Observation apparatus and observation method

Abstract

To provide a device and method with which it is possible to easily observe a moving object that is to be observed, with an inexpensive structure.SOLUTION: An observation device 1 comprises a light source 11, a branch unit 12, a multiplexing unit 15, a first modulation unit 21, a second modulation unit 22, an imaging unit 23, and a processing unit 24, etc. The first modulation unit 21 accepts as input a first branch light L1 having arrived from a mirror 13, modulates the first branch light L1 at each of a plurality of mutually different modulation frequencies, and outputs the first branch light L1 after the frequency modulation. Lenses 31-33 irradiate an observation object S with the first branch light L1 having been modulated by the first modulation unit 21, along the direction of irradiation that corresponds to a modulation frequency Ωn. The imaging unit 23 has, on an imaging plane (plane P3) on which an image of the observation object S is formed, a plurality of pixels that are one dimensionally arranged in a direction orthogonal to the movement direction of the image of the observation object S by the first branch light L1. The imaging unit 23 receives multiplexed light and repeatedly outputs a detection signal that represents a one-dimensional interference image.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus and method for observing a moving observation object.

Background Art

[0002] Patent Document 1 discloses an invention of an apparatus and method for observing a moving observation object. The observation apparatus described in this document branches the light output from a light source into first branched light and second branched light, and combines the first branched light that has undergone Doppler shift by passing through a moving observation object and the second branched light whose optical frequency has been shifted by only the heterodyne frequency, and heterodyne-interferes the first branched light and the second branched light. Then, this observation apparatus can acquire time-series data of the complex amplitude image of the first branched light on the imaging surface based on the time-series data of the intensity image (two-dimensional interference image) of the interference light that has reached the imaging surface of the camera. This observation apparatus can image a moving observation object non-stained and non-invasively, and can be used, for example, to observe moving cells with a flow cytometer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

[0005] When considering the application of the invention disclosed in Patent Document 1 to a flow cytometer, the camera used to acquire the intensity image of the interference light needs to be an area camera in which multiple pixels are arranged in two dimensions (e.g., 1280 x 800) on the imaging surface and have a high frame rate (e.g., 25 kfps). Such cameras are very expensive, and therefore the observation device is also expensive.

[0006] Furthermore, in the invention disclosed in Patent Document 1, the optical system from the object to be observed to the camera is special, making it difficult to adjust this optical system and thus difficult to observe the object to be observed.

[0007] This invention was made to solve the above-mentioned problems and aims to provide an apparatus and method that can easily observe a moving object with an inexpensive configuration. [Means for solving the problem]

[0008] The observation device of the present invention is a device for observing a moving object. A first aspect of the observation apparatus of the present invention includes: (1) a light source that outputs light; (2) a branching unit that branches the light into a first branched light and a second branched light; (3) a first modulation unit that modulates the first branched light at a plurality of mutually different modulation frequencies; (4) an illumination unit that illuminates an object to be observed with the first branched light modulated by the first modulation unit along an illumination direction corresponding to the modulation frequency; (5) a multiplexing unit that combines the first branched light and the second branched light after they have passed through the object to output multiplexed light; (6) an imaging unit having a plurality of pixels arranged in a direction intersecting the direction of movement of the image of the object to be observed on an imaging surface where an image of the object to be observed is formed, and receiving the multiplexed light with these pixels and repeatedly outputting a detection signal representing a one-dimensional interference image; and (7) The system includes a processing unit that generates complex amplitude images for each of multiple irradiation directions on the object to be observed, corresponding to multiple modulation frequencies, based on time-series data of a one-dimensional interference image generated from detection signals repeatedly output from the imaging unit, and generates a three-dimensional refractive index distribution image of the object to be observed based on these complex amplitude images for each of the multiple irradiation directions.

[0009] A second aspect of the observation apparatus of the present invention further comprises, in addition to the first aspect, a second modulation unit provided on the optical path of the first branched light between the branching unit and the first modulation unit, or on the optical path of the second branched light between the branching unit and the multiplexing unit, which provides a frequency difference between the first branched light and the second branched light.

[0010] In a third aspect of the observation apparatus of the present invention, in addition to the first or second aspect, the first modulation unit includes an acousto-optic element that frequency modulates light by Bragg diffraction. The acousto-optic element is supplied with an RF signal having multiple distinct frequency components, and the first branched light is incident on the acousto-optic element to modulate the first branched light at a modulation frequency corresponding to each frequency component of the RF signal.

[0011] In a fourth aspect of the observation apparatus of the present invention, in addition to the first or second aspect, the first modulation unit includes an acousto-optic element that frequency modulates light by Ramans diffraction, and modulates the first branched light at each of several different modulation frequencies by applying a single-frequency RF signal to the acousto-optic element and by injecting the first branched light into the acousto-optic element.

[0012] In a fifth aspect of the observation apparatus of the present invention, in addition to the first or second aspect, the first modulation unit includes a plate-shaped object on which diffraction gratings having multiple spatial frequency components of different natures are superimposed and recorded, and the first branched light is modulated at each of the multiple different modulation frequencies by moving the plate-shaped object and passing the first branched light through the plate-shaped object.

[0013] In a sixth aspect of the observation apparatus of the present invention, in addition to the first or second aspect, the first modulation unit includes a phase-modulated spatial light modulator, which changes the amount of phase modulation at different speeds depending on the region of the modulation surface of the spatial light modulator, and modulates the first branched light at a modulation frequency corresponding to the speed of change of the amount of phase modulation in each region of the modulation surface of the spatial light modulator by injecting the first branched light onto the modulation surface of the spatial light modulator.

[0014] In a seventh aspect of the observation apparatus of the present invention, in addition to the first or second aspect, the first modulation unit includes an intensity-modulated spatial light modulator, wherein the intensity modulation amount distribution along a predetermined direction on the modulation surface of the spatial light modulator has a plurality of spatial frequency components that are different from each other, and the intensity modulation amount distribution is moved in a predetermined direction on the modulation surface of the spatial light modulator, and the first branched light is modulated at each of the plurality of different modulation frequencies by injecting the first branched light onto the modulation surface of the spatial light modulator.

[0015] A seventh aspect of the observation apparatus of the present invention further comprises, in addition to any of the first to seventh aspects, (1) an irradiation position detection unit for detecting the irradiation position of a first branched light on the movement path of an object to be observed, and (2) a control unit for controlling the optical system from the object to be observed to the imaging unit or the position of the imaging unit, based on the irradiation position detected by the irradiation position detection unit, so that multiple pixels of the imaging unit can receive multiple wave light.

[0016] The observation method of the present invention is a method for observing a moving object. A first aspect of the observation method of the present invention is: (1) a branching step in which light output from a light source is branched into a first branched light and a second branched light using a branching unit; (2) a first modulation step in which the first branched light is modulated at multiple different modulation frequencies using a first modulation unit; (3) an irradiation step in which the first branched light modulated by the first modulation unit is irradiated onto an object to be observed along an irradiation direction corresponding to the modulation frequency; (4) a multiplexing step in which the first branched light and the second branched light after passing through the object to be observed are combined using a multiplexing unit to output combined light; (5) an imaging step in which multiple pixels are received by an imaging unit having multiple pixels arranged in a direction intersecting the direction of movement of the image of the object to be observed on an imaging surface in which an image of the object to be observed is formed, and a detection signal representing a one-dimensional interference image is repeatedly output; (6) The system includes a processing step of generating a complex amplitude image for each of several irradiation directions on the object to be observed, corresponding to multiple modulation frequencies, based on time-series data of a one-dimensional interference image generated from a detection signal repeatedly output from an imaging unit, and generating a three-dimensional refractive index distribution image of the object to be observed based on these complex amplitude images for each of the multiple irradiation directions.

[0017] A second aspect of the observation method of the present invention further comprises, in addition to the first aspect, a second modulation step in which a frequency difference is introduced between the first branched light and the second branched light using a second modulation unit provided on the optical path of the first branched light between the branching unit and the first modulation unit, or on the optical path of the second branched light between the branching unit and the multiplexing unit.

[0018] In a third aspect of the observation method of the present invention, in addition to the first or second aspect, in the first modulation step, a first modulation unit including an acousto-optic element that frequency modulates light by Bragg diffraction is used to supply an RF signal having multiple different frequency components to the acousto-optic element, and a first branched light is incident on the acousto-optic element to modulate the first branched light at a modulation frequency corresponding to each frequency component of the RF signal.

[0019] In a fourth aspect of the observation method of the present invention, in addition to the first or second aspect, in the first modulation step, a first modulation unit including an acousto-optic element that frequency modulates light by Ramans diffraction is used to apply a single-frequency RF signal to the acousto-optic element and to inject a first branched light into the acousto-optic element, thereby modulating the first branched light at each of several mutually different modulation frequencies.

[0020] In a fifth aspect of the observation method of the present invention, in addition to the first or second aspect, in the first modulation step, a first modulation unit is used which includes a plate-like object on which diffraction gratings having multiple different spatial frequency components are superimposed and recorded. The plate-like object is moved and the first branched light is passed through the plate-like object to modulate the first branched light at each of multiple different modulation frequencies.

[0021] In a sixth aspect of the observation method of the present invention, in addition to the first or second aspect, in the first modulation step, a first modulation unit including a phase-modulated spatial light modulator is used to change the amount of phase modulation at different speeds depending on the region of the modulation surface of the spatial light modulator, and the first branched light is incident on the modulation surface of the spatial light modulator to modulate the first branched light at a modulation frequency corresponding to the speed of change of the amount of phase modulation in each region of the modulation surface of the spatial light modulator.

[0022] In a seventh aspect of the observation method of the present invention, in addition to the first or second aspect, in the first modulation step, a first modulation unit including an intensity-modulated spatial light modulator is used to make the intensity modulation amount distribution along a predetermined direction of the modulation surface of the spatial light modulator have multiple spatial frequency components that are different from each other. The intensity modulation amount distribution is moved in a predetermined direction on the modulation surface of the spatial light modulator, and the first branched light is incident on the modulation surface of the spatial light modulator to modulate the first branched light at each of the multiple different modulation frequencies.

[0023] An eighth aspect of the observation method of the present invention, in addition to any of the first to seventh aspects, detects the irradiation position of the first branched light on the movement path of the object to be observed, and controls the optical system from the object to the imaging unit or the position of the imaging unit so that multiple pixels of the imaging unit can receive combined wave light based on the detected irradiation position. [Effects of the Invention]

[0024] According to the present invention, moving objects can be easily observed with an inexpensive configuration. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 shows the configuration of the observation device 1. [Figure 2] Figure 2 shows the point images of the first branched light for each modulation frequency Ωn that are formed at the front focal plane (P1 plane) of lens 33. [Figure 3] Figure 3 illustrates the irradiation of the object S by the lens 33 with the first branched light. [Figure 4] Figure 4 shows the configuration of observation device 1A. [Figure 5] Figure 5 shows the configuration of observation device 1B. [Figure 6] Figure 6 shows the configuration of observation device 1C. [Figure 7] Figure 7 shows the configuration of the first modulation unit 21A and the surrounding optical system. [Figure 8] Figure 8 shows the configuration of the first modulation unit 21A and the surrounding optical system. [Figure 9] Figure 9 illustrates the diffraction grating recorded on the plate-shaped object of the first modulation unit 21A. Figure 9(a) shows the modulation distribution of each diffraction grating having multiple spatial frequency components kn (kmin~kmax). Figure 9(b) shows the modulation distribution after the diffraction gratings having multiple spatial frequency components are superimposed. [Figure 10]Figure 10(a) shows the first modulation unit 21B and the surrounding optical system. Figure 10(b) shows the modulation frequencies of each region on the modulation plane of the spatial light modulator of the first modulation unit 21B, indicated by varying shades of gray. [Figure 11] Figure 11(a) shows the first modulation unit 21C and the surrounding optical system. Figure 11(b) shows the modulation frequencies of each region on the modulation plane of the spatial light modulator of the first modulation unit 21C, indicated by varying shades of gray. [Figure 12] Figure 12(a) shows the first modulation unit 21D and the surrounding optical system. Figure 12(b) shows the intensity modulation amount in each region on the modulation plane of the spatial light modulator of the first modulation unit 21D, indicated by shades of gray. Figure 12(c) is a graph showing the intensity modulation amount in each region along the y-direction on the modulation plane of the spatial light modulator of the first modulation unit 21D. [Figure 13] Figure 13 shows a modified example of the configuration around the imaging unit 23. [Modes for carrying out the invention]

[0026] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the attached drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted. The present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0027] Figure 1 shows the configuration of the observation device 1. The observation device 1 is a device for observing a moving object S, and includes a light source 11, a branching unit 12, a multiplexing unit 15, a first modulation unit 21, a second modulation unit 22, an imaging unit 23, and a processing unit 24, etc. The observation method using this observation device 1 includes a branching step, a multiplexing step, a first modulation step, a second modulation step, an imaging step, and a processing step, etc.

[0028] The light source 11 outputs light. Preferably, the light source 11 is a laser light source that outputs laser light having a single optical frequency ω0. The light source 11 is, for example, a He-Ne laser light source. The branching unit 12 is an optical system that is optically connected to the light source 11. The branching unit 12 receives the light output from the light source 11 and splits the light into two: a first branched beam L1 and a second branched beam L2 (branching step). The branching unit 12 outputs the first branched beam L1 to the mirror 13 and the second branched beam L2 to the second modulation unit 22. The branching unit 12 is a beam splitter, and may also be a half-mirror.

[0029] Mirror 13 is optically connected to the branching section 12. Mirror 13 receives the first branched light L1 output from the branching section 12, reflects the first branched light L1, and outputs it to the first modulation section 21. Mirror 14 is optically connected to the second modulation section 22. Mirror 14 receives the second branched light L2 output from the branching section 12 and after passing through the second modulation section 22, reflects the second branched light L2, and outputs it to the lens 36.

[0030] The beam combiner 15 is an optical system that receives the first branched light L1, which has been reflected by the mirror 13 and passed through the first modulation unit 21 and the object to be observed S, and the second branched light L2, which has been reflected by the mirror 14 and passed through the lens 36, etc. The beam combiner 15 combines these input first branched light L1 and second branched light L2 and outputs the combined light to the lens 35 (beam combiner step). The beam combiner 15 is a beam splitter, and may also be a half mirror.

[0031] The imaging unit 23 receives the combined light output from the multiplexing unit 15 and after passing through the lens 35, and outputs a detection signal representing the interference image of the first branched light L1 and the second branched light L2 to the processing unit 24 (imaging step). Based on the detection signal repeatedly output from the imaging unit 23, the processing unit 24 generates a three-dimensional refractive index distribution image of the object to be observed S (processing step).

[0032] The optical system from the branching section 12 through mirrors 13 and 14 to the multiplexing section 15 constitutes a Mach-Zehnder interferometer. The object to be observed S moves so as to intersect with the optical path of the first branched light L1 from mirror 13 to the multiplexing section 15. The object to be observed S has, for example, a cross-sectional size of 250 × 250 μm. 2 These are cells moving in a line at an average speed of 20 mm / s along the flow channel of a flow cytometer. In the following, we set up an xyz orthogonal coordinate system, defining the direction of movement of the object being observed S as the y-direction, the direction parallel to the optical axis of the lens 34 located behind the object being observed S as the z-direction, and the direction perpendicular to both the y-direction and the z-direction as the x-direction.

[0033] The first modulation unit 21, lens 31, lens 32, and lens 33 are arranged in order along the optical path of the first branched light L1 from the mirror 13 to the object to be observed S. Lens 34 is arranged along the optical path of the first branched light L1 from the object to be observed S to the multiplexing unit 15. The second modulation unit 22, lens 36, lens 37, and lens 38 are arranged in order along the optical path of the second branched light L2 from the branching unit 12 through the mirror 14 to the multiplexing unit 15. Lens 35 is arranged along the optical path of the multiplexed light from the multiplexing unit 15 to the imaging unit 23.

[0034] The first modulation unit 21 receives the first branched light L1 arriving from the mirror 13, modulates the first branched light L1 at each of several different modulation frequencies, and outputs the frequency-modulated first branched light L1 (first modulation step). The first modulation unit 21 can be configured to include an acousto-optic element that frequency modulates light by Bragg diffraction. In this case, the first modulation unit 21 can modulate the first branched light L1 at a modulation frequency corresponding to each frequency component of the RF signal by supplying an RF signal having several different frequency components to the acousto-optic element and injecting the first branched light L1 into the acousto-optic element.

[0035] Let λ be the wavelength of the first branched light L1, and Va be the speed of acoustic waves in the acousto-optic element. Then, let Ω1~Ω be the N frequency components of the RF signal. N The nth frequency component among them is Ω n Therefore, the frequency Ωn Diffraction angle θ of the first branched light L1 modulated by n is represented by the following equation (1). The first modulation unit 21 is at each frequency Ω n The optical frequency ω0 + Ω modulated by n of the first branched light L1 can be output in the direction of the diffraction angle θ n That is, the first modulation unit 21 can output the first branched light L1 modulated by each of the N frequency components Ω1 to Ω N in different directions from each other.

[0036]

Equation

[0037] For example, diffracted light having a positive diffraction order (diffracted light output in the same direction as the traveling direction of the acoustic wave) is used. The moving speed Vs of the observation object S is set to 20 mm / s, the optical resolution Δy is set to 0.2 μm, and the bandwidth BW is set to 100 kHz (= Vs / Δy). The interval between modulation frequencies is set to 100 kHz, N = 100, and Ω n =(195 + 0.1n) MHz. That is, the minimum modulation frequency Ω1 is 195. MHz, and the maximum modulation frequency Ω N is 205.0 MHz.

[0038] Lenses 31 to 33 are an optical system constituting the irradiation unit, and irradiate the observation object S along the irradiation direction corresponding to the modulation frequency Ω n of the first branched light L1 modulated by the first modulation unit 21 (irradiation step). Lenses 31 and 32 are cylindrical lenses. Lens 33 is a spherical lens. In this figure, the light beam of the first branched light L1 in the yz plane (in the plane of the paper) is shown by a solid line, and the light beam of the first branched light L1 in the xz plane (in a plane perpendicular to the plane of the paper) is shown by a broken line (the same applies to the second branched light L2, and the same applies to subsequent figures). Also, the lens shape of the cylindrical lens shown by the broken line indicates the lens shape in the xz plane (in a plane perpendicular to the plane of the paper).

[0039] Lens 32 has a modulation frequency Ω at discrete positions along the y-direction on the front focal plane (P1 plane) of lens 33. n Each time, a point image of the first branched light L1 is formed. The back focal plane (P2 plane) of lens 33 is the plane that contains the movement path of the object being observed S. Figure 2 shows the modulation frequency Ω formed at the front focal plane (P1 plane) of lens 33. n This diagram shows the point image of each first branched beam. Each point image is indicated by a black circle. Since the P1 plane is the Fourier plane of the P2 plane, the horizontal axis (x-axis) of the P1 plane corresponds to the spatial frequency k in the x-direction of the P2 plane. x This corresponds to the vertical axis (y-axis) of the P1 plane, and the spatial frequency k in the y-direction of the P2 plane. y This corresponds to the modulation frequency Ω shown in Figure 2 for lens 33. n The light from the point image of each first branched light L1 is input, and the modulation frequency Ω n The first branched light L1 is a plane wave, and the modulation frequency Ω n The object S can be irradiated along the direction of irradiation according to the appropriate direction.

[0040] Figure 3 illustrates the illumination of the object S by the lens 33 with the first branched light. This figure shows the light frequency ω modulated by frequency Ω1. min When the first bifurcation light L1 of (=ω0+Ω1) is incident on the P2 plane as a plane wave, the y component of the wave vector is k. min This demonstrates that the frequency Ω N Modulated optical frequency ω max (=ω0+Ω N When the first branched light L1 of ) is incident on the P2 plane as a plane wave, the y component of the wave vector is k max This indicates that...

[0041] Lenses 34 and 35 constitute an imaging optical system that receives the first branched light L1 that has passed through the object to be observed S and forms an image of the object to be observed S on the imaging surface (P3 surface) of the imaging unit 23. The imaging surface (P3 surface) is optically conjugate to the surface (P2 surface) that contains the movement path of the object to be observed S. For example, lens 34 is an objective lens with a magnification of 60x, and lens 35 is an imaging lens with a focal length of 200 mm. A multiplexing unit 15 is positioned in the optical path between lens 34 and lens 35.

[0042] The second modulation unit 22 provides a frequency difference between the first branched light L1 and the second branched light L2 (second modulation step). The second modulation unit 22 is positioned on the optical path of the second branched light L2. The second modulation unit 22 receives the second branched light L2 as input, frequency modulates it, and outputs it. The second modulation unit 22 can be configured to include, for example, an Acousto-Optic Frequency Shifter (AOFS, e.g., ISOMET model 1250C), a function generator (e.g., Tektronics AFG3252C), and a high-speed amplifier. In this case, the sine wave signal output from the function generator is amplified by the high-speed amplifier with an amplification factor of, for example, +25 dB, and the sine wave signal with an amplitude of, for example, 25 dBm is applied to the AOFS. By injecting the second branched light L2 into this AOFS, the frequency Ω LO The second branched light L2 can be modulated. If diffracted light with a positive diffraction order (diffracted light output in the same direction as the propagation of the acoustic wave) is used, the optical frequency ω of the modulated second branched light L2 can be obtained. LO is ω0+Ω LO This is the result. For example, Ω LO Let's assume it equals 195MHz.

[0043] The second modulation unit 22 has an optical heterodyne frequency ΔΩ n (The difference in optical frequency between the first branched light L1 and the second branched light L2 during wave multiplexing by the wave multiplexing unit 15) is equal to the sampling frequency Ω of the imaging unit 23. S It is provided to adjust it so that it is less than half of the original value. Therefore, the modulation frequency Ω of the first branched light L1 n It is small enough, Ω LO Even if = 0, the optical heterodyne frequency ΔΩ n The sampling frequency of the imaging unit 23 is Ω S If it is less than half of that, the second modulation unit 22 does not need to be provided.

[0044] Lenses 36-38 constitute an optical system that directs the second branched light L2, modulated by the second modulation unit 22, into the multiplexing unit 15. Lenses 36 and 37 are spherical lenses and constitute a beam expander that enlarges the beam diameter of the second branched light L2. Lens 38 is a cylindrical lens. Lenses 36-38, together with lens 35, focus the second branched light L2 in a line shape on the imaging plane of the imaging unit 23.

[0045] The imaging unit 23 has a plurality of pixels arranged in one dimension on the imaging surface (P3 surface) where an image of the object to be observed S is formed, in a direction intersecting the direction of movement of the image of the object to be observed S caused by the first branched light L1. For example, a sensor such as a line sensor can be used as the imaging unit 23. The second branched light L2 is focused in a line shape along these one-dimensionally arranged plurality of pixels. The imaging unit 23 receives the combined light with the one-dimensionally arranged plurality of pixels and repeatedly outputs a detection signal representing a one-dimensional interference image.

[0046] The lowest optical frequency ω among the first branched light L1 frequency modulated by the first modulation unit 21 min (=ω0+Ω1), the highest optical frequency ω among the first branched light L1 frequency modulated by the first modulation unit 21. max (=ω0+Ω N ), and the optical frequency ω of the second branched light L2 frequency modulated by the second modulation unit 22. LO (=ω0+Ω LO It is preferable that the following relationship (2) is satisfied between ) where ω0 is the optical frequency of the light output from the light source 11. Also, the sampling frequency Ω of the imaging unit 23. S It is preferable that the following conditions (3) or (4) are met.

[0047]

number

[0048]

number

[0049]

number

[0050] Maximum modulation frequency Ω of the first branched light L1 N Set to 205MHz, the modulation frequency of the second branched optical fiber L2 is Ω LO If we set it to 195MHz, the maximum value of the optical heterodyne frequency is 10MHz, so the sampling frequency of the imaging unit 23 is Ω S You should set it to 20MHz.

[0051] The processing unit 24 generates complex amplitude images for each of the multiple irradiation directions on the object S corresponding to multiple modulation frequencies, based on the time-series data of the one-dimensional interference image generated from the detection signal repeatedly output from the imaging unit 23. The processing unit 24 is a computing device (computer, etc.) that incorporates, for example, a processor such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit), a storage medium such as RAM (Random Access Memory) or ROM (Read Only Memory), a communication module, and an input / output module. Alternatively, the processing unit 24 may be composed of an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The processing unit 24 then generates a three-dimensional refractive index distribution image of the object S based on these complex amplitude images for each of the multiple irradiation directions. Specifically, this is done as follows.

[0052] The time-series data of the one-dimensional interference image generated from the detection signal repeatedly output from the imaging unit 23 is represented as I(x,t). x is a variable representing the position (position in the x-direction) of each of the multiple pixels arranged in a one-dimensional array on the imaging plane of the imaging unit 23. t is a variable representing the time when the imaging unit 23 captured the one-dimensional interference image. The processing unit 24 performs a Fourier transform on this time-series data I(x,t) with respect to time t. The result of this Fourier transform is represented as J(x,f). f is a variable representing the frequency.

[0053] The processing unit 24 selects the optical heterodyne frequency ΔΩ from the data of J(x,f). n The frequency range of the bandwidth BW centered on (ΔΩ n -BW / 2 <f<ΔΩ n The data for +BW / 2) is extracted, and a Fourier transform with respect to frequency f is performed on the extracted data in that frequency range. The result of this Fourier transform is I n Let's represent this as (x,t). Here, since the object S is moving in the y direction, the variable t representing time can be converted to the variable y representing position in the y direction. Therefore, I n (x,t) is I n It can be expressed as (x,y).

[0054] I n (x,y) is the optical heterodyne frequency ΔΩ n Irradiation direction according to the frequency (i.e., modulation frequency Ω) n When the first branched light L1 is irradiated onto the object S along the irradiation direction (corresponding to the irradiation direction), the image represents a two-dimensional complex amplitude image of the object S caused by the first branched light L1 that reaches the imaging surface of the imaging unit 23. The processing unit 24 processes each modulation frequency Ω n Complex amplitude image I for the direction of illumination to the object S corresponding to the observation target. n Generate (x,y).

[0055] Then, the processing unit 24 generates complex amplitude images I1(x,y)~I for each of the multiple irradiation directions. N Based on (x,y), a 3D refractive index distribution image of the object S is generated. Complex amplitude image I1(x,y)~I NWhen generating a three-dimensional refractive index distribution image based on (x,y), the methods described in Non-Patent Document 1 or Non-Patent Document 2 can be used. The method described in Non-Patent Document 1 uses the Fourier Slice theorem and is applicable when light scattering in the object S can be ignored. The method described in Non-Patent Document 2 uses the Fourier Diffraction theorem and generates a three-dimensional refractive index distribution image of the object S while considering light scattering in the object S.

[0056] As described above, the observation device 1 can use a line sensor instead of an area sensor as the imaging unit 23, so the line rate (sampling frequency Ω) can be adjusted. S This allows for a higher efficiency and a lower-cost configuration. Furthermore, since the optical system from the object to be observed S to the imaging unit 23 can be a standard imaging optical system, this optical system can be easily adjusted, and the object to be observed S can be easily observed.

[0057] Next, a modified example of the overall configuration of observation device 1 will be explained using Figures 4 to 6. The first modified observation device 1A shown in Figure 4 differs from the configuration of observation device 1 (Figure 1) in the position where the second modulation unit 22 is located. In observation device 1 (Figure 1), the second modulation unit 22 was located on the optical path of the second branched light L2. In contrast, in observation device 1A (Figure 4), the second modulation unit 22 is located on the optical path of the first branched light L1 between the branching unit 12 and the first modulation unit 21. In this configuration as well, the second modulation unit 22 has an optical heterodyne frequency ΔΩ n (The difference in optical frequency between the first branched light L1 and the second branched light L2 during wave multiplexing by the wave multiplexing unit 15) is equal to the sampling frequency Ω of the imaging unit 23. S It can be adjusted to be less than half of that.

[0058] The observation device 1B of the second modified example shown in Figure 5 differs from the configurations of observation device 1 (Figure 1) and observation device 1A (Figure 4) in that it does not have a second modulation unit 22. As mentioned above, the modulation frequency Ω of the first branched light n It is small enough, Ω LO Even if = 0, the optical heterodyne frequency ΔΩ n The sampling frequency of the imaging unit 23 is Ω S If it is less than half of that, the second modulation unit 22 does not need to be provided.

[0059] The observation device 1C, a third modified example shown in Figure 6, differs from the configuration of observation device 1 (Figure 1) in the arrangement of the multiplexer 15, lens 34, and lens 35. In observation device 1 (Figure 1), the multiplexer 15 was located in the optical path between lens 34 and lens 35. In contrast, in observation device 1C (Figure 6), the multiplexer 15 is located downstream of lens 35. Consequently, in observation device 1C (Figure 6), lens 36 is a spherical lens, and lenses 37 and 38 are cylindrical lenses.

[0060] In the observation apparatus 1C of the third modified example shown in Figure 6, the second modulation unit 22 may be located on the optical path of the first branched light L1 between the branching unit 12 and the first modulation unit 21, rather than on the optical path of the second branched light L2. Also, in the observation apparatus 1C of the third modified example shown in Figure 6, the modulation frequency Ω of the first branched light n It is small enough, Ω LO Even if = 0, the optical heterodyne frequency ΔΩ n The sampling frequency of the imaging unit 23 is Ω S If it is less than half of that, the second modulation unit 22 does not need to be provided.

[0061] Next, an example configuration of the first modulation unit 21 will be explained using Figures 7 to 12. The first modulation unit 21, as already described, includes an acousto-optic element that frequency modulates light by Bragg diffraction. This first modulation unit 21 applies an RF signal having multiple distinct frequency components to the acousto-optic element and also injects a first branched light L1 into the acousto-optic element, thereby modulating the first branched light L1 at a modulation frequency corresponding to each frequency component of the RF signal. The first modulation unit 21 has N frequency components Ω1 to Ω N The first branched light L1, modulated in each of these directions, can be output in different directions.

[0062] The first modulation unit of the first modified example may include an acousto-optic element that frequency modulates light by Ramans diffraction. In this case, the first modulation unit applies a single frequency (e.g., 3 MHz) RF signal to the acousto-optic element and incidents the first branched light L1 onto the acousto-optic element, thereby modulating the first branched light L1 at multiple modulation frequencies that differ from each other according to the diffraction order. The first modulation unit has N frequency components Ω1 to Ω N The first branched light L1, modulated by each unit, can be output in different directions according to the diffraction order. The optical system of the illumination unit between this first modulation unit and the object S can have the same configuration as shown in Figure 1.

[0063] The first modulation unit 21A of the second modified example shown in Figures 7 and 8 includes a plate-shaped object on which diffraction gratings having multiple different spatial frequency components are superimposed and recorded. The plate-shaped object of the first modulation unit 21A shown in these figures is a disk-shaped object parallel to the xy plane, rotatable about a central axis O parallel to the z direction, and on which diffraction gratings having multiple spatial frequency components along the circumferential direction are superimposed and recorded. The first modulation unit 21A rotates this plate-shaped object about the central axis at a constant speed and passes the first branched light L1 through this plate-shaped object. At this time, the first branched light L1 is incident on a position in the approximately xz plane that includes the central axis O of rotation of the plate-shaped object, so that the plate-shaped object is moving in the y direction at the incident position. This makes it possible to modulate the first branched light L1 at multiple different modulation frequencies.

[0064] In the configuration shown in Figure 7, the optical system of the illumination unit between the first modulation unit 21A and the object to be observed S includes two cylindrical lenses 41 and 42. In the configuration shown in Figure 8, the optical system of the illumination unit between the first modulation unit 21A and the object to be observed S includes one cylindrical lens 43. In either case, the illumination unit modulates the first branched light L1 modulated by the first modulation unit 21A at a modulation frequency Ω n The object S to be observed is irradiated along the direction of irradiation corresponding to the irradiation direction.

[0065] Figure 9 illustrates the diffraction grating recorded on the plate-shaped object of the first modulation unit 21A of the second modified example. In this figure, the horizontal axis represents the circumferential position, and the vertical axis represents the modulation amount. Figure 9(a) shows multiple spatial frequency components k n (k min ~k max Figure 9(b) shows the modulation distribution of each diffraction grating having ).

[0066] Although the plate-shaped object of the first modulation unit 21A shown in Figures 7 and 8 was disc-shaped, the plate-shaped object on which diffraction gratings having multiple different spatial frequency components are superimposed and recorded may be strip-shaped. In this case, the strip-shaped plate-shaped object of the first modulation unit 21A is movable in the y-direction, and diffraction gratings having multiple spatial frequency components are superimposed and recorded along its direction of movement. The first modulation unit 21A can modulate the first branched light L1 at multiple different modulation frequencies by moving this strip-shaped plate-shaped object in the y-direction and passing the first branched light L1 through this plate-shaped object. By connecting both ends of the strip-shaped plate-shaped object to form a ring shape and rotating the ring-shaped plate-shaped object, the plate-shaped object can be moved in the y-direction for a long period of time.

[0067] The first modulation unit 21B of the third modified example shown in Figure 10 includes a phase-modulated spatial light modulator (SLM). In this figure, a reflective spatial light modulator is shown. Figure 10(a) shows the first modulation unit 21B and the surrounding optical system. Figure 10(b) shows the modulation frequencies of each region on the modulation plane of the spatial light modulator of the first modulation unit 21B using varying shades.

[0068] The spatial light modulator of the first modulation unit 21B changes the phase modulation amount at different speeds in each of the multiple regions divided along the y-direction within a region of the modulation plane (P1 plane) that has a limited width in the x-direction. That is, the phase modulation amount φ of each region is given by φ = Ω with respect to time t. n The frequency is continuously changed over time according to the relationship t. The first branched light L1 passes through cylindrical lenses 52 and 53, is reflected by the beam splitter 51, and is incident on the modulation plane of the spatial light modulator. Cylindrical lens 52 is a concave lens, and cylindrical lens 53 is a convex lens. By incidenting the first branched light L1 on the region of the modulation plane of the spatial light modulator that extends in the y direction (a region with a limited width in the x direction), the modulation frequency Ω is determined in each region along the y direction of the modulation plane of the spatial light modulator. n The first branched light L1 can be modulated. After the modulated first branched light L1 passes through the beam splitter 51, it is modulated to a modulation frequency Ω by the cylindrical lens 54. n The light is irradiated onto the object S according to the irradiation direction. Light reflected from the modulation plane, where the phase modulation amount does not change continuously over time, is prevented from irradiating the object S by a mask or the like (not shown).

[0069] The first modulation unit 21C of the fourth modified example shown in Figure 11 also includes a phase-modulated spatial light modulator (SLM). In this figure, a reflective spatial light modulator is shown. Figure 11(a) shows the first modulation unit 21C and the surrounding optical system. Figure 11(b) shows the modulation frequencies of each region on the modulation plane of the spatial light modulator of the first modulation unit 21C using varying shades of gray.

[0070] The spatial light modulator of the first modulation unit 21C changes the phase modulation amount at different speeds in each of the multiple regions divided along the y-direction over the entire x-direction region of the modulation plane (P1 plane). That is, the phase modulation amount φ of each region is given by φ = Ω with respect to time t. n The relationship t is used to continuously change the frequency over time. The first branched light is reflected by the beam splitter 61 after its beam diameter is expanded by lenses 62 and 63, and then incident on almost the entire modulation surface of the spatial light modulator. By incidenting the first branched light L1 on almost the entire modulation surface of the spatial light modulator, the modulation frequency Ω is determined in each region along the y-direction of the modulation surface of the spatial light modulator. n The first branched light L1 can be modulated. After the modulated first branched light L1 passes through the beam splitter 61, the lenses 64 and 65 modulate it to a modulation frequency Ω n The light is irradiated onto the object S according to the irradiation direction. Light reflected from the modulation plane, where the phase modulation amount does not change continuously over time, is prevented from irradiating the object S by a mask or the like (not shown).

[0071] The first modulation unit 21D of the fifth modified example shown in Figure 12 includes an intensity-modulated spatial light modulator (SLM). In this figure, a reflective spatial light modulator is also shown. Figure 12(a) shows the first modulation unit 21D and the surrounding optical system. Figure 12(b) shows the intensity modulation amount in each region on the modulation surface of the spatial light modulator of the first modulation unit 21D using grayscale. Figure 12(c) shows the intensity modulation amount in each region along the y-direction on the modulation surface of the spatial light modulator of the first modulation unit 21D as a graph.

[0072] The spatial light modulator of the first modulation unit 21D sets the intensity modulation amount in each of the multiple regions divided along the y direction within a region of the modulation plane (P0 plane) with a limited width in the x direction, and shifts the y-direction distribution of the intensity modulation amount in the y direction. i If the waveform is sinusoidal and the y-direction velocity is V, then in the Fourier plane (P1 plane) relative to the modulation plane (P0 plane), exp(ik i A phase shift occurs at Vt, and Ω=k i Frequency modulation of V occurs. This is utilized in the fifth modification.

[0073] The intensity modulation distribution along the y-direction of the modulation plane of the spatial light modulator has multiple spatial frequency components that are different from each other, and the intensity modulation distribution is moved at a constant speed in the y-direction on the modulation plane of the spatial light modulator. The first branched light L1 passes through cylindrical lenses 72 and 73, is reflected by the beam splitter 71, and enters the modulation plane of the spatial light modulator. Cylindrical lens 72 is a concave lens, and cylindrical lens 73 is a convex lens. The front focal plane of cylindrical lens 74 is the modulation plane (P0 plane) of the spatial light modulator, and the back focal plane of cylindrical lens 74 is the P1 plane. The front focal plane of cylindrical lens 75 is the P1 plane, and the back focal plane of cylindrical lens 75 is the plane containing the movement path of the object to be observed S (P2 plane).

[0074] When the first branched light L1 is incident on the region of the modulation plane (P0 plane) of the spatial light modulator that extends in the y direction (a region with limited width in the x direction), the modulation frequency Ω is determined in each region along the y direction on the P1 plane, similar to Figure 2. n A point image of the first branched light L1 modulated by Ω can be formed. The lens 75 then has a modulation frequency Ω on the P1 plane. n The light from the point image of each first branched light L1 is input, and the modulation frequency Ω n The first branched light L1 is a plane wave, and the modulation frequency Ω n The object S can be irradiated along the direction of irradiation according to the appropriate direction.

[0075] In addition, the first modulation units 21B to 21D in the third to fifth modified examples included a reflective spatial light modulator, but they may also include a transmissive spatial light modulator. Furthermore, a DMD (Digital Mirror Device) may be used as a reflective, intensity-modulated spatial light modulator, in which case multi-stage intensity modulation can be applied to the light by PWM (Pulse Width Modulation) modulation.

[0076] Next, a modified configuration of the area surrounding the imaging unit 23 will be described using Figure 13. In the modified configuration shown in this figure, a lens 81, an illumination position detection unit 82, a control unit 83, and a moving unit 84 are further provided. The wave multiplexing unit 15, which is located in the optical path between lens 34 and lens 35, combines the first branched light L1 and the second branched light L2, outputs the combined light to lens 35, and also outputs the combined light to lens 81.

[0077] Lens 81 is positioned on the optical path of the combined light between the combined light unit 15 and the illumination position detection unit 82. Lenses 34 and 81 constitute an imaging optical system that receives the first branched light L1 that has passed through the object to be observed S and forms an image of the object to be observed S on the imaging surface (P4 surface) of the illumination position detection unit 82. The illumination position detection unit 82 detects the illumination position of the first branched light L1 on the movement path of the object to be observed S, and is an area camera capable of capturing, for example, a two-dimensional image. This area camera does not need to be capable of high-speed imaging.

[0078] The control unit 83 controls the y-direction position of the imaging unit 23 so that multiple pixels arranged in one dimension on the imaging unit 23 can receive multiplexed light by driving the movement unit 84 based on the irradiation position detected by the irradiation position detection unit 82. The movement unit 84 moves the imaging unit 23 in the direction of movement (y-direction) of the image of the object to be observed S on the imaging surface (P3 surface) of the imaging unit 23 in accordance with the drive by the control unit 83, and is, for example, a one-axis stage with an electric actuator.

[0079] With this configuration, even if the irradiation position of the first branched light L1 on the movement path of the object S to be observed drifts in time in the y direction, the incident position of the first branched light L1 on the imaging surface (P3 surface) of the imaging unit 23 can be fixed, so that the imaging unit 23 can always stably acquire a one-dimensional interference image.

[0080] Furthermore, in order to ensure that the multiple pixels of the imaging unit 23, which are arranged in one dimension, can stably receive multiplexed light, the optical system from the object to be observed S to the imaging unit 23 may be controlled in addition to, or instead of, controlling the y-direction position of the imaging unit 23. In the latter case, for example, a mirror with a variable reflective surface orientation can be placed in the middle of the optical system from the object to be observed S to the imaging unit 23, and the orientation of the reflective surface of this mirror can be controlled by the control unit 83.

[0081] Furthermore, the irradiation position detection unit 82 only needs to be able to detect the irradiation position of the first branched light L1 on the movement path of the object to be observed S, so it does not need to receive combined light, but only the first branched light L1. For example, in the configuration shown in Figure 6, a beam splitter may be placed between lens 34 and lens 35, and the image of the object to be observed S by the first branched light L1 branched by this beam splitter may be formed on the imaging surface (P4 surface) of the irradiation position detection unit 82 by lens 81.

[0082] Furthermore, as the irradiation position detection unit 82, a profile sensor with a centroid calculation circuit for detecting the spot light incidence position (for example, S15366-512 manufactured by Hamamatsu Photonics K.K.) may be used, or a PSD (Position Sensitive Detector, for example, S2044 manufactured by Hamamatsu Photonics K.K.) may be used. [Explanation of Symbols]

[0083] 1,1A~1C... Observation device, 11... Light source, 12... Branching section, 13,14... Mirror, 15... Multiplexing section, 21,21A~21D... First modulation section, 22... Second modulation section, 23... Imaging section, 24... Processing section, 31~38... Lens.

Claims

1. A device for observing moving objects, A light source that emits light, A branching section that splits the aforementioned light into a first branched light and a second branched light, A first modulation unit modulates the first branched light at each of several different modulation frequencies, An irradiation unit that irradiates the object to be observed with the first branched light modulated by the first modulation unit along an irradiation direction corresponding to the modulation frequency, A multiplexing unit that combines the first branched light and the second branched light after they have passed through the object to be observed and outputs combined light, An imaging unit having a plurality of pixels arranged in a direction intersecting the direction of movement of the image of the object being observed on the imaging surface where the image of the object being observed is formed, receiving the multiplexed light with these plurality of pixels and repeatedly outputting a detection signal representing a one-dimensional interference image, A processing unit generates a complex amplitude image for each of the multiple irradiation directions to the object being observed, corresponding to the multiple modulation frequencies, based on the time-series data of the one-dimensional interference image generated from the detection signal repeatedly output from the imaging unit, and generates a three-dimensional refractive index distribution image of the object being observed based on the complex amplitude images for each of the multiple irradiation directions. An observation device equipped with the following features.

2. The device further comprises a second modulation unit provided on the optical path of the first branched light between the branching unit and the first modulation unit, or on the optical path of the second branched light between the branching unit and the multiplexing unit, which provides a frequency difference between the first branched light and the second branched light. The observation apparatus according to claim 1.

3. The first modulation unit includes an acousto-optic element that frequency modulates light by Bragg diffraction, and modulates the first branched light at a modulation frequency corresponding to each frequency component of the RF signal by applying an RF signal having multiple different frequency components to the acousto-optic element and by injecting the first branched light into the acousto-optic element. The observation apparatus according to claim 1 or 2.

4. The first modulation unit includes an acousto-optic element that frequency modulates light by Ramans diffraction, and modulates the first branched light at multiple different modulation frequencies by applying a single-frequency RF signal to the acousto-optic element and by injecting the first branched light into the acousto-optic element. The observation apparatus according to claim 1 or 2.

5. The first modulation unit includes a plate-shaped object on which diffraction gratings having multiple spatial frequency components of different kinds are superimposed and recorded, and modulates the first branched light at each of the multiple different modulation frequencies by moving the plate-shaped object and passing the first branched light through the plate-shaped object. The observation apparatus according to claim 1 or 2.

6. The first modulation unit includes a phase-modulated spatial light modulator, which changes the amount of phase modulation at different speeds depending on the region of the modulation surface of the spatial light modulator, and modulates the first branched light at a modulation frequency corresponding to the speed of change of the amount of phase modulation in each region of the modulation surface of the spatial light modulator by injecting the first branched light into the modulation surface of the spatial light modulator. The observation apparatus according to claim 1 or 2.

7. The first modulation unit includes an intensity-modulated spatial light modulator, wherein the intensity modulation amount distribution along a predetermined direction on the modulation surface of the spatial light modulator has a plurality of spatial frequency components that are different from each other, and the intensity modulation amount distribution is moved in the predetermined direction on the modulation surface of the spatial light modulator, and the first branched light is incident on the modulation surface of the spatial light modulator, thereby modulating the first branched light at each of the plurality of different modulation frequencies. The observation apparatus according to claim 1 or 2.

8. An irradiation position detection unit for detecting the irradiation position of the first branched light on the movement path of the object to be observed, A control unit controls the optical system from the object to be observed to the imaging unit or the position of the imaging unit, based on the irradiation position detected by the irradiation position detection unit, so that the multiple pixels of the imaging unit can receive the combined wave light. The observation apparatus according to claim 1 or 2, further comprising:

9. A method for observing a moving object, A branching step in which the light output from the light source is split into a first branched beam and a second branched beam using a branching section, A first modulation step involves using a first modulation unit to modulate the first branched light at multiple mutually different modulation frequencies, An irradiation step in which the first branched light modulated by the first modulation unit is irradiated onto the object to be observed along an irradiation direction corresponding to the modulation frequency, A multiplexing step is performed by using a multiplexing unit to combine the first branched light and the second branched light after they have passed through the object to be observed and outputting a multiplexed light, An imaging step in which an imaging unit having a plurality of pixels arranged in a direction intersecting the direction of movement of the image of the object being observed on the imaging surface in which the image of the object being observed is formed receives the multiplexed light with these plurality of pixels and repeatedly outputs a detection signal representing a one-dimensional interference image, A processing step of generating a complex amplitude image for each of the multiple irradiation directions to the object being observed corresponding to the multiple modulation frequencies, based on the time-series data of the one-dimensional interference image generated from the detection signal repeatedly output from the imaging unit, and generating a three-dimensional refractive index distribution image of the object being observed based on the complex amplitude images for each of the multiple irradiation directions, An observation method that includes the following features.

10. The system further comprises a second modulation step that provides a frequency difference between the first branched light and the second branched light using a second modulation unit provided on the optical path of the first branched light between the branching unit and the first modulation unit, or on the optical path of the second branched light between the branching unit and the multiplexing unit. The observation method according to claim 9.

11. In the first modulation step, the first modulation unit, which includes an acousto-optic element that frequency modulates light by Bragg diffraction, is used to apply an RF signal having multiple distinct frequency components to the acousto-optic element, and the first branched light is incident on the acousto-optic element to modulate the first branched light at a modulation frequency corresponding to each frequency component of the RF signal. The observation method according to claim 9 or 10.

12. In the first modulation step, a first modulation unit including an acousto-optic element that frequency modulates light by Ramans diffraction is used to apply a single-frequency RF signal to the acousto-optic element and to inject a first branched light into the acousto-optic element, thereby modulating the first branched light at each of several different modulation frequencies. The observation method according to claim 9 or 10.

13. In the first modulation step, the first modulation unit, which includes a plate-shaped object on which diffraction gratings having multiple spatial frequency components having different spatial frequency components are superimposed and recorded, is used to move the plate-shaped object and pass the first branched light through the plate-shaped object, thereby modulating the first branched light at each of the multiple different modulation frequencies. The observation method according to claim 9 or 10.

14. In the first modulation step, the first modulation unit, which includes a phase-modulated spatial light modulator, is used to change the amount of phase modulation at different speeds depending on the region of the modulation surface of the spatial light modulator, and the first branched light is incident on the modulation surface of the spatial light modulator to modulate the first branched light at a modulation frequency corresponding to the speed of change of the amount of phase modulation in each region of the modulation surface of the spatial light modulator. The observation method according to claim 9 or 10.

15. In the first modulation step, the first modulation unit, which includes an intensity-modulated spatial light modulator, is used to make the intensity modulation amount distribution along a predetermined direction on the modulation surface of the spatial light modulator have a plurality of spatial frequency components that are different from each other, the intensity modulation amount distribution is moved in the predetermined direction on the modulation surface of the spatial light modulator, and the first branched light is incident on the modulation surface of the spatial light modulator, thereby modulating the first branched light at each of the plurality of different modulation frequencies. The observation method according to claim 9 or 10.

16. The system detects the irradiation position of the first branched light on the movement path of the object to be observed, and controls the optical system from the object to be observed or the position of the imaging unit so that the multiple pixels of the imaging unit can receive the combined light, based on the detected irradiation position. The observation method according to claim 9 or 10.

Images