by a spectroscope, and the interference light intensity (interference spectrum) for each wavelength component is detected, which corresponds to z scan. A desired signal is obtained by Fourier transforming the obtained interference spectrum.

The following Patent Document 1 describes a technique related to OCT. The document states, "To suppress the influence of reflected light from a specific part and obtain a clear image of the object to be measured. The subject is "a light source 301 that emits laser light, an optical branching portion 304 that branches the laser light into signal light and reference light, and an objective lens 306 that condenses and irradiates the signal light on the measurement target in the container 308." , Condensing position scanning unit 307 that scans the condensing position of signal light, objective lens 311 that condenses reference light, reflection mirror 314, flat plate 313 arranged between objective lens 311 and reflection mirror 314, depending on the measurement target. Detects interference light, an interference optical system that combines reflected or scattered signal light with reference light reflected by a reflection mirror and passed through the objective lens 311 to generate three or more interference lights with different phase relationships from each other. The light detector 324, 325 is provided. Here, the objective lens 311 is the same as the objective lens 306, and the flat plate 313 has the same material and the same thickness as the portion through which the signal light of the container 308 is transmitted. 』(See summary).

Japanese Unexamined Patent Publication No. 2016-0449999

Since OCT uses light as a probe, the three-dimensional structure of the sample can be visualized with high resolution in a non-contact manner. Due to this feature, it is suitable for quality inspection of products in the bio-medical field such as cultured cells and biopharmacy in regenerative medicine without taking them out of the container.

Containers used in the bio-medical field, such as spheroid culture containers, which are one of the transplanted tissues in regenerative medicine, and vials and ampoules used for storing biopharmacy, often have a curved shape. .. Even if it looks like a plane, in most cases it is not a strict plane that does not affect the optical measurement. When the OCT measurement is performed through a container having such a curved surface shape, the signal strength and the spatial resolution are lowered due to the influence of the aberration generated on the curved surface. Further, the amount of aberration generated changes at high speed in time according to the scanning of the condensing position of the signal light applied to the sample. Therefore, it is difficult to suppress the influence of aberration by the conventional quantitative aberration correction method using a relay lens, a liquid crystal display, or the like. For this reason, it is difficult for the conventional OCT to obtain an accurate measurement result in the measurement over the curved surface of the container.

The present invention has been made in view of the above problems, and when a sample contained in a container having a curved surface is measured by OCT, an optical image capable of obtaining an accurate measurement result even through the curved surface can be obtained. The purpose is to provide a measuring device.

The optical image measuring apparatus according to the present invention houses an object in a container that generates a different amount of aberration depending on the condensing position of signal light, is arranged in the middle of an optical path, and the aberration caused by the container. It is provided with an optical member that reduces the influence of the amount. As a result, an aberration similar to the aberration applied to the signal light can be applied to the reference light, so that the wavefront shape of the signal light and the wavefront shape of the reference light match. Therefore, it is possible to suppress a decrease in signal strength and resolution due to aberrations generated in the container.

As an example, the container has a curved surface, and the optical member also has a curved surface similar to or the same shape as the container. As a result, the influence of aberration can be suppressed with high accuracy with a simple configuration.

As an example, the optical member is formed integrally with a reflecting portion that reflects the reference light. As a result, the number of parts and the number of adjustment points can be reduced, so that a compact and inexpensive optical image measuring device can be provided.

As an example, the optical member is formed so as to be spatially separated from the reflecting portion that reflects the reference light. As a result, the position of the portion of the container where the aberration is generated and the position of the reflecting portion can be adjusted independently, so that the influence of the aberration can be suppressed with high accuracy.

As an example, the light collection position of the signal light and the light collection position of the reference light are arranged between the light source and the optical branch portion, and scanning is performed using an optical element that changes the angle of the optical axis. As a result, since the focused position of the signal light and the focused position of the reference light can be scanned in synchronization by using a single optical element, the influence of aberration can be suppressed with a simple configuration.

As an example, the light collection position of the signal light is scanned by the first scanning unit arranged between the optical branch portion and the object, and the light collection position of the reference light is the optical branch portion and the optical member. It was decided to scan by the second scanning unit arranged between the two. Thereby, the focusing position of the reference light can be controlled independently of the focusing position of the signal light. Therefore, the degree of freedom in designing the optical member for suppressing the influence of aberration is increased, and the influence of aberration can be suppressed with higher accuracy.

As an example, it was decided to branch a part of the interference light to monitor the spatial intensity distribution of the interference light and adjust the position of the optical member based on the monitor signal. As a result, the position of the optical member can be adjusted with high accuracy, so that the influence of aberration can be suppressed with higher accuracy.

As an example, after defocusing aberration is applied to the signal light in advance, the signal light and the reference light are irradiated to the object via the same optical path, and the signal light reflected from the object is defocused. It was decided to correct the aberration. As a result, the influence of the aberration of the container can be corrected with high accuracy.

According to the present invention, even when the sample is housed in a container in which the amount of aberration generated differs depending on the condensing position of the signal light, the optical measurement can be accurately performed. Issues, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

It is a schematic diagram which shows the structure of the optical image measuring apparatus 100 which concerns on Embodiment 1. FIG. It is a figure explaining the aberration caused by the shape of a sample container 109. This is the result of calculating the response function in the z direction when the optical member 113 is present (solid line) and when it is not present (dotted line). It is a spot profile of the signal light when there is an aberration (solid line) and when there is no aberration (dotted line) generated by the sample container 109. It is a schematic diagram which shows the structure of the optical image measuring apparatus 100 which concerns on Embodiment 2. FIG. It is a schematic diagram which shows the structure of the optical image measuring apparatus 100 which concerns on Embodiment 3.

<Embodiment 1: Device Configuration>
FIG. 1 is a schematic diagram showing the configuration of the optical image measuring device 100 according to the first embodiment of the present invention. The laser light emitted from the light source 101 in a linearly polarized state is converted into parallel light by the collimating lens 102. The galvano mirrors 103 and 104 can scan the optical axis direction of the laser beam by scanning the angle of the reflecting surface. The λ / 2 plate 105 adjusts the polarization state of the laser beam by adjusting the crystal axis direction. The polarization beam splitter 106 splits the laser beam into signal light and reference light. The branch ratio of the signal light and the reference light can be freely adjusted by the λ / 2 plate 105, and the typical intensity ratio is 1: 1. The galvano mirrors 103 and 104 scan in the optical axis direction of the laser beam before the laser beam is split into the signal light and the reference light. As a result, the position where the signal light is collected by the objective lens 108 and the position where the reference light is collected by the reference light lens 112 are two-dimensionally and synchronously scanned in a plane perpendicular to the optical axis.

The signal light reflected from the polarization beam splitter 106 is the objective after the polarization state is converted from s-polarization to circular polarization by the λ / 4 plate 107 whose optical axis direction is set to about 22.5 degrees with respect to the horizontal direction. The sample 110 is focused and irradiated by the lens 108. The signal light reflected from the sample 110 passes through the objective lens 108 again, the polarization state is converted from circular polarization to p-polarization by the λ / 4 plate 107, and the light is incident on the polarization beam splitter 106.

The reference light has the same numerical aperture as the objective lens 108 after the polarization state is converted from p-polarization to circular polarization by the λ / 4 plate 111 whose optical axis direction is set to about 22.5 degrees with respect to the horizontal direction. A reference light lens 112 having a focal distance focuses and irradiates the reflecting portion 114 of the optical member 113. The optical member 113 is made of the same material as the sample container 109 and has substantially the same shape. Therefore, the aberration applied to the signal light by the sample container 109 and the aberration applied to the reference light by the reflecting unit 114 are substantially equal to each other. Further, since the focusing position of the signal light and the focusing position of the reference light are carried out by a single galvano mirror pair (galvano mirrors 103 and 104), they are completely synchronized in time. As a result, the same aberration is always applied to the signal light and the reference light, and as shown in FIG. 2 described later, the wavefront shape of the signal light and the wavefront shape of the reference light almost match at any time.

The polarization beam splitter 106 combines the signal light reflected from the sample 110 with the reference light reflected from the reflecting unit 114, whereby synthetic light is generated. A part of the synthesized light is reflected by the half beam splitter 116 and passes through the splitter 117. The transducer 117 is set so that the transmission axis direction is about 45 degrees with respect to the horizontal direction. The CCD camera 118 detects the generated interference light. The CCD camera 118 outputs the spatial intensity distribution of the interference light.

The spatial intensity distribution of the interference light is uniform when the wavefront shape of the signal light and the wavefront shape of the reference light match, and when the wavefront shape deviates, the interference fringes correspond to the deviation. A pattern is formed. That is, by monitoring the output of the CCD camera 118, it is possible to confirm the degree of coincidence between the wavefront of the signal light and the wavefront of the reference light. In the first embodiment, the user monitors the output from the CCD camera 118 and adjusts the position of the optical member 113 by using the electric stage 115 so that the wavefront of the signal light and the wavefront of the reference light match. I decided. As a result, the influence of aberrations generated in the sample container 109 can be suppressed with high accuracy.

The combined light transmitted through the half beam splitter 116 is guided to the interference optical system 126. The interference optical system 126 includes a half beam splitter 119, a λ / 2 plate 120, a λ / 4 plate 123, a condenser lens 121 and 124, and a Wollaston prism 122 and 125. The combined light incident on the interference optical system 126 is split into two branches, transmitted light and reflected light, by the half beam splitter 119.

The combined light transmitted through the half beam splitter 119 is transmitted by the condenser lens 121 after passing through the λ / 2 plate 120 whose optical axis is set to about 22.5 degrees with respect to the horizontal direction, and is condensed by the condenser lens 121. It is split by 122. As a result, the first interference light and the second interference light having a phase relationship different from each other by 180 degrees are generated. The current differential type photodetector 127 detects the first interference light and the second interference light, and outputs a differential output signal 129 proportional to the difference in intensity between them.

The combined light reflected from the half beam splitter 119 passes through the λ / 4 plate 123 whose optical axis is set to about 45 degrees with respect to the horizontal direction, is then focused by the condenser lens 124, and is focused by the Wollaston prism 125. It is split into polarization. As a result, the third interference light and the fourth interference light having a phase relationship different from each other by about 180 degrees are generated. The phase of the third interference light differs from that of the first interference light by about 90 degrees. The current differential type photodetector 128 detects the third interference light and the fourth interference light, and outputs a differential output signal 130 proportional to the difference in intensity between them. The differential output signals 129 and 130 are input to the image generation unit 131, and the image display unit 132 generates and displays an image based on these signals.

FIG. 2 is a diagram illustrating aberration caused by the shape of the sample container 109. The sample 110 is arranged in a sample container 109 whose bottom surface has a curved surface shape. The signal light is focused on the sample 110 through the bottom surface of the sample container 109. At this time, aberrations are added to the signal light according to the shape of the bottom surface of the sample container 109 and its thickness. The type and magnitude of this aberration differ depending on the position where the signal light is collected with respect to the sample container 109. Therefore, this aberration will fluctuate with time as the signal light condensing position is scanned by the galvano mirrors 103 and 104.

As the sample 110, for example, cell spheroids, which are attracting attention in the fields of drug discovery and regenerative medicine, can be considered. Cell spheroids are three-dimensional structures formed by cell adhesion due to the cell adhesion ability of cells, and are used for drug screening of anticancer agents and disease treatment by regenerative medicine. Cell spheroids are often cultured in a culture vessel having a spherical bottom surface, such as sample vessel 109. Due to the influence of aberrations generated from the spherical shape of the sample container 109, it has been difficult to perform precise optical measurement through the sample container 109 in the prior art.

As another example of sample 110, a biopharmacy can be considered. Biopharmacy includes drugs manufactured, extracted, and semi-synthesized using living organisms, and is expected to be effective for diseases that could not be sufficiently solved by small molecule drugs manufactured by chemical synthesis. Biopharmacy is stored in special containers called vials and ampoules, which also have a curved shape. Therefore, similarly, in the prior art, it was difficult to carry out precise optical measurement through the container.

According to the first embodiment, the optical member 113 imparts an aberration substantially equal to the aberration imparted to the signal light by the sample container 109 to the reference light. As a result, the wavefront shape of the signal light and the wavefront shape of the reference light are almost the same at any time, so that precise optical measurement can be performed through the sample container 109.

<Embodiment 1: Spatial resolution>
The spatial resolution and signal intensity in the optical axis direction (depth direction of the sample 110) of the optical image measuring device 100 will be described. In the first embodiment, the reflected light component from other than the focal point of the objective lens 108 included in the signal light has a defocus aberration. Therefore, since the wavefront shape of the signal light does not match the wavefront shape of the reference light, the signal light and the reference light do not interfere with each other spatially uniformly. As a result, a large number of interference fringes are formed on the light receiving surface of the detector. When such interference fringes are formed, the value obtained by integrating the detected interference light intensities in the light receiving surface is substantially equal to the sum of the intensity of the signal light and the reference light. That is, the differential output signals 129 and 130 corresponding to the reflected light components from other than the focal point of the objective lens 108 become substantially 0. By such a principle, the reflected light component from other than the focal point of the objective lens 108 does not effectively interfere with the reference light, and only the reflected light component from the focal point of the objective lens 108 is selectively detected, resulting in high z-resolution. Can be achieved.

The z resolution is defined by the full width at half maximum of the response function in the z direction. The z-resolution is determined by the numerical aperture NA of the objective lens 108 and the wavelength λ of the laser beam, and is proportional to λ / NA ² . Generally, the wavelength of light used in an OCT device is about 600 nm to 1300 nm, which is difficult to be absorbed by both hemoglobin and water. For example, when the numerical aperture of the objective lens 108 is 0.4 or more, the spatial resolution in the z direction at a wavelength of 600 nm to 1300 nm is about 3.3 μm to about 7.2 μm.

The intensity of the detected signal is proportional to the product of the amplitude of the signal photoelectric field and the amplitude of the reference photoelectric field. Therefore, even if the signal light power is small, the detection sensitivity can be improved by increasing the reference light power. As a result, highly sensitive reflected light detection can be realized while suppressing damage to the sample 110 due to signal light.

In the case of the conventional configuration in which the optical member 113 is used and no aberration is given to the reference light, the wavefront shape of the signal light reflected from the focal point of the objective lens 108 and the wavefront shape of the reference light are affected by the aberration generated in the sample container 109. Since they do not match, the signal strength and z-resolution are lower than those in the first embodiment.

FIG. 3A is a result of calculating the response function in the z direction when the optical member 113 is present (solid line) and when it is not present (dotted line). The parameters used in the calculation are as follows. (A) Outer radius of curvature and inner radius of curvature of the bottom surface of the sample container 109: 4.14 mm and 3.24 mm, respectively, (b) Thickness: 1.06 mm, (c) Material refractive index: 1.59, (d) Numerical aperture of objective lens 108: 0.35, (e) Laser light wavelength: 785 nm, (f) Signal light focusing position: Sample container 109 In the optical axis direction from the surface on the bottom surface where the sample is placed. 0.1m, 0.3mm in the direction perpendicular to the optical axis. When the optical member 113 is not provided, the z resolution is about 25% lower and the signal strength is about 50% lower than that of the first embodiment. From the calculation results, it can be seen that in the first embodiment, the influence of aberration can be significantly suppressed with a simple configuration.

FIG. 3B is a spot profile of the signal light with and without aberration (solid line) generated by the sample container 109. The parameters used in the calculation are the same as in FIG. 3A. The xy resolution of the optical image measuring device 100 is defined by the full width at half maximum of the spot size of the signal light. As shown in FIG. 3B, it can be seen that the full width at half maximum (that is, xy resolution) of the spot size hardly changes depending on the presence or absence of aberration.

The xy resolution is basically determined by the spot size and is proportional to λ / NA in the case of no aberration. When aberration is added to the signal light, the spot size tends to be large (xy resolution is low), and the spot size of the signal light is determined regardless of the wavefront shape of the reference light. Therefore, when the optical member 113 imparts an aberration to the reference light, it is not possible to suppress an increase in the spot size due to the aberration imparted to the signal light. However, as shown by the calculation result of FIG. 3B, the decrease in xy resolution due to the occurrence of aberration is much smaller than the decrease in z resolution, so it can be said that there is almost no problem in practical use.

<Embodiment 1: Optical system>
The function of the interference optical system 126 will be described using a mathematical formula. The Jones vector of the synthesized light at the time of incident on the interference optical system 126 is expressed by the following equation 1. In Equation 1, E _sig is the complex amplitude of the signal light reflected from the focal point of the objective lens 108, E _ref is the complex amplitude of the reference light, r is the position coordinate in the direction perpendicular to the optical axis, and t is the time.

The Jones vector of the synthetic light after passing through the half beam splitter 119 and the λ / 2 plate 120 is expressed by the following equation 2.

The synthetic light represented by the formula 2 is branched into a p-polarized component and an s-polarized component by the Wollaston prism 122, and then differentially detected by the current differential type photodetector 127. At this time, the differential output signal 129 (symbol I) output by the photodetector 127 is represented by the following equation 3. A _sig and A _ref , and θ _sig and θ _ref are amplitudes and topologies when the complex numbers E _sig and E _ref are expressed in polar coordinates, respectively. d is the radius of the light receiving portion of the photodetector. The integration region is in the plane of the light receiving portion of the photodetector 127. 1 / πd ² is a factor introduced to simplify the calculation. Here, the electric field amplitude is out of the integral, assuming that the signal light and the reference light have a flat intensity distribution.

θ _sig and θ _ref are divided into space-independent components (aberration-free components) θ ⁽⁰⁾ _sig and θ ⁽⁰⁾ _ref and space-dependent components (aberration components) φ _sig and φ _ref , respectively. It can be expressed by 4 and Equation 5.

The aberration component φ _sig of the signal light and the aberration component φ _ref of the reference light are generated by the sample container 109 and the optical member 113, respectively, and change with time as the condensing position is scanned, as described above. The amount of aberration is equal. That is, in the first embodiment, the following equation 6 approximately holds due to the effect of inserting the optical member 113.

Equation 7 is obtained by substituting Equations 4 to 6 into Equation 3.

The Jones vector of the synthetic light after being reflected by the half beam splitter 119 and further transmitted through the λ / 4 plate 123 is as shown in Equation 8 below.

The synthetic light represented by the formula 4 is bifurcated into a p-polarized component and an s-polarized component by the Wollaston prism 125, and then differentially detected by the current differential type photodetector 128. At this time, the differential output signal 130 (symbol Q) output by the photodetector 128 is represented by the following equation 9.

By substituting equations 4 to 6 into equation 9 as in the case of the differential output signal 129, the following equation 10 can be obtained.

The image generation unit 131 performs the calculation of the following equation 11 on the signals represented by the equations 7 and 5, so that the reflection proportional to the intensity of the signal light is independent of the phase difference between the signal light and the reference light. Generate a signal strength S. It can be seen that the equation 11 does not include the aberration components φ _sig and φ _ref , and the influence of the aberration is removed from the signal.

<Embodiment 1: Summary>
The optical image measuring apparatus 100 according to the first embodiment imparts substantially the same aberration to the reference light by the optical member 113, which is substantially the same as the aberration imparted to the signal light by the sample container 109. As a result, compared to the case where the reference light is irradiated to a normal plane mirror (when no aberration is added to the reference light), the signal strength is lowered and z due to the mismatch between the wavefront shape of the signal light and the wavefront shape of the reference light. The decrease in resolution can be significantly suppressed. Therefore, accurate measurement results can be obtained through the sample container 109 having a curved surface.

In the first embodiment, the optical member 113 having the same shape as the sample container 109 is used, but any optical member 113 may be used as long as it can impart the same aberration as the signal light to the reference light. .. For example, an element that electrically controls the amount of aberration generated, such as a spatial phase modulator or a deformable mirror, can also be used.

<Embodiment 2>
FIG. 4 is a schematic diagram showing the configuration of the optical image measuring device 100 according to the second embodiment of the present invention. The same parts as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In the second embodiment, the galvano mirrors 401 and 402 are used to scan the light condensing position of the signal light, and the galvano mirrors 403 and 404 are used to scan the condensing position of the reference light. That is, individual optical elements are used to scan each of the signal light and the reference light. Further, the optical member 113 and the reflecting portion 114 are formed so as to be spatially separated from each other, and the reference light passes through the optical member 113 and is incident on the reflecting portion 114. Since other configurations are substantially the same as those of the first embodiment, the differences will be mainly described below.

The laser light emitted from the light source 101 is split into signal light and reference light by the polarizing beam splitter 106. The signal light reflected from the polarization beam splitter 106 reflects the galvano mirrors 401 and 402, and the polarization state is changed from s-polarization by the λ / 4 plate 107 whose optical axis direction is set to about 22.5 degrees with respect to the horizontal direction. After being converted to circular polarization, the sample 110 is focused and irradiated by the objective lens 108. At this time, the focusing position of the signal light by the objective lens 108 is two-dimensionally scanned by the galvanometer mirrors 401 and 402 in a plane perpendicular to the optical axis.

The reference light transmitted through the polarizing beam splitter 106 reflects the galvanometer mirrors 403 and 404, and the polarization state is changed from p-polarization by the λ / 4 plate 111 whose optical axis direction is set to about 22.5 degrees with respect to the horizontal direction. After being converted into circularly polarized light, the optical member 113 is focused and irradiated by the reference light lens 112. At this time, the focused position of the reference light by the reference light lens 112 is two-dimensionally scanned by the galvanometer mirrors 403 and 404 in a plane perpendicular to the optical axis in synchronization with the scanning of the focused position of the signal light. ..

In the second embodiment, since different galvano mirror pairs are used for scanning the light collection position of the signal light and scanning the light collection position of the reference light, each light collection position can be scanned independently. As a result, in order to minimize the influence of aberration, the amplitude and direction of the focused position scanning of the reference light can be freely adjusted. Therefore, the influence of the aberration generated in the sample container 109 can be suppressed with higher accuracy. For example, when the optical member 113 and the sample container 109 are composed of spherical surfaces having different radii of curvature, the aberration imparted to the reference light and the aberration imparted to the signal light are given in consideration of the difference in the radii of curvature. The focus position of the reference light can be scanned so that is always approximately equal.

In the second embodiment, the reflecting portion 114 is formed so as to be spatially separated from the optical member 113, and its position can be adjusted by the stage 405. That is, the position of the optical member 113 and the position of the reflecting portion 114 can be adjusted independently. With such a configuration, the degree of freedom of adjustment for minimizing the influence of aberration is improved. Therefore, the influence of the aberration generated in the sample container 109 can be suppressed with higher accuracy. Specifically, in the first embodiment, since the optical member 113 and the reflecting portion 114 are integrally formed, the condensing position of the reference light in the optical axis direction must be fixed to the reflecting portion 114. That is, the position of the optical member 113 in the optical axis direction had substantially no degree of freedom in adjustment. In the second embodiment, the aberration applied to the reference light can be freely adjusted including the position in the optical axis direction so as to be substantially equal to the aberration applied to the signal light.

<Embodiment 2: Summary>
The optical image measuring device 100 according to the second embodiment scans the light collecting position of the signal light and the light collecting position of the reference light by independent scanning units, and further spatially separates the optical member 113 and the reflecting unit 114. Formed. As a result, the influence of the aberration generated in the sample container 109 can be suppressed with higher accuracy than in the first embodiment, and an accurate measurement result can be obtained.

<Embodiment 3>
FIG. 5 is a schematic diagram showing the configuration of the optical image measuring device 100 according to the third embodiment of the present invention. The same parts as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. The third embodiment is different from the first embodiment in that the reflected light from the sample container 109 is used as the reference light. Hereinafter, the differences from the first embodiment will be mainly described.

The laser light emitted from the light source 101 in a linearly polarized state is converted into parallel light by the collimating lens 102, the polarization state is adjusted by the λ / 2 plate 105 whose crystal axis direction can be adjusted, and the signal light is signaled by the polarization beam splitter 501. And the reference light. The signal light reflected from the polarizing beam splitter 501 is reflected on the mirror 502, passes through the defocus adjustment lenses 503 and 505, is reflected on the mirror 506, and is incident on the polarizing beam splitter 507. The position of the defocus adjustment lens 503 in the optical axis direction can be adjusted by the actuator 504. This makes it possible to add arbitrary defocus aberration to the signal light. In the third embodiment, by adjusting the position in the optical axis direction of the defocus adjustment lens 503, the focusing position of the signal light by the objective lens 108 in the optical axis direction can be set to an arbitrary position.

The signal light reflected from the polarization beam splitter 507 passes through the galvanometer mirrors 103 and 104 after being reflected from the half beam splitter 508, and is focused and irradiated on the sample 110 arranged in the sample container 109 by the objective lens 108. Will be split. The signal light reflected from the sample 110 passes through the galvano mirrors 103 and 104 again, passes through the half beam splitter 508, and then enters the defocus adjustment unit 515.

The signal light incident on the defocus adjustment unit 515 reflects the polarization beam splitter 509, and the polarization state is changed from s polarization by the λ / 4 plate 510 whose optical axis direction is set to about 22.5 degrees with respect to the horizontal direction. After being converted to circular polarization, it passes through the defocus adjusting lens 511 and is incident on the deformable mirror 512. The deformable mirror 512 adjusts the wavefront shape so that the signal light is converted into parallel light when the signal light passes through the defocus adjustment lens 511 again. The signal light reflected from the deformable mirror 512 is converted into parallel light by the defocus adjustment lens 511, the polarization state is converted from circular polarization to p-polarization by the λ / 4 plate 510, and then the light is transmitted through the polarization beam splitter 509. .. The signal light transmitted through the polarized beam splitter 509 is mirrored after the polarization state is converted from p-polarization to circular polarization by the λ / 4 plate 513 whose optical axis direction is set to about 22.5 degrees with respect to the horizontal direction. The 514 is reflected, the polarization state is converted from circular polarization to s polarization by the λ / 4 plate 513, and the light is incident on the polarization beam splitter 509 again.

In the third embodiment, the defocus adjustment lenses 503 and 505 included in the defocus adjustment unit 515 correct the defocus applied to the signal light. As a result, the wavefront shape of the signal light and the wavefront shape of the reference light can be matched.

The reference light transmitted through the polarizing beam splitter 507 passes through the galvano mirrors 103 and 104 in the same manner as the signal light, and is focused and irradiated on the surface of the sample container 109 on the sample 110 side by the objective lens 108. At this time, since the reference light passes through the same sample container 109 in the same optical path as the signal light, an aberration substantially equal to the aberration applied to the signal light by the sample container 109 is also applied to the reference light. As a result, compared to the first embodiment in which the optical member 113 for imparting aberration to the reference light is separately provided, the wavefront of the signal light and the wavefront of the reference light are highly accurate without being affected by the dimensional error of the optical member 113. Can be matched with. Therefore, the influence of the aberration of the sample container 109 can be corrected with high accuracy. The reference light reflected from the sample container 109 passes through the galvanometer mirrors 103 and 104 again, passes through the half beam splitter 508, and then enters the polarizing beam splitter 509.

The signal light and the reference light are combined by the polarizing beam splitter 509 in a state where the wavefronts substantially match, and synthetic light is generated. Since the subsequent operation of the optical system is exactly the same as that of the first embodiment, the description thereof will be omitted here.

<Embodiment 3: Summary>
The optical image measuring device 100 according to the third embodiment uses the reflected light from the sample container 109 as reference light. As a result, the influence of the aberration generated in the sample container 109 can be suppressed with higher accuracy than in the first embodiment, and an accurate measurement result can be obtained.

<About a modification of the present invention>
The present invention is not limited to the above-mentioned examples, and includes various modifications. The above-mentioned examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

The image generation unit 131 can be configured by using hardware such as a circuit device that implements these functions, or can be configured by executing software that implements these functions by an arithmetic unit.

In the first embodiment, the user monitors the output of the CCD camera 118 to adjust the position of the optical member 113 so as to suppress the interference fringes. Instead of this, for example, a calculation unit such as an image generation unit 131 may automatically adjust the position of the optical member 113 so as to suppress interference fringes by controlling the electric stage 115. For example, by acquiring the output of the CCD camera 118 and performing image analysis on it, the degree of interference fringes can be quantified. The electric stage 115 may be controlled so that the value becomes small. The degree of interference fringes can be quantified, for example, by calculating the degree of similarity with an image pattern having no (or few) interference fringes, or by detecting the edges of the interference fringes. can. Other suitable image analysis methods may be used.

In the above embodiments, a sample container 109 having a curved bottom surface is used, but the scope of application of the present invention is not limited to the curved surface shape, and any shape (or any material) such as a V-shape or an aspherical shape is used. , Thickness) can be applied to the sample container 109. For example, the present invention can be applied even when the sample 110 is housed in a flow path or a capillary having a curvature.

In the above embodiment, it is decided to generate four interference lights in the interference optical system 126, but the number of interference lights may be any number as long as it is three or more in order to acquire a phase-independent signal. ..

101: Light source 102: Collimating lens 103, 104: Galvano mirror 106: Polarized beam splitter 105, 120: λ / 2 plate 107, 111, 123: λ / 4 plate 108: Objective lens 109: Sample container 110: Sample 112: Reference Optical lens 113: Optical member 114: Reflector 116: Half beam splitter 121, 124: Condensing lens 122, 125: Wollaston prism 126: Interference optical system 127, 128: Current differential type optical detector 131: Image generation Part 132: Image display part

Claims (11)

An optical image measuring device that acquires an image of an object.
A light source that emits laser light,
An optical branching portion that branches the laser beam emitted by the light source into signal light and reference light.
A condensing position scanning unit that scans the condensing position of the signal light and the condensing position of the reference light in synchronization with each other.
An interference optical system that generates interference light by combining the signal light reflected from the object and the reference light.
Equipped with
The object is housed in a container that generates a different amount of aberration depending on the condensing position of the signal light.
The optical image measuring device is further provided with an optical member which is arranged in the middle of the optical path and reduces the influence of the amount of aberration caused by the container .
The light collecting position scanning unit is arranged between the light source and the optical branching unit.
The condensing position scanning unit scans the condensing position of the signal light and the condensing position of the reference light in synchronization with each other by changing the angle of the optical axis of the laser light emitted by the light source.
An optical image measuring device characterized by this. An optical image measuring device that acquires an image of an object.
A light source that emits laser light,
An optical branching portion that branches the laser beam emitted by the light source into signal light and reference light.
A condensing position scanning unit that scans the condensing position of the signal light and the condensing position of the reference light in synchronization with each other.
An interference optical system that generates interference light by combining the signal light reflected from the object and the reference light.
Equipped with
The object is housed in a container that generates a different amount of aberration depending on the condensing position of the signal light.
The optical image measuring device is further provided with an optical member which is arranged in the middle of the optical path and reduces the influence of the amount of aberration caused by the container .
The optical image measuring device further
An interference light branching portion that branches a part of the interference light,
A monitor that monitors the intensity distribution of the branched interference light,
An optical member drive unit that adjusts the position of the optical member,
Equipped with
The optical member driving unit adjusts the position of the optical member based on the monitoring result by the monitor to match the wavefront of the signal light with the wavefront of the reference light.
An optical image measuring device characterized by this. The optical branching portion directs the signal light to a signal optical path toward the object and directs the reference light to a reference optical path different from the signal optical path.
The optical member is arranged in the middle of the reference optical path, and the optical member is arranged in the middle of the reference optical path.
The optical image measuring device further includes a first objective lens that concentrates the signal light on the object, and a second objective lens that concentrates the reference light on the optical member. The optical image measuring apparatus according to claim 1 or 2 . The optical image measuring apparatus according to claim 1 or 2 , wherein the container has a curved surface at a portion where the signal light is collected. The optical image measuring apparatus according to claim 1 or 2 , wherein the optical member has a curved surface at a portion where the reference light is collected. The container has a curved surface at a portion where the signal light is collected, and the container has a curved surface.
The optical member has a curved surface at a portion where the reference light is focused, and the optical member has a curved surface.
The optical image measuring apparatus according to claim 1 or 2 , wherein the curved surface of the container and the curved surface of the optical member have the same shape. The optical member reflects the reference light and returns it to the optical branch portion.
The optical image measuring apparatus according to claim 1 or 2 , wherein the optical branching portion guides the reference light reflected from the optical member to the interference optical system. The optical member includes a reflecting portion that reflects the reference light and returns it to the optical branching portion.
The optical member has a transmission portion through which the reference light is transmitted.
The optical image measuring apparatus according to claim 7 , wherein the reflecting portion is arranged at a position away from the transmitting portion and reflects the reference light transmitted through the transmitting portion. The condensing position scanning unit is
A first scanning unit, which is arranged between the optical branching portion and the object and scans the condensing position of the signal light.
A second scanning unit, which is arranged between the optical branching portion and the optical member and changes the condensing position of the reference light.
The optical image measuring apparatus according to claim 1 or 2 , wherein the optical image measuring apparatus is provided. The optical image measuring apparatus according to claim 1 or 2 , wherein the interference optical system generates three or more of the interference lights having different phase relationships with each other. The optical image measuring device further includes an irradiation optical system that irradiates the object with the signal light and the reference light output by the optical branch portion via the same optical path.
The optical member is
A defocus aberration imparting unit, which imparts defocus aberration to the signal light branched by the optical branch portion before the signal light is applied to the object.
An optical combiner, which combines the signal light to which the defocus aberration is applied with the reference light propagating on the optical path of the irradiation optical system.
A defocus aberration corrector, which reduces the difference between the signal light and the wavefront and the wavefront of the reference light by correcting the defocus aberration of the signal light reflected from the object.
The optical image measuring apparatus according to claim 1 or 2 , wherein the optical image measuring apparatus is provided.

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