JP4673955B2 - Optical device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical device for obtaining the internal structure of an optical scatterer (object to be observed) typified by biological tissue and the structure information of a laminated pattern formed on a semiconductor substrate.
[0002]
[Prior art]
In the biological / medical field, when observing the physiological function of a living body or performing pathological diagnosis, it is desired to observe an internal tissue or the like non-invasively in the state of the living body without creating a specimen for observation. .
A living tissue is optically a light scatterer, and when observing the inside of a living body, the observation light is affected by scattering by the tissues before and after the region to be observed, and it is difficult to identify the region to be observed. .
In order to solve this problem, an observation method using a low coherence interference technique proposed in Japanese Patent Publication No. 6-35946 and US Pat. No. 5,321,501 has been used. When a living body is observed using a low coherence interference technique, only a signal in a specific region can be detected in the living body. Furthermore, the influence of light scattering by the medium before and after the observed region can be reduced.
Also in the semiconductor field, in order to realize high-density integration of ICs, it is advancing to form three-dimensionally by laminating circuit patterns to be formed on a silicon wafer. Along with such a three-dimensional circuit pattern, a method for inspecting the structure and defects of a specific circuit pattern layer laminated on a silicon wafer is also required.
Conventionally, as a method for inspecting a circuit pattern of an IC, there is a method of observing a circuit pattern by transmitting infrared light through a silicon substrate. However, by adopting this method, a portion that cannot be observed from the surface of a silicon wafer. As for, it became possible to observe.
[0003]
[Problems to be solved by the invention]
By the way, the current low coherence interference technique detects a signal from a specific area of an object to be observed by using the short coherence distance of the light source, and thereby obtains the coordinates and reflectance of the area to be observed. However, since no consideration is given to the reduction of the interference signal due to light scattering in the medium before and after the observed region, it is possible to separate the scattered light and the interference signal, but the phase of the observed region There is a problem that it is difficult to detect the change and reproduce the phase information, and therefore it is difficult to detect the change in the structure and density of the observation region.
In addition, when observing the physiological function of a living body or performing pathological diagnosis, it is necessary to detect changes in the structure and density of the observed region. In addition to obtaining the coordinates of the observed region and the light reflectance, the phase change It is also important to detect.
In addition, when a circuit pattern formed three-dimensionally on a silicon substrate is transmitted and observed using infrared light to inspect a structure or defect in a specific region, the circuit pattern before and after the region to be observed depends on the circuit pattern. Scattered light and diffracted light are generated. In addition, step information and the like forming a circuit pattern are attenuated in detection signals due to light scattering in regions before and after the step. In addition, when observing the structure and defects of the circuit pattern of each layer, it is necessary to separate the scattered light and detection light generated outside the region to be observed, but by combining an infrared light source and low-coherence interference technology The scattered light and the detection light can be separated. However, since the detection signal is attenuated due to light scattering in a region other than the region to be observed, as in the case of observation inside the living body, it is necessary to consider the attenuation of the detection signal due to light scattering. It is difficult to reproduce the structural information.
[0004]
The present invention has been made in view of such problems of the prior art, and the object of the present invention is to avoid phase information in a specific region of an object to be observed without being affected by light scattering. An object of the present invention is to provide an optical device that can be reproduced.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an optical apparatus according to the present invention includes a light source, an illumination optical system that guides light from the light source to an object to be observed, and a light that is disposed in the illumination optical system and that emits light from the light source. A member that divides and guides light to be observed and reference light for forming an interference image of the object to be observed, and an image that guides the interference image formed by the interference between the light to be observed and the reference light to the image sensor. An optical system, an image sensor that captures an interference image, an arithmetic device that calculates image information from the image sensor to obtain phase information, and an interference image disposed in the illumination optical system or the imaging optical system An optical apparatus having means for changing the relative phase difference between the observation light and the reference light forming the light intensity information at a plurality of points in the depth direction within the observation object, and performing the calculation device, reducing the light intensity information of at least two points of the plurality of points Obtains the light scattering coefficient of said object under observation object based on the characteristics, the phase information of attenuation due to scattering of light at a particular point in the depth direction of the observed the object is corrected by using the light scattering coefficient obtained Rukoto is characterized in.
[0006]
In general, the light transmitted through the light scattering medium is classified into scattered light and non-scattered light in terms of optical characteristics as schematically shown in FIGS. 1 and 2. It collides repeatedly with the light scattering material inside, and is distributed statistically within the scattering angle. The scattered light is considered to be incoherent when the optical path length becomes relatively random by repeatedly colliding with the light scattering material, and when the coherence of the light source is low. Non-scattered light is light that transmits without colliding with the light scattering material in the medium, or light that does not collide with the light scattering material and whose optical path length is within the coherence length of the light source. Light that transmits phase information such as distribution and unevenness.
[0007]
Thus, light source and an illumination optical system that guides the observation target object light from the light source, the reference light from the light source be located in the illumination optical system for forming an interference image of the observed light and the observed object a member for light guide and each divided into a light, an imaging device for obtaining an imaging optical system for guiding to the imaging device an interference image formed by the interference of the reference light and the observation light, a phase information by imaging the interference image And an arithmetic unit that calculates image information from the image sensor, and a relative phase difference between the observation light and the reference light that are arranged in the illumination optical system or the imaging optical system and form an interference image are changed. By configuring the optical device having the means, non-scattered light from a specific region in the light scattering medium can be detected as an interference image.
[0008]
When light passes through the light scattering medium, it is divided into scattered light generated by light colliding with a light scattering material and non-scattered light traveling without colliding. The non-scattered light traveling without colliding with the light scattering material has a higher probability of colliding with the light scattering material as the traveling distance becomes longer, and collides with the light scattering material to change into scattered light. Therefore, the ratio of non-scattered light to scattered light or incident light becomes small depending on the light scattering coefficient determined by the concentration of the light scattering material in the medium and the transmission distance.
Considering the light scattering coefficient as the probability that light collides with a light scattering material, the probability that non-scattered light exists depends on the light scattering coefficient and the transmission distance, and the ratio to scattered light and incident light decreases.
[0009]
The phase information of the observation point is a function of the ratio of the non-scattered light component and the scattered light component. When the light is transmitted through the light scattering medium, the attenuation rate of the non-scattered light component becomes larger than the attenuation rate of the scattered light component, so that the phase information is reduced and measured. Therefore, the interference image acquired by the optical apparatus having the above configuration is information in which the non-scattered light component is attenuated by the light scattering coefficient and the transmission distance of the medium.
[0010]
Create a sample to measure the light scattering coefficient from the same type of object as the object to be observed in advance, measure the light scattering coefficient, find the relationship between transmission distance and attenuation rate by computer simulation, etc., and store it as reference data inside the arithmetic unit Let me put. Then, the coordinates of the observation point in the observed object are measured with reference to the surface thereof, and the attenuation rate of the non-scattered light at the observation point is obtained from the reference data. Then, by correcting the acquired interference image using this attenuation factor, the phase distribution in the light scattering medium can be obtained without being affected by light scattering.
[0011]
Also, in the case of obtaining the phase information for a specific point in the light scattering medium is to estimate the attenuation characteristics of the non-scattered light is important. As a method for estimating the attenuation characteristics, first, a sample for measuring the light scattering coefficient is prepared from the same kind of substance as the observed substance, the light scattering coefficient is measured, and the non-scattered light is calculated using the Lambert-Beer equation. It is conceivable to obtain the relationship between the thickness of the object to be observed and the attenuation by numerical calculation. The light scattering coefficient can be obtained by measuring scattered light from at least two points in the observed object without preparing a measurement sample from the observed object. is there.
[0012]
Therefore, as in the present invention, the light intensity information at a plurality of points in the depth direction within the observation object is acquired, and based on the attenuation characteristics of the light intensity information of at least two of the plurality of points. By calculating the light scattering coefficient of the object to be observed, the attenuation characteristic of the non-scattered light is calculated, the attenuation data in the thickness direction is retained as reference data, and the light intensity information is obtained at the point or other points. It is possible to calculate the attenuation characteristic of non-scattered light and obtain phase information in which the attenuation amount due to light scattering at a specific point in the depth direction in the observed object is corrected .
[0013]
Further, the optical device that by the present invention, light source and an illumination optical system that guides the observation target object light from the light source, and the observation light light from the light source is disposed in the illumination optical system A member that divides and guides the reference light for forming an interference image of the object to be observed, and an imaging optical system that guides the interference image formed by the interference between the observation light and the reference light to the image sensor; An image pickup device that picks up an interference image, a calculation device that calculates image information from the image pickup device to obtain phase information, and an object that is disposed in the illumination optical system or the imaging optical system and forms an interference image. An optical device having means for changing a relative phase difference amount between observation light and reference light , wherein the arithmetic device acquires phase information of similar structures at a plurality of points in the depth direction in the object to be observed. Is based on the attenuation characteristics of the phase information of at least two of the plurality of points. There obtains a light scattering coefficient of said object to be observed object, so that to obtain the phase information of attenuation due to scattering of light is corrected at a particular point in the depth direction in the observed object using the light scattering coefficient I have to.
Since the circuit pattern formed on the silicon wafer has almost the same circuit pattern thickness, the phase information of the two points in the observed object is obtained and its signal ratio is obtained. The partial attenuation rate of the phase information can be obtained. In the case of an object in which similar structures are periodically laminated, such as a laminated circuit pattern, it is considered as uniform as a whole, and the attenuation characteristics in the depth direction can be estimated from the partial attenuation rate.
Therefore, as in the above-described invention, phase information of a similar structure is obtained at a plurality of points in the depth direction within the observed body, and the object to be observed is obtained from the attenuation characteristics of the phase information of at least two of the plurality of points. Determination of light scattering coefficient, attenuation corrected phase information to obtain Rukoto can due to scattering of light at the point specified in the depth direction of the observed in the object with the light scattering coefficient.
[0014]
According to the invention, the imaging optical system is configured to be a microscope optical system. Thereby, the physiological function of the living body and the circuit pattern on the silicon wafer can be enlarged, and more detailed information can be obtained.
[0015]
Further, according to the present invention, the illumination optical system and the imaging optical system are configured to be a confocal optical system. As a result, the resolution of the information in the depth direction of the non-scattered light is improved, the position of the observation point can be specified accurately, and the accuracy of correcting the attenuation of the phase information can be improved. Moreover, the leakage of scattered light can be reduced in the interference image for acquiring the phase information, and the acquisition accuracy of the phase information can be improved.
The scattered light can be reduced in the influence of light from other than the observation point, and can be treated as equivalent to the presence of an independent point light source at the observation point. By moving the observation point in the observed object and measuring the scattered light at a plurality of observation points, the attenuation characteristic of the scattered light of the observed object can be obtained. The light scattering coefficient can be obtained from this attenuation characteristic, and further the attenuation characteristic of the phase information can be obtained.
[0016]
Further, according to the present invention, the light source is configured to be a low coherence light source. Thereby, when acquiring the phase information of the observed object from the interference image, not only the non-scattered light can be separated from the scattered light but also the accuracy of the separation of the scattered light and the non-scattered light can be improved.
[0017]
According to the present invention, the light intensity information and the phase information are acquired at at least two points in the depth direction in the observed object, and the arithmetic unit attenuates the light intensity information and the phase information between the two points. obtains the light scattering coefficient of the observed object from the characteristics, to so that to obtain the phase information attenuation due to scattering of light at a particular point in the depth direction of the observed the object is corrected by using the light scattering coefficient ing.
Further, in applying the present invention, by configuring a confocal microscope, it is possible to obtain a sectioning effect when measuring scattered light intensity and phase information, so that the attenuation rate of light is measured more accurately. I can do it.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on illustrated examples.
Example 1
FIG. 3 is a schematic configuration diagram when the optical apparatus according to the present invention is applied to a differential interference microscope. Here, a configuration of an upright microscope using an infinite correction optical system in which light from an object is converted into a parallel light beam by an objective lens and an image of the object to be observed is formed by the imaging lens will be described as an imaging optical system. The differential interference microscope is an interference microscope that applies the shearing interferometry, which generates two interfering light beams by arranging a Nomarski prism in the optical path and generates an interference image by interfering the two light beams. It is. Therefore, in the shearing interferometry, the two light beams generated by the Nomarski prism alternately serve as the observation light and the reference light.
In the figure, 1 is a specimen which is an object to be observed suppressed on the stage 2, 3 is an objective lens, 4 is a piezo element, 5 is a Nomarski prism, 6 is a half mirror, 7 is an imaging lens, and 8 is an aperture pattern disk. , 9 is a motor, 10 is a relay lens, 11 is a half mirror, 12 is a relay lens, 13 is an analyzer, 14 is an image sensor, 15 is a storage / arithmetic unit, 16 is a display device, 17 is a light source, and 18 is a light collector. Lens, 19 is a phase change device, 20 is a light source, 21 is a condenser lens, 22 is a phase change device, 23 is a light source, 24 is a condenser lens, 25 is a phase change device, 26 is a mirror, 27 is a Nomarski prism, 28 Is a condenser lens. The aperture pattern disk 8 and the motor 9 are aperture members, the relay lenses 10 and 12, the half mirror 11 and the analyzer 13 are relay optical systems, and the light source 17, the condenser lens 18 and the phase change device 19 are confocal illumination optics. The light source 20, the condenser lens 21, and the phase change device 22 are incident illumination optical systems, and the light source 23, the condenser lens 24, the phase change device 25, the mirror 26, the Nomarski prism 27, and the condenser lens 28 are transmitted illumination optical systems. Respectively.
[0019]
An aperture pattern disk (Nipkow Disk) 8 is disposed at the focal position of the imaging lens 7, and the relay optical system forms an image of light transmitted through the aperture pattern disk 8 on the light receiving surface of the image sensor 14. Are arranged as follows. Further, a half mirror 11 is provided in the relay optical system, and the surface of the object to be observed 1 is confocally illuminated via the half mirror 11 and the aperture pattern disk 8 by the confocal illumination optical system. Yes. Further, the Nomarski prism 5 is arranged in the imaging optical system, and the analyzer 13 is arranged in the relay optical system to constitute a Nipo disk scanning confocal differential interference microscope capable of observing incident-light differential interference.
A phase change device 19 is disposed in the confocal illumination optical system, and a device 15 for storing / calculating an image of the observed object imaged by the image sensor 14 and a display for displaying the computed image. A device 16 is added. The objective lens 3 is attached to the piezo element 4 so that the distance between the objective lens 3 and the observed object 1 can be accurately controlled in cooperation with the stage 2 on which the observed object 1 is placed. It has become. In this embodiment, the phase change device 19 changes the amount of retardation to pick up a plurality of differential interference images, which can be calculated by the storage / calculation device 15 to extract the phase information. .
[0020]
Next, the case where the structure inside the living body is observed using a confocal optical system will be described. First, the biological specimen 1 which is an object to be observed is placed on the stage 2 and is movable in the depth direction, that is, the vertical direction. Light intensity information and phase information are acquired by confocal observation while moving the observation point from the vicinity of the surface of the biological specimen 1 toward the inside using both the stage 2 and the piezo element 4, and these are stored and calculated, respectively. The data is stored in the device 15 as data. And the change by the movement of the observation point of light intensity information is calculated | required from the acquired data, and it converts into the attenuation | damping characteristic of scattered light. Then, the light scattering coefficient is calculated from the attenuation characteristic of the scattered light, and further the attenuation characteristic of the phase information is obtained. Using the attenuation characteristics of the phase information thus calculated and the phase information measured at each observation point, a three-dimensional phase distribution inside the living body is reproduced. The above processing relating to phase reproduction is performed by the storage / arithmetic unit 15 in a series of programs.
In addition, according to the present Example, since it has a transmission illumination optical system and an epi-illumination optical system, observation other than confocal observation is also possible.
[0021]
Example 2
A case where an object to be observed having a property different from that of the first embodiment is observed using the differential interference microscope shown in FIG.
First, a circuit pattern formed on a silicon substrate whose internal characteristics are known in advance is used as a reference sample, and this reference sample is placed on the stage 2 and imaged using a transmission illumination optical system using the light source 23 as an infrared light source. While rotating the Nipou disc 8 in the optical system, the retardation amount is changed by the phase change device 19 arranged in the illumination optical system, and a plurality of differential interference images are taken and calculated by the storage / calculation device 15. Extract phase information. Next, in the laminated circuit pattern, one point near the surface and one point in the inside having the same structure are selected, the phase information is compared, and the phase between the two points is calculated from the comparison value of the coordinates of the two points and the phase information Obtain the attenuation rate of information. Further, the phase information of the phase structure near the surface is measured using an epi-illumination optical system or a confocal optical system.
Next, the phase attenuation characteristic inside the reference sample is estimated from the phase information measured using the epi-illumination optical system, the phase attenuation characteristic measured using the transmission illumination optical system, and the coordinates of one point. This attenuation characteristic is held in the storage / arithmetic unit 15 as reference data.
Next, a sample of the same type as the reference sample is placed on the stage 2 and the structure near the surface is measured using an epi-illumination optical system or a confocal optical system. By switching the illumination optical system, phase information inside the circuit pattern is measured using the transmission illumination optical system. Using the phase attenuation characteristic reference data held in the storage / arithmetic unit, the phase information in which the attenuation due to light scattering at a specific point in the depth direction in the observed object is corrected is reproduced. .
[0022]
Example 3
FIG. 4 is a schematic configuration diagram when the optical device according to the present invention is applied to a Michelson interferometer. In the figure, 29 is a low coherence light source using an SLD, 30 is a condensing lens, 31, 32 and 33 are mirrors, 34 is a beam splitter, 35 is an objective lens, 36 is an object to be observed, 37 is a stage, 38 is A stepping motor, 39 is an imaging lens, 40 is an optical detector comprising a CCD, 41 is a condenser lens, 42 is a reference mirror, and 43 is a piezo element. The stage 37 is configured so that the position can be accurately moved in the optical axis direction by the stepping motor 38, and the reference mirror 42 is also configured so that the position can be changed in the optical axis direction by the piezo element 43. Although not shown, the detector 40 is connected to the storage / arithmetic unit 15 and the display unit 16 as shown in the first embodiment.
Since the present embodiment is configured as described above, the light from the light source 29 that has reached the beam splitter 34 via the condenser lens 30 and the mirrors 31, 32, 33 is transmitted to the object 36 by the beam splitter 34 . It is divided into two light toward the light and the reference mirror 42 toward. Then, the light reflected by the observed object 36 and the light reflected by the reference mirror 42 are combined by the beam splitter 34 to form an interference fringe at the observation point on the optical detector 40. With low coherence light source as the light source 29 as in the present embodiment, the reference optical interference signal only at a position where the optical path length matches the that reflection by the reference mirror 42 and the optical path length of the observation light reflected by the observed object 36 Therefore, when observing a specific point on the observed object 36, the reference mirror 42 is moved by the piezo element 43 to match the optical path lengths. When the reference mirror 42 is moved, the signal from the optical detector 40 takes the form shown in FIG. 5 when the horizontal axis indicates the movement distance of the reference mirror 42 and the vertical axis indicates the signal intensity of the optical detector. . Here, the signal intensity is displayed as a negative voltage value.
[0023]
When observing the inside of the object to be observed 36, the intensity of the received signal from the light detector 40 decreases due to the presence of the light scattering material. This will be described with reference to FIG. 5. In the figure, P is an interference signal that changes as the reference mirror 42 moves, and S is the sum of the intensities of the light that reaches the photodetector 40. Therefore, P can be considered as a non-scattered light component and S as a scattered light component. When the observation point is moved from the surface of the observed object 36 to the inside, both the non-scattered light component P and the scattered light component S are attenuated. By making this attenuation amount correspond to the coordinates of the observation point, it is possible to know the attenuation characteristics of the scattered light component and the non-scattered light component. Furthermore, the phase information at the observation point can be obtained by scanning the reference mirror 42 at a specific observation point and using a phase detection method such as a fringe scanning method. and by using the damping characteristics of the scattered light, the phase information not affected by scattering of light at the observation point by correcting the attenuation due to scattering of light at the point specified in the depth direction of the observed in the object Can be played.
[0024]
Although not shown in FIG. 4, if the observed object 36 is moved also in a plane perpendicular to the optical axis, or if the observation light is scanned in that plane, the inside of the observed object will be shown. Three-dimensional phase information can also be reproduced. In addition, since the local light scattering coefficient near the observation point can be detected from the attenuation characteristics of the scattered light component and the non-scattered light component, by comparing this local light scattering coefficient, It is also possible to detect a change in internal structure or a difference from a reference object.
In each embodiment including this embodiment, the light intensity information and the phase information in the depth direction are acquired at two points, but the light intensity information and the phase information may be acquired at a plurality of two or more points. . In obtaining the attenuation characteristics, all of the acquired plurality of information may be used, or some of the acquired plurality of information may be used.
[0026]
【The invention's effect】
As described above, according to the present invention, phase information and scattered light information are detected at two or more observation points in a substance with light scattering, such as inside a living body, and the respective changes are obtained to find the inside of the substance. Determine the attenuation characteristics of unscattered light and scattered light, use this attenuation characteristic to determine the light scattering coefficient of the object under observation, and use the light scattering coefficient to determine the light scattering coefficient at a specific point in the depth direction within the object under observation. can attenuation due to scattering of light provides an optical apparatus capable of obtaining a three-dimensional structural information of the internal above substances by Rukoto obtain the phase information corrected. Further, according to the present invention, the local light scattering coefficient inside the substance can be calculated from the light not scattered inside the substance and the attenuation information of the scattered light, and the local light scattering coefficient can be calculated from the local light scattering coefficient. An optical device capable of knowing the structural change can be provided. Similarly, according to the present invention, it is possible to provide an optical device capable of knowing the three-dimensional structural information of the laminated circuit pattern formed on the silicon substrate and the change in the internal structure.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically showing the progress of scattered light and non-scattered light in a substance that transmits light.
FIG. 2 is a diagram showing coherence between scattered light and non-scattered light shown in FIG. 1;
FIG. 3 is a schematic configuration diagram of an embodiment in which an optical apparatus according to the present invention is applied to a differential interference microscope.
FIG. 4 is a schematic configuration diagram of an embodiment in which the optical device according to the present invention is applied to a Michelson interferometer.
5 is a schematic diagram showing the relationship between the moving distance of the reference mirror 42 and the signal intensity at the detector 40 in the embodiment shown in FIG.
[Explanation of symbols]
1,36 Object to be observed (specimen)
2,37 Stage 3,35 Objective lens 4,43 Piezo element 5,27 Nomarski prism 6,11 Half mirror 7,39 Imaging lens 8 Aperture pattern disk (Nipou disk)
DESCRIPTION OF SYMBOLS 9 Motor 10, 12 Relay lens 13 Analyzer 14 Image pick-up element 15 Memory | storage / arithmetic apparatus 16 Display apparatus 17, 20, 23, 29 Light source 18, 21, 24, 30, 41 Condensing lens 19, 22, 25 Phase change apparatus 26 , 31, 32, 33 Mirror 28 Condenser lens 34 Beam splitter 38 Stepping motor 40 Optical detector 42 Reference mirror

Claims (6)

A light source;
An illumination optical system that guides light from the light source to an object to be observed;
A member that is arranged in the illumination optical system and that divides and guides light from the light source into light to be observed and reference light for forming an interference image of the object to be observed;
An imaging optical system for guiding an interference image formed by the interference between the observation light and the reference light to the image sensor;
An image sensor that captures an interference image;
A computing device that computes image information from the image sensor to obtain phase information;
An optical apparatus having means for changing a relative phase difference amount of observation light and reference light which are arranged in the illumination optical system or the imaging optical system and form an interference image,
Obtain light intensity information at multiple points in the depth direction within the observed object,
The arithmetic unit determines the light scattering coefficient of said object under observation object based on the attenuation characteristic of the light intensity information of at least two points of the plurality of points, the depth of the observation target object by using the light scattering coefficient optical apparatus attenuation due to scattering of light at a particular point in the direction, characterized in Rukoto obtain a corrected phase information. A light source;
An illumination optical system that guides light from the light source to an object to be observed;
A member that is arranged in the illumination optical system and that divides and guides light from the light source into observation light and reference light for forming an interference image of the observation object;
An imaging optical system for guiding an interference image formed by the interference between the observation light and the reference light to the image sensor;
An image sensor that captures an interference image;
A computing device that computes image information from the image sensor to obtain phase information;
An optical apparatus having means for changing the relative phase difference between the observation light and the reference light that are arranged in the illumination optical system or the imaging optical system and form an interference image,
Obtain phase information of similar structures at multiple points in the depth direction within the observed object,
The arithmetic unit obtains a light scattering coefficient of the object to be observed based on attenuation characteristics of phase information of at least two points of the plurality of points, and uses the light scattering coefficient to determine a depth direction in the object to be observed An optical device characterized by obtaining phase information in which attenuation due to light scattering at a specific point is corrected. The optical device according to claim 1 or 2, wherein the imaging optical system is characterized in that the microscopic optical system. The optical apparatus according to any one of claims 1 to 3, wherein the illumination optical system and the imaging optical system are confocal optical systems. The optical device according to any one of claims 1 to 4, wherein said light source is a low coherence light source. Light intensity information and phase information are acquired at at least two points in the depth direction in the object to be observed, and the arithmetic unit scatters light of the object to be observed from the attenuation characteristics of the light intensity information and phase information between the two points. obtains the coefficients, according to claim 1 in which the attenuation due to scattering of light at a particular point in the depth direction of the observed in the object with the light scattering coefficient, wherein Rukoto obtain a corrected phase information The optical device according to any one of 5 .

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