JP2017207304A - Optical interference measurement device and optical interference measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase modulation type optical interference measurement device which eliminates the need for a PZT element in phase modulation and which excels in durability and an optical interference measurement method.SOLUTION: An optical interference measurement device comprises: a heating light source 222 having a center wavelength λd different from a measuring light source 201 having a center wavelength λc; and a control unit 221a for controlling the drive of radiation energy of the heating light source 222 with a frequency f, the temperature of a second liquid 218 whose reference face 216 is arranged in the liquid and which absorbs light of a center wavelength of heating light L4 incident from the heating light source 222 being frequency controlled by the control unit 221a, with the refractive index of the second liquid 218 thereby changed and the optical length changed to achieve phase modulation, eliminating the need for a PZT element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical interference measuring apparatus and an optical interference measuring method.

There is known a phase modulation type optical interference measuring apparatus that measures an object by applying phase modulation of about the wavelength of light to the optical path length difference between signal light and reference light (Patent Document 1).

  FIG. 7 shows an optical interference measuring apparatus using the Linnik interferometer of Patent Document 1. Light from the light source 100 enters the beam splitter 101 and reaches the arms 102 and 105 of the optical interferometer.

  A lens 103 and an object 104 are disposed on the first arm 102, and a lens 106 and a reference surface 107 are disposed on the second arm 105. A PZT element 108 is disposed on the reference surface 107 in order to give a fine amount of movement about the wavelength of light. The light sent to the arms 102 and 105 is reflected from the object 104 and the reference surface 107 and enters the camera 109. In Patent Document 1, the phase of the interference light is continuously sinusoidally modulated by the PZT element 108.

JP-T-2004-528586

  However, the conventional configuration has a problem that the durability of the PZT element deteriorates.

  An object of the present invention is to solve the above-described conventional problems, and to provide a phase modulation type optical interference measuring apparatus and optical interference measuring method which eliminates the need for a PZT element for phase modulation and has excellent robustness.

An optical interference measurement apparatus according to one aspect of the present invention includes:
A measurement light source emitting measurement light having a central wavelength;
A heating light source that emits heating light having a center wavelength that is longer than the center wavelength of the measurement light;
A first beam splitter on which the measurement light and the heating light are incident;
A second beam splitter that splits the measurement light and the heating light emitted from the first beam splitter, respectively, and enters the target and the reference surface, respectively;
A first lens disposed in an optical path of light from the second beam splitter to the object;
A second lens disposed in an optical path of light from the second beam splitter to the reference surface;
A camera on which interference light obtained by interference between light reflected or scattered by the reference surface and light reflected or scattered by the object is incident;
A calculation unit that constructs an image by calculation from the interference signal intensity of the interference light incident on the camera;
A low-pass filter that blocks a wavelength equal to or greater than the center wavelength of the heating light disposed in the optical path from the second beam splitter to the object;
A first liquid disposed between the object and the first lens;
A second liquid that is disposed between the reference surface and the second lens and absorbs the light having the center wavelength of the heating light incident on the second lens;
A control unit that drives and controls the radiant energy of the heating light emitted from the heating light source at a frequency;
The control unit changes the refractive index of the second liquid by changing the temperature of the second liquid by frequency-controlling the heating light, and the second beam splitter of the measurement light uses the second beam splitter. The reference light separated toward the reference surface is phase-modulated.

An optical interference measurement method according to another aspect of the present invention includes:
Arranging the object on the optical interference measurement device according to the aspect,
Next, the object is measured using the optical interference measuring apparatus.

  As described above, according to the aspect of the present invention, phase modulation of reference light is performed using a heating light source that emits heating light having a center wavelength that is longer than the center wavelength of the measurement light. Therefore, a PZT element is not required for phase modulation, and a phase modulation type optical interference measuring apparatus and optical interference measuring method excellent in robustness can be provided.

Schematic diagram of an optical interference measuring apparatus in Embodiment 1 of the present invention Relationship diagram between wavelength and water absorption coefficient in Embodiment 1 of the present invention The enlarged view of the 2nd arm of the optical interference measuring apparatus in Embodiment 1 of this invention Relationship diagram between water temperature and refractive index in Embodiment 1 of the present invention Flowchart showing an optical interference measuring method of the optical interference measuring apparatus in the first embodiment Schematic diagram of the interference waveform of the pixel of interest obtained by the optical interference measurement of the optical interference measuring apparatus in the first embodiment Schematic diagram of a conventional optical interference measuring apparatus described in Patent Document 1

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram of an optical interference measuring apparatus 200 according to Embodiment 1 of the present invention.

  The optical interference measuring apparatus 200 is a kind of linnic interferometer, and includes a measurement light source 201, a heating light source 222, a first beam splitter 205, a second beam splitter 206, a first lens 210, a first lens 210, and a first lens 210. A two-lens 215, a camera 219, a calculation unit 221c, a low-pass filter 209, and a control unit 221a. The optical interference measurement apparatus 200 may further include a storage unit 221b.

  The measurement light source 201 is a unit that emits measurement light L1 having a center wavelength λc, and includes a lamp 202, a slit 203, and a first collimator lens 204. The lamp 202 is a light source that emits low coherence light such as a halogen lamp, a xenon arc lamp, a mercury lamp, or an LED. Further, the measurement light emitted from the lamp 202 passes through the slit 203 and the first collimator lens 204, so that the measurement light having a center wavelength λc = 400 nm or more and less than 1350 nm and a coherence length Lc = 1 to 2 μm, for example. L1.

  The measurement light L1 emitted from the measurement light source 201 enters the first beam splitter 205 and is transmitted therethrough, and further enters the second beam splitter 206. Each of the first beam splitter 205 and the second beam splitter 206 may be a cube type or a plate type.

  The measurement light L1 incident on the second beam splitter 206 is separated into two, a signal light L2 and a reference light L3 having the same amplitude. The signal light L2 is sent to the first arm 207 of the interferometer, and the reference light L3 is sent to the second arm 208.

  The first arm 207 includes a low-pass filter 209, a first objective lens 210 that functions as an example of the first lens, a target object 211 (mainly a biomaterial), and a container (hereinafter simply referred to as a target object 211). (Referred to as “dish”) 212. The first arm 207 is supported by a Z-direction stage 271 that can be driven under the control of the control unit 221a, and is movable in the Z direction (optical path direction) so that the optical path length can be adjusted. The dish 212 is filled with a first liquid (hereinafter simply referred to as “culture liquid”) 213 for culturing a biological material as an example of the object 211. Further, the tip of the first objective lens 210 is immersed in the culture solution 213. A culture solution 213 is disposed between the object 211 and the tip of the first objective lens 210.

  Although the reason will be described later, the low-pass filter 209 cuts (shields) light having a wavelength of 1350 nm or more, which is the central wavelength of the heating light L4.

  The culture solution 213 is not particularly limited as long as it is suitable for culturing a biomaterial (living body or cell). For example, the culture solution 213 is often obtained by adding an additive to pure water.

  The focal plane of the signal light L2 branched from the measurement light L1 is adjusted to the inside of the object 211 by the first objective lens 210. The signal light L2b reflected or scattered by the focal plane returns to the second beam splitter 206 through the first objective lens 210. The reflection includes Fresnel reflection, and the scattering includes backscattering.

  Therefore, the signal light L2 from the second beam splitter 206 first passes through the low-pass filter 209, then passes through the first objective lens 210, enters the culture solution 213 from the tip of the first objective lens 210, After irradiating the object 211, it is reflected or scattered by the object 211, passes through the culture solution 213, the first objective lens 210, and the low-pass filter 209 again, and returns to the second beam splitter 206.

  On the other hand, in the second arm 208, a transparent glass material 214, a second objective lens 215 functioning as an example of the first lens, a reference surface 216, and a container for storing the reference surface 216 (hereinafter simply referred to as “water tank”). 217) is arranged. The second arm 208 is supported by a Z-direction stage 272 that can be driven under the control of the control unit 221a, and is movable in the Z direction (optical path direction) so that the optical path length can be adjusted. The water tank 217 is filled with a second liquid (hereinafter simply referred to as “aqueous solution”) 218 having a refractive index close to that of the culture solution 213. Further, the tip of the second objective lens 215 is immersed in the aqueous solution 218. An aqueous solution 218 is disposed between the reference surface 216 and the second objective lens 215.

  The transparent glass material 214 is preferably adjusted to have the same refractive index and dispersion as the low-pass filter 209 in order to eliminate the influence of wavelength dispersion, but it may be omitted.

  The aqueous solution 218 is preferably obtained by adding a preservative having a concentration of 0.1% to 5% to pure water. If there is no concern about dissolution of the reference surface 216, it is best to remove the influence of wavelength dispersion by putting the same liquid as the culture solution 213 into the water tank 217. As a preservative, phenoxyethanol, paraben, dehydroacetic acid Na, ethylene glycol, dichloroisocyanuric acid Na, or the like can be used. Further, Aquaclean G or Aquaclean L manufactured by Shikoku Kasei Kogyo Co., Ltd., White 7-SW manufactured by UI Kasei Co., Ltd., or Apizzas manufactured by Zenith Advan Co., Ltd. can be used as a preservative.

  The reference light L3 is focused on the reference surface 216 by the second objective lens 215. The reference light reflected or scattered by the reference surface 216 returns to the second beam splitter 206 through the second objective lens 215.

  Therefore, the reference light L3 from the second beam splitter 206 first passes through the transparent glass material 214, then passes through the second objective lens 215, enters the aqueous solution 218i from the tip of the second objective lens 215, and is referred to. After irradiating 216, the light is reflected or scattered by the reference surface 216, passes through the aqueous solution 218 and the second objective lens 215, the transparent glass material 214, and returns to the second beam splitter 206.

  When the optical path length Ls of the signal light L2 in the first arm 207 and the optical path length Lref of the reference light L3 in the second arm 208 coincide within the range of the coherence length Lc of the measurement light source 201, the second beam The signal light L2b and the reference light L3b that have returned to the splitter 206 cause optical interference. The interfered light (interference light) L5 is reflected by the second beam splitter 206 toward the camera 219, and is imaged on the camera 219 by the imaging lens 220 that focuses on the camera 219.

  The camera 219 has a sensor surface composed of, for example, a CCD type two-dimensional pixel. The sensor surface and the object 211, and the sensor surface and the reference surface 216 are arranged so as to be optically conjugate with each other. That is, the camera 219 stores the object 211 and the reference surface 216 in the field of view. Note that in order to reduce measurement errors due to optical system aberrations, it is desirable to image the object 211 and the reference surface 216 at the same magnification. To reduce measurement errors due to wavelength dispersion, magnification is achieved using the same glass material. It is desirable to adjust. Interference light L5 formed by interference between the light reflected or scattered by the reference surface 216 and the light reflected or scattered by the object 211 is incident on the camera 219.

  The computer 221 computes at least the data acquired by the camera 219 and constructs an image of the object 211, and instructs the shutters of the camera 219 and the radiant power of the heating light source 222 to control driving. And a control unit 221a. Furthermore, the computer 221 may include a storage unit 221b that stores data acquired by the camera 219. Note that the shutter of the camera 219 may be electronic or mechanical. The storage unit 221b stores the interference signal intensity of the interference light L5 measured by the camera 219. The computing unit 221c performs computation so as to construct an image from the interference signal intensity stored in the storage unit 221b.

  The control unit 221a uses the data stored in the storage unit 221b to perform calculations in the calculation unit 221c, and controls the radiant power (radiant energy) of the heating light L4 from the heating light source 222 with the frequency f to obtain a physical distance. In addition to changing the optical path length ΔLref in D, drive control of the lamp 202, the camera 219, the Z stages 271 and 272, and the like is performed.

  The heating light source 222 is a unit that emits infrared heating light (heating light) L 4 having a center wavelength λd, and includes an infrared lamp 223 and a second collimator lens 224. The infrared lamp 223 is a light source capable of high frequency driving such as a laser, an SLD (Superluminescent diode), or an LED.

  The center wavelength λd of the heating light L4 emitted from the infrared lamp 223 is set to be longer than the center wavelength λc of the measurement light L1. The reason for setting in this way is to shield the heating light L4 with the low-pass filter 209. The center wavelength λd of the heating light L4 is a wavelength that is absorbed by the second liquid 218 in order to perform phase modulation described later. When the second liquid 218 contains water as a main component, infrared light having a high water absorption spectrum with a center wavelength λd of 1350 nm or more is heated from the relationship between the wavelength and water absorption coefficient shown in FIG. As an example of the light L4, it is desirable to irradiate from an infrared lamp 223. A preferable range of the center wavelength λd is 1350 nm or more and less than 3000 nm. More specifically, an infrared light source having a center wavelength λd = 1450 nm or λd = 1940 nm may be used as the heating light source 222.

  The infrared heating light L4 as an example of the heating light L4 is incident on the first beam splitter 205, reflected toward the second beam splitter 206, and further incident on the second beam splitter 206. That is, both the measurement light L1 and the infrared heating light L4 enter the first beam splitter 205, and then the measurement light L1 and the infrared heating light L4 emitted from the first beam splitter 205 Enters the second beam splitter 206.

  The infrared heating light L4 incident on the second beam splitter 206 is separated into two, and a part of the infrared heating light L4a is sent to the first arm 207 of the interferometer on the signal light side, and the remaining red light The external heating light L4b is sent to the second arm 208 as the reference light side. The infrared heating light L4a sent to the first arm 207 on the signal light side is blocked from passing by the low-pass filter 209. For this reason, the infrared heating light L4a on the signal light side is not irradiated on the object 211 and does not affect the measurement.

  The optical interference measurement apparatus 200 uses the infrared heating light L4 to perform phase modulation of the reference light L3 separated toward the reference surface 216 by the second beam splitter 206 in the measurement light L1. For this reason, it is not necessary to use a PZT element for phase modulation. When culturing the biomaterial 211, the optical interference measurement apparatus 200 is disposed in the incubator 300. At this time, the inside of the incubator 300 is in a high humidity environment where the humidity is 60% or more and 95% or less in order to culture the biomaterial 211. In this high humidity environment, the durability deterioration of the PZT element has been a problem, but the optical interference measurement apparatus 200 performs the phase modulation using the infrared heating light L4b instead of the PZT element. The problem is solved. The phase modulation method using the infrared heating light L4b will be described in detail below.

  FIG. 3 is an enlarged view of the second arm 208 in the first embodiment of the present invention.

  Similarly to the reference light L3, the infrared heating light L4b sent to the second arm 208 on the reference light L3 side passes through the transparent glass material 214 and is condensed by the second objective lens 215 to form an image on the reference surface 216. And At this time, the infrared heating light L4b is absorbed by the aqueous solution 218a existing in the region on the optical path of the second objective lens 215 and the reference surface 216. For this reason, the temperature of the aqueous solution 218a existing in the region on the optical path rises. Here, the aqueous solution 218 existing in the water tank 217 between the second objective lens 215 and the reference surface 216 is an optical path region (red) of the infrared heating light L4b between the second objective lens 215 and the reference surface 216. The aqueous solution 218a existing in the region irradiated with the external heating light L4) and the aqueous solution 218b in the region not irradiated with the infrared heating light L4b are considered separately. The temperature of the aqueous solution 218a irradiated with the infrared heating light L4b rises.

  FIG. 4 is a relationship diagram between the temperature of water and the refractive index in the first embodiment of the present invention. When the temperature of the aqueous solution 218a increases, the refractive index n of the aqueous solution 218a decreases. Even if the physical distance is the same, the optical distance (optical path length) changes when the refractive index n changes.

  Assuming that the reduced refractive index of the aqueous solution 218a is Δn, and the physical distance between the tip of the second objective lens 215 and the surface of the reference surface 216 is D, as shown in FIG. The changing optical path length ΔLref is expressed by the following (formula 1).

ΔLref = Δn × D (Expression 1)
Further, assuming that the refractive index n and the temperature gradient coefficient are Cn and the temperature fluctuation amount is ΔC, these relationships are expressed by (Equation 2).

Δn = Cn × ΔC (Formula 2)
Therefore, the control unit 221a controls the radiation power of the heating light L4 from the heating light source 222 in FIG. 1 and drives the heating light source 222 at the frequency f, thereby changing the optical path length ΔLref at the physical distance D. Can do. This optical path also passes through the reference light L3. For this reason, the phase modulation of the reference light L3 can be realized by changing the radiation power of the heating light L4 by the control unit 221a.

Here, it is assumed that the center wavelength λc of the measurement light L1 from the measurement light source 201 is λc = 800 nm and the phase modulation amount ΔLref is ΔLref = λc / 2 = 400 nm. Assuming that the physical distance D is 5 mm,
Δn = ΔLref / D = 400/5000000 = 0.00008
It becomes. From FIG. 4, the gradient coefficient Cn between the refractive index and temperature near 35 degrees, which is often used for the culture temperature of the object 211, is
Cn = | (1.3325-1.3315) / (25-35) | = 0.0001
And can be calculated.

Therefore, the required temperature fluctuation amount ΔC is
ΔC = Δn / Cn = 0.00008 / 0.0001 = 0.8 ° C.
Is calculated. Regarding heat dissipation, the aqueous solution 218b in a region other than the aqueous solution 218a on the optical path of the aqueous solution 218 serves as water cooling, and assists heat dissipation of the heated aqueous solution 218a. That is, only the aqueous solution 218a locally varies in temperature. The volume of the aqueous solution 218b is significantly larger than the volume of the aqueous solution 218a, for example, 100 times or more, more preferably 1000 times or more and 100000 times or less.

Further, another condition will be described. From the relationship between the temperature and the refractive index in FIG. 4, the coefficient α = 0.00013 [1 / ° C.] is known. Assuming that the physical distance D (focal length) is 4.5 mm and the spot diameter of the light that has passed through the transparent glass material 214 is 7.2 mm, the temperature change β [necessary for the optical distance variation Δ = 100 [nm]. [° C.] is β = Δ / (α × D) = 100 [nm] / (0.00013 [1 / ° C.] × 4500000 [nm]) ≈0.17 [° C.]
It becomes. The volume V of the aqueous solution 218a in the optical path is 0.61 [ml] from the focal length D and the spot diameter. Since the required heat amount J = 4.2 × volume V × temperature change β, 0.042 [J] is obtained. If the frequency f of light is 100 [Hz], the necessary heat source (light source) power P is 4.3 [W]. If the light frequency f is 60 [Hz], the required power is 2.6 [W]. Here, assuming that the center wavelength λc is 1450 nm, the absorption coefficient of water (aqueous solution 218a) is 12, the absorbance is 23.45, and the absorptance is 100%. Therefore, in order to change the optical distance by 100 nm, the frequency 100 [Hz] and power 4, 3 [W] may be used. If the center wavelength λc is 940 nm, the absorption coefficient of water (aqueous solution 218a) is 0.3, the absorbance is 0.59, and the absorptance is 74%. Therefore, the center wavelength λc is 1450 nm and 1 [100 Hz]. .4 times more power is required. The aqueous solution 218b other than on the optical path exhibits a water cooling function, and the temperature of the heated aqueous solution 218a immediately decreases, so that phase modulation described later becomes possible.

  Here, a phase modulation interferometer will be briefly described.

  When the optical path difference between the object 211 and the reference surface 216 is continuously changed by the control unit 221a as described above, the optical path difference between the object 211 and the reference surface 216 becomes zero. The interference image with the maximum contrast is captured by the camera 219.

  Here, a measurement method using the optical interference measurement apparatus 200 will be described with reference to FIGS. 1, 5, and 6. FIG. FIG. 5 is a flowchart showing the measurement method in the first embodiment of the present invention. FIG. 6 is a schematic diagram of the interference waveform of the target pixel obtained by measurement in Embodiment 1 of the present invention.

  First, in step S1, after the object 211 is arranged in the optical interference measuring apparatus 200, the optical path length is adjusted under the control of the control unit 221a. Specifically, under the control of the control unit 221a, the Z direction stage 271 or 272 of the object 211 or the reference surface 216 is driven to adjust the position of the object 211 or the reference surface 216 in the Z direction (optical path direction). As a result, the optical path lengths of the signal light L2 and the reference light L3 are matched within the coherence length Lc of the light from the measurement light source 201. The Z-direction stage 271 or 272 may be a mechanism that can be adjusted so that the optical path length difference is within the range of the coherence length Lc, such as a stepping motor, and need not be a PZT element.

  Next, in step S2, phase modulation is performed by changing the optical path length by heating the aqueous solution 218a with the heating light L4 using the heating light source 222 and the control unit 221a at the position where the optical path length is adjusted. Under the control of the control unit 221a, a signal (interference signal) of the first interference light L5 of the reference light L3b and the signal light L2b reflected or scattered from the surface of the object 211 is acquired by the camera 219 and stored. Stored in the part 221b.

  Note that, under the control of the control unit 221a, at the time of storage, the camera 219 may take a plurality of shots at the same position, and the S / N ratio may be improved by integrating the plurality of images. The S / N ratio may be improved by lowering the gain after photoelectric conversion and exposing for a long time.

  Next, in step S3, under the control of the control unit 221a, the Z stage 271 of the first arm 207 is moved from the surface of the object 211 to the inside in the thickness direction (in the direction in which the optical path length is increased) by about λc / 2. Let

  Next, in step S4, an interference signal is acquired by the camera 219 under the control of the control unit 221a at the moved position, and stored in the storage unit 221b.

  Next, in step S5, the interference signal acquisition operation from step S3 to step S4 is performed from the surface of the object 211 under the control of the control unit 221a (from the surface of the object 211 to the object 211. Repeat until the optical path length is increased by approximately the thickness dimension.

  In step S5, it is determined that the designated position has been reached under the control of the control unit 221a, and then in step S6, the calculation unit 221c picks up an image by moving the first arm 207 in the Z direction by the Z stage 271. Then, an interference signal is acquired, and an image is acquired by calculation in the calculation unit 221c. Then, when the luminance of each point of the acquired plurality of images is calculated by the calculation unit 221c, an interference waveform (solid line portion) as shown in FIG. 6 is obtained.

  Next, in step S7, an envelope (dotted line) of this interference waveform is obtained by the calculation unit 221c.

  Next, in step S8, the interference amplitude is calculated from the envelope by the calculation unit 221c and obtained. By performing the same calculation for all the pixels of the camera 219 by the calculation unit 221c, an XY plane image of the object 211 can be constructed by the calculation unit 221c.

  When light from the measurement light source 201 passes through the object 211, a tomographic image can be constructed by the calculation unit 221c.

  The above is the details of constructing an image based on the phase-modulated interference signal.

  Although it is desirable for the speedup of the image processing that the control unit 221a adjusts the phase by adjusting the radiation power (radiant energy) of the heating light source 222 so that the refractive index variation profile of the aqueous solution 218 is sinusoidal. If the frequency f is varied, there is no problem. Since the refractive index variation correlates with the temperature variation, when the refractive index variation profile of the aqueous solution 218 is sinusoidal, the temperature variation of the aqueous solution 218 is also a sine wave. That is, the controller 221a may adjust the phase of the heating light source 222 by adjusting the radiation power (radiant energy) so that the temperature variation of the aqueous solution 218 becomes sinusoidal.

  As described above, according to the first embodiment, the reference surface 216 is formed by using the heating light source 222 that emits the heating light L4 having the center wavelength λd that is longer than the center wavelength λc of the measurement light L1. The temperature of the aqueous solution 218 that is disposed in the liquid and absorbs light having the center wavelength λd of the heating light L4 incident from the heating light source 222 is frequency-controlled by the control unit 221a. With this configuration, the phase modulation of the reference light L3 is performed, so that no PZT element is required for the phase modulation, and the phase modulation type optical interference measuring apparatus 200 and the optical interference measuring method excellent in robustness even under high humidity. Can provide.

  Therefore, an optical interference measurement method in which the object 211 is arranged on the optical interference measurement apparatus 200 and the object 211 is measured using the optical interference measurement apparatus 200 can be implemented. Thereby, highly accurate measurement is realizable. The object 211 is preferably a living body or a cell. In addition, it is desirable to measure the object 211 using the optical interference measuring apparatus 200 in the incubator 300. According to such a configuration, more reliable measurement can be performed by performing phase modulation with high accuracy while culturing a living body or a cell.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably. In addition, combinations of the embodiments, combinations of the examples, or combinations of the embodiments and examples are possible, and combinations of features in different embodiments or examples are also possible.

  The optical interference measuring apparatus and the optical interference measuring method according to the above aspect of the present invention realize a phase modulation method having excellent robustness in a high humidity environment, and can measure an object in an industrial field or a chemical field. It can also be applied to surface or inner layer measurement applications.

DESCRIPTION OF SYMBOLS 200 Optical interference measuring device 201 Measurement light source 202 Lamp 203 Slit 204 1st collimator lens 205 1st beam splitter 206 2nd beam splitter 207 1st arm 208 2nd arm 209 Low pass filter 210 1st objective lens 211 Object 212 Dish 213 Culture solution 214 Transparent glass material 215 Second objective lens 216 Reference surface 217 Water tank 218 Aqueous solution 219 Camera 220 Imaging lens 221 Computer 221a Control unit 221b Storage unit 221c Calculation unit 222 Heating light source 223 Infrared lamp 224 Second collimator lens 271 Z stage of first arm 272 Z stage of second arm 300 Incubator L1 Measurement light L2 Signal light L2b Signal reflected or scattered from the reference surface Signal light L3 Reference light L3b Reference light reflected or scattered from the surface of the object L4 Heating light L4a Heating light separated on the signal light side L4b Heating light separated on the reference light side L5 Interference light

Claims (10)

A measurement light source emitting measurement light having a central wavelength;
A heating light source that emits heating light having a center wavelength that is longer than the center wavelength of the measurement light;
A first beam splitter on which the measurement light and the heating light are incident;
A second beam splitter that splits the measurement light and the heating light emitted from the first beam splitter, respectively, and enters the target and the reference surface, respectively;
A first lens disposed in an optical path of light from the second beam splitter to the object;
A second lens disposed in an optical path of light from the second beam splitter to the reference surface;
A camera on which interference light obtained by interference between light reflected or scattered by the reference surface and light reflected or scattered by the object is incident;
A calculation unit that constructs an image by calculation from the interference signal intensity of the interference light incident on the camera;
A low-pass filter that blocks a wavelength equal to or greater than the center wavelength of the heating light disposed in the optical path from the second beam splitter to the object;
A first liquid disposed between the object and the first lens;
A second liquid that is disposed between the reference surface and the second lens and absorbs the light having the center wavelength of the heating light incident on the second lens;
A control unit that drives and controls the radiant energy of the heating light emitted from the heating light source at a frequency;
The control unit changes the refractive index of the second liquid by changing the temperature of the second liquid by frequency-controlling the heating light, and the second beam splitter of the measurement light uses the second beam splitter. Phase-modulating the reference light separated toward the reference surface;
Optical interference measurement device.   The optical interference measurement apparatus according to claim 1, further comprising a storage unit that stores an interference signal intensity of the interference light measured by the camera.   The optical interference measuring apparatus according to claim 1 or 2, wherein the central wavelength of the heating light is 1350 nm or more and 3000 nm or less.   The optical interference measurement apparatus according to claim 1, wherein the second liquid is composed of pure water and a preservative having a concentration of 0.1% to 5%.   The optical interference measurement apparatus according to claim 1, wherein the second liquid is the same liquid as the first liquid.   6. The optical interference measurement apparatus according to claim 1, wherein the control unit controls the radiant energy of the heating light so that a change in temperature of the first liquid becomes a sine wave.   The optical interference according to any one of claims 1 to 6, further comprising a transparent glass material having the same refractive index and the same dispersion as the low-pass filter in the optical path from the second beam splitter to the reference surface. measuring device. The object is arranged in the optical interference measurement device according to any one of claims 1 to 7,
Next, an optical interference measuring method for measuring the object using the optical interference measuring apparatus.   The optical interference measurement method according to claim 8, wherein the object is a living body or a cell.   The optical interference measuring method according to claim 9, wherein the object is measured using the optical interference measuring device in an incubator.

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