WO2020017017A1 - Light measurement device and sample observation method - Google Patents

Abstract

This light measurement device comprises: a light source; a light splitting part for splitting light emitted from the light source into reference light and signal light; a scanning unit for irradiating the signal light so as to scan an object of measurement; an optical system for generating interference light by combining signal light that has been reflected or scattered by the object of measurement and the reference light; a photodetection unit for receiving the interference light generated by the optical system and converting the same into an electrical signal; and a signal processing unit for calculating the intensity of the signal light on the basis of the electrical signal produced from the conversion by the photodetection unit. The photodetection unit detects the signal light using a plurality of photodetection elements associated with a plurality of measurement areas overlapping a signal light irradiation area. The signal processing unit calculates the intensities of the signal light detected by each of the plurality of photodetection elements. The scanning unit scans the object of measurement by moving the irradiation area of the signal light irradiated onto the object of measurement such that some of the plurality of measurement areas at a first point in time overlap with other measurement areas from among the plurality of measurement areas at a second point in time.

Description

Optical measurement device and sample observation method

The present disclosure relates to an optical measurement device and a sample observation method using the same.

Optical measurement devices are devices that can non-destructively acquire information reflecting the surface structure and internal structure of a measurement target, and are used in a wide range of fields. As one type of such an optical measurement device, there is optical coherence tomography (OCT: Optical Coherence Tomography).

Since OCT has no invasiveness to the human body, it is expected to be applied particularly to the medical field and the biological field. In the ophthalmic field, an apparatus for forming an image of a fundus, a cornea, or the like is used. In OCT, light from a light source is split into two parts, a signal light that irradiates the measurement target and a reference light that is reflected by a reference light mirror without irradiating the measurement target, and the signal light reflected from the measurement target is combined with the reference light. A signal is obtained by wave and interference.

技術 In recent years, a technique of applying OCT to obtain time-dependent change information of a measurement target has attracted attention. An angiographic OCT is an example of an optical measurement device that uses the acquisition of aging information. In Patent Document 1, scanning is performed while simultaneously irradiating light emitted from a light source into two independent polarized beams and simultaneously irradiating the two polarized beams to two different portions on a line along a scanning direction by a galvanometer mirror. The reflected light is separated into a vertical component and a horizontal component, detected by two detectors at the same time, and two tomographic images of the same part at different times are acquired by one scan, and the two tomographic images are obtained. A scanning OCT apparatus that measures the time change amount of the phase of the same region from an image is disclosed. According to this device, it is possible to visualize a blood vessel, which is a portion of a human body tissue having a large amount of temporal change.

In the scanning optical measurement device as described above, in order to obtain time-dependent change information of a predetermined portion of the measurement target, the predetermined portion is measured a plurality of times at a time δt, and the obtained plurality of times are measured. The temporal change amount δS is obtained from the measurement result, and the temporal change information of the predetermined portion is obtained using δt and δS. At this time, the measurement interval δt becomes the time resolution of the temporal change information. By measuring with higher time resolution, more information can be obtained.

WO 2010/143601

走 査 In a scanning optical measurement device including a scanning OCT, it is necessary to increase the time resolution in order to obtain a large amount of time-dependent change information. However, since the time resolution depends on the scanning cycle, it is difficult to obtain a time resolution shorter than the scanning cycle. If an expensive scanning mechanism with a short scanning cycle is used, the apparatus becomes expensive and complicated.

The angiographic OCT of Patent Document 1 describes an OCT that irradiates a measurement object with two signal light beams in order to obtain temporal change information with a time resolution shorter than a beam scanning cycle. In the above-mentioned OCT, two polarized beams having different polarization states are irradiated to two different parts, and the two beams are separated according to the polarization state in order to separately detect information of the two different parts. For this reason, the OCT described in Patent Literature 1 requires a beam separation mechanism, and further requires an independent detection mechanism for each beam, which increases the device size. In the OCT described in Patent Document 1, two beams having different polarization states are used to separate beams. Therefore, there is a possibility that a difference occurs due to a difference in the polarization state between the information acquired by the two beams, resulting in a measurement error of the temporal change information.

The present disclosure has been made in view of the above points, and provides a technique capable of measuring temporal change information at a low cost and with a temporal resolution shorter than a scanning cycle.

As means for solving the above-described problems, for example, a light source, a light branching unit that branches light emitted from the light source into reference light and signal light, and scans the measurement target by irradiating the signal light A scanning unit that combines the signal light and the reference light reflected or scattered by the object to be measured, an optical system that generates interference light, and receives the interference light generated by the optical system. An optical measurement device comprising: a light detection unit that converts an electric signal, and a signal processing unit that calculates the intensity of the signal light based on the electric signal converted by the light detection unit, wherein the light detection unit Detecting the signal light by a plurality of light detection elements associated with each of a plurality of measurement areas overlapping the irradiation area of the signal light, wherein the signal processing unit detects each of the plurality of light detection elements Calculated signal light intensity Then, the scanning unit may be configured to irradiate the irradiation area of the signal light irradiating the measurement object with a part of the plurality of measurement areas at a first time different from the plurality of measurement areas at a second time. Provided is an optical measurement device that scans the measurement object by moving the measurement object so as to partially overlap the measurement object.

Also, for example, in a sample observation method using an optical measurement device that acquires an optical coherence tomographic image, the measurement object is irradiated with signal light, and the reflected or scattered signal light and reference light are combined to generate interference light. And detecting a signal intensity of the interference light at a first time by a plurality of photodetectors corresponding to a plurality of measurement regions overlapping with the irradiation region of the signal light; and Moving the irradiation area so that a part of the plurality of measurement areas at a time point and another part of the plurality of measurement areas at a second time point overlap with each of the plurality of measurement areas. Detecting the signal intensity of the interference light at the second point in time with the plurality of light detection elements.

According to the present disclosure, temporal change information can be measured at low cost and with a temporal resolution shorter than the scanning period. Problems, configurations, and effects other than those described above will be apparent from the following description of the embodiments.

1 is a schematic diagram illustrating a basic embodiment of an optical measurement device according to the present disclosure. FIG. 3 is a schematic diagram illustrating a correspondence relationship between a beam spot and an arrangement of a differential detection circuit in an operation state of the optical measurement device according to the first embodiment. It is a schematic diagram which shows a mode that the beam spot irradiated on the measurement object moves. FIG. 4 is a schematic diagram illustrating a relationship between a temporal change in a position of a measurement region and a time resolution. FIG. 3 is a schematic diagram illustrating a configuration of a reference optical system for expanding a beam diameter described above. FIG. 9 is a diagram illustrating a basic configuration example of an optical measurement device according to a second embodiment. FIG. 9 is a schematic diagram illustrating a configuration of an optical measurement device according to a third embodiment. FIG. 13 is a schematic diagram illustrating a configuration of an optical measurement device according to a fourth embodiment. FIG. 3 is a schematic diagram illustrating a state of movement of a beam spot on a measurement object. FIG. 9 is a diagram illustrating a scanning method in which a plurality of measurement regions are defined in both the x direction and the y direction.

Hereinafter, various embodiments of the present disclosure will be described with reference to the accompanying drawings. However, these embodiments are merely examples for realizing the present disclosure, and do not limit the technical scope of the present disclosure. Further, in each of the drawings, the same reference numerals are given to the common components.

<Example 1>
Hereinafter, an optical measurement device according to a first embodiment will be described with reference to FIGS.
FIG. 1 is a schematic diagram illustrating a basic embodiment of an optical measurement device 1 according to the present disclosure. In FIG. 1, the vertical direction in the figure is the z direction, the horizontal direction is the x direction, and the direction perpendicular to the paper is the y direction.

The optical measurement device 1 includes a light source unit 190, a polarization beam splitter 106, a reference optical system 191, a scanning unit 159, a sample stage 139, a cover glass 114, an interference optical system 132, a photodiode array (124, 125, 130, and 131), It includes a differential detection circuit (134 and 135), a signal processing unit 136, and a control unit 116.

The light source unit 190 includes a light source 101, a collimating lens 102, a beam shaping prism 103, an ND (Neutral Density) filter 104, and a λ / 2 plate 105 whose optical axis direction can be adjusted. Laser light having a single wavelength component emitted from the light source 101 is converted into parallel light by the collimating lens 102. Subsequently, the laser beam converted into parallel light is shaped into an elliptical beam cross-sectional shape by the beam shaping prism 103 so that the y direction is longer than the x direction. After that, the intensity of the laser light is reduced by the ND filter 104, the polarization direction is rotated by the λ / 2 plate 105 whose optical axis direction is adjustable, and then the polarization beam splitter 106 converts the laser light into a signal light and a reference light. Branched.

The scanning unit 159 includes the two-dimensional scanner 107, the λ / 4 plate 112, the lens 113, and the lens actuator 117. The signal light enters the optical system provided in the scanning unit 159, passes through the two-dimensional scanner 107, and passes through the λ / 4 plate 112 whose optical axis direction is set to about 22.5 degrees with respect to the xz plane. The transmitted light is converted from s-polarized light to circularly polarized light. After that, the signal light is transmitted through the cover glass 114 while being converged by the lens 113 having a numerical aperture of 0.3 or more, and irradiates the measurement object 115 to form a beam spot 140 at the condensing position.

Here, since the cross-sectional shape of the beam incident on the lens 113 is an ellipse in the y direction longer than the x direction, the numerical aperture at the time of focusing is larger in the y direction than in the x direction. Therefore, the shape of the beam spot 140 on the xy plane is an ellipse in which the x direction is longer than the y direction.

The position of the beam spot 140 is moved by the scanning unit 159 in any of the x, y, and z directions. The lens 113 is moved at least in the z direction by the control of the lens actuator 117 by the control unit 116, whereby the focus position (measurement position) of the signal light by the lens 113 is moved.

Further, the movement of the condensing position of the signal light in the xy directions is performed by two galvanometer mirrors 108 and 109 and a two-dimensional scanner 107 including lenses 110 and 111 provided in the optical path of the signal light. The scanning of the object to be measured is performed based on the condensing position of the signal light.

信号 The signal light reflected or scattered from the measurement object is converted by the lens 113 into parallel light (beam). After that, the polarization state of the signal light is changed from circularly polarized light to p-polarized light by the λ / 4 plate 112, and the polarized light enters the polarization beam splitter 106. By moving the measurement target 115 by moving the sample stage 139, the position of the signal light focusing position in the measurement target 115 is roughly moved.

On the other hand, the reference light is transmitted through the λ / 4 plate 118, and the polarization state is converted from p-polarized light to circularly-polarized light. After that, the reference light is incident on the mirror 119 whose position is fixed, is reflected, and then passes through the λ / 4 plate 118 again, where the polarization state is changed from circularly polarized light to s-polarized light, and is incident on the polarization beam splitter 106. I do.

The signal light and the reference light are multiplexed by the polarization beam splitter 106 to generate a combined light. The combined light is guided to an interference optical system 132 including a half beam splitter 120, a λ / 2 plate (121 and 127), a λ / 4 plate 126, a condenser lens (122 and 128), and a polarizing beam splitter (123 and 129). I will

合成 The combined light that has entered the interference optical system 132 is split into two by the half beam splitter 120 into transmitted light and reflected light. The transmitted light passes through the λ / 2 plate 121 whose optical axis is set to about 22.5 degrees with respect to the xz plane, and is then condensed by the condenser lens 122. After that, the transmitted light is split into two by the polarization beam splitter 123, and a first interference light 144 and a second interference light 145 having a phase relationship different from each other by 180 degrees are generated.

The first interference light 144 is condensed by the condenser lens 122 and forms an image 153 of the beam spot 140 at the position of the photodiode array 124. The photodiode array 124 is arranged such that a plurality of photodetectors (photodiodes) 148 overlap the image 153 of the beam spot 140.

Similarly, the second interference light 145 is condensed by the condenser lens 122 and forms an image 154 of the beam spot 140 at the position of the photodiode array 125. The photodiode array 125 includes a plurality of light detection elements 149 each functioning as a light detector, and the plurality of light detection elements 149 are arranged so as to overlap the image 154 of the beam spot 140.

Each of the first interference light 144 and the second interference light 145 is converted by the photodiode arrays 124 and 125 and the differential detection circuit 134 into a corresponding one of the plurality of light detection elements 148 and the plurality of light detection elements 149. The outputs are combined and current differential detection is performed, and a signal 137 proportional to the difference between the intensities of the two interference lights is output. Here, the mutually corresponding elements of the plurality of light detection elements 148 and the plurality of light detection elements 149 are, for example, in the example shown in FIG. And the leftmost light detection element of the plurality of light detection elements 149 correspond to each other.

On the other hand, the reflected light reflected by the half beam splitter 120 passes through the λ / 4 plate 126 whose optical axis is set at about 45 degrees with respect to the xz plane, and then has an optical axis of about 22.5 with respect to the xz plane. The light is transmitted through the λ / 2 plate 127 set at each time, and is condensed by the condenser lens 128. Thereafter, the reflected light is split into two by the polarizing beam splitter 129, and a third interference light and a fourth interference light having a phase relationship different from each other by 180 degrees are generated. Each of the third interference light and the fourth interference light is subjected to current differential detection by the photodiode arrays 131 and 130 and the differential detection circuit 135, and a signal 138 proportional to the difference between the intensities of the two interference lights is output. Is done.

The third interference light 146 is condensed by the condenser lens 128 and forms an image 155 of the beam spot 140 at the position of the photodiode array 131. The photodiode array 131 is arranged such that a plurality of photodetectors (photodiodes) 150 overlap the image 155 of the beam spot 140.

Similarly, the fourth interference light 147 is condensed by the condenser lens 128 to form an image 156 of the beam spot 140 at the position of the photodiode array 130. The photodiode array 130 includes a plurality of light detecting elements 151 each functioning as a light detector, and the plurality of light detecting elements 151 are arranged so as to overlap the image 156 of the beam spot 140.

Each of the third interference light 146 and the fourth interference light 147 is, by the photodiode arrays 130 and 131 and the differential detection circuit 135, an output of a corresponding one of the plurality of light detection elements 150 and the plurality of light detection elements 151. The outputs are combined and current differential detection is performed, and a signal 138 proportional to the difference between the intensities of the two interference lights is output. The meaning of “elements corresponding to each other” is as described above.

The signals 137 and 138 generated as described above are input to the signal processing unit 136 and operated to obtain a signal proportional to the amplitude of the signal light. Specifically, the amplitude of the signal light component at the time when the combined light enters the interference optical system 132 is E _sig , the amplitude of the reference light component is E _ref , the intensity of the signal 137 is I, and the intensity of the signal 138 is Q. The signal processing unit 136 performs the operation of the following equation 1, thereby obtaining a signal that does not depend on the phase and is proportional to the absolute value of the amplitude of the signal light.
| E _sig | · | E _ref | = {I ² + Q ² } ^1/2 (Equation 1)

Here, the signals 137 and 138 are output by the number of photodetectors 148, 149, 150, and 151 of each of the photodiode arrays 124, 125, 130, and 131. Is performed, and a signal proportional to the amplitude of the signal light corresponding to the number is obtained (four in the example shown in FIG. 1). In the present embodiment, since three or more interference light beams having different phase relationships are detected, a stable signal independent of the interference phase can be obtained by performing an operation on these detection signals.

FIG. 2 is a schematic diagram illustrating the correspondence between the beam spot 140 and the differential detection circuit 134 in the operation state of the optical measurement device 1 according to the first embodiment.

形状 The shape of the beam spot 140 on the measurement object 115 on the xy plane is an ellipse whose x direction is longer than the y direction, as described above. The signal light reflected by the measurement object 115 is multiplexed with the reference light to become interference lights 144, 145, 146, and 147, and the light receiving surfaces of the photodiode arrays 124, 125, 130, and 131 via the optical system of the apparatus. Above are formed images 153, 154, 155, and 156, respectively.

FIG. 2 shows the positional relationship between the photodiode arrays 124 and 125 and the images 153 and 154 corresponding to the first interference light and the second interference light. The positional relationship between the photodiode arrays 130 and 131 corresponding to the third interference light and the fourth interference light and the images 155 and 156 is the same as that of the first interference light and the second interference light.

The image 153 formed by the interference light 144 has an elliptical shape that is long in the direction 301 in which the four light detection elements 148 (D ₁₁ , D ₁₂ , D ₁₃ , and D ₁₄ ) of the photodiode array 124 are arranged. The image 153 extends over the four photodetectors 148, and each photodetector outputs a current proportional to the intensity of the component of the interference light 144 applied to each detector. In FIG. 2, the direction 301 in which the four photodetectors 148 are arranged is drawn on the image 153 so as to match the direction corresponding to the x direction on the measurement target 115.

The image 154 formed by the interference light 145 has an elliptical shape that is long in the direction 302 in which the four light detection elements 149 (D ₂₁ , D ₂₂ , D ₂₃ , and D ₂₄ ) of the photodiode array 125 are arranged. The image 154 extends over the four light detection elements 149, and each light detection element outputs a current proportional to the intensity of the component of the interference light 145 irradiated to each detection element. In FIG. 2, the direction 302 in which the four light detection elements 149 are arranged is drawn on the image 154 so as to match the direction corresponding to the x direction on the measurement target 115.

The relative positional relationship between the image 153 and the four light detecting elements 148 matches the relative positional relationship between the image 154 and the four light detecting elements 149, and the four light detecting elements 148 (D ₁₁ , D ₁₂ , D ₁₃ , and D ₁₄ ) and the four photodetectors 149 (D ₂₁ , D ₂₂ , D ₂₃ , and D ₂₄ ) together form four measurement regions 303 (A ₁ , A ₂ ) on the measurement target 115. , A ₃ , A ₄ ). Here, assuming that the interval between the respective photodetectors is δx and the magnification of the optical system is M, the interval δx ′ between the four measurement areas 303 is δx ′ = M × δx.

The current outputs of the four light detecting elements 148 (D ₁₁ , D ₁₂ , D ₁₃ , D ₁₄ ) and the four light detecting elements 149 (D ₂₁ , D ₂₂ , D ₂₃ , D ₂₄ ) correspond to the corresponding light detecting elements. (D ₁₁ and D ₂₁ , D ₁₂ and D ₂₂ , D ₁₃ and D ₂₃ , and D ₁₄ and D ₂₄ ) are input to the differential detection circuits 304, 305, 306, and 307, respectively. Then, the signals are differentially detected and input to the signal processing unit 136 as a signal 137 as a set of four signals.

As for the third interference light and the fourth interference light, similarly to the first interference light and the second interference light, the four light detection elements 150 and the four light detection elements 151 are both measured objects 115. The position is optically conjugate with the upper four measurement regions 303 (A ₁ , A ₂ , A ₃ , A ₄ ). The outputs of the corresponding photodetectors are combined, and four sets of signals are respectively input to four differential detection circuits and differentially detected. As a result, a signal 138 that is a set of four signals is input to the signal processing unit 136.

The signal processing unit 136 performs the calculation of the above equation 1 four times with the signal 137 and the signal 138 as inputs, and the signal light reflected by the four measurement areas 303 (A ₁ , A ₂ , A ₃ , A ₄ ). Four signals (S ₁ , S ₂ , S ₃ , S ₄ ) proportional to the amplitude of each component are calculated. As described above, the measurement of signals for the four measurement areas 303 (A ₁ , A ₂ , A ₃ , A ₄ ) can be performed simultaneously.

Hereinafter, an operation when the optical measurement device 1 of the present embodiment acquires the time-dependent change information while scanning the measurement target 115 with the beam spot 140 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a schematic diagram showing a state in which the beam spots 140, 157, and 158 irradiated on the measurement target 115 move.

When scanning the measurement object 115 with the beam spot 140, the beam spot 140 on the measurement object 115 moves at a constant speed in the x direction. Figure 3 is the position at time _{t 1} of the beam spot 140 moving at a uniform scanning speed v in a scanning direction 152, the time of the four measurement regions _{303 (A 1, A 2,} A 3, A 4) The position of is shown. The distance between the four measurement areas 303 (A ₁ , A ₂ , A ₃ , A ₄ ) is a value (δx ′) determined by the distance between the photodetectors and the characteristics of the optical system as described above. It is constant regardless of In the drawing 1, and after .DELTA.t from the time _{t 1,} at time after 2 × .DELTA.t, respectively predetermined position of the beam spot 140 indicated by reference numeral 157 and reference numeral 158. Here, the time δt is a value given by the following equation.
δt = δx ′ / v (Equation 2)
In other words, the moving distance of the beam spot 140 at the time δt is v · δt = δx ′, which is equal to the interval between the measurement areas.

FIG. 4 is a schematic diagram showing the relationship between the temporal change in the position of the measurement area and the time resolution (that is, the sampling interval). In the graph of FIG. 4, the horizontal axis indicates time t, and the vertical axis indicates the position of the measurement region 303 in the x direction. In FIG. 4, the positions of the four measurement areas 303 (A ₁ , A ₂ , A ₃ , A ₄ ) are shown as traces 401, 402, 403, and 404, respectively. The solid line portion of each trace indicates a measurement period, and the broken line portion indicates a period in which the trace is simply moving without measurement. In the example shown in FIG. 4, measurement is performed only while the measurement area 303 is moving in the positive x direction, and measurement is performed while the measurement area 303 is moving in the negative x direction (returning to the scan start position). Not.

Position of one _{A 1} of the measurement region 303 at time _{t 1} is _{x 1,} each of the other position of the three _{A 2, A 3, A 4} , x 1 -δx ', x 1 -2δx', x ₁ −3δx ′. Thereafter, since the measurement region 303 to move at a speed v, the time each measurement region 303 reaches the position x ₁ is made as follows, respectively.
A ₂ : t ₁ + δt
A ₃ : t ₁ + 2δt
A ₄ : t ₁ + 3δt

Thus, the four signals obtained by the four measurement regions _{303 (S 1, S 2,} S 3, S 4), the signal value at time t of the n-th measurement region when put out and _S n (t), S ₁ (t ₁ ), S ₂ (t ₁ + δt), S ₃ (t ₁ + 2δt), and S ₄ (t ₁ + 3δt) are time-series measured values of the position x ₁ obtained at time δt from time t _1. Becomes

More generally, a time-series measurement value Y (x ₀ , n) at a position x ₀ at which the m-th measurement area passes at a certain time t ₀ is obtained as S _{m + n} (t ₀ + n · δt). when you acquire the temporal change information of the position x ₀ by using a sequence measurements. Furthermore, the position _{x 0} from the positive direction to the 'time series measurements of position apart _{Y (x 0+ x' x,} n) _is obtained as _{S m + n (t 0 +} x '/ v + n · δt). In this way, by scanning only once on one scan line on the measurement target 115 in the four measurement regions 303, it is possible to acquire a time-series measurement value for each time δt at each point on the scan line.

Here, x direction of the scanning amplitude _{X A} of the measurement region 303 and the scan period 405 and _{T x,} the movement at the time of scanning becomes so constant speed _X A = v · _{T x.} Further, since the scanning amplitude is sufficiently large (δx ′ << X _A ) with respect to the interval between the measurement regions, δt = δx ′ / v = (δx ′ / X _A ) · T _x << T _x . That is, the light measuring device 1 of the present embodiment, by executing the above operation, a change with time information of the upper measuring object 115 located obtainable, the time resolution δt is sufficiently than the scanning period 405T _x Can be shortened.

Further, by setting the time resolution (AD conversion frequency or response frequency) of the differential detection circuits 134 and 135 and the photodiode arrays 124, 125, 130 and 131 to about the same or less than the above δt, the measured value at the intended time Can be obtained. Further, by desirably setting the time resolution to δt / 2 or less, it is possible to satisfy the sampling theorem and obtain information at the intended time resolution. Further, by setting the time resolution to δt / 10 or less, it becomes possible to perform measurement without being affected by the state of the measurement object 115 at the time point adjacent to the measurement, and it is possible to accurately detect temporal change information.

As described above, according to the present disclosure, a plurality of detectors provided in a direction corresponding to a scanning direction can measure a predetermined portion of a measurement target at different times, and the plurality of measurement results can be used to determine the predetermined portion. Time-dependent change information of the site can be obtained. That is, the optical measurement device 1 of the present disclosure can measure temporal change information with a time resolution shorter than the scanning period without using two signal light beams.

In the optical measurement device 1 according to the first embodiment, for the photodiode arrays 148, 149, 150, and 151, the number of photodetectors on each array is two or more, thereby acquiring a signal between two or more time points. Then, the amount of change with time can be calculated. More preferably, the number of photodetectors on each photodiode array is three or more. In this case, the time resolution can be made variable, or information with a plurality of time resolutions can be obtained at once. Specifically, among the three signals S ₁ , S ₂ , and S ₃ obtained using a photodiode array having three photodetectors, information on the time resolution δt can be obtained by using S ₁ and S _2. Then, if S ₁ and S ₃ are used, information with a time resolution of 2δt can be obtained.

In the optical measurement device 1 according to the present embodiment, for the photodiode arrays 148, 149, 150, and 151, the minimum value δx _min , the maximum value δx _max of the interval between arbitrary photodetectors on each photodiode array, and the optical system Assuming that the magnification is M and the scanning speed of the beam spot 140 is v, time-dependent change information can be acquired with a time resolution δt in the range of (δx _min / M) / v ≦ δt ≦ (δx _max / M) / v. It is possible. Here, the minimum value δx _min is, for example, an interval between adjacent light detection elements, and the maximum value δx _max is, for example, (the number of light detection elements−1) × δx _min .

Also, in FIG. 3, the shape of the beam spot 140 has been described as being large enough to fit in the plurality of measurement areas 303. The shape (irradiation area) of the beam spot 140 may be a shape including the measurement area 303. By doing so, the intensity of the signal light applied to each of the measurement areas (A ₁ , A ₂ , A ₃ , A ₄ ) can be made uniform, and the accuracy of the temporal change information can be improved.

As shown in FIG. 3, when the beam spot 140 has an elliptical shape, there is a possibility that the signal light irradiation amount may differ between both ends and the center of the plurality of measurement regions 303. In that case, the difference in the irradiation amount (difference in signal intensity) between both ends and the center of the plurality of measurement regions 303 is measured in advance, and the signal processing unit 136 determines the intensity of the signal light corresponding to each of the plurality of measurement regions 303. It may be calculated by calibration. By doing so, the measurement accuracy of the temporal change information of the measurement object 115 is improved.

Next, a scanning method for obtaining a two-dimensional image and a three-dimensional image of the measurement target 115 will be described. A two-dimensional image (zx image) of the measurement target 115 is obtained by scanning the two-dimensional region of the measurement target 115 with the beam spot 140. For example, the two-dimensional scanner 107 constituting the scanning unit 159 is controlled by the control unit 116, and the galvanomirror 108 (first scanning unit) is moved to scan repeatedly in the x direction, and the galvanomirror 108 reaches the turn-back position. Each time, the lens actuator 117 is operated by the control unit 116 to move the lens 113 (second scanning unit) by a predetermined amount (about the diameter of the focused beam spot 140 in the z direction) in the z direction. A two-dimensional image (zx image) can be obtained. Note that, for example, scanning in the x direction moves the beam spot 140 (irradiation area) faster than scanning in the z direction.

The three-dimensional image of the measurement target is obtained by repeating a procedure of moving the lens 113 by a predetermined amount (about the spot diameter of the condensed signal light) in the y direction after obtaining the zx image by the above-described scanning method. Can be. Alternatively, a procedure of acquiring the zx image by scanning the galvanometer mirror 108 and the lens 113 and then moving the measurement object 115 or the entire optical measurement device 1 in the y direction by using an electric stage or the like may be repeated. In this embodiment, the z-scan is performed by scanning the lens 113. For example, at least one lens is further inserted in front of the lens 113, and the condensing position is scanned by scanning the lens. The movement in the y-direction may be performed by the two-dimensional scanner 107.

As described above, by using the lens actuator 117 and the two-dimensional scanner 107, the optical measurement device 1 of the present disclosure can scan a two-dimensional region or a three-dimensional region, and acquire temporal change information of the region. It is also possible to output a two-dimensional or three-dimensional image having the acquired temporal change amount as the luminance value of each pixel.

The numerical aperture of the lens 113 that condenses the signal light and forms the beam spot 140 in the measurement object 115 is preferably 0.3. When the numerical aperture of the lens 113 is increased to 0.4 or more, a high Z-direction resolution can be obtained. Further, when the numerical aperture of the lens 113 is set to 0.3 to 0.4, the depth of focus of the lens can be made deep, so that the range of the measurable depth in the measurement object 115 can be widened.

(4) As the light source 101, a laser light source in which the coherence length of the emitted laser light is longer than the change in the optical path length of the signal light generated by scanning the lens 113 in the optical axis direction. With this configuration, even when the optical path length difference occurs between the signal light and the reference light when the lens 113 is scanned in the optical axis direction, it is possible to suppress a decrease in the interference amplitude. Therefore, the position of the beam spot 140 can be moved in the z direction by driving the lens 113 in the z direction, and a simpler and more compact device can be realized as compared with a method in which the reference mirror 119 is driven.

The shape of the beam spot 140 may be circular, elliptical, linear, rectangular, or the like. When the circular beam spot 140 is used, a normal optical system configuration can be used, so that the configuration of the optical measurement device 1 can be simply constructed. A linear or rectangular beam spot can be realized using a cylindrical lens or the like, and the signal light intensity in the beam spot 140 hardly changes in the x direction, so that a stable signal can be easily obtained during scanning.

Further, the size of the beam spot 140 in the x direction is such that, in an image formed on the photodiode arrays 148, 149, 150, and 151 by the optical system, the size in the direction corresponding to the x direction is at least two or more. And a size including the photodetector of FIG. That is, the magnification of the optical system M, the distance L _max between the farthest element of the light detecting element used for the _detection, in the x-direction of the beam spot 140 magnitude as D _x in each photodiode array, D _x ≧ L _max / M.

Further, the size of the beam spot 140 in the y direction may be smaller than the size in the x direction. Desirably, the size in the y direction is such that, in an image formed on the photodiode arrays 148, 149, 150, and 151 by the optical system, the size in the direction corresponding to the y direction fits on the light receiving surface of the photodetector. It is size. That is, the magnification of the optical system M, the direction of the width corresponding to the y-direction of the light detecting element _{L y,} in the y direction of the beam spot 140 magnitude as _{D y,} a _{D y} ≦ _{L y} / M. In this case, since the information on the intensity of the signal light contributes to the detected signal, the signal having a high SN ratio can be obtained.

Such an elliptical beam spot 140 is obtained by irradiating a signal light into the lens 113 as a beam having an elliptical cross section. If the cross-sectional shape of the beam incident on the lens 113 is an elliptical shape in which the y direction is longer than the x direction, the numerical aperture at the time of condensing is larger in the y direction than in the x direction, and the shape of the beam spot 140 on the xy plane is The ellipse is longer in the x direction than in the y direction. By changing the diameter in the y direction and the diameter in the x direction of the elliptical beam of the signal light, the diameter in the x direction and the diameter in the y direction of the elliptical shape of the beam spot 140 can also be changed. The adjustment of the elliptical beam shape is made possible by the beam shaping prism 103 inserted in the optical path of the signal light.

If an element that outputs an elliptical beam, such as a semiconductor laser, is used as the light source 101, the beam shaping prism 103 can be omitted. When the elliptical beam spot 140 is formed by this method, even if the x direction of the beam spot 140 is increased, the defocus of the beam spot in the z direction can be suppressed, and the beam spot can be enlarged. The deterioration of the spatial resolution at the time of measurement caused by this can be minimized.

The signal light incident on and reflected by the measurement target 115 ideally becomes a beam having the same diameter as the signal light at the time of the incidence, but actually, due to optical nonuniformity of the measurement target 115, etc. However, there is a possibility that the beam will have a larger diameter than that at the time of incidence. By making the beam diameter of the reference light larger than the beam diameter of the signal light, even in such a case, all components of the reflected signal light can contribute to interference and signal generation. As a result, an improvement in the SN ratio due to an increase in the signal light amount and an improvement in the resolution due to an increase in the effective numerical aperture are achieved.

<Modification of First Embodiment>
FIG. 5 is a schematic diagram showing the configuration of the reference optical system 500 for expanding the beam diameter described above. In FIG. 5, the vertical direction is the z direction, the horizontal direction is the x direction, and the direction perpendicular to the paper is the y direction. The laser light emitted from the light source 101 is split into two by the polarization beam splitter 501 into s-polarized signal light and p-polarized reference light. The reference light is expanded in beam diameter by a beam expander 506 including two lenses 502 and 503, is reflected by mirrors 504 and 505, changes its direction, and is converted from p-polarized light to s-polarized light by a λ / 2 plate 507. , Into the polarization beam splitter 106. After passing through the polarization beam splitter 106, the signal light returns through the same optical system as in FIG. 1 and is combined with the reference light by the polarization beam splitter 106 to generate a combined light. Subsequent operations are the same as those in FIG.

<Example 2>
FIG. 6 is a diagram illustrating a basic configuration example of the optical measurement device 2 according to the second embodiment. In FIG. 6, the vertical direction in the figure is the z direction, the horizontal direction is the x direction, and the direction perpendicular to the paper is the y direction.

The configuration of the optical measurement device 2 according to the second embodiment until the laser light emitted from the light source 101 is split into two, a signal light and a reference light, and then combined again to generate a combined light. Same as 1. The optical measurement device 2 according to the second embodiment is different from the optical measurement device 1 according to the first embodiment in that a current that is proportional to the intensity of the interference light is output using a photodiode array 607 in which a plurality of light detection elements are arranged in a line. different.

In the optical measurement device 2 according to the second embodiment, the generated combined light is first branched into ± 1st-order diffracted light by the diffraction grating 602, and a first branched combined light and a second branched combined light are generated. . These combined lights are arranged such that the phase difference between the s-polarized light component and the p-polarized light component of the first branched combined light differs from the phase difference between the s-polarized light component and the p-polarized light component of the second branched combined light by 90 degrees. Through the phase plate 603.

After that, the polarization directions of the first split combined light and the second split combined light are rotated by the λ / 2 plate 604 set at about 22.5 degrees with respect to the xz plane, and are polarized by the Wollaston prism 605. By being separated, four interference light beams whose interference phases are different from each other by approximately 90 degrees are generated. These interference lights are condensed by the condensing lens 606, and form an image of the beam spot 140 on four regions 608, 609, 610, and 611 on the photodiode array 607, each of which includes a plurality of photodetectors. As a result, each of the interference lights is converted into a current by each photodetector, and a pair of currents from the regions corresponding to the interference lights having a phase relationship different by 180 degrees are differentially detected by the differential detection circuits 134 and 135.

The detection signal is calculated by the signal processing unit 136, and a signal independent of the phase and proportional to the absolute value of the amplitude of the signal light is obtained. Since the function of the interference optical system 601 is the same as that of the interference optical system 132 of the first embodiment, the description is omitted here. As described above, by employing a configuration in which a plurality of interference light beams having different interference phases are received and detected by one photodiode array 607, the number of components can be reduced.

That is, since the optical measurement device 2 of the second embodiment has a smaller number of components of the interference optical system and is smaller than the optical measurement device 1 of the first embodiment, the entire device is smaller than the optical measurement device 1 of the first embodiment. Become.

<Example 3>
FIG. 7 is a schematic diagram illustrating a configuration of the optical measurement device 3 according to the third embodiment. In FIG. 7, the vertical direction is the z direction, the horizontal direction is the x direction, and the direction perpendicular to the paper is the y direction. The same members as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

The optical measurement device 3 of the third embodiment is different from the OCT device of the first embodiment in that the technology of the present disclosure is applied to an OCT device of a type using a low coherence light source. Light emitted from a light source 701, which is a low coherence light source such as SLD (Super Luminescence Diode), is converted into parallel light by a collimating lens 702, and the beam shaping prism 703 changes the beam cross-sectional shape to an elliptical shape in which the y direction is longer than the x direction. The beam is split into a signal light and a reference light by a beam splitter 706.

The signal light is condensed by the lens 713 and forms an elliptical beam spot 740 at a condensing position on the measurement object 115 held by the sample stage 739. Here, since the cross-sectional shape of the beam incident on the lens 713 is an elliptical shape in which the y direction is longer than the x direction, the numerical aperture at the time of condensing becomes larger in the y direction than in the x direction. Has an elliptical shape in which the x direction is longer than the y direction.

信号 The signal light reflected or diffused by the measurement object 715 is converted into a beam by the lens 713 and returns to the beam splitter 706. The reference light is reflected by the mirror 719 and returns to the beam splitter 706, and is combined with the signal light and interferes to generate a combined light. The combined light is condensed by the condenser lens 722 and forms an image 753 of the beam spot 740 on the photodiode array 724. The image 753 is detected by the plurality of light detection elements 748 of the photodiode array 724, and the detected signals 737 are sent to the signal processing unit 736.

In the optical measurement device 3 according to the third embodiment, a low coherence light source is used, and among components included in the signal light, only a component having the same optical path length as the reference light interferes to give the signal 737, so that the measurement target 715 is specified. Can be obtained using the z position of the measurement point as a measurement point. The optical measurement device 3 scans the mirror 719 by driving the actuator 760 by the control unit 716 during measurement, thereby performing z scanning of the measurement point. The optical measurement device 3 performs xy scanning by the two-dimensional scanner 759 controlled by the control unit 716. By combining the above operations, a two-dimensional image or a three-dimensional image of the measurement object 715 can be obtained.

In the optical measurement device 3 according to the third embodiment, the scanning in the x direction is performed by the two-dimensional scanner 759 at the time of measurement, and signals from a plurality of photodetectors are compared as in the first embodiment. Temporal change information can be acquired with a temporal resolution shorter than the period. Further, the optical measurement device 3 of the third embodiment can achieve the same function as that of the first embodiment with a smaller number of components than the optical measurement device 1 of the first embodiment, and can provide a smaller device. .

<Example 4>
FIG. 8 is a schematic diagram illustrating a configuration of the optical measurement device 4 according to the fourth embodiment. 8, the vertical direction in the figure is the z direction, the horizontal direction is the x direction, and the direction perpendicular to the paper is the y direction. The same members as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 8, the optical measurement device 4 of the fourth embodiment is different from the first embodiment in that the light observation unit 801 and the light detection unit 804 are connected by a polarization-maintaining optical fiber bundle 803. Different from the measuring device 1. The polarization maintaining optical fiber bundle 803 is detachably fixed to a fiber connection part 807 of the light observation unit 801 and a fiber connection part 808 of the light detection unit 804.

The optical measuring device 4 according to the fourth embodiment has the same configuration and functions as the first embodiment in which the laser light emitted from the light source 101 is branched into two and then combined again to generate a combined light. The generated combined light forms an image 809 at the incident end of the polarization maintaining optical fiber bundle 803 by the condenser lens 802, and is coupled to the polarization maintaining optical fiber bundle 803. The spatial distribution information of the image 809 of the combined light is transmitted to the light detection unit 804 by the polarization maintaining optical fiber bundle 803, and is presented as an image 810 at the emission end of the polarization maintaining optical fiber bundle 803. The combined light emitted from the image 810 is converted into parallel light by the collimator lens 805 and then enters the interference optical system 132. Subsequent configurations and functions are the same as those in the first embodiment, and a description thereof will not be repeated.

As described above, in the optical measurement device 4 according to the fourth embodiment, the light detection unit 804 and the light observation unit 801 are connected by the polarization maintaining fiber bundle 803. Therefore, when measuring a large measurement target such as a human body, the measurement is facilitated by bringing only the light observation unit 801 close to the measurement target 115. Further, the polarization maintaining optical fiber bundle 803 is easily detachable. Therefore, for example, when the light detection unit 804 fails, only the light detection unit 804 can be replaced, and there is no need to replace the entire device. Therefore, the running cost of the optical measurement device 4 decreases.

<Example 5>
FIG. 9 is a schematic diagram showing the movement of the beam spots 940, 957, 958 on the measurement object. The same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The optical measurement device of the fifth embodiment is realized with the same member configuration as the optical measurement device 1 of the first embodiment, but differs from the first embodiment in that the installation angle of the beam shaping prism 103 is rotated by 90 degrees. In this case, the cross-sectional shape of the beam incident on the lens 113 is an ellipse in which the x direction is longer than the y direction. Therefore, the numerical aperture at the time of light collection is larger in the x direction than in the y direction, and as shown in FIG. 9, the shape of the beam spot 940 in the measurement object 115 on the xy plane is such that the y direction is the x direction. It becomes a longer ellipse.

The beam spot 940 scans a two-dimensional area of the measurement target 115, and acquires a two-dimensional image (xy image) of the measurement target 115. Uniform scanning speed v in a scanning direction 152, while repeatedly scanned with a scanning period _{T x,} and reaches the return position 901 in the scanning direction 152, the sub-scanning direction 952, wherein the scanning line width δy a beam spot 940 in the y-direction Just move. As a result, the beam spot 940 follows the trajectory 902. A solid line portion of the trajectory 902 indicates a section for scanning while measuring, and a broken line indicates a section for scanning without measuring. Beam spot 940 at time _{t 1} is in the position of the hatched portion, the time _t 1 + _{T x} scheduled position 957, at time _t 1 + 2T _x located predetermined position 958. Thus, in the scanning method of Example 5, returns to the same x-position for each scanning period T _x (x ₁ in this _case).

In the example shown in FIG. 9, scanning is performed so that the scanning line width δy and the interval δx ′ between the four measurement regions 903 match. In this case, the position _{where A 1} is measured in the measurement region at a time _{t 1,} the time _t 1 + _{T x A 2} of the measurement region in the, the time _t 1 + 2T _{x A 3} of the measurement region in, measuring respectively next, time resolution can be obtained changes with time information equal to the scanning period T _x. Furthermore, in this case, for example, by comparing the measurement result of _{A 1} in the measurement area at time _{t 1,} the measurement results of _{A 3} in the measurement region at time _t 1 + 2T _x, equal time to n times the scan period _{T x} Change information can also be obtained.

The distance .delta.x of scanlines wide .delta.y and four measurement area 903 'is, .delta.y = .delta.x' when / is m, A ₂ is again measured in the measurement region the position where A ₁ is measured in the measurement region at a time t ₁ time, time _t 1 + mT _x, and the time resolution is mT _x to.

Interval .delta.x of scanlines wide .delta.y and four measurement area 903 'is, .delta.y = .delta.x' if a × m (= 2), the position _{of A 1} was measured in the measurement region at a time _{t 1,} the time _t 1 + _{T x} is _{a 3} of the measurement region in, the position _{where a 2} is measured in the measurement region at a time _{t 1,} the time _t 1 + _{T x a 4} of the measurement region in becomes the measuring each time resolution is _{T x} However, since δy can be increased to m times, the time required to scan and measure a predetermined area can be shortened.

As described above, by using the beam spot 940 having a long diameter in the direction perpendicular to the scanning direction 152 and the plurality of detectors provided in the direction corresponding to the direction perpendicular to the scanning direction 152, the scanning cycle T Information with a time resolution longer than _x can be obtained.

Further, by arranging to tilt the major axis of the ellipse with respect to the scanning direction 152 (e.g., 45 degrees), it is possible to obtain a time resolution of non-integer times of the scanning period T _x.

<Modification of Embodiment 5>
FIG. 10 is a diagram illustrating a scanning method in which a plurality of measurement regions are defined in both the x direction and the y direction. FIG. 10 shows a measurement area 1003 (A ₁₁ , A ₁₂ , A ₁₃ , A ₁₄ , A ₂₁ , and A ₂₁ ) when a plurality of detectors are provided in directions corresponding to both the x direction and the y direction of the beam spot 1040. A ₂₂ , A ₂₃ , A ₂₄ ) are shown. By implementing the same scanning and scanning described above, in this example, the time course information for both short time resolution and long time resolution than the scanning period T _x can be simultaneously acquired.

101, 701 Light source 102, 702 Collimating lens 103, 703 Beam shaping prism 104 ND filter 105 λ / 2 plate 106, 706 Polarizing beam splitter 107 Two-dimensional scanner 108, 109 Galvano mirror 110, 111 Lens 112, 118 λ / 4 plate 113 , 713 Lens 114 Cover glass 115, 715 Measurement object 116, 716 Control unit 117 Lens actuator 119, 719 Mirror 120 Half beam splitter 121, 127 λ / 2 plate 122, 128, 722 Condensing lens 123, 129 Polarizing beam splitter 124 , 125, 130, 131, 724 Photodiode array 126 λ / 4 plate 132 Interference optical system 134, 135 Differential detection circuit 136, 736 Signal processor 137, 138, 737 Signal 139 , 739 Sample stage 140, 740, 940, 1040 Beam spot 141 Signal light 142 Reflected signal light 143, 743 Reference light 144, 145, 146, 147 Interference light 148, 149, 150, 151, 748 Light detection element 152 Scanning Direction 153, 154, 155, 156, 753 Images 157, 158, 957, 958, 1057, 1058 Planned positions of future beam spots 159, 759 Scanning units 190, 790 Light source units 191, 791 Reference optical systems 301, 302 Light detection Element arrangement direction 303, 903, 1003 Measurement area 304, 305, 306, 307 Differential detection circuit 401, 302, 403, 404 Trace 500 at measurement area position Reference optical system 501 for expanding beam diameter Polarizing beam splitter 502, 503 Lens 504, 5 5 Mirror 506 Beam expander 507 λ / 2 plate 601 Interfering optical system 602 Diffraction grating 603 Phase plate 604 λ / 2 plate 605 Wollaston prism 606 Condensing lens 607 Photodiode array 608, 609, 610, 611 Multiple photodetectors Area 760 Actuator 801 Light observation unit 802 Condensing lens 803 Polarization maintaining optical fiber bundle 804 Photodetection unit 805 Collimating lens 807 Fiber connection parts 809, 810

Claims (14)

1. Light source,
   An optical branching unit that branches the light emitted from the light source into reference light and signal light,
   A scanning unit that irradiates the signal light and scans the measurement object,
   An optical system that combines the signal light and the reference light reflected or scattered by the measurement object and generates interference light,
   A light detection unit that receives the interference light generated by the optical system and converts the interference light into an electric signal;
   A signal processing unit that calculates the intensity of the signal light based on the electric signal converted by the light detection unit,
   An optical measurement device comprising:
   The light detection unit detects the signal light by a plurality of light detection elements associated with each of a plurality of measurement regions overlapping with the irradiation region of the signal light,
   The signal processing unit calculates the intensity of the signal light detected by each of the plurality of light detection elements,
   The scanning unit may be configured to irradiate the irradiation area of the signal light irradiating the measurement target with a part of the plurality of measurement areas at a first time point and another part of the plurality of measurement areas at a second time point. Scanning the measurement object by moving so as to overlap with,
   Optical measuring device.
2. The optical measurement device according to claim 1,
   The scanning unit scans the measurement target along a direction in which each of the plurality of measurement regions is arranged,
   Each of the plurality of optical elements is arranged in an optically conjugated positional relationship with the plurality of measurement regions,
   Optical measuring device.
3. The optical measurement device according to claim 1,
   The signal processing unit may further include an intensity of the signal light detected by a photodetector corresponding to a part of the plurality of measurement regions at the first time and another one of the plurality of measurement regions at the second time. Processing the intensity of the signal light detected by the light detection element corresponding to the unit as time-series information of the same location of the measurement object,
   Optical measuring device.
4. The optical measurement device according to claim 3,
   The time interval between the first time point and the second time point is an interval between a part of the plurality of measurement areas and another part of the plurality of measurement areas, and the scanning unit moves the irradiation area. Value divided by speed,
   Optical measuring device.
5. The optical measurement device according to claim 2,
   A first scanning unit that scans the measurement object in a first direction, a second scanning unit that scans the measurement object in a second direction different from the first direction, With
   The first scanning unit moves the irradiation area faster than the second scanning unit,
   Optical measuring device.
6. The optical measurement device according to claim 1,
   The shape of the irradiation area, the diameter in the scanning direction for scanning the measurement object is a shape larger than the diameter in the direction perpendicular to the scanning direction,
   Optical measuring device.
7. The optical measurement device according to claim 6,
   At least one point on the optical path in the scanning unit, the shape of the beam of the signal light, the diameter in the scanning direction is smaller than the diameter in a direction perpendicular to the scanning direction,
   Optical measuring device.
8. The optical measurement device according to claim 1,
   The irradiation area includes the plurality of measurement areas,
   Optical measuring device.
9. The optical measurement device according to claim 1,
   The signal processing unit calculates and calculates the intensity of the signal light corresponding to each of the plurality of measurement regions,
   Optical measuring device.
10. The optical measurement device according to claim 1,
    A plurality of the light detection units,
    An interference optical system that disperses the interference light into three or more interference lights having different interference phases from each other,
    With
    An interference phase between the signal light and the reference light of the three or more interference lights in the plurality of light detectors is an integral multiple of substantially 90 degrees from each other, and the phase difference differs by approximately 180 degrees. A pair of output currents corresponding to light is input to a differential detection circuit that performs current differential detection,
    Optical measuring device.
11. The optical measurement device according to claim 10,
    The number of the light detection unit is four,
    The interference optical system disperses the interference light into four interference lights having different interference phases,
    Two pairs of interference light having a phase difference between the two sets of interference phases of approximately 180 degrees are input to the differential detection circuit,
    Optical measuring device.
12. The optical measurement device according to claim 1,
    Further comprising an optical fiber bundle,
    The optical system that generates the interference light, the combined interference light is made incident on an optical fiber connection portion to which one end of the optical fiber bundle is connected,
    Optical measuring device.
13. The optical measurement device according to claim 1,
    The light detection unit detects the signal light by three or more of the light detection elements,
    Optical measuring device.
14. A sample observation method using an optical measurement device that acquires an optical coherence tomographic image,
    Irradiating the measurement target with signal light, and generating interference light by combining the reflected or scattered signal light and the reference light,
    Detecting a signal intensity of the interference light at a first time by a plurality of light detection elements corresponding to a plurality of measurement regions overlapping with the irradiation region of the signal light,
    Moving the irradiation area so that a part of the plurality of measurement areas at the first time and another part of the plurality of measurement areas at the second time overlap.
    Detecting the signal intensity of the interference light at the second time point by the plurality of light detection elements corresponding to each of the plurality of measurement regions;
    A sample observation method including:

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