JPH0434337A - Detecting apparatus for reflected amplitude image using heterodyne detection light-sensing system - Google Patents

Abstract

PURPOSE:To detect a reflected image of an object in a scattered object by applying a coherent light to a sample, by synthesizing the coherent light reflected from the sample and a reference coherent light and by determining an amplitude image of the sample from a beat component detected from the synthesized light. CONSTITUTION:A laser light outputted from a laser oscillator 11 is transformed by a beam transformer 12 and led to a beam splitter 14 through a lens 13. One laser light 1 split by the beam splitter 14 is applied to a sample S through a half mirror 15, e.g. a scattering body N. In the half mirror 15, the laser light reflected from the sample S and a local oscillation light Il are synthesized. This synthesized light is led to a zero dimension type heterodyne light-sensing element 20 through a polarizing plate 19. In the light-sensing element 20, accordingly, the beat component of the reflected light from the sample S and the local oscillation light Il is subjected to photoelectric conversion. By separating the beat component from an output signal of the light-sensing element 20 by a modulated component detecting element 21, the amplitude intensity of the reflected light from the sample S can be detected with excellent directivity.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a device for detecting an amplitude image by separating light reflected from a sample from scattered components and incoherent optical signals, for example. In particular, the present invention relates to a reflection amplitude image detection device using a heterodyne detection light receiving system.

(Prior art) For example, objects in dense fog or exhaust smoke, objects in water with scattered objects floating inside that cannot be seen visually, or images on the other side of frosted glass can be detected with the naked eye, as well as with conventional methods. Even the imaging optical device produces a blurred image, and if the scattering becomes strong, the blurred image will no longer be formed.

This is because even if the image could be captured with the naked eye or a camera without a scattering object, the reflected light from the object is scattered by the scattering objects in the middle, and the reflected light from each point on the object is reflected from each other. This is because it affects the

In this way, it has been impossible to create an image of an object on the other side of the scattering object or a reflected image of an object existing within the scattering object using conventional imaging means.

(Problems to be Solved by the Invention) This invention solves the above-mentioned conventional am, and its purpose is to detect the reflection of an object in a scattering object, which cannot be detected as an image by conventional imaging means. The present invention aims to provide a reflection amplitude image detection device using a heterodyne detection light receiving system capable of detecting an image.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the first invention includes an irradiation means that generates coherent light and irradiates a sample with the coherent light, and a frequency difference between the coherent light and the frequency. a generating means for generating reference coherent light having different values; a synthesizing means for synthesizing the coherent light reflected from the sample and the reference coherent light; a detecting means for detecting a beat component from the synthesized light; A signal processing means is provided for obtaining an amplitude image of the sample from the beat component detected by the detection means.

In this case, the combining means combines the reference coherent light over the entire cross section of the beam of coherent light reflected from the sample.

Further, the sample is moved in a one-dimensional or two-dimensional direction by a driving means, the detecting means is constituted by a zero-dimensional photoelectric conversion means, and the signal processing means is configured to detect a one-dimensional beat component output from the photoelectric conversion means. Alternatively, a two-dimensional amplitude image is obtained.

Further, the coherent light generated by the irradiation means is focused by a condensing means and irradiated onto the sample.

Further, the detection means is constituted by a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged one-dimensionally or two-dimensionally,
The signal processing means obtains a one-dimensional or two-dimensional amplitude image from the beat component output from the photoelectric conversion means.

Further, the generating means is constituted by modulating means for shifting the frequency of the coherent light generated by the irradiating means.

Furthermore, the present invention has a condensing means on the front surface of the sample, condensing the light beam reflected from the sample into small areas and guiding it to the detection means.

The second invention also provides a generating means for generating coherent light, a half-mirror means of Ml for obliquely irradiating the sample with the coherent light generated by the generating means, and a light beam that passes through the first half-mirror means. a generating means for shifting the frequency of light to generate a reference coherent light; a synthesizing means for synthesizing the reference coherent light with light other than the specularly reflected light reflected from the sample; and light synthesized by the synthesizing means. detection means for detecting a beat component from the
A signal processing means for obtaining an amplitude image of the sample from the beat component detected by the detection means is provided.

In this case, the reference coherent light is guided to the combining means via mirror means that moves in one or two dimensions.

Furthermore, the detection means is constituted by a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged one-dimensionally or two-dimensionally, and the signal processing means detects a one-dimensional or two-dimensional signal from the beat component outputted from the photoelectric conversion means. It is designed to obtain an amplitude image.

Furthermore, a third invention includes: irradiation means for generating coherent light and irradiating the sample with the coherent light; generation means for generating reference coherent light having a different frequency from the coherent light; and a reference coherent light that is reflected from the sample. Fourier transform means for Fourier transforming coherent light; and half mirror means for guiding and synthesizing the reference coherent light into a spectral plane of light Fourier transformed by the transform means;
It has a detection means for detecting a beat component from this combined light, and a signal processing means for obtaining an amplitude image of the sample from the beat component detected by the detection means.

Furthermore, the invention of 'M4 includes an irradiation means for irradiating a sample with coherent light, a generation means for generating a reference coherent light having a frequency different from that of the coherent light, and a generation means for Fourier transforming the coherent light reflected from the sample. 1
a Fourier transform means, a second Fourier transform means for further Fourier transforming the amplitude distribution in this spectral plane, and guiding the reference coherent light to the transform plane of the second Fourier transform means and combining it into Fourier transformed light. A detecting means detecting a beat component from the combined light, and a signal processing means detecting an amplitude image of the sample from the beat component detected by the detecting means.

In the third and fourth inventions, the detection means is constituted by a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged one-dimensionally or two-dimensionally, and the signal processing means is a beat component output from the photoelectric conversion means. A more one-dimensional or two-dimensional amplitude image is obtained.

Further, the half mirror means guides the reference coherent light onto the entire surface of the conversion surface, and combines it with the light that has been Fourier transformed on the entire surface of the conversion surface.

Further, the half-mirror means is moved in one or two dimensions so as to combine the reference coherent light into the Fourier transformed light in a part of the spectral plane.

Further, a spatial filter is provided on the spectral plane, and the detection means detects the combined light flux that has passed through this spatial filter.

(Function) An optical heterodyne detection light receiving system using laser light, which is coherent light, has a characteristic of being able to selectively detect coherent light from scattered incoherent light. This invention utilizes this characteristic of the heterodyne detection light receiving system to extract coherent light having reflection amplitude information of the object from the light reflected from the object and further scattered by the scattering object, and to sample the entire object. For example, it makes use of the fact that an object reflection image of each point can be obtained.

In particular, when you want to obtain a reflected image of a large object that is far away, or an object that is inside a scattering object, or when light does not pass through the sample but is reflected, for example, there is a metal plate on the back side, and a scattering layer is formed on the surface. This makes it possible to separate the reflection amplitude image of a sample from scattered components and incoherent light and detect it.

That is, according to the first invention, parallel coherent light is irradiated onto a sample, reflected light from the sample and reference coherent light are combined, and a one-dimensional or two-dimensional beat component in a cross section of the combined beam is detected. Accordingly, the amplitude image of the sample can be detected with high precision by separating it from the scattered components and the incoherent optical signal.

Further, according to the second invention, parallel coherent light is obliquely irradiated onto the sample, light other than the specularly reflected light reflected from the sample and reference coherent light are combined, and one-dimensional or By detecting two-dimensional beat components, it is possible to separate scattered components and incoherent optical signals from a sample with a smooth surface, and to detect an amplitude image with high precision.

Furthermore, according to the third invention, the sample is irradiated with parallel coherent light, the amplitude distribution of the reflected light from the sample is Fourier transformed by the Fourier transform means, and the reference coherent light and the reflected light are combined on the spectral plane. By detecting the one-dimensional or two-dimensional beat component in the spectral plane, the amplitude image of the sample can be detected with high precision by separating it from the scattered component and the incoherent optical signal, and the detected amplitude Images can be subjected to image processing to improve contrast.

Further, according to the fourth invention, the sample is irradiated with parallel coherent light, the amplitude distribution of the reflected light from the sample is Fourier transformed by the first Fourier transform means, and the distribution in the spectral plane is further transformed by the second Fourier transform means. The reference coherent light and the reflected light are combined in the spectral plane by Fourier transformation using the transformation means, and the one-dimensional or two-dimensional beat component in the spectral plane is detected, thereby separating it from the scattered component and the incoherent optical signal. The amplitude image of the sample can be detected with high accuracy, and the contrast can be improved by performing image processing on the detected amplitude image.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In a heterodyne detection light receiving system, the diameter of the light receiving surface of the detector (when taking a beat at the focusing point, the aperture system of the focusing optical system)
Let d be the wavelength of the light to be detected, and λ be the wavelength of the light to be detected, then the angular resolution is approximately d/λ.

Therefore, if the diameter d of the light-receiving surface of the detector is made sufficiently large compared to the wavelength λ of the light to be detected, a highly directional light-receiving system can be constructed without using a highly directional optical system. I can do it. Examples thereof are shown in FIGS. 1 to 3.

FIG. 1 shows a plane wave single beam scanning type reflection image inspection device. In the figure, the laser oscillator 11 is, for example, A
r laser oscillator. The laser beam output from this laser oscillator 11 is transmitted to a beam converter 12.
The beam is converted into a predetermined diameter by the lens 13 and guided to the beam splitter 14 via the lens 13. This beam splitter 1
One of the laser beams I divided by 4 is a half mirror.
15, the sample S, such as a semiconductor device, is irradiated via, for example, a scatterer N. In the figure, the scatterer N is shown at a position away from the sample S for convenience of explanation, but it may be in contact with the sample S in some cases.

On the other hand, the other laser beam split by the beam splitter 14 is guided to a modulator 17 via a mirror 16. This modulator 17 is, for example, a so-called frequency shifter constituted by an ultrasonic modulator, and in this modulator 17, the frequency is changed to, for example, I based on the control of the modulation control section 17a.
MHz-shifted local oscillation light 11 is generated. This locally oscillated light 11 is guided to the half mirror 15 via the mirror 18, and in this half mirror 15, the laser beam reflected from the sample S and the locally oscillated light 1g are combined. This combined light is guided to an O-dimensional heterodyne light receiving section 20 via a polarizing plate 19. Therefore, this 0
In the dimensional heterodyne light receiving section 20, the beat components of the reflected light from the sample S and the locally oscillated light III are photoelectrically converted. The output of this zero-dimensional heterodyne light receiving section 20 is a signal in which a beat component is superimposed on a DC component. Since the intensity of this beat component is proportional to the amplitude of the light reflected by the sample S, the average amplitude reflectance within the illuminated area of the sample S can be determined. On the other hand, even if the light scattered by the scatterer N and the local oscillation light 11 are combined, the light receiving section 2
At 0, no beat component occurs and only a DC component occurs. Therefore, by separating the beat component from the output signal of the light receiving section 20 by the modulation component detection section 21, the amplitude intensity of the reflected light from the sample S can be detected with good directivity. This modulation component detection section 21 is connected to the variable # control section 17.
g in synchronization with the modulator 17.

In addition, in order to obtain a one-dimensional or two-dimensional amplitude reflectance distribution (amplitude image of the sample) of the sample S, the sample S is moved one-dimensionally or two-dimensionally in a direction perpendicular to the optical axis by the drive unit 22. However, the above detection may be performed. In this way, by scanning the sample S one-dimensionally or two-dimensionally and processing the beat components at each position by the data processing unit 23, the one-dimensional or two-dimensional amplitude reflectance distribution of the sample S is obtained. This amplitude reflectance distribution can be displayed on the display section 24. As the data processing section 23,
Devices similar to those used in normal CT devices can be applied.

According to the above embodiment, by extracting the beat component of the light reflected from the sample and the local oscillation light, it is possible to remove the scattered component and incoherent light and detect the desired amplitude image of the sample with high precision. can.

Therefore, by utilizing this, it is possible to detect a pattern of a semiconductor device in one-dimensional direction or two-dimensional direction, for example, without damaging the semiconductor device.

FIG. 2 shows a second embodiment of the invention,
The same parts as in FIG. 1 are given the same reference numerals, and only the different parts will be explained.

In this embodiment, a condenser lens 25 is provided between the half mirror 15 and the scatterer N, and the laser beam is condensed by the condenser lens 25 and irradiated onto the sample S.

According to this embodiment, the diameter of the laser beam irradiated onto the sample S can be made small, so that the spatial resolution can be improved compared to the first embodiment.

FIG. 3 shows a third embodiment of the invention,
This figure shows a plane wave single beam scanning reflected image detection device. In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals.

In the figure, a laser beam output from a laser oscillator 11 is converted into a predetermined diameter by a beam converter 12. The laser light output from the beam converter 12 is obliquely irradiated onto the sample S via the beam splitter 31 and lenses 32 and 33.

Of the laser light irradiated on the sample S, the specularly reflected component is guided to the trap 35 via the mirror 34, and the light other than the specularly reflected component is directed to the half mirror 36, the pinhole P, and the polarizing plate 19.
The light is guided to the zero-dimensional heterodyne light receiving section 20 via the light receiving section 20.

The reason why specular reflection light is not used is that when the surface of the sample S is smooth, the intensity of the light is too strong and it is difficult to obtain color information.

On the other hand, the other laser beam split by the beam splitter 31 is guided to a modulator 17, and the modulator 17 generates local oscillation light Ill with a shifted frequency. This locally oscillated light IB is guided to the half mirror 36 via the mirror 37, and is combined with light other than the specularly reflected component. The mirror 37 is moved by the drive unit 38 in the direction of the arrow shown in the figure, and the pinhole P1 polarizing plate 19 and the pinhole P1 polarizing plate 19 and
The dimensional heterodyne light receiving section 20 is driven by the driving section 39.
It is moved in the direction of the arrow shown in the figure in synchronization with the mirror 37.

Therefore, the one-dimensional amplitude reflectance distribution of the sample S can be determined according to the movement of the mirror 37 and the zero-dimensional heterodyne light receiving section 20. Note that by moving the mirror 37, the light receiving section 20, etc. two-dimensionally, the two-dimensional amplitude reflectance distribution of the sample S can be determined.

This embodiment also provides the same effects as the above embodiment. Moreover, since the specularly reflected light from the sample S is not used, an amplitude image of the sample S with a smooth surface can be obtained with high precision.

As mentioned above, using the heterodyne detection light receiving diameter, the sample S
It is possible to detect a one-dimensional or two-dimensional amplitude image of the sample S by scanning it relatively, but without moving any of the sample S1 optical systems, the one-dimensional or two-dimensional amplitude image of the sample S can be detected. can be detected.

FIG. 4 shows a fourth embodiment of the present invention, showing only the main parts thereof.

The diameter of the laser beam output from a laser oscillator (not shown) is expanded beyond the observation range of the sample S by a beam converter (not shown). This laser beam I is guided to the half mirror 41, the laser beam reflected by the half mirror 41 is irradiated onto the sample S via the scatterer N, and the light transmitted through the half mirror 41 is guided to the mirror 42. This mirror 42 is moved by a drive unit 43 in the direction of the arrow shown in the figure, and the frequency of the laser beam is shifted. This frequency-shifted laser light is used as local oscillation light 19 for the sample S.
The laser beam reflected from the laser beam is guided to the light receiving section 44 via the half mirror 41.

The light receiving section 44 is a one-dimensional or two-dimensional heterodyne light receiving section, and is configured by a plurality of unit detection elements Do arranged in a one-dimensional direction or a two-dimensional direction. therefore,
The light incident on each unit detection element Do is a composite light of the light reflected from the region of the sample S corresponding to the unit detection element DO and the corresponding portion of the local oscillation light III, and the beat component is the light reflected from the area of the sample S corresponding to the unit detection element DO. is proportional to the amplitude reflectance of that area. In this case, the greater the mutual distance between the light receiving section 44 and the sample S, the larger the sampling area of the detection image by the unit detection element. Furthermore, if the size of the unit detection element Do is reduced to increase the density, not only will the sampling area become larger, but also the sampling areas will overlap, so it is necessary to reproduce the image in consideration of the overlap pattern.

Note that, as the light receiving section 44, for example, a CCD sensor is applied.

FIG. 5 shows a fifth embodiment of the invention,
The same parts as in FIG. 4 are given the same reference numerals, and only the different parts will be explained.

In this embodiment, a plurality of microlenses 51 are provided between the half mirror 41 and the scatterer N, and the light reflected by the sample S is spatially sampled by the microlenses 51 and guided to each unit detection element Do. This is what I did. In this case, the signal-to-noise ratio can be further improved if the emitted light from each lens 51 is separated by a hollow tube coated with an absorbent so that it does not enter the adjacent lens.

In this case, the local oscillation light Ifl may be made incident on the unit detection element Do as a plane wave as shown in the figure, or may be made to enter the unit detection element Do as a plane wave as shown in the figure.
It is also possible to convert the light into a spherical wave similar to the light from 1 and make it incident.

Furthermore, in the fourth and fifth embodiments, by driving the mirror 42 by the driving section 43, the local oscillation light 1
1, but it is not limited to this.

Next, an apparatus for detecting an amplitude image of a sample mixed with scattered light using a one-dimensional or two-dimensional detector using a heterodyne detection light receiving system will be described.

FIG. 6 shows a sixth embodiment of the invention,
This figure shows a plane wave multiple beam parallel type reflected image detection device. In FIG. 6, the same parts as in FIGS. 1 and 4 are given the same reference numerals, and only the different parts will be explained.

In the first embodiment, the diameter of the laser beam is narrowed to a small size by the beam converter 12, and the laser beam is irradiated onto the sample S in the form of a spot, but in this embodiment, the diameter of the laser beam is increased to a certain extent. , by irradiating the sample S with laser light over a wide range, the two-dimensional amplitude reflectance distribution of the sample S is determined without moving the sample S.

In this case, the reflected light from the sample S and the local oscillation light IM
is guided through a polarizing plate 19 to a light receiving section 44 of a one-dimensional or two-dimensional heterodyne.

In the unit detection element of the light receiving section 44, a diffraction limit image (zero-order Franfauf diffraction image) defined by its size
The incident light is sampled with a magnitude of , and a signal is obtained in which a beat component proportional to the average amplitude reflectance of each sampling region of the sample S is superimposed on a DC component. The output signal of the light receiving section 44 is supplied to the modulation component detection section 21, and the modulation component detection section 21 separates the beat component at each position, and this beat component is processed by the data processing section 23 to detect the sample. A two-dimensional amplitude reflectance distribution of S is obtained.

According to this embodiment, a two-dimensional amplitude image can be detected without moving the sample S or the light receiving section.

FIG. 7 shows a seventh embodiment of the invention,
This figure shows an amplitude image detection device using an enlarging optical system.

The laser light output from the laser oscillator 11 is split by a beam splitter 71, and one is split by a beam expander 7.
2. The sample S is irradiated via the scatterer N. The other laser beam split by the beam splitter 71 is reflected by a mirror 73, and this reflected light is combined in the beam splitter 71 with the reflected light from the sample S guided via the beam expander 71. This combined light is supplied to the light receiving section 44 via the modulator 17 and the polarizing plate 19, and the beat component is detected by the light receiving section 44.

Thereafter, an amplitude image is detected by the same processing as in the above embodiment.

According to this embodiment, it is possible to detect an amplitude image of a minute sample such as a semiconductor, for example.

8th v! J shows an eighth embodiment of the present invention, and shows an amplitude image detection device using a reduction optical system.

In this embodiment, a beam condenser 81 is provided in place of the beam expander 71 in FIG.
! ! Same as J.

According to this embodiment, it is possible to detect the entire large sample at once.

FIG. 9 shows a ninth embodiment of the present invention which is a modification of the embodiment shown in FIG.
This is an example of the following.

In the embodiment shown in FIG. 3, a one-dimensional or two-dimensional image is detected by moving the sample and the light receiving section, but in this embodiment, a one-dimensional or two-dimensional light receiving section 44 is used. This makes it possible to detect one-dimensional or two-dimensional images without moving the sample or the like.

FIG. 10 shows a tenth embodiment of the present invention, which is a modification of the embodiment shown in FIG.

The embodiment shown in Fig. 2 uses a spherical wave and a single beam, and detects a one-dimensional or two-dimensional image by moving the sample and the light receiving part. By using a one-dimensional or two-dimensional light receiving section 44, a one-dimensional or two-dimensional image can be detected without moving the sample or the like.

The above method detects the amplitude image by detecting the beat component of the light reflected by the sample and the local oscillation light in the vicinity of the sample, but the Fourier transform spectral signal of the amplitude image is detected on the spectral plane of the object. It is also possible to do so. As is well known, when an object is placed at the front focal plane of a lens and coherent light is irradiated onto it, a Fourier transform of the amplitude distribution of the object is obtained at the rear focal plane of the lens.

Also, if this object is irradiated with incoherent light,
The power spectrum of an object can be obtained from incoherent scattered light from the object.

FIG. 11 schematically shows the relationship between coherent light and incoherent light.

When attempting to extract beats by heterodyne detection on such a spectrum, if locally oscillated light of a frequency different from the frequency of the illumination light is simultaneously incident, the Fourier transform signal of the coherent light will generate a beat component proportional to its amplitude. Since an incoherent power spectrum does not produce a beat even when combined with local oscillation light, it is possible to separate the two in terms of spectrum and extract only the signal due to coherent light.

FIG. 12 shows an eleventh embodiment of the present invention, in which the two are separated in terms of spectrum and only the signal due to coherent light is extracted.

A sample S is placed on the front focal plane of the convex lens 91, and a one-dimensional or two-dimensional light receiving section 44 is placed on the rear focal plane. A half mirror 92 is provided between the convex lens 91 and the scatterer N, and a half mirror 93 is provided between the convex lens 91 and the light receiving section 44. When the sample S is irradiated with a laser beam through the half mirror 92, the light reflected from the sample S is reflected by the half mirror 92.
, lens 91, and half mirror 93, and are guided to the spectral plane of the light receiving section 44. When the local oscillation light Ij is incident on this spectral plane via the half mirror 93,
A signal containing a beat component proportional to the magnitude of the amplitude at that position is obtained from each unit detection element OD of the light receiving section 44.

Therefore, by extracting only this beat component for each unit detection element OD, only the Fourier component of the amplitude image of the beat signal S can be detected. This detected signal represents the spatial frequency distribution of the amplitude image of the sample S, but in order to directly obtain the amplitude image of the sample S, this detection signal may be electrically Fourier transformed again.

Incidentally, in order to obtain the spatial Fourier transform of the amplitude distribution of the sample S, the illumination by coherent light is not limited to the direction of the optical axis as shown in FIG.

FIG. 13(a) shows a twelfth embodiment of the present invention, in which the half mirror 92 shown in FIG. 12 is set at an angle other than 45°, and coherent light is directed obliquely toward the sample S. It is designed to irradiate.

Figure (b) shows the spectrum due to incoherent light appearing on spectral plane F in figure (a) and the spectrum due to coherent light hidden in that spectrum.
According to this embodiment, even in such a case, only the spectrum of coherent light can be separated and extracted.

Further, even if a simple detector is used instead of a one-dimensional or two-dimensional detector, it is possible to detect a Fourier transformed spectral signal of an amplitude image on a spectral plane.

FIG. 14 shows a thirteenth embodiment of the present invention, in which a zero-dimensional light receiver 20 is used. In this figure, the same parts as in FIG. 13(a) are given the same reference numerals.

The half mirror 100 provided between the convex lens 91 and the spectral plane F, and the pinhole P provided between the spectral plane F and the O-dimensional light receiver 20 are arranged in the direction of the arrow shown in the figure and in the direction orthogonal to the plane of the paper. It is considered movable. Therefore, the spectrum that has been Fourier transformed by the convex lens 91 is
Local oscillation light 1 guided to spectral plane F by 100
1 and is converted by the zero-dimensional photodetector 20 into a signal containing a beat component. By determining the secondary distribution of this beat component, it is possible to detect the Fourier transform due to reflection from the sample S on the spectral plane F.

By the way, according to the optical two-dimensional Fourier transform method using coherent light, the zero component of the spectral plane F only carries information about the brightness of the image and does not contain image information, but the zero component is cut. When the image is reconstructed using this method, it becomes an image with twice the spatial frequency, which is equivalent to a reduced image. However, since the direct current component of the image is eliminated, the contrast becomes better when the image is reproduced. Furthermore, the characteristics of the reproduced image can be changed by passing only spectral components of a specific frequency, or by cutting them, or by changing the attenuation rate for each frequency. Such processing is generally called spatial filtering, and for this purpose, a spatial filter with desired characteristics may be inserted into the spectral plane F.

FIG. 15(a) shows a fourteenth embodiment of the present invention, and the same parts as in FIG. 13(a) are given the same reference numerals.

In the figure, an O-fire component cut filter 101 is provided in front of the light receiving section 44, and this filter 101 cuts the O-fire component in the spectrum of the light reflected from the sample S. The output signal of the light receiving section 44 is supplied to the signal processing section 103 via a band pass filter (BPF) 102.

The reproduction processing order in this case is shown in FIG.

For image reproduction, a filter 101 cuts off the zero component from the spectrum of coherent light, a two-dimensional heterodyne light receiving section 44 and a bandpass filter 102 perform heterodyne detection to detect a two-dimensional beat component, and the detected output is sent to a signal processing section. 103 performs two-dimensional Fourier transformation to obtain a reconstructed image. This reproduced image has improved contrast as described above.

In the above embodiment, the 0-fire component was cut by inserting an optical spatial filter into the spectral plane, but this can also be done electrically.

Figure (C) shows an example of this. The signal from coherent light on the spectral plane is directly detected as a two-dimensional beat component by heterodyne detection, and the signal processing unit 1
03, the two-dimensional beat component is cut, and then two-dimensional Fourier transform is performed to obtain a reproduced image. Note that in the above description, the spectrum signal detected by heterodyne detection is reproduced by Fourier transform on the spectrum plane F, but the Fourier transform spectrum signal of the amplitude image of the sample S on the spectrum plane is used as is. You can.

As described above, instead of detecting the Fourier transform spectrum of the amplitude image in the spectral plane by the heterodyne detection light receiving system of the present invention, and reproducing the filtered image by electrically Fourier transforming the signal, the 16th As shown in the figure, image processing of the sample S is performed by optically performing Fourier transformation for image reproduction using the convex lens L2 and performing heterodyne detection on the image plane, excluding components caused by incoherent light from scatterers. An amplitude image can be obtained.

Note that by setting the focal length f1 of the lens L1 and the focal length f2 of the lens L2 to different sizes, the reconstructed image can be enlarged or reduced with respect to the sample. fl>f
2, it becomes a reduced image, and when fl<f2, it becomes an enlarged image.

Note that this invention is not limited to the above embodiments,
Of course, various modifications can be made without departing from the gist.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to obtain amplitude images of large samples, samples that cannot be arranged to obtain transmission images, and samples that do not transmit light but have reflections from inside the sample. It is possible to provide a reflection amplitude image detection device using a heterodyne detection light receiving system that can separate and detect scattered components and incoherent light.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing a heterodyne detection light receiving system, Figure 2 is a configuration diagram using a spherical wave, Figure 3 is a configuration diagram showing the case where the sample is irradiated with light obliquely, Figures 4 and 5 is a configuration diagram showing the case where a one-dimensional or two-dimensional light receiving section is used, I@
Figure 6 is a configuration diagram that is a modified version of Figure 1, Figure 7 is a configuration diagram showing the case where an enlarged optical system is used, Figure 18 is a configuration diagram showing the case where a reduction optical system is used, and Figure 9 is the configuration diagram shown in Figure 3. Figure 10 is a modified version of Figure 2, Figure 11 is a diagram for explaining the relationship between coherent light and incoherent light, and Figure 12 is for heterodyne detection in the spectrum plane. 13(a) is a diagram showing the configuration of the main parts, and FIG. 13(a) is a diagram shown to explain the irradiation direction of the sample.
Figure 3 (b) is a diagram shown to explain the relationship between coherent light and incoherent light, and Figure 14 is a diagram shown in Figure 13 (a).
Fig. 15 is a diagram showing the principle of image reproduction when image processing is introduced in the case of heterodyne detection on the spectral plane, and Fig. 16 shows the amplitude of heterodyne detection on the image plane. FIG. 2 is a configuration diagram showing main parts of an image detection device. 11... Laser oscillator, 15... Half mirror 17
... Modulator, 20... Light receiving section (0 dimension), 23...
・Data processing section, 24... Light receiving section (1, 2 dimensional), S
...sample, N...scatterer. Applicant's Representative Patent Attorney Takehiko Suzue Figure 7a Figure 6 Figure $8 Figure 10 Figure 17a 13th ffl (a) #13f! f(b) f Ff14 Figure

Claims (16)

[Claims] (1) irradiation means for generating coherent light and irradiating the sample with the coherent light; generating means for generating reference coherent light having a different frequency from the coherent light; coherent light reflected from the sample and the reference coherent light; A composition means for combining coherent light with a coherent light, a detection means for detecting a beat component from the combined light, and a signal processing means for obtaining an amplitude image of the sample from the beat component detected by the detection means. A reflection amplitude image detection device using a heterodyne detection light receiving system. (2) Detection of a reflection amplitude image using the heterodyne detection light receiving system according to claim 1, wherein the synthesizing means synthesizes the reference coherent light in the entire cross section of the beam of coherent light reflected from the sample. Device. (3) The sample is moved in a one-dimensional or two-dimensional direction by a driving means, the detection means is constituted by a zero-dimensional photoelectric conversion means, and the signal processing means converts the beat component output from the photoelectric conversion means into a one-dimensional or two-dimensional direction. 2. A reflection amplitude image detection apparatus using a heterodyne detection light receiving system according to claim 1, wherein a dimensional or two-dimensional amplitude image is obtained. (4) The apparatus for detecting a reflection amplitude image using a heterodyne detection light receiving system according to claim 1, wherein the coherent light generated by the irradiation means is focused by a focusing means and irradiated onto the sample. (5) The detection means is constituted by a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged one-dimensionally or two-dimensionally,
2. A reflection amplitude image detection apparatus using a heterodyne detection light receiving system according to claim 1, wherein said signal processing means obtains a one-dimensional or two-dimensional amplitude image from the beat component output from said photoelectric conversion means. (6) The apparatus for detecting a reflection amplitude image using a heterodyne detection light receiving system according to claim 1, wherein the generation means is constituted by a modulation means for shifting the frequency of the coherent light generated by the irradiation means. . (7) The heterodyne detection light reception according to claim 5, characterized in that a light focusing means is provided on the front surface of the sample to collect the light beam reflected from the sample into small areas and guide it to the detection means. A reflection amplitude image detection device using a system. (8) A generating means for generating coherent light, a first half mirror means for obliquely irradiating the sample with the coherent light generated by the generating means, and a frequency of the light transmitted through the first half mirror means. generating means for shifting and generating a reference coherent light; a synthesizing means for synthesizing the reference coherent light with light other than the specularly reflected light reflected from the sample; and a beat component from the light synthesized by the synthesizing means. A detection device for a reflection amplitude image using a heterodyne detection light receiving system, comprising: a detection means for detecting a beat component; and a signal processing means for obtaining an amplitude image of a sample from a beat component detected by the detection means. (9) Detection of a reflection amplitude image using the heterodyne detection light receiving system according to claim 8, wherein the reference coherent light is guided to the synthesizing means via a mirror means that moves in one or two dimensions. Device. (10) The detection means is constituted by a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged in one or two dimensions, and the signal processing means is one-dimensional or two-dimensional from the beat component output from the photoelectric conversion means. 9. A reflection amplitude image detection apparatus using a heterodyne detection light receiving system according to claim 8, wherein an amplitude image of . (11) Irradiation means for generating coherent light and irradiating the sample with the coherent light; generation means for generating reference coherent light having a different frequency from the coherent light; and Fourier transformation of the coherent light reflected from the sample. a Fourier transform means for converting the reference coherent light into a spectral plane of light Fourier transformed by the transform means; a half mirror means for combining the reference coherent light with the spectrum plane of the light Fourier transformed by the transform means; a detecting means for detecting a beat component from the combined light; A detection device for a reflection amplitude image using a heterodyne detection light receiving system, comprising: a signal processing means for obtaining an amplitude image of a sample from a detected beat component. (12) Irradiation means for irradiating a sample with coherent light; generation means for generating reference coherent light having a different frequency from the coherent light; and first Fourier transformation means for Fourier transforming the coherent light reflected from the sample. and a second Fourier transform means that further Fourier transforms the amplitude distribution in this spectral plane, and a half mirror means that guides the reference coherent light to the transform plane of the second Fourier transform means and combines it with the Fourier transformed light. A heterodyne detection light receiving system comprising: a detection means for detecting a beat component from the combined light; and a signal processing means for obtaining an amplitude image of a sample from the beat component detected by the detection means. A reflection amplitude image detection device using (13) The detection means is constituted by a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged in one or two dimensions, and the signal processing means is one-dimensional or two-dimensional from the beat component output from the photoelectric conversion means. 13. The apparatus for detecting a reflection amplitude image using a heterodyne detection light receiving system according to claim 11 or 12, wherein an amplitude image of a reflection amplitude image is obtained. (14) The half mirror means guides the reference coherent light onto the entire surface of the conversion surface, and combines the reference coherent light into light that has been Fourier transformed on the entire surface of the conversion surface.
A detection device for a reflection amplitude image using the heterodyne detection light receiving system described above. (15) The half mirror means is moved in a one-dimensional or two-dimensional direction and combines the reference coherent light into the Fourier-transformed light in a part of the spectral plane. Reflection amplitude image detection device using a heterodyne detection light receiving system. (16) A reflection amplitude image using the heterodyne detection light receiving system according to claim 11 or 12, characterized in that a spatial filter is provided on the spectral plane, and the detection means detects the combined light beam that has passed through the spatial filter. detection device.