JP5856440B2 - Observation device - Google Patents

Description

  The present invention relates to an apparatus for observing an image of an object.

  As a technique for obtaining quantitative information by observing an image of a moving object, one using a phase shift method described in Patent Document 1 or Non-Patent Document 1 is known. In the observation apparatus based on these phase shift methods, the light of wavelength λ output from the light source is branched into two, one branched light is transmitted through the object as object light, and the other branched light is used as reference light. Thus, a two-dimensional image is captured by the interference between the object light and the reference light. Then, the optical path length of the reference light is changed by λ / 4 to obtain four two-dimensional images, and a predetermined calculation is performed on these four two-dimensional images to obtain the amplitude image and phase of the object. An image is obtained. Here, in the apparatuses described in Patent Document 1 and Non-Patent Document 1, a two-dimensional image is obtained using a two-dimensional photodetector having a spatial pixel structure in two dimensions.

Japanese Patent No. 3471556

F. Le Clerc, et al, "Numerical heterodyne holography withtwo-dimensional corresponding arrays," Optics Letters, Vol. 25, No. 10, pp. 716-718, (2000).

  In the observation apparatus using the phase shift method described in Non-Patent Document 1 or Non-Patent Document 2, the object needs to be stationary while obtaining four two-dimensional images. In order to obtain an image of a moving object, a photo detector capable of high-speed imaging with a high frame rate is used to obtain four two-dimensional images in a period during which it can be considered that the object is stationary. It is necessary to get. However, a photodetector capable of high-speed imaging is expensive, or has a small number of pixels and poor spatial resolution. In particular, in the observation apparatus described in Patent Document 1 and Non-Patent Document 1, since it is necessary to obtain a two-dimensional image using a two-dimensional photodetector having a low data update rate of the light receiver, the movement of the object is fast. In such a case, it is difficult to acquire a two-dimensional image within a period during which it can be considered that the object is stationary.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an observation apparatus that can obtain an image of an object that moves at high speed.

  An observation apparatus according to the present invention inputs a light source unit that irradiates light to a moving object, and light output from the light source unit, and converts the input light to the preceding stage of the object. The optical system that causes the first light and the second light to be heterodyne-interfered on a predetermined plane, and the Doppler shift effect due to the movement of the object is constant. A direction on the predetermined plane that is perpendicular to the moving direction of the object is the first direction, and is a direction on the predetermined plane that is orthogonal to the first direction and is parallel to the moving direction of the object. When the direction is the second direction, the first light or the second light is input, and the input light has a frequency shifted by a plurality of specific frequencies different from each other in the first direction. A frequency modulation unit that modulates light having the same frequency in two directions, and a predetermined plane The detection unit is a detection unit that detects light that has arrived at the detection unit from among the scattered light generated by the object, and the scattered light data that changes with time at a frequency corresponding to the Doppler shift amount at each time point. An output detection unit, a process of dividing the data output from the detection unit into a plurality of frequency regions based on a specific frequency, a one-dimensional Fourier transform related to a time variable, and a one-dimensional Fourier transform related to a frequency And an operation unit that obtains the data obtained as an image of the object.

  The observation apparatus includes a light source unit, a frequency modulation unit, a detection unit, and a calculation unit. The first light or the second light is input and modulated to light having a frequency shifted by a plurality of different specific frequencies in the first direction and having the same frequency in the second direction. That is, the modulated light has a frequency that is shifted by a specific frequency from the light before modulation in the first direction, and has the same frequency as the light before modulation in the second direction. The detection unit is located on a predetermined plane, detects the light reaching the detection unit among the scattered light generated in the object, and the scattered light data that changes with time at a frequency according to the Doppler shift amount, Output at each time. The calculation unit is obtained by performing a process of dividing the output from the detection unit into a plurality of frequency regions based on a specific frequency, a one-dimensional Fourier transform related to a time variable, and a one-dimensional Fourier transform related to a frequency. Data is obtained as an image of the object. According to such a configuration, it is possible to restore the image of the object in the second direction without interference by using light having frequencies shifted by a plurality of different specific frequencies in the first direction. Due to the Doppler effect, the spatial frequency of the object is converted into a temporal frequency, so that the dimension of the detector can be reduced by one dimension. Further, the image of the object is converted into a time frequency by the frequency modulation unit, so that the dimension of the detector can be reduced by one dimension. For this reason, in this observation apparatus, a desired image can be obtained using a detection unit having a number of dimensions lower than the dimension of the captured image. For example, a two-dimensional image can be obtained using a detection unit having a zero-dimensional photodetector, and a three-dimensional image can be obtained using a detection unit having a one-dimensional photodetector. For this reason, the readout time of the detector is shortened, and an image of the object moving at high speed can be obtained.

  The frequency modulation unit is disposed on the optical path of the first light, and has a frequency obtained by inputting the first light and shifting the input light by a plurality of different specific frequencies in the first direction. Then, it may be modulated into light having the same frequency in the second direction, and the modulated light may be irradiated on the object or the image of the object located on the optical path of the first light.

  In addition, the frequency modulation unit is disposed on the optical path of the second light, and has a frequency obtained by inputting the second light and shifting the input light by a plurality of different specific frequencies in the first direction. However, it may be modulated into light having the same frequency in the second direction.

  The detection unit may be a single-pixel photodetector.

  In addition, the optical system further includes an illumination optical system that is disposed between the light source unit and the object, inputs light from the light source unit, and irradiates the object from multiple directions, and the detection unit has a light receiving surface on a predetermined plane. And a photodetector having a pixel structure in the first direction on the light receiving surface.

  Moreover, it is arrange | positioned between a light source part and a target object, is further provided with the illumination optical system which inputs the light from a light source part, and irradiates light to a target object from multiple directions, and a frequency modulation part is 1st frequency. A modulation unit and a second frequency modulation unit, wherein the first frequency modulation unit is disposed on the optical path of the first light, inputs the first light, and converts the input light into the first light; A light having a frequency shifted by a first specific frequency, which is a plurality of specific frequencies different from each other in the direction, is modulated into light having the same frequency in the second direction, and the target is irradiated with the modulated light. The frequency modulation unit is arranged on the optical path of the second light, receives the second light, and transitions the input light by a second specific frequency that is a plurality of different specific frequencies in the first direction. Modulated to light having the same frequency in the second direction The detection unit is a single-pixel photodetector, and the calculation unit divides the data output from the detection unit into a plurality of frequency regions based on the first specific frequency and the second specific frequency; The data obtained by performing the one-dimensional Fourier transform on the time variable and the one-dimensional Fourier transform on the frequency may be obtained as an image of the object.

  In addition, with respect to the data that is output from the detection unit, the demultiplexer that divides the data output from the detection unit into regions including the maximum Doppler shift frequency around the specific frequency, and the time variable for the data divided by the demultiplexer A first Fourier transform unit that performs a one-dimensional Fourier transform on the data, and a second Fourier transform unit that performs a one-dimensional Fourier transform on a frequency with respect to data output from the first Fourier transform unit.

  In addition, with respect to the data output from the detection unit, the calculation unit converts the data output from the first Fourier transform unit and the first Fourier transform unit with respect to a time variable to a maximum Doppler centered on a specific frequency. You may include the frequency division part which divides | segments for every area | region which includes a shift frequency before and behind, and the 2nd Fourier-transform part which performs the one-dimensional Fourier transformation regarding a frequency about the data output from the division part.

  The calculation unit may further include a secondary phase division unit that divides data output from the detection unit by a secondary phase that is a value determined by a position where the detection unit is arranged.

  Further, the apparatus further includes a speed detection unit that detects the moving speed of the object, and the calculation unit performs correction related to a change in the speed of the object during Fourier transform based on the speed of the object detected by the speed detection unit. It is good as well.

  Moreover, the irradiation of light on the object may be performed by an optical arrangement of transmitted illumination, and the irradiation of light on the object may be performed by an optical arrangement of reflected illumination. The light source unit may be a light source that generates light in a single longitudinal mode, or the light source unit may generate broadband light. Furthermore, the light source unit may be a mode-locked laser.

  The light source unit may generate broadband light.

  The light source unit may generate a pulse wave as light.

  According to the present invention, an image of an object moving at high speed can be obtained.

It is a figure explaining the principle of acquisition of the image of the target object by the observation apparatus of this embodiment. It is a figure explaining the scattering direction of the scattered light which arises in a target object. It is a figure explaining the position where the scattered light which arises in a target object arrives at the back focal plane of a lens. It is a figure which further explains the position where the scattered light which arises in a subject reaches the back focal plane of a lens. It is a figure explaining the position where the scattered light which arises in a subject reaches the back focal plane of a lens when a subject moves. It is a figure explaining the change of the optical path length until the scattered light which arises in a target object arrives at the back focal plane of a lens when a target object moves. It is a figure explaining the angle which the scattering direction unit vector of the scattered light which arises in a target object makes, and the velocity vector of the moving target object. It is a figure which shows the structure of the observation apparatus 1 of 1st Embodiment. 3 is a diagram illustrating an example of a configuration of a frequency modulation unit 20. FIG. 3 is a diagram illustrating a pixel structure of a modulator 22. FIG. 4 is a diagram illustrating an example of a signal observed in a detection unit 40. FIG. 3 is a diagram illustrating a configuration of a calculation unit 50. FIG. It is a figure explaining the arrangement | positioning relationship between the target object 2, the condensing lens 32, and the detection part 40 in the observation apparatus 1 of this embodiment. It is a figure which shows the structure of 1 A of observation apparatuses of 2nd Embodiment. It is a figure which shows the structure of the observation apparatus 1B of 3rd Embodiment. It is a figure which shows the structure of 1 C of observation apparatuses of 4th Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  The observation apparatus of this embodiment irradiates light to the moving target object and acquires an image of the target object. First, in order to facilitate the understanding of the present invention, the basic matters regarding acquisition of a phase image of an object by the observation apparatus of the present embodiment will be described with reference to FIGS.

  FIG. 1 is a diagram for explaining the principle of acquisition of a phase image of an object by the observation apparatus of the present embodiment. This figure shows the ξη coordinate system, the xy coordinate system, and the uv coordinate system. The ξ, η, x, y, u, and v axes are all perpendicular to the optical axis of the condenser lens 32. The ξ axis, the x axis, and the u axis are parallel to each other. The η axis, y axis, and v axis are parallel to each other. The object 2 to be observed exists on the ξη plane. The condenser lens 32 exists on the xy plane. The rear focal plane of the condenser lens 32 coincides with the uv plane. The distance between the ξη plane and the xy plane is d. The distance between the xy plane and the uv plane coincides with the focal length f of the condenser lens 32. In this specification, the direction parallel to the ξ-axis direction, the x-axis direction, and the first direction is called the X-axis direction, and the direction parallel to the η-axis direction, the y-axis direction, and the second direction is called the Y-axis. is there.

  It is assumed that the object 2 is moving in the -η direction on the ξη plane. It is assumed that the object 2 is irradiated with light L0 traveling in the ζ direction perpendicular to the ξη plane. This light L0 is, for example, a plane wave. Scattered light L <b> 1 to L <b> 3 generated by irradiating the object 2 with the light L <b> 0 travels in various directions and undergoes a Doppler shift due to the movement of the object 2. The scattered light L1 having the scattering direction vector component in the same direction as the moving direction of the object 2 has a high optical frequency. The scattered light L2 having no scattering direction vector component in the moving direction of the object 2 does not change the optical frequency. The scattered light L3 having the scattering direction vector component in the direction opposite to the moving direction of the object 2 has a low optical frequency. These scattered lights L <b> 1 to L <b> 3 reach the uv plane through the condenser lens 32.

  FIG. 2 is a diagram for explaining the scattering direction of the scattered light generated in the object. In order to express the scattering direction of the scattered light generated by the object 2, it is necessary to describe with two variables of an elevation angle θ and an azimuth angle φ. The point light source virtually arranged in the object 2 is set as the origin of the ξηζ coordinate system. The angle formed by the direction vector of scattered light from the point light source located at the origin and the ζ axis is defined as an elevation angle θ. Further, an angle formed by the projection vector of the scattering direction vector on the ξη plane and the ξ axis is defined as an azimuth angle φ.

  FIG. 3 is a diagram for explaining a position where scattered light generated in the object reaches the rear focal plane of the lens. Scattered light generated by irradiating the object 2 with the light L0 can be treated as a secondary wave by Huygens' principle, and can be treated as light emitted from a point light source virtually arranged in the object 2. it can. In the figure, five virtual point light sources are arranged in the object 2. These point light sources may exist not only on the front focal plane of the condenser lens 32 but also before and after the front focal plane of the condenser lens 32.

Of the light emitted from these point light sources, scattered light L1 to L3 having the same elevation angle θ and azimuth angle φ reaches one point Pa on the rear focal plane of the condenser lens 32. Moreover, scattered light L4~L6 with other same elevation θ and azimuth φ reaches the another point P _b on the focal plane of the condenser lens 32. Since the light beams L2 and L5 are light emitted from the point light source at the front focal position of the condenser lens 32, the light rays L2 and L5 travel in parallel to the optical axis of the condenser lens 32 after the condenser lens 32. Of the light L0, the light that has not been scattered by the object 2 travels parallel to the optical axis of the condensing lens 32 and enters the condensing lens 32. Therefore, the light is collected at the rear focal position Po of the condensing lens 32. The

If the object 2 is moving in the -η direction on ξη plane, due to the Doppler shift effect, the optical frequency observed at point Pa is smaller than the original optical frequency fb, the optical frequency observed at point P _b is It is larger than the original optical frequency fb. Since the scattering angle (elevation angle θ, azimuth angle φ) is developed on the rear focal plane of the lens, an image on the rear focal plane is sometimes called an angle spectrum. A light beam having a large elevation angle θ is collected at a position far from the center point Po on the rear focal plane of the lens. In summary, even with different virtual point light sources, scattered light having the same scattering angle is collected at one point on the focal plane after the lens.

  FIG. 4 is a diagram for further explaining the position where the scattered light generated by the object reaches the rear focal plane of the lens. Here, it is assumed that scattered lights L1 to L3 are emitted from different virtual point light sources existing on the front lens focal plane in the object 2 at different scattering angles. The scattered light L4 emitted from the virtual point light source at the front focal position of the condenser lens 32 travels parallel to the optical axis of the condenser lens 32 after the condenser lens 32, and the point Ps on the rear focal plane of the condenser lens 32. Pass through. Assume that the scattered light L1 emitted from a virtual point light source on the front focal plane of the condenser lens 32 has the same scattering angle as the scattered light L4 emitted from the virtual point light source at the front focal position of the condenser lens 32. The point Ps on the rear focal plane of the condenser lens 32 passes. Since the scattered light L2 emitted from the virtual point light source at the front focal position of the condensing lens 32 has a scattering angle different from that of L4, the condensing lens 32 and later proceed in parallel to the optical axis of the condensing lens 32, but the point Ps Do not pass through. If the scattered light L3 emitted from some other virtual point light source on the front focal plane of the condenser lens 32 passes through the center of the condenser lens 32, the traveling direction is before and after the incidence of the condenser lens 32. does not change. Eventually, the light beams L1 to L3 are condensed at a point Pr further rearward from the rear focal plane of the lens. Scattered light having different scattering angles does not intersect at one point on the focal plane after the lens.

  FIG. 5 is a diagram for explaining a position where scattered light generated in the object reaches the back focal plane of the lens when the object moves. Here, the objects 2a to 2e moved to the respective positions are shown. Further, it is assumed that virtual point light sources exist in the objects 2a to 2e. The virtual point light source in the object 2a exists at the front lens focal position. The virtual point light sources in the objects 2b and 2c exist above and below the position of the virtual point light source in the object 2a. The virtual point light sources in the objects 2d and 2e exist before and after the position of the virtual point light source in the object 2a. Since the spatially uniform light L0 is irradiated onto the objects 2a to 2e, the intensity distribution of the angular spectrum of the scattered light emitted from each point light source in the objects 2a to 2e is constant. That is, even if the object 2 moves, the intensity distribution of the angle spectrum on the rear focal plane of the lens is constant.

  As the object 2 moves, the phase of light changes. For example, the optical path length difference until the light L1b, L1c emitted from each point light source in the objects 2b, 2c on the lens front focal plane reaches the position Pa on the lens rear focal plane is as follows. The optical path length until the light L1b emitted from the point light source in the object 2b reaches the incident surface of the condenser lens 32, and the light L1c emitted from the point light source in the object 2c reaches the incident surface of the condenser lens 32. Are equal to each other. However, due to the difference in thickness of the condenser lens 32, the optical path lengths of the lights L1b and L1c from the incident surface of the condenser lens 32 to the point Pa are different. As the object 2 moves at a constant speed, the optical path length difference changes linearly with time.

  FIG. 6 is a diagram for explaining the change in the optical path length until the scattered light generated in the object reaches the rear focal plane of the lens when the object moves. However, here, it is assumed that scattered light is observed at infinity without using the condenser lens 32. When the object 2 moves from the position of the object 2b to the position of the object 2c on the front lens focal plane, the case where the scattered light is observed at the point Pa is the same as the case where the scattered light is observed at infinity.

When the object 2 moves in the -η direction on the ξη plane, the amount of change ΔL per unit time of the optical path length until the scattered light emitted from the object 2 reaches the point Pp on the uv plane at infinity Is represented by the following formula (1). Here, e _pr is the scattering direction unit vector, and v _p is the velocity vector of the object 2. When this optical path length change amount ΔL per unit time is used, the phase difference, that is, the optical frequency change amount f _d is expressed by the following equation (2). λ is the wavelength of light. When the scattered light is observed at the position Pp on the uv plane, the optical path length of the scattered light reaching the position Pp is changed and the optical frequency is changed by the movement of the object 2. This is the cause of the Doppler shift.

The Doppler shift can also be explained by time axis movement which is one of the properties of Fourier transform. The complex amplitude of the object 2 is represented by g (x), and the Fourier transform of the object 2 is represented by G (k). When the object 2 moves from the position x0 to the position (x0 + x), the Fourier transform G ′ (x) of the object 2 after the movement is expressed by the following equation (3). The term in the exponential function on the right side of equation (3) represents the phase. As the object 2 moves, this phase rotates in proportion to the wave vector k, so that a frequency shift occurs. When the phase in the exponential function is φ, the frequency shift f _d is expressed by the following equation (4). e _pr is a unit vector of the wave vector k. v _p represents the time derivative of the position x, that is, the velocity of the object 2. This equation (4) is in agreement with the frequency shift equation (2) described from the change in optical path length per unit time described above.

FIG. 7 is a diagram for explaining the angle formed by the scattering direction unit vector of the scattered light generated in the object and the velocity vector of the object 2. An angle formed by a vector obtained by projecting the scattering direction unit vector e _pr onto the ηζ plane and the ζ axis is represented by θ ′. At this time, the angle formed by the scattering direction unit vector e _pr and the velocity vector v _{p of the} object 2 is θ ′ + π / 2. From this, the inner product of the scattering vector and the velocity vector on the right side of the equation (2) or (4) is expressed by the following equation (5). V is the speed of movement of the object 2. Since the numerical aperture NA of the condenser lens 32 is defined by sin θ ′, the Nyquist frequency f _nyq for obtaining a blur-free image is expressed by the following equation (6).

Next, by applying specific numerical values to estimate the amount of change f _d of the optical frequency due to the Doppler shift. Assume that the moving speed of the object 2 is 1 m / sec, assuming that the object 2 flows with a flow cytometer currently on the market. The light L0 irradiated to the object 2 is assumed to be HeNe laser light having a wavelength of 633 nm. The condenser lens 32 has an NA of 0.45 and a magnification equivalent to 20 times. When such a condensing lens 32 is used, the maximum value of the sine of the scattering angle θ ′ with respect to the velocity vector v _p is 0.45. Therefore, the maximum Doppler shift frequency is estimated to be 710 kHz from the equation (5). Further, if the speed is 100 μm / second, a maximum Doppler shift frequency of 71 Hz is observed.

The scattered light having the scattering angle θ ′ reaches the position represented by the following expression (7) on the uv plane by the condenser lens 32 having the focal length f. Therefore, using the equations (5) and (7) and using the approximate equation of tanθ′≈sinθ ′ that holds when the angle θ ′ is small, the Doppler shift frequency f _d is expressed by the following equation (8): It can be expressed as a function of the v coordinate value. When approximation is not used, it is expressed by the following equation (9).

(First embodiment)
An observation apparatus according to the following embodiment is an apparatus that acquires an image of the object 2 based on the principle described above. In the observation apparatus 1 of the present embodiment, a two-dimensional image of the object 2 is obtained using a single pixel zero-dimensional photodetector. FIG. 8 is a diagram showing a configuration of the observation apparatus 1 of the present embodiment. The observation apparatus 1 of this embodiment includes a light source unit 10, a beam splitter HM1, a frequency modulation unit 20, a condenser lens 32, an illumination lens 31, a beam splitter HM2, a mirror M1, a mirror M2, a detection unit 40, and a calculation unit 50. Prepare.

The light source unit 10 is, for example, a HeNe laser light source, and outputs light (optical frequency f _b ) to be irradiated on the object 2. The beam splitter HM1 inputs the light output from the light source unit 10, divides the light into two to form first light and second light, and outputs the first light to the frequency modulation unit 20, The second light is output to the mirror M1. The light output to the mirror M1 is sequentially reflected by the mirrors M1 and M2 and output to the beam splitter HM2.

  The frequency modulation unit 20 modulates the light output from the light source unit 10 into light having a plurality of different frequencies in the X-axis direction and the same frequency in the Y-axis direction, and the modulated light is an illumination lens 31. The object 2 is irradiated via As shown in FIG. 9, the frequency modulation unit 20 includes a lens 21, a beam splitter HM <b> 3, and a modulator 22. The lens 21 adjusts the beam diameter of the light output from the beam splitter HM <b> 1 to the same size as that of the modulator 22, and then outputs the light to the modulator 22. The illumination lens 31 has an effect of imaging the object light cross sections arranged at frequencies orthogonal to each other in the X-axis direction by the frequency modulation unit 20 on the ξ-η plane where the object 2 exists. That is, the illumination lens 31 illuminates the output from the frequency modulation unit 20 on the ξ-η plane. Note that the illumination lens 31 may illuminate the image plane of the object equivalent (conjugated) to the ξ-η plane.

The modulator 22, for example, as shown in FIG. 10, the pixel structure in the X-axis direction _{d n (n = 1,2, ...} , N) the spatial light modulator with a (Spatial Light Modulator) is used. A spatial light modulator is a device that applies phase modulation to incident light. Modulator 22, the light incident on each pixel _{d n,} each pixel _{d n} different modulation frequencies for each _{Ω n (n = 1,2, ...} , N) modulated by (specific frequency), its The modulated light is output to the beam splitter HM3. Here, the modulation frequency Ω _n is a frequency satisfying the following expression (10). (10) _{B w} in the equation is the maximum Doppler shift frequency _{B w} shown in the following equation (11). In equation (11), λ is the wavelength of light, V is the speed of the moving object, and θ _max is the maximum scattering angle at which the condenser lens 32 can take scattered light from the object 2.

The modulator 22 outputs light having a plurality of different frequencies f _b + Ω _{1 to} f _b + Ω _N in the X-axis direction and modulated into light having the same frequency in the Y-axis direction. The beam splitter HM3 outputs the light output from the modulator 22 as an output of the frequency modulation unit 20 to the object 2 via the illumination lens 31. As the modulator 22, instead of the spatial light modulator having a pixel structure d _n in the X-axis direction, it may be used an acoustic optical element are arranged in parallel in the X direction.

  The light output from the frequency modulation unit 20 is irradiated onto the object 2 through the illumination lens 31. The condenser lens 32 receives the scattered light generated by the object 2 by the light irradiation from the frequency modulation unit 20 and forms a francophor diffraction image of the object 2 on the light receiving surface of the detection unit 40. The condenser lens 32 outputs the light output from the frequency modulation unit 20 to the beam splitter HM2.

  The beam splitter HM2 receives light (first light) that has arrived from the condenser lens 32 and light (second light) that has arrived from the mirror M2 on the light receiving surface of the detection unit 40, and receives both lights. Heterodyne interference occurs on the surface. Hereinafter, in this specification, the light that passes through the optical path in which the target object 2 is disposed is referred to as object light, and the light that passes through the optical path in which the target object 2 is not disposed may be referred to as reference light. In the present embodiment, the first light is object light, and the second light is reference light. When the object light and the reference light are subjected to heterodyne interference on the light receiving surface of the detection unit 40, the detection unit 40 observes an interference beat signal between the object light and the reference light.

  Assuming that the object 2 moves in the -η direction on the ξη plane, the Doppler shift frequency due to the movement of the object 2 is constant in the light that has reached the light receiving surface of the detection unit 40 via the condenser lens 32. The first direction is the u direction parallel to the ξ axis. That is, the first direction is a direction perpendicular to the moving direction of the object 2. The second direction on the light receiving surface perpendicular to the first direction is the v direction parallel to the η axis. That is, the second direction is a direction parallel to the moving direction of the object 2.

  The detection unit 40 detects light that has reached the light receiving surface of the detection unit 40 from the scattered light generated in the object 2 by light irradiation by the frequency modulation unit 20, and temporally changes at a frequency according to the Doppler shift amount. The scattered light data is output at each time. The detection unit 40 is a zero-dimensional light detection element composed of a single pixel. A photodiode (PD) or a photomultiplier tube (PMT) is used as the light detection element. The light receiving surface of the detection unit 40 is disposed at a position that coincides with the rear focal plane of the condenser lens 32.

FIG. 11 is a diagram illustrating an example of signals observed in the detection unit 40. In FIG. 11, the horizontal axis represents frequency. As shown in FIG. 11, the detection unit 40 observes a signal including a Doppler shift frequency f _d due to scattered light from a moving object around the Ω _n that is an interference beat signal between the object light and the reference light. Is done. The detection unit 40 outputs the detected signal to the calculation unit 50.

The calculation unit 50 performs a predetermined calculation on the data having the time output from the detection unit 40 as a variable to obtain an image of the object 2. As illustrated in FIG. 12, the calculation unit 50 includes a first Fourier transform unit 51, a frequency division unit 52, and a second Fourier transform unit 53. The first Fourier transform unit 51 performs a one-dimensional Fourier transform on time for data having the time output from the detection unit 40 as a variable. The frequency dividing unit 52 receives the signal output from the first Fourier transform unit 51 and divides the signal into a predetermined frequency band. Specifically, the signal output from the first Fourier transform unit 51, around the modulation frequency Omega _n, and outputs the divided every N frequency region including the maximum Doppler shift frequency B _w before and after. The second Fourier transform unit 53 performs a one-dimensional Fourier transform on the frequency for the N pieces of data output from the frequency division unit 52.

  In the observation apparatus 1 of the present embodiment, the light receiving surface of the detection unit 40 is disposed at a position that coincides with the rear focal plane of the condenser lens 32. However, the light receiving surface of the detection unit 40 is different from that of the present embodiment. It may be arranged in a position. FIG. 13 is a diagram for explaining the arrangement relationship of the object 2, the condenser lens 32, and the detection unit 40 in the observation apparatus 1 of the present embodiment. The figure (a) is the figure seen in the (eta) direction, The figure (b) is the figure seen in the (xi) direction. In the figure, a ξη coordinate system having the origin at the front focal position of the condenser lens 32, an xy coordinate system having the origin at the center of the condenser lens 32, a uv coordinate system having the origin at the rear focal position of the condenser lens 32, A u′v ′ coordinate system having an origin at the center position of the image forming surface by the condenser lens 32 and a u ″ v ”coordinate system having an origin at an arbitrary position on the optical axis of the condenser lens 32 are shown. . Hereinafter, an arrangement in which the light receiving surface of the detection unit 40 matches the uv plane is referred to as a first arrangement example, and an arrangement in which the light receiving surface of the detection unit 40 matches the u′v ′ plane is referred to as a second arrangement example. An arrangement in which the light receiving surface of the detection unit 40 coincides with the u "v" plane is referred to as a third arrangement example.

  As shown in FIG. 5B, the light beams L4 to L6 generated at the same angle by the virtual point light sources g1 to g3 in the object 2 intersect at a point a on the uv plane which is the rear focal plane of the lens, and eventually. The light diverges and reaches points h, g, and f on the u′v ′ plane, which is the lens imaging plane. Since these rays L4 to L6 have the same scattering angle θ ′, they undergo the same amount of Doppler shift.

  The difference between signals received by the detection unit 40 in each of the first arrangement example and the second arrangement example will be described as follows. In the first arrangement example, the frequency shift is regularly observed in the v direction, and there is a one-to-one correspondence between the position in the v direction and the frequency shift amount. On the other hand, in the second arrangement example, the frequency shift is not regularly arranged in the v ′ direction, and there is no one-to-one correspondence between the position in the v ′ direction and the frequency shift amount.

  Here, in order to make the frequency shift amounts irregularly arranged in the v ′ direction in the second arrangement example in order (that is, in an order as observed on the light receiving surface of the detection unit 40 in the first arrangement example). Is obtained by combining (summing) the waveforms observed at the points f, g, and h on the u′v ′ plane and then performing a Fourier transform. By doing so, the frequency axis becomes linear, And its amplitude and phase are obtained.

  That is, as long as the detection unit 40 has a light-receiving surface large enough to cover the scattered light that has been subjected to Doppler shift by the object 2, a signal obtained regardless of the position at which the detection unit 40 receives light. Is not changed and is encoded in frequency, so that the distribution obtained on the light receiving surface of the detection unit 40 in the first arrangement example can be recovered.

  On the other hand, as shown in FIG. 9A, since the Doppler shift is not performed in the u direction, the distribution cannot be recovered by calculation or the like even if the signal is integrated in the u direction. Therefore, in the observation apparatus 1 of the present embodiment, the one-dimensional image in the Y direction developed in the time direction is obtained by arranging the frequencies orthogonal to each other in the X-axis direction in the cross section of the object light and obtaining an interference signal with the reference light. Can be restored without interference. By arranging frequencies orthogonal to each other in the X-axis direction in the cross section of the object light and obtaining an interference signal with the object light, signals output from each region of the light receiving surface of the detector can be restored without interference. Therefore, even if the detection unit 40 is a 0-dimensional light detection element composed of a single pixel, the observation apparatus 1 can obtain a two-dimensional image. As described above, according to the observation apparatus of the present embodiment, an image of an object can be obtained using a 0-dimensional photodetecting element composed of a single pixel, and thus an image of an object moving at high speed can be obtained. .

(Second Embodiment)
In the first embodiment, the frequency modulation unit 20 is disposed on the object optical path (on the optical path of the first light). The observation apparatus 1A according to the second embodiment is different from the first embodiment in that the frequency modulation unit 20 is disposed on the reference optical path (on the optical path of the second light). The other points are the same as those in the first embodiment. In the following, differences from the first embodiment will be mainly described, and description of points that are the same as those of the first embodiment will be omitted.

  FIG. 14 is a diagram illustrating a configuration of an observation apparatus 1A according to the second embodiment. As in the first embodiment, the observation apparatus 1A of the present embodiment includes a light source unit 10, a beam splitter HM1, a frequency modulation unit 20, a condensing lens 32, an illumination lens 31, a beam splitter HM2, a mirror M1, a mirror M2, The detection part 40 and the calculating part 50 are provided. However, in the observation apparatus 1A, the frequency modulation unit 20 is disposed on the reference optical path.

  The light source unit 10 irradiates the moving object with light. The condenser lens 32 inputs scattered light generated by the object 2 by light irradiation from the light source unit 10, and forms a Franforfer diffraction image of the object 2 on the light receiving surface of the detection unit 40. The condenser lens 32 outputs the light output from the frequency modulation unit 20 to the beam splitter HM2.

The frequency modulation unit 20 inputs the light output from the light source unit 10 via the beam splitter HM1 and the mirror M1, and has a plurality of frequencies f _b + Ω _{1 to} f _b + Ω _N different from each other in the X-axis direction, and the Y-axis The light is modulated into light having the same frequency in the direction, and the modulated light is output to the beam splitter HM2 via the illumination lens 31. The illumination lens 31 has an effect of imaging the reference light cross sections arranged at frequencies orthogonal to each other in the X-axis direction by the frequency modulation unit 20 on the light receiving surface of the detection unit 40. That is, the illumination lens 31 illuminates the light receiving surface of the detection unit 40 with the output from the frequency modulation unit 20.

  The beam splitter HM2 causes the light (object light) that has arrived from the condensing lens 32 and the light (reference light) that has arrived from the condensing lens 33 to enter the light-receiving surface of the detection unit 40, and both lights are incident on the light-receiving surface. Causes heterodyne interference. When the object light and the reference light are subjected to heterodyne interference on the light receiving surface of the detection unit 40, the detection unit 40 observes an interference beat signal between the object light and the reference light.

The interference beat signal observed by the detection unit 40 of the present embodiment is the same as that observed in the first embodiment. That is, in the detection unit 40, a signal including the Doppler shift frequency f _d due to scattered light from the moving object around the Ω _n that is an interference beat signal between the object light and the reference light shown in FIG. Observed. Therefore, the function of the calculation unit 50 arranged at the subsequent stage of the detection unit 40 is the same as that of the first embodiment, and the description thereof is omitted.

  Also in the observation apparatus 1A of the present embodiment, by arranging frequencies orthogonal to each other in the X-axis direction in the reference light section and obtaining an interference signal with object light, a one-dimensional image in the Y direction developed in the time direction is obtained. It can be restored without interference. By arranging frequencies orthogonal to each other in the X-axis direction in the cross section of the reference optical path and obtaining an interference signal with the object light, signals output from each region of the detector light receiving surface can be restored without interference. Therefore, even if the detection unit 40 is a 0-dimensional light detection element composed of a single pixel, the observation apparatus 1 can obtain a two-dimensional image. As described above, according to the observation apparatus of the present embodiment, since a two-dimensional image of an object can be obtained using a 0-dimensional photodetecting element composed of a single pixel, an image of the object moving at high speed can be obtained. Can do.

(Third embodiment)
In the observation apparatuses 1 and 1A of the first and second embodiments, a two-dimensional image of the object 2 is obtained using a zero-dimensional light detection element composed of a single pixel. The observation device 1B of the third embodiment obtains a three-dimensional image of the object 2 using a one-dimensional photodetector having a pixel structure in the X-axis direction. In the following, differences from the first embodiment will be mainly described, and description of points that are the same as those of the first embodiment will be omitted.

First, a general principle for obtaining a three-dimensional image will be described. It is assumed that the object 2 is irradiated with light from multiple directions. In this case, when the object 2 moving at the velocity vector V is irradiated with light having the frequency f, the frequency of the scattered wave generated in the object 2 is the Doppler shift frequency f _d expressed by the following equation (12) due to the Doppler effect. Only changes. In the equation (12), the incident unit vector of incident light on the object 2 is s _0, and the scattering unit vector indicating the scattering direction of the scattered wave generated by the object 2 is s. In the equation (12), λ is the wavelength of light. Equation (12) indicates that the Doppler shift amount f _d is proportional to the inner product of (s−s ₀ ) and the velocity vector V of the moving object.

From equation (12), it can be seen that when the velocity V and the scattering unit vector s are constant, the Doppler shift frequency f _d of the diffracted wave observed at a certain position has a one-to-one correspondence with the incident unit vector s ₀ . As described above, the Doppler shift frequency f _d depends on the incident angle θ ₀ of the incident wave.

It is a well-known technique to obtain a three-dimensional complex amplitude image from a complex amplitude image having the incident angle θ ₀ as a variable using a Fourier diffraction theorem or the like. For example, such methods include “W. Choi, C. Fang-Yen, K. Badizadegan, S. Oh, N. Lue, RR Dasari, and MS Feld,“ Tomographic phase microscopy, ”Nature Methods 4,717-719. (2007) ". Thus, as used herein, describes the procedure for obtaining the complex amplitude image of the incident angle theta ₀ and variables, a description of how to generate a three-dimensional image from the complex amplitude image of the incident angle theta ₀ and variable omitted .

  FIG. 15 is a diagram illustrating a configuration of an observation apparatus 1B according to the third embodiment. As shown in FIG. 15, the observation apparatus 1B of the present embodiment includes a light source unit 10, a beam splitter HM1, a frequency modulation unit 20, an illumination lens 31, a condenser lens 32, a beam splitter HM2, a mirror M1, a mirror M2, and a detection unit. 40 and a calculation unit 50.

The frequency modulation unit 20 receives the light output from the light source unit 10, and has a plurality of frequencies f _b + Ω _{1 to} f _b + Ω _N that are different from each other in the X-axis direction, and has the same frequency in the Y-axis direction. The modulated light is modulated and the modulated light is output to the illumination lens 31.

The illumination lens 31 receives the light output from the frequency modulation unit 20 and irradiates the object 2 with light having various directions in the X-axis direction and a certain direction in the Y-axis direction. A cylindrical lens is used as the illumination lens 31. In the illumination lens 31, a surface having a curvature is disposed in parallel to the X-axis direction, and a surface having no curvature is disposed in parallel to the Y-axis direction. By such an illumination lens 31, the object 2 is irradiated with light whose X-axis direction is convergent light or divergent light and whose Y-axis direction is parallel light. That is, the object 2 is irradiated with light from multiple directions in the X-axis direction. With such an illumination lens 31, each light f _b + Ω _n modulated and output at a different frequency in the X-axis direction by the frequency modulation unit 20 is irradiated onto the object 2 at a different incident angle θ _0. It becomes.

  The condenser lens 32 receives the scattered light generated by the object 2 by the irradiation of the light output from the illumination lens 31, and forms a Franforfer diffraction image of the object 2 on the light receiving surface of the detection unit 40. The condenser lens 32 outputs the light output from the frequency modulation unit 20 to the beam splitter HM2.

  The light output as the second light from the beam splitter HM1 to the mirror M1 is sequentially reflected by the mirrors M1 and M2 and output to the beam splitter HM2. The beam splitter HM2 causes the light (object light) that has arrived from the condensing lens 32 and the light (reference light) that has arrived from the mirror M2 to enter the light-receiving surface of the detection unit 40, and both lights are heterodyne on the light-receiving surface. Make it interfere. When the object light and the reference light are subjected to heterodyne interference on the light receiving surface of the detection unit 40, the detection unit 40 observes an interference beat signal between the object light and the reference light.

The detection unit 40 detects the light that has reached the detection unit 40 among the scattered light generated in the object 2, and outputs the scattered light data that changes with time at a frequency corresponding to the Doppler shift amount at each time. To do. The light receiving surface of the detection unit 40 is disposed at a position that coincides with the rear focal plane of the condenser lens 32. Therefore, scattered light having the same scattering angle is collected at one point of the detection unit 40. Detector 40 has a pixel structure in which pixels d ₁ to d _n are arranged in the u direction, the elongate shape in the photosensitive region of each pixel d _n is the v direction.

Calculation unit 50, for each of the data output from each pixel d _n, performs one-dimensional Fourier transform time-related variable is divided into a plurality of frequency domain based on the modulation frequency Omega _n, and one-dimensional Fourier transform on Frequency Data obtained by performing is obtained as an image of the object 2.

The configuration of the calculation unit 50 of the observation apparatus 1B of the present embodiment is the same as that shown in FIG. That is, the calculation unit 50 includes a first Fourier transform unit 51, a frequency division unit 52, and a second Fourier transform unit 53. The first Fourier transform unit 51 performs a one-dimensional Fourier transform on time for data having the time output from the detection unit 40 as a variable. The frequency dividing unit 52 receives the signal output from the first Fourier transform unit 51 and divides the signal into a predetermined frequency band. Specifically, around the modulation frequency Omega _n, and it outputs the divided N number of frequency bands including the maximum Doppler shift frequency B _w before and after. The third Fourier transform unit 53 performs a one-dimensional Fourier transform on the frequency for the N pieces of data output from the frequency division unit 52.

The data obtained by the calculation unit 50 in this way is a complex amplitude image with the incident angle θ ₀ as a variable. As described above, it is a well-known technique to obtain a three-dimensional complex amplitude image from the complex amplitude image having the incident angle θ ₀ as a variable using the Fourier diffraction theorem. Therefore, in the present specification, description of a method for generating a three-dimensional image from a complex amplitude image having the incident angle θ ₀ as a variable is omitted.

  Also in the observation apparatus 1B of the present embodiment, in the object light, the frequencies orthogonal to each other are arranged in the angular direction of the incident light to the target object, and an interference signal with the object light is obtained, thereby developing the Y direction in the time direction. Can be restored without interference. By arranging frequencies orthogonal to each other in the angular direction of the incident light on the object in the object light and obtaining an interference signal with the reference light, the signal for the light at each angle of the incident light can be restored without interference. it can. Therefore, even if the detection unit 40 is a one-dimensional photodetector having a pixel structure in the X-axis direction, the observation apparatus 1 can obtain a three-dimensional image. As described above, according to the observation apparatus of the present embodiment, a three-dimensional image of an object can be obtained using a one-dimensional photodetector having a pixel structure in the X-axis direction. An image can be obtained.

(Fourth embodiment)
The observation devices 1 and 1A of the first and second embodiments obtained a two-dimensional image of the object 2 using a zero-dimensional photodetecting element composed of a single pixel. The observation apparatus 1B of the third embodiment has obtained a three-dimensional image of the object 2 using a one-dimensional photodetector having a pixel structure in the X-axis direction. The observation apparatus 1 </ b> C of the fourth embodiment obtains a three-dimensional image of the target object 2 using a zero-dimensional light detection element composed of a single pixel.

  FIG. 16 is a diagram illustrating a configuration of an observation apparatus 1C according to the fourth embodiment. As illustrated in FIG. 16, the observation apparatus 1C of the present embodiment includes a first frequency modulation unit 20A instead of the frequency modulation unit 20 of the observation apparatus 1B. In addition, the observation apparatus 1C according to the embodiment includes the second frequency modulation unit 20B in the reference optical path. Other configurations are the same as those of the observation apparatus 1B. Hereinafter, only differences from the observation apparatus 1B will be mainly described, and descriptions of points that can be regarded as the same as the observation apparatus 1B will be omitted.

The first frequency modulation unit 20A receives light output from the light source unit 10 via the beam splitter HM1, and converts the light having a plurality of different frequencies in the X-axis direction and the same frequency in the Y-axis direction. Outputs modulated light. The first frequency modulation unit 20A includes a pixel structure d _n (n = 1, 2,..., N) in the X-axis direction. Modulation signals with different modulation frequencies Ω _n are input to the first frequency modulation unit 20A. First frequency modulating unit 20A outputs the light input to each pixel d _n modulation frequency Omega _{n (first} specific frequency) only by the frequency transition. The first frequency modulation unit 20 </ _b > A has a plurality of different frequencies f _b + Ω _{1 to} f _b + Ω _N in the X-axis direction and outputs light modulated to light having the same frequency in the Y-axis direction to the illumination lens 31. . The illumination lens 31 converts the light output from the first frequency modulation unit 20A into light that converges or diverges in the X-axis direction, and irradiates the object 2 as parallel light in the Y-axis direction.

The second frequency modulation unit 20B inputs light output from the light source unit 10 via the beam splitter HM1, and converts the light having a plurality of different frequencies in the X-axis direction and the same frequency in the Y-axis direction. Outputs modulated light. The second frequency modulation unit 20B includes a pixel structure d _m (m = 1, 2,..., M) in the X-axis direction. Modulation signals having different modulation frequencies Ω _m ′ (second specific frequency) are input to the second frequency modulation unit 20B. The second frequency modulating unit 20B outputs the light input to each pixel d _m modulation frequency Omega _{m 'only} by the frequency transition. The first frequency modulation unit 20 </ _b > A has a plurality of frequencies f _b + Ω ₁ ′ to f _b + Ω _M ′ different from each other in the X-axis direction, and converts the light modulated into light having the same frequency in the Y-axis direction to the illumination lens 33. Output.

The beam splitter HM2 causes the object light and the reference light to enter the light receiving surface of the detection unit 40, and causes both lights to heterodyne interfere on the light reception surface of the detection unit 40. Light incident on the light receiving surface of the detector 40 is output from the condenser lens 32 has a frequency of f + Omega _n by the action of the first frequency modulation section 20A. The light output from the illumination lens 33 and incident on the light receiving surface of the detection unit 40 has a frequency of f + Ω _M ′ by the action of the second frequency modulation unit 20B. When the object light and the reference light are subjected to heterodyne interference on the light receiving surface of the detection unit 40, the detection unit 40 observes an interference beat signal between the object light and the reference light.

  The detection unit 40 detects light that has reached the detection unit 40 among the scattered light generated by the object 2 by light irradiation by the frequency modulation unit 20, and is scattered light that changes with time at a frequency corresponding to the Doppler shift amount. Are output at each time. The detection unit 40 is a zero-dimensional light detection element composed of a single pixel. The light receiving surface of the detection unit 40 is disposed at a position that coincides with the rear focal plane of the condenser lens 32.

The calculation unit 50 performs one-dimensional Fourier transform on the time variable for each of the data output from the detection unit 40, divides the data into a plurality of frequency regions based on the modulation frequency Ω _n and the modulation frequency Ω _m ′, and relates to the frequency Data obtained by performing the one-dimensional Fourier transform is obtained as an image of the object 2.

The configuration of the calculation unit 50 of the observation apparatus 1C of the present embodiment is the same as that shown in FIG. That is, the calculation unit 50 includes a first Fourier transform unit 51, a frequency division unit 52, and a second Fourier transform unit 53. The first Fourier transform unit 51 performs a one-dimensional Fourier transform on time for data having the time output from the detection unit 40 as a variable. The frequency dividing unit 52 receives the signal output from the first Fourier transform unit 51 and divides the signal into a predetermined frequency band. Specifically, the modulation frequency Omega _n, around the Omega _{m ',} and outputs the extracted NxM number of frequency bands including the maximum Doppler shift frequency B _w before and after.

  The third Fourier transform unit 53 performs a one-dimensional Fourier transform on the frequency for the N pieces of data output from the frequency division unit 52. Note that the first Fourier transform unit 61 and the third Fourier transform unit 53 may be interchanged with each other and arranged in any order.

The data obtained by the calculation unit 50 in this way is a complex amplitude image with the incident angle θ ₀ as a variable. As described above, it is a well-known technique to obtain a three-dimensional complex amplitude image from the complex amplitude image having the incident angle θ ₀ as a variable using the Fourier diffraction theorem. Therefore, in the present specification, description of a method for generating a three-dimensional image from a complex amplitude image having the incident angle θ ₀ as a variable is omitted.

  Also in the observation apparatus 1B of the present embodiment, in the object light, the frequencies orthogonal to each other are arranged in the angular direction of the incident light to the target object, and an interference signal with the object light is obtained, thereby developing the Y direction in the time direction. Can be restored without interference. By arranging frequencies orthogonal to each other in the angular direction of the incident light on the object in the object light and obtaining an interference signal with the reference light, the signal for the light at each angle of the incident light can be restored without interference. it can. Further, by arranging frequencies orthogonal to each other in the X-axis direction in the reference light section and obtaining an interference signal with the object light, the one-dimensional image in the Y direction developed in the time direction can be restored without interference. . By arranging frequencies orthogonal to each other in the X-axis direction in the cross section of the reference optical path and obtaining an interference signal with the object light, signals output from each region of the detector light receiving surface can be restored without interference. Therefore, even if the detection unit 40 is a 0-dimensional light detection element composed of a single pixel, the observation apparatus 1 can obtain a three-dimensional image. As described above, according to the observation apparatus of the present embodiment, a three-dimensional image of an object can be obtained using a single pixel 0-dimensional photodetecting element, and therefore an image of an object moving at high speed can be obtained. it can.

(Modification)
In this arrangement example, the light receiving surface of the detection unit 50 is arranged on the rear focal plane of the condenser lens 32. However, even if the light receiving surface of the detection unit 50 is not disposed on the rear focal plane of the condenser lens 32, the light reception surface of the detection unit 50 can be changed by the predetermined calculation. It is possible to obtain the same complex amplitude image as that disposed on the back focal plane. However, when the detection unit 50 is disposed on the Fresnel diffraction image plane, the secondary phase H (u) appears as blurring of the image. In this case, it is preferable that the arithmetic unit 50 includes a secondary phase division unit that divides the output of the detection unit 50 by the secondary phase H (u) after performing a one-dimensional Fourier transform in the first direction. The secondary phase H (u) is a value determined by the position where the detection unit 50 is disposed, and is expressed by the following equation (13). In the equation (13), α is a constant.

In the above embodiment, the frequency division unit 52 of the arithmetic unit 50, around the modulation frequency Omega _n, but by dividing the N frequency band including the maximum Doppler shift frequency B _w before and after a frequency band in a different way May be divided. For example, a duplexer may be provided after the detector, a signal output from the detection unit 40 may be input, and the signal may be divided for each predetermined frequency. As such a duplexer, N band-pass filters arranged in parallel in the X-axis direction are used.

  In the observation apparatus 1 of the present embodiment, when the speed of the object 2 changes, frequency modulation occurs in the Doppler signal, and the finally obtained image of the object 2 expands and contracts in the flow direction. In order to correct such expansion and contraction, it is preferable that the observation apparatus 1 of the present embodiment further includes a speed detection unit that detects the moving speed of the object 2. And the calculating part 50 correct | amends regarding the speed change of the target object 2 in the time of the one-dimensional Fourier transformation of a time direction, or two-dimensional Fourier transformation based on the speed of the target object 2 detected by the speed detection part. Is preferred. Alternatively, the imaging timing of the detection unit 40 may be achieved based on the speed of the object 2 detected by the speed detection unit.

Any speed detection unit may be used, and the frequency of the signal at the scattered light arrival position of the rear focal plane of the condenser lens 32 is detected using the relationship between the moving speed and the Doppler shift amount. By doing so, the moving speed of the object 2 can be obtained. In this case, the speed detection unit may detect a part of the light branched from the beam splitter HM2 to the detection unit 40 on the Fourier plane, or may detect a part of the light receiving surface of the detection unit 40. It may include pixels provided independently. The size of the pixel, it is preferable to have an area with a resolution of the moving speed derived from the relationship between the moving speed V and the Doppler frequency f _d of the object 2.

  In the above description, the embodiment in which the phase image of the object of the light source is mainly obtained by the transmitted illumination is shown. However, it is obvious that it may be obtained by the reflected illumination. In order to detect the Doppler shift amount with high sensitivity as the light source, it is preferable to use light in a single longitudinal mode, but the present invention is not limited to this. For example, information on the depth of the phase object can be acquired by using broadband light. In order to measure the Doppler shift of each wavelength component, it is preferable to use a broadband light whose phase relationship between wavelength components is constant. For example, a mode-locked laser can be used as such a light source. Since the mode-locked laser has discrete wavelength components, it is a very effective light source in applications for detecting the Doppler shift amount.

DESCRIPTION OF SYMBOLS 1,1A, 1B, 1C ... Observation apparatus, 2 ... Object, 10 ... Light source part, 20 ... Frequency modulation part, 20A ... 1st frequency modulation part, 20B ... 2nd frequency modulation part, 31, 33 ... Illumination lens, 32 ... Condensing lens, 40 ... Detection unit, 50 ... Calculation unit, 51 ... First Fourier transform unit, 52 ... Frequency division unit, 52 ... Second Fourier transform unit

Claims (15)

A light source unit that outputs light emitted to the object is moving on a predetermined plane,
The light output from the light source unit is input, the input light is divided into two at the front stage of the object to be the first light and the second light, and the first light is directed to the object A first optical system that outputs
When the direction on the predetermined plane perpendicular to the moving direction of the object is a first direction and the direction on the predetermined plane parallel to the moving direction of the object is a second direction, the first light Alternatively, the second light is input, and the input light has a frequency shifted by a plurality of different specific frequencies in a direction corresponding to the first direction, and in the direction corresponding to the second direction . A frequency modulation unit that modulates light having the same frequency;
A second optical system that causes heterodyne interference between the scattered light generated by the object and the second light on a predetermined plane different from the predetermined plane;
A detection unit located on the other predetermined plane, receiving the heterodyne-interfered light, and outputting the received light data at each time; and
Obtained by performing a process of dividing the data output from the detection unit into a plurality of frequency regions based on the specific frequency, a one-dimensional Fourier transform related to a time variable, and a one-dimensional Fourier transform related to a frequency And an arithmetic unit that obtains data as an image of the object. The frequency modulation unit is disposed on an optical path of the first light, inputs the first light, and inputs the input light by a plurality of specific frequencies different from each other in a direction corresponding to the first direction. The object or object having a transitioned frequency and modulating into light having the same frequency in a direction corresponding to the second direction, and the modulated light being positioned on the optical path of the first light The observation apparatus according to claim 1, which irradiates an image of The frequency modulation unit is disposed on the optical path of the second light, inputs the second light, and inputs the input light to a plurality of specific frequencies different from each other in a direction corresponding to the first direction. The observation apparatus according to claim 1, wherein the observation apparatus modulates light having a transitioned frequency and having the same frequency in a direction corresponding to the second direction.   The observation device according to claim 1, wherein the detection unit is a single-pixel photodetector. An illumination optical system that is disposed between the light source unit and the object, inputs light from the light source unit, and irradiates light from multiple directions to the object;
The said detection part is a photodetector which has a light-receiving surface in said another predetermined plane, and has a pixel structure in the direction corresponding to a said 1st direction in this light-receiving surface. The observation apparatus described in 1. An illumination optical system that is disposed between the light source unit and the object, inputs light from the light source unit, and irradiates light from multiple directions to the object;
The frequency modulation unit includes a first frequency modulation unit and a second frequency modulation unit,
The first frequency modulation unit is disposed on an optical path of the first light, inputs the first light, and inputs the input light to a plurality of different ones in a direction corresponding to the first direction. A frequency that has been shifted by a first specific frequency that is a specific frequency is modulated into light having the same frequency in a direction corresponding to the second direction, and the object is irradiated with the modulated light,
The second frequency modulation unit is disposed on an optical path of the second light, inputs the second light, and inputs the input light to a plurality of different ones in a direction corresponding to the first direction. A specific frequency having a frequency shifted by a second specific frequency different from the first specific frequency, and modulating to light having the same frequency in a direction corresponding to the second direction;
The detector is a single-pixel photodetector;
The calculation unit divides the data output from the detection unit into a plurality of frequency regions based on the first specific frequency and the second specific frequency, a one-dimensional Fourier transform related to a time variable, and a frequency The observation apparatus according to claim 1, wherein data obtained by performing a one-dimensional Fourier transform on the image is obtained as an image of the object. The computing unit is
A duplexer that divides the data output from the detection unit into regions each including a maximum Doppler shift frequency around the specific frequency, and
A first Fourier transform unit for performing a one-dimensional Fourier transform on a time variable for the data divided by the duplexer;
The observation apparatus according to claim 1, further comprising: a second Fourier transform unit that performs one-dimensional Fourier transform on the frequency of the data output from the first Fourier transform unit. The computing unit is
A first Fourier transform unit that performs a one-dimensional Fourier transform on a time variable for data output from the detection unit;
A frequency division unit that divides the data output from the first Fourier transform unit into regions each including a maximum Doppler shift frequency around the specific frequency;
The observation apparatus according to claim 1, further comprising: a second Fourier transform unit that performs a one-dimensional Fourier transform on the frequency of the data output from the dividing unit.   The said calculating part is further equipped with the secondary phase division part which remove | divides the data output from the said detection part by the secondary phase which is a value decided by the position where the said detection part is arrange | positioned. The observation device according to any one of the above. A speed detector for detecting the moving speed of the object;
Based on the speed of the object detected by the speed detection unit, the calculation unit performs correction related to the speed change of the object during the Fourier transform.
The observation apparatus according to any one of claims 1 to 9.   The observation apparatus according to claim 1, wherein the irradiation of light to the object is performed by an optical arrangement of transmitted illumination.   The observation apparatus according to claim 1, wherein the object is irradiated with light by an optical arrangement of reflected illumination.   The observation apparatus according to claim 1, wherein the light source unit is a light source that generates light in a single longitudinal mode.   The observation device according to claim 1, wherein the light source unit generates broadband light.   The observation apparatus according to claim 14, wherein the light source unit is a mode-locked laser.