JP4479391B2 - Image processing apparatus, phase contrast microscope, and image processing method - Google Patents

Description

  The present invention relates to an image processing device, a phase contrast microscope, and an image processing method that generate a phase difference image of an object.

In a general phase contrast microscope, a phase plate is disposed on the pupil plane of an imaging optical system (see, for example, Non-Patent Documents 1 and 2). This phase plate is arranged in combination with an aperture stop (ring shape, dot shape, etc.) of the illumination optical system, and a portion conjugate to the aperture stop (that is, a portion through which direct light from an object passes) is a phase shift region. . In this phase-contrast microscope, direct light from an object is captured through a phase shift region provided on the phase plate, and diffracted light from an object is captured through another region (non-shift region) of the phase plate. A phase difference image of the object is obtained by interference.
Kei Komatsu “Basics and Applications of Optical Microscope (3)” Applied Physics Vol. 60, No. 10 (1991) p.1032-1034 Kei Komatsu “Basics and Applications of Optical Microscopy (4)” Applied Physics Vol. 60, No. 11 (1991) p.1136-1138

  However, in order to obtain a phase difference image of an object, the above-described dedicated optical member (phase plate) is necessary. If a dedicated optical member (phase plate) is omitted, the configuration is the same as that of a normal optical microscope, and only a bright field image of an object can be obtained. Further, even if an attempt is made to estimate a phase difference image from a bright field image of an object by image processing, the phase difference image cannot be estimated because the bright field image does not include phase information.

  An object of the present invention is to provide an image processing apparatus, a phase contrast microscope, and an image processing method capable of generating a phase contrast image of an object without using a dedicated optical member (phase plate).

  The image processing apparatus according to claim 1, wherein each pixel data of a first data group representing a complex amplitude distribution of an object image formed on an image plane of an imaging optical system based on direct light and diffracted light from an object. And a first processing means for generating a second data group representing a complex amplitude distribution on the pupil plane of the imaging optical system, and among the pixel data of the second data group, the pupil among the pixel data of the second data group A second processing means for generating a third data group by performing a process of shifting a phase of a complex amplitude of the pixel data by a predetermined amount on the pixel data corresponding to the passing position of the direct light on the surface; A third processing unit that performs inverse Fourier transform using each pixel data of the three data groups to generate a fourth data group representing a complex amplitude distribution in the image plane; and each pixel data of the fourth data group The Kuseru calculates the square of the absolute value of the complex amplitude of the data, in which a fourth processing means for generating a fifth data group.

According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the second processing unit shifts the phase of the complex amplitude of the pixel data corresponding to the passing position of the direct light by a predetermined amount. At this time, processing for reducing the amplitude of the complex amplitude is also performed to generate the third data group.
A phase-contrast microscope according to a third aspect includes the image processing apparatus according to the first or second aspect and display means for displaying each pixel data of the fifth data group.

  According to a fourth aspect of the present invention, in the phase-contrast microscope according to the third aspect, the illuminating means for illuminating the object with pulsed light, and the pulse-like shape generated from the object when illuminated by the illuminating means. An imaging optical system that forms the object image based on the direct light and the diffracted light, a measuring unit that measures a time change of an electric field of pulsed light incident on an image plane of the imaging optical system, and the electric field And a generation means for generating the first data group for each wavelength component.

According to a fifth aspect of the present invention, in the phase contrast microscope according to the fourth aspect, the illumination unit illuminates the object with pulsed light in a terahertz frequency region.
The image processing method according to claim 6, wherein each pixel data of a first data group representing a complex amplitude distribution of an object image formed on an image plane of an imaging optical system based on direct light and diffracted light from an object. And a first processing step for generating a second data group representing a complex amplitude distribution on the pupil plane of the imaging optical system, and the pupil among the pixel data of the second data group. A second processing step of generating a third data group by performing a process of shifting the phase of the complex amplitude of the pixel data by a predetermined amount on the pixel data corresponding to the direct light passing position on the surface; A third processing step of performing a Fourier transform using each pixel data of the three data groups to generate a fourth data group representing a complex amplitude distribution in the image plane; and using each pixel data of the fourth data group The Kuseru calculates the square of the absolute value of the complex amplitude of the data, in which a fourth processing step of generating a fifth data group.

  According to the present invention, a phase difference image of an object can be generated without using a dedicated optical member (phase plate).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the phase-contrast microscope 10 of this embodiment includes an imaging device 11, an image processing device 12, and a display device 13. The phase contrast microscope 10 of the present embodiment does not incorporate an optical member (phase plate) that is essential for a conventional general phase contrast microscope. The phase-contrast microscope 10 captures an imaging signal from the imaging device 11 into an image processing device 12, and generates a phase-contrast image of the test object 10A by image processing.

Here, the imaging device 11 will be briefly described. Details of the imaging apparatus 11 are described in, for example, Japanese Patent Application Laid-Open No. 2002-98634.
In the imaging apparatus 11, the light emitted from the femtosecond pulse laser 21 is branched in two directions by the semi-transmissive mirror 22 (lights L1 and L2). One light L <b> 1 enters the semiconductor substrate 24 through the mirror 23. An electrode 25 is formed on the semiconductor substrate 24, and a voltage is constantly applied to the electrode 25 from a power supply 26. For this reason, at the moment when the light L1 is incident on the semiconductor substrate 24, a discharge occurs between the electrodes 25, which becomes a dipole and emits pulsed light in the terahertz frequency region (terahertz pulsed light).

Then, the test object 10A is entirely illuminated by the terahertz pulse light. Illumination with terahertz pulsed light is equivalent to point light source illumination (that is, illumination with parallel light). In the present embodiment, the traveling direction of the terahertz pulse light is parallel to the optical axis of a lens 27 (imaging optical system) described later.
When the test object 10A is illuminated by the terahertz pulse light, the transmitted pulsed light L3 generated from the test object 10A is collected by a lens 27 made of a special plastic (for example, polyethylene) and passes through a semi-transmission mirror 28. Then, the light enters the crystal 29 exhibiting the electro-optic effect. At this time, an image (object image) of the test object 10A by the transmitted pulsed light L3 is formed on the crystal 29 (image surface of the lens 27). Further, at each point on the crystal 29, “modulation of birefringence” occurs according to the brightness of the object image (that is, the strength of the electric field of the transmitted pulsed light L3 illustrated in FIG. 2).

  Note that the transmitted pulsed light L3 from the test object 10A includes pulsed direct light and diffracted light. Direct light is zero-order diffracted light. “Diffraction light” used in contrast to direct light is diffracted light of ± 1st order or higher. In the phase-contrast microscope 10 of the present embodiment, no phase plate is arranged on the pupil plane 27A of the lens 27. Therefore, when the test object 10A has a minute undulation (phase) structure, direct light and diffracted light of the transmitted pulsed light L3. Is 90 degrees. Therefore, even if direct light and diffracted light interfere with each other on the image plane (crystal 29) of the lens 27, an object image with high contrast cannot be obtained. That is, it is considered that the contrast of the object image is low.

Then, in order to detect “modulation of the birefringence” induced in the crystal 29 according to the brightness of the object image, the other light L2 branched by the semi-transmissive mirror 22 is used as the probe light. The pulse width of the light L2 is on the order of femtoseconds. After passing through the optical delay device 30 (light L4), the light L2 enters the crystal 29 via the mirror 31 and the semi-transmissive mirror 28. The time t ₀ + Δt (FIG. 2) at which the light L4 is incident on the crystal 29 can be freely adjusted by the optical delay device 30 with reference to the time t _{0 at} which the transmitted pulsed light L3 is incident on the crystal 29. As a configuration of the optical delay device 30, for example, a reflection optical system that changes the optical path length can be considered.

The light L4 is incident on the crystal 29 in a linearly polarized state. Then, the polarization of the light L4 according to the “modulation of the birefringence” at the time t ₀ + Δt (FIG. 2) induced in the crystal 29 according to the brightness of the object image by the transmitted pulsed light L3 from the test object 10A. The state changes. Further, the amount of change in the polarization state is converted into the intensity of the photoelectric field via the polarizing plate 32 and detected by the image sensor 33.

The detection signal from the image sensor 33 is proportional to the amount of change in the polarization state of the light L 4, is proportional to the “birefringence modulation” at the time t ₀ + Δt of the crystal 29, and is formed on the crystal 29. It is proportional to the brightness of the object image, and is further proportional to the instantaneous value (real number) at time t ₀ + Δt of the electric field of the transmitted pulsed light L3 (transmitted pulsed light L3 incident on the crystal 29) from the object 10A. This detection signal is output to the image processing apparatus 12 as an imaging signal.

The image processing device 12 digitizes the image pickup signal from the image sensor 33 of the above-described imaging device 11 and captures it as digital data. Therefore, in the image processing apparatus 12, the instantaneous value (real number) at the time t ₀ + Δt of the electric field of the transmitted pulsed light L3 (transmitted pulsed light L3 incident on the crystal 29) from the object 10A according to the digital data. I can know.

Further, using the optical delay device 30 of the imaging device 11, the same digital data is taken into the image processing device 12 while adjusting the time t ₀ + Δt (FIG. 2) at which the light L 4 is incident on the crystal 29. Thereby, each instantaneous value of the electric field within one pulse width of the transmitted pulsed light L3 from the test object 10A, that is, the time change E (t) of the electric field can be measured. The time change E (t) of the electric field of the transmitted pulsed light L3 represents the time change of light and dark of the object image formed on the crystal 29, and is obtained as a set of pixel data (data group) for each position of the object image. .

When the measurement of the electric field time change E (t) is completed in this way, the image processing apparatus 12 Fourier-transforms (that is, spectrally separates) the electric field time change E (t) for each position of the object image. As a result, the complex amplitude E ₁ (ω) of the following equation (1) can be obtained for each of various wavelength components constituting the transmitted pulsed light L3 at each position of the object image. Of the complex amplitude E ₁ (ω), | E ₁ (ω) | represents the amplitude, and ψ ₁ represents the phase. The complex amplitude E ₁ (ω) is a complex number.

E ₁ (ω) = ΣE (t) exp (−iωt) = | E ₁ (ω) | exp (iψ ₁ ) (1)
The complex amplitude E ₁ (ω) of each wavelength component at each position of the object image is also a set of pixel data (data group). If a data group related to any one wavelength component is extracted, this represents a complex amplitude distribution of an object image of the wavelength component (an image of the test object 10A formed on the crystal 29). .

However, the phase ψ ₁ of the complex amplitude E ₁ (ω) obtained by the above Fourier transform includes not only the phase information of the test object 10A itself but also the crystal 29 (that is, the image) from each point on the test object 10A. A component depending on the distance to the conjugate point on the surface) (hereinafter, “error component ψ ₂ ”) is superimposed. This error component ψ ₂ varies depending on the position of each point on the test object 10A and is irrelevant to the phase information of the test object 10A itself, so it must be removed as follows.

In order to obtain the error component ψ ₂ , the time change E (t) of the electric field similar to the above is measured without placing the test object 10A, and this is Fourier transformed. As a result, the complex amplitude E ₂ (ω) of each wavelength component at each position on the crystal 29 (that is, the image plane) can be obtained. Of the complex amplitude E ₂ (ω), the phase ψ ₂ corresponds to the “error component ψ ₂ ”.
E ₂ (ω) = | E ₂ (ω) | exp (iψ ₂ ) (2)
Then, using the error component ψ ₂ of equation (2), the phase ψ ₁ of equation (1) is corrected according to the following equation (3). Therefore, the error component ψ ₂ that varies depending on the position of each point on the test object 10A regardless of the phase information of the test object 10A itself can be easily removed. As a result, the complex amplitude E ₃ (ω) of Expression (3) including only the phase information of the test object 10A itself as the phase [ψ ₁ −ψ ₂ ] can be obtained.

E ₃ (ω) = | E ₁ (ω) | exp (i [ψ ₁ −ψ ₂ ]) (3)
The corrected complex amplitude E ₃ (ω) according to the equation (3) is also generated for each wavelength component at each position of the object image (the image of the test object 10A formed on the crystal 29). (Data group) is configured. Among these, a data group related to any one wavelength component (corresponding to “first data group” in the claims) represents a pure complex amplitude distribution of an object image of the wavelength component.

The image processing device 12, after finishing to produce the complex amplitude E ₃ after correction (omega), using the complex amplitude E ₃ after the correction (omega), performs image processing in accordance with the procedure of the flow chart of FIG. 3, the A phase difference image of the test object 10A is generated. The image processing in FIG. 3 is performed for each data group related to each wavelength component.
In step S1, a data group related to the complex amplitude E ₃ (ω) after correction of a certain wavelength component (that is, a data group representing the complex amplitude distribution of the object image on the image plane (crystal 29) of the lens 27) is calculated. Store in array A (i, j). “I” and “j” represent the addresses of the pixel data of the stored data group. Each pixel data of the data group of the array A (i, j) is expressed image plane of the lens 27 the complex amplitude E ₃ at each position (crystal 29) (omega).

  Next (step S2), two-dimensional Fourier transform is performed using each pixel data of the data group of the array A (i, j). This process corresponds to a process of converting the complex amplitude distribution on the image plane (crystal 29) of the lens 27 into a complex amplitude distribution on the pupil plane 27A of the lens 27. A data group (a data group representing a complex amplitude distribution on the pupil plane 27A) (corresponding to “second data group” in the claims) generated by this processing is stored in the array B (i, j). Each pixel data in the data group of the array B (i, j) represents a complex amplitude at each position on the pupil plane 27A.

  Next (step S3), among the pixel data of the data group of the array B (i, j), the pixel data of the specific region on the pupil plane 27A is multiplied by a predetermined complex number given by F × exp [iθ]. . This process corresponds to a process of shifting the complex amplitude phase of pixel data in a specific region by a predetermined amount (phase θ) and increasing the amplitude by F times. “F” is a positive number of 1 or less. The data group generated by this process (corresponding to “third data group” in the claims) is stored in the array C (i, j). Each pixel data in the data group of the array C (i, j) also represents a complex amplitude at each position on the pupil plane 27A.

  Here, the specific area on the pupil plane 27A will be described. In the present embodiment, as shown in FIG. 4A, a dot-like neighboring area 27B including an intersection (so-called frequency coordinate origin) with the optical axis of the lens 27 in the pupil surface 27A is defined as the specific area. Set. As shown in FIG. 4B, the vicinity region 27B corresponds to the passing position of the direct light L3a in the transmitted pulsed light L3 from the test object 10A.

The passage position of the direct light L3a is in the vicinity of the origin of the frequency coordinate because the terahertz pulse light that illuminates the test object 10A is parallel light (point light source illumination), and the traveling direction of the terahertz pulse light is that of the lens 27. This is because it is parallel to the optical axis. Incidentally, the passing position of the diffracted light L3b in the transmitted pulsed light L3 extends to the peripheral portion of the vicinity region 27B of the pupil plane 27A.
In the phase-contrast microscope 10 of the present embodiment, since no phase plate is disposed on the pupil surface 27A of the lens 27, the transmitted pulse light L3 (that is, the direct light L3a and the diffracted light L3b) from the test object 10A is the pupil surface of the lens 27. When actually passing through 27A, no phase modulation occurs for both the direct light L3a and the diffracted light L3b. Therefore, the complex amplitude distribution (data group of the array A (i, j)) on the image plane (crystal 29) of the lens 27 has a low contrast.

  However, the complex amplitude distribution (data group of the array A (i, j)) by the direct light L3a and the diffracted light L3b not subjected to phase modulation is converted into the complex amplitude distribution (array B (i, j) on the pupil plane 27A. This is equivalent to the case where the phase plate is arranged on the pupil plane 27A by shifting the phase of the complex amplitude of the pixel data of the neighboring region 27B in the complex amplitude distribution by a predetermined amount (phase θ). Can be numerically applied directly to the light L3a. The vicinity region 27B corresponds to the phase shift region provided in the conventional phase plate.

  Further, when the phase modulation of the pixel data of the neighboring region 27B is performed, the amplitude of the direct light L3a is obtained by using a positive number smaller than 1 as “F” in order to multiply the amplitude of the complex amplitude of the pixel data by F. Can be numerically reduced. That is, the intensity of the direct light L3a can be numerically reduced. This process is equivalent to giving absorption to the phase shift region in the conventional phase plate (decreasing the transmittance of the phase shift region). Generally, since the intensity of the direct light L3a is stronger than that of the diffracted light L3b, the interference effect with the diffracted light L3b can be enhanced by weakening the direct light L3a.

  Next (step S4), a two-dimensional inverse Fourier transform is performed using each pixel data of the data group of the array C (i, j) generated by the process of step S3. This process corresponds to a process of converting again the complex amplitude distribution (after phase modulation) on the pupil plane 27A into the complex amplitude distribution on the image plane (crystal 29) of the lens 27. A data group (a data group representing a complex amplitude distribution on the image plane) generated by this processing (corresponding to the “fourth data group” in the claims) is stored in the array D (i, j). Each pixel data in the data group of the array D (i, j) represents a complex amplitude at each position on the image plane of the lens 27.

  In the process of step S4 (two-dimensional inverse Fourier transform), the direct light L3a that has undergone phase modulation in the vicinity region 27B of the pupil surface 27A and the diffraction that has not undergone phase modulation in the peripheral portion of the vicinity region 27B of the pupil surface 27A. Interference with the light L3b can be caused numerically. That is, it is possible to numerically generate an interference effect similar to the case where an optical member (phase plate) essential for a conventional phase contrast microscope is used.

  As a result, the complex amplitude distribution (data group of the array D (i, j)) on the image plane (crystal 29) of the lens 27 has a high contrast according to the setting of the phase θ and the F value. When the test object 10A has a fine phase structure, the phase difference between the direct light L3a and the diffracted light L3b can be set to zero (or 180 degrees) by setting the phase θ = ± π / 2. Therefore, an object image with high contrast can be obtained.

  When the processes of steps S3 and S4 are completed, the image processing apparatus 12 proceeds to the process of step S5, and a data group representing the complex amplitude distribution after the inverse Fourier transform described above (that is, a data group of the array D (i, j)). Is used to obtain the square of the absolute value of the complex amplitude of the pixel data. The data group generated by this processing (corresponding to the “fifth data group” in the claims) is stored in the array I (i, j). The data group of the array I (i, j) represents the intensity distribution of the object image (that is, the phase difference image of the test object 10A).

  As described above, in the phase-contrast microscope 10 of the present embodiment, the imaging signal from the imaging device 11 is taken into the image processing device 12 and image processing is performed according to the procedure of the flowchart of FIG. A phase difference image can be generated deterministically. That is, it is possible to generate a phase difference image of the test object 10A without using a dedicated optical member (phase plate) that is essential for a conventional general phase contrast microscope.

  Further, in the phase-contrast microscope 10 of the present embodiment, by using the data group of the array I (i, j) finally obtained by the image processing of FIG. 3, each pixel data is output to the display device 13. The phase difference image of the test object 10A can be observed. At this time, the phase difference image of the object to be inspected 10A may be displayed for each wavelength component, or may be displayed after performing arithmetic processing between the data groups of each wavelength component.

Furthermore, in the phase-contrast microscope 10 of the present embodiment, in step S3 of FIG. 3, the area of the neighboring region 27B (number of pixel data ≧ 1) corresponding to the passing position of the direct light L3a on the pupil surface 27A, the neighboring region 27B The phase θ and F value of a complex number (F × exp [iθ]) multiplied by the complex amplitude of the pixel data can be freely set. For this reason, phase difference images under various conditions can be easily obtained for the same image, and the best observation condition for the object to be inspected 10A can be selected to obtain the phase difference image at that time. The area of the neighboring region 27B (number of pixel data ≧ 1) is preferably set so that a good contrast can be obtained in consideration of the aberration of the lens 27.
(Modification)
In the above-described embodiment, the example in which the traveling direction of the terahertz pulse light that illuminates the test object 10A is parallel to the optical axis of the lens 27 is described, but the present invention is not limited to this. The traveling direction of the terahertz pulse light may be inclined with respect to the optical axis of the lens 27. In this case, it is necessary to incline the angle of the semiconductor substrate 24 with respect to the optical axis. The traveling direction of the terahertz pulse light can be tilted in accordance with the tilt angle α of the semiconductor substrate 24 to change the incident angle on the test object 10A. In the case of such oblique illumination, the processing in step S3 in FIG. 3 may be performed on a dot-like neighboring region 27C (FIG. 5) including a point that is deviated by “sin α” from the origin of the frequency coordinate.

  Furthermore, in the above-described embodiment, an example of generating a phase difference image of an object image by point light source illumination has been described, but the present invention is not limited to this. In addition, the present invention can also be applied when generating a phase difference image of an object image by annular illumination. In this case, it is necessary to rotate the tilt direction (incident direction of the terahertz pulse light) of the semiconductor substrate 24 around the optical axis while keeping the tilt angle α (angle with respect to the optical axis) of the semiconductor substrate 24 constant.

Then, in each of the plurality of incident directions, the time change E (t) of the electric field similar to that described above is measured, and a complex amplitude distribution (corrected complex amplitude E ₃ (ω)) of the object image is generated. 3 up to step S4. The processing in step S3 at this time may be performed sequentially for each neighboring region 27E in the ring-shaped region 27D as shown in FIG. 6 according to the incident direction of the terahertz pulse light. The processing up to step S4 in each incident direction is repeated in a time division manner, and when a plurality of complex amplitude distributions (data group of array D (i, j)) having different incident directions are obtained, these are combined and then the processing in step S5 Proceed to processing. As a result, it is possible to obtain a phase difference image of the object 10A to be examined by annular illumination.

  In the above-described embodiment, the non-scanning example in which the amount of change in the polarization state of the probe light (L4) is collectively detected by the image sensor 33 of the imaging apparatus 11 has been described, but the present invention is not limited to this. . The terahertz pulse light is irradiated to the local region of the test object 10A, and the change amount of the polarization state of the probe light (L4) is detected while changing the relative position between the irradiation region of the terahertz pulse light and the test object 10A. The present invention can also be applied to the case (scanning type).

Furthermore, in the above-described embodiment, the example (transmission-type imaging apparatus 11) in which the object image is formed on the crystal 29 based on the transmission pulsed light L3 generated from the test object 10A has been described. It is not limited. The present invention can also be applied to a case where an object image is formed based on reflected pulsed light generated from a test object (reflection type).
In the above-described embodiment, the example in which the test object 10A is illuminated with the terahertz pulse light has been described, but the present invention is not limited to this. The present invention can also be applied to the case where the test object 10A is illuminated using pulsed light in other frequency regions. For example, when the central wavelength band is a visible light region, it is necessary to increase the time resolution of the femtosecond pulse laser 21 of the imaging apparatus 11, change the material of the lens 27, and use a crystal 29 having a faster response time. become.

Further, in the above-described embodiment, the phase contrast microscope 10 including the imaging device 11 has been described as an example, but the present invention is not limited to this. The present invention can also be applied to the case where the imaging device 11 is omitted (that is, a phase contrast microscope including the image processing device 12 and the display device 13). In this case, the data group relating to the complex amplitude E ₃ (ω) similar to the above (that is, the data group representing the complex amplitude distribution of the object image) is simply input to the image processing device 12, and the level of the object 10 A to be examined. A phase difference image can be generated.

It is a figure which shows the whole structure of the phase-contrast microscope 10 of this embodiment. It is a figure explaining the measurement principle of the time change E (t) of the electric field of the transmitted pulsed light L3 in the imaging apparatus 11. FIG. 4 is a flowchart showing a procedure for generating a phase difference image of a test object 10A in the image processing apparatus 12. It is a figure explaining the phase shift area | region (27B) in the pupil surface 27A. It is a figure explaining the phase shift area | region (27C) in the pupil surface 27A. It is a figure explaining the phase shift area | region (27D) in the pupil surface 27A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Phase difference microscope 11 Imaging apparatus 12 Image processing apparatus 13 Display apparatus 21 Femtosecond pulse laser 24 Semiconductor substrate 25 Electrode 27 Lens 29 Crystal 30 Optical delay apparatus 32 Polarizing plate 33 Image sensor

Claims (6)

Fourier transform is performed using each pixel data of the first data group representing the complex amplitude distribution of the object image formed on the image plane of the imaging optical system based on the direct light and diffracted light from the object, and the imaging First processing means for generating a second data group representing a complex amplitude distribution in the pupil plane of the optical system;
A process of shifting the phase of the complex amplitude of the pixel data by a predetermined amount is performed on the pixel data corresponding to the passing position of the direct light on the pupil plane among the pixel data of the second data group. A second processing means for generating a data group;
Third processing means for performing inverse Fourier transform using each pixel data of the third data group to generate a fourth data group representing a complex amplitude distribution in the image plane;
An image processing apparatus comprising: a fourth processing unit that uses each pixel data of the fourth data group, calculates a square of an absolute value of a complex amplitude of the pixel data, and generates a fifth data group. . The image processing apparatus according to claim 1.
The second processing means also performs a process of reducing the amplitude of the complex amplitude when shifting the phase of the complex amplitude of the pixel data corresponding to the passing position of the direct light by a predetermined amount, and the third data group An image processing apparatus characterized by generating. The image processing apparatus according to claim 1 or 2,
A phase contrast microscope comprising: display means for displaying each pixel data of the fifth data group. The phase contrast microscope according to claim 3,
Illumination means for illuminating the object with pulsed light;
An imaging optical system that forms the object image based on the pulsed direct light and the diffracted light generated from the object when illuminated by the illumination means;
Measuring means for measuring the time change of the electric field of the pulsed light incident on the image plane of the imaging optical system;
A phase contrast microscope comprising: a generating unit that Fourier-transforms the time change of the electric field and generates the first data group for each wavelength component. The phase-contrast microscope according to claim 4,
The phase contrast microscope, wherein the illuminating means illuminates the object with pulsed light in a terahertz frequency region. Fourier transform is performed using each pixel data of the first data group representing the complex amplitude distribution of the object image formed on the image plane of the imaging optical system based on the direct light and diffracted light from the object, and the imaging A first processing step of generating a second data group representing a complex amplitude distribution in the pupil plane of the optical system;
A process of shifting the phase of the complex amplitude of the pixel data by a predetermined amount is performed on the pixel data corresponding to the passing position of the direct light on the pupil plane among the pixel data of the second data group. A second processing step for generating a data group;
A third processing step of performing an inverse Fourier transform using each pixel data of the third data group to generate a fourth data group representing a complex amplitude distribution in the image plane;
And a fourth processing step of generating a fifth data group by using each pixel data of the fourth data group, obtaining a square of an absolute value of a complex amplitude of the pixel data, and generating a fifth data group. .

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