JP6173486B2 - Scattered light information processing method, scattered light information processing apparatus, and scattered light information processing system - Google Patents

Description

  The present invention relates to a scattered light information processing method and a scattered light information processing apparatus for acquiring scattered light information necessary for performing optical design simulation with optical design software used in cameras, endoscopes, microscopes, etc. And a scattered light information processing system.

  The optical design software sets the parameters of r (curvature radius), d (surface spacing), n (refractive index), and reflectance and transmittance by the coat of each optical element included in the lens frame as parameters. It then calculates the refraction and reflection of various rays propagating through the optical system.

  In the optical design, each parameter is changed so as to satisfy a desired optical performance on the image plane. In addition, the optical performance can be estimated by acquiring and setting each parameter of the manufactured lens frame by measurement.

  The optical design software can evaluate not only a spot diagram on the image plane, MTF (Modulation Transfer Function), and wavefront aberration but also ghost and flare which are unnecessary light as an evaluation of optical performance.

  Ghost or flare is a phenomenon that occurs when unnecessary light other than regular light reaches the image plane. The causes of ghosts and flares are multiple reflections at each optical surface and incident unexpected light, as well as the lens surface, the surface after antireflection coating, the core of the lens after centering, the chamfered part, and the edge part. Further, it is conceivable that scattered light is generated due to a rough surface such as the inside of the lens frame, and the scattered light becomes unnecessary light.

  Therefore, when evaluating ghosts and flares by optical design simulation, it is necessary to accurately input the scattered light intensity distribution, which is the scattered light information on each surface, in addition to the normal parameters. When scattered light information is input, in each optical surface, ray tracing by the Monte Carlo method is performed in addition to geometric optical ray tracing, and rays reaching the image plane are calculated.

  The scattered light information is generally expressed using a bidirectional scattering distribution function (Bidirectional Scattering Distribution Function, hereinafter referred to as “BSDF” as appropriate) or a parameter called ARS obtained by dividing the Cosθ component from BSDF.

  As shown in FIG. 12, for the light L incident on the measurement surface 10, scattered light Sc reflected from the measurement surface 10 of the object to be measured and scattered light Sc transmitted through the measurement surface 10 are generated. The scattered light reflected from the measurement surface 10 of the measurement object is referred to as a bidirectional reflectance distribution function (hereinafter referred to as “BRDF” as appropriate). Further, the scattered light that has passed through the measurement surface 10 of the object to be measured is referred to as a bidirectional transmittance distribution function (hereinafter referred to as “BTDF” as appropriate).

  BSDF is defined as scattered light including both BRDF and BTDF.

  As an apparatus and method for obtaining scattered light information reflected from an object to be measured, for example, the one disclosed in Patent Document 1 below is known.

Japanese Patent No. 50583838

  However, the apparatus and method described in Patent Document 1 acquire scattered light information reflected from an object to be measured, which is an impermeable substance, with higher accuracy. That is, in the prior art, scattered light information cannot be acquired for a measurement object having a transmission portion such as an optical element.

  The present invention has been made in view of the above, and as an object to be measured, a scattered light information processing method, a scattered light information processing apparatus, and a scattered light capable of acquiring with high accuracy scattered light information of an optical element having a transmission part. The object is to provide an information processing system.

In order to solve the above-described problems and achieve the object, the scattered light information processing method of the present invention includes:
A scattered light information processing method for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition step for acquiring information on the scattered light intensity distribution of light irradiated at a predetermined angle to the object to be measured;
A model generation process for creating a measurement object model from the measurement conditions of the shape and optical properties of the measurement object and the scattered light intensity distribution;
A function parameter setting step for setting a parameter of a function representing scattered light information on the exit side transmitted through the object to be measured at least for the object model to be measured;
A scattered light intensity distribution calculating step for calculating a scattered light intensity distribution calculation result by calculation in consideration of reflection of scattered light and refraction of scattered light inside the substance of the measured object based on the measured object model;
Function parameter calculation for calculating function parameters so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition step matches the scattered light intensity distribution calculation result calculated by calculation based on the measured object model Processing steps;
It is characterized by having.
In addition, another scattered light information processing method of the present invention,
A scattered light information processing method for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition step for acquiring information on a scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured;
A model generation process for creating a measurement object model from the measurement conditions of the shape and optical properties of the measurement object and the scattered light intensity distribution;
A function parameter setting step for setting a parameter of a function representing scattered light information on the exit side transmitted through the object to be measured at least for the object model to be measured;
A scattered light intensity distribution calculating step of calculating a scattered light intensity distribution calculation result by calculation based on a measured object model;
Function parameters for each incident angle so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition step matches the scattered light intensity distribution calculation result calculated based on the measured object model. A formal function parameter calculation processing step for calculating as a formal function parameter,
The scattered light intensity distribution information acquired in the scattered light measurement information acquisition step and the scattered light intensity distribution calculation result calculated using at least part of the provisional function parameters of each incident angle with respect to the measured object model, A function parameter determining step of determining a final function parameter by adjusting the temporary function parameter so as to coincide with each other is provided.

The scattered light information processing apparatus of the present invention is
A scattered light information processing apparatus for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition unit that acquires information on the scattered light intensity distribution of light irradiated at a predetermined angle to the object to be measured;
From the measurement conditions of the shape and optical properties of the object to be measured and the scattered light intensity distribution, a model generation unit for creating an object model to be measured,
A function parameter setting unit that sets parameters of a function representing scattered light information on the exit side that has passed through the object to be measured, with respect to the object model,
A scattered light intensity distribution calculation unit for calculating a scattered light intensity distribution calculation result by calculation taking into account reflection of scattered light and refraction of scattered light inside the substance of the measured object based on the measured object model;
Function parameter calculation that calculates function parameters so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit matches the scattered light intensity distribution calculation result calculated by the calculation based on the measured object model A processing unit;
It is characterized by having.
In addition, another scattered light information processing apparatus of the present invention,
A scattered light information processing apparatus for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition unit for acquiring information on the scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured;
From the measurement conditions of the shape and optical properties of the object to be measured and the scattered light intensity distribution, a model generation unit for creating an object model to be measured,
A function parameter setting unit that sets parameters of a function representing scattered light information on the exit side that has passed through the object to be measured, with respect to the object model,
A scattered light intensity distribution calculation unit for calculating a scattered light intensity distribution calculation result by calculation based on a measured object model;
The function parameter of each incident angle so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit and the scattered light intensity distribution calculation result calculated by calculation based on the measured object model match. A formal function parameter calculation processing unit for calculating as a formal function parameter;
The scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit, and the scattered light intensity distribution calculation result calculated using at least a part of the provisional function parameters of each incident angle with respect to the measured object model, A function parameter determining unit that determines the final function parameter by adjusting the temporary function parameter so as to match is provided.

The scattered light information processing system of the present invention is
A scattered light information processing system for measuring scattered light of an object to be measured and processing scattered light information,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A light irradiation unit that irradiates light at a predetermined angle with respect to the object to be measured;
A scattered light measurement unit that receives at least light scattered by the object to be measured; and
Based on the information received by the scattered light measurement unit, a scattered light measurement information acquisition unit for acquiring information on the scattered light intensity distribution of the object to be measured;
An information storage unit for storing measurement conditions of the shape, optical properties, and scattered light intensity distribution of the object to be measured;
From the stored shape, optical properties, and measurement conditions, a model generation unit that creates an object model,
A function parameter setting unit that sets parameters of a function that represents at least scattered light information on the exit side transmitted through the object to be measured with respect to the object model;
A scattered light intensity distribution calculation unit for calculating a scattered light intensity distribution calculation result by calculation in consideration of reflection of scattered light and refraction of scattered light inside the substance of the measured object from the measured object model;
A function parameter calculation processing unit that calculates function parameters so that the scattered light intensity distribution information acquired by the scattered light measurement information acquisition unit matches the scattered light intensity distribution calculation result calculated from the measured object model. When,
It is characterized by having.
Further, another scattered light information processing system of the present invention,
A scattered light information processing system for measuring scattered light of an object to be measured and processing scattered light information,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A light irradiation unit that irradiates light at a predetermined angle with respect to the object to be measured;
A scattered light measurement unit that receives at least light scattered by the object to be measured; and
Based on the information received by the scattered light measurement unit, the scattered light measurement information acquisition unit for acquiring information on the scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured;
An information storage unit for storing measurement conditions of the shape, optical properties, and scattered light intensity distribution of the object to be measured;
From the stored shape, optical properties, and measurement conditions, a model generation unit that creates an object model,
A function parameter setting unit that sets parameters of a function that represents at least scattered light information on the exit side transmitted through the object to be measured with respect to the object model;
A scattered light intensity distribution calculation unit for calculating a scattered light intensity distribution calculation result by calculation from a measured object model;
A function of each incident angle so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit matches the scattered light intensity distribution calculation result calculated by the calculation based on the measured object model. A temporary function parameter calculation processing unit for calculating the parameter as a temporary function parameter;
The scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit, and the scattered light intensity distribution calculation result calculated using at least a part of the provisional function parameters of each incident angle with respect to the measured object model, A function parameter determining unit that determines the final function parameter by adjusting the temporary function parameter so as to match is provided.

  According to the present invention, it is possible to obtain scattered light information with high accuracy even when the object to be measured is a transmission substance.

FIG. 1A is a functional block diagram showing an outline of the scattered light information processing system according to the first embodiment of the present invention. FIG. 1B is a functional block diagram for explaining the scattered light information processing system in more detail. It is a flowchart explaining the measuring method of the scattered light in 1st Embodiment. It is a figure which shows schematic structure of the scattered light information processing system of BSDF. It is a flowchart explaining a data processing method. It is a figure which shows intensity distribution of scattered light when scattering of the surface of a to-be-measured object is small. (A), (b) is a figure which shows the measurement range of scattered light. It is a functional block diagram which shows the outline | summary of the scattered light information processing system of 2nd Embodiment of this invention. It is a figure which shows the drive state of a light irradiation part and a light-receiving part. It is a flowchart explaining the measuring method of the scattered light in 2nd Embodiment. It is a flowchart explaining the data processing method in 2nd Embodiment. It is a flowchart explaining the data processing method of the modification of 2nd Embodiment. It is a figure explaining scattered light information. It is a figure explaining a parameter. (A), (b) is a figure explaining reflection of light. It is another figure explaining scattered light.

  Hereinafter, embodiments of a scattered light information processing method, a scattered light information processing apparatus, and a scattered light information processing system according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

  First, as a premise for explaining the embodiment of the present invention, the scattered light information and measurement will be further described in detail based on the prior art.

  The scattered light information BSDF represents the radiance of the scattered light as a function of the angle of the scattered light from the normal of the surface and possibly as a function of the angle of the incident light that irradiates the scattering surface. Specifically, for example, BRDF of BSDF is defined by the following formula 1.

FIG. 13 shows the symbols and parameters of Equation 1 using an XYZ orthogonal coordinate system, taking as an example the case where light is irradiated onto the surface of the opaque material. As shown in FIG. 13, the incident light angle (θ _i ), the incident azimuth angle (φ _i ), the light receiving angle (θ _r ), the light receiving azimuth angle (φ _r ), and the incident light wavelength (λ) are five. Given as a variable. Also, P _i denotes the light intensity of the incident light, P _r is the intensity of the reflected light of the measurement region dA of the measurement surface, respectively. Further, dω _i and dω _r represent solid angles.

  The BSDF is a flat scattered light intensity distribution by definition without regard to the transmission / impermeability relationship of the object to be measured, and does not take into account the outer shape and optical properties of the object to be measured. That is, when the object to be measured is a transmissive substance, the effects of front and back surface shapes (spherical, aspherical, free-form surface, etc.), outer diameter, surface interval (thickness), ribs, chamfers, edges, refractive index Is not considered. BSDF represents the behavior of scattered light generated by one plane.

  By defining the BSDF in this way, it becomes possible to input it as a surface parameter to the optical design software, and an accurate optical design simulation can be performed even if the radius of curvature and the surface interval, which are other input parameters, are changed. be able to.

FIG. 3 shows a schematic configuration of a BSDF scattered light information processing system when a parallel plate 300 of a transmissive material is used as an object to be measured. In the XYZ orthogonal coordinate system, which is an orthogonal coordinate system, the vertical direction is the Y-axis direction, the horizontal direction parallel to the incident light is the Z-axis direction, and the direction orthogonal to the horizontal plane is the X-axis direction.
The reason why the parallel plane is used for the object to be measured 300 is to eliminate the influence of the shape of the front and back surfaces of the object to be measured as much as possible.

Further, the parallel plate 300 of the object to be measured often has a desired roughness approximate to the roughness of the surface to be measured on the one surface 300a, for example, the surface of the lens, the rib portion, the chamfered portion, or the like.
By using such an object to be measured, the relationship between the surface roughness and the scattered light intensity distribution can be measured.

  The light irradiation unit 101 uses a laser or a white light source that irradiates light having a predetermined wavelength. And the light from the light irradiation part 101 injects into the parallel plate 300 which is a to-be-measured object at a predetermined angle. The incident light is scattered on the surface of the parallel plate 300 that is the object to be measured, which has a roughness, is transmitted through the object to be measured, and is emitted into the air.

  The light receiving unit 102 acquires the intensity distribution of scattered light two-dimensionally or three-dimensionally with respect to the light emitted from the parallel plate 300 about the measurement surface 300a of the object to be measured. The light receiving unit 102 can be moved to the position A, the position B, and the like by the driving unit 305, for example. As described above, the BSDF that is the transmitted and reflected scattered light intensity distribution can be acquired.

  When the object to be measured is an impermeable substance, only BRDF that is a reflected scattered light intensity distribution can be acquired.

When the BSDF acquired as described above is input as a parameter to the optical design software, an error occurs when the object to be measured deviates from the BSDF definition.
For example, when BRDF is acquired when the object to be measured is an impermeable substance, if the measurement result of the scattered light intensity distribution by the scattered light information processing system is BRDF when the surface of the object to be measured is other than a flat surface in the conventional technology, The influence of the surface shape of the surface is included, resulting in an error.

  Therefore, in the prior art, BRDF excluding the influence of the surface shape is calculated using the information on the measurement result of the scattered light intensity distribution and the surface shape information of the object to be measured.

  FIG. 14A is a diagram for explaining reflected light by a geometrical optical component when incident light Lin is incident on the measurement surface 10. The incident light Lin is reflected as reflected light Lref at the same angle as the incident angle with respect to the normal N to the tangent to the incident position.

FIG. 14B is a diagram for explaining the reflected light by the wave optical component when the incident light Lin is incident on the measurement surface 10a.
As described in the prior art, when light is incident on the object to be measured, the scattered light intensity distribution is calculated from the combination of the surface shape information and the BRDF in the irradiation region of the measurement surface 10a. Then, the BRDF is changed so that the calculated scattered light intensity distribution approximates the actually measured scattered light intensity distribution measurement result. Thereby, the BRDF is calculated separately from the influence of the surface shape in the irradiation area of the reflection surface.

  However, as described above, the conventional technique cannot be applied when the object to be measured is a permeable substance. Needless to say, when the object to be measured is a transmissive substance, an error occurs if the measurement surface of the object to be measured is not flat in the light irradiation region from the light irradiation unit. In addition, the shape other than the region irradiated with light from the light irradiation unit and the inside of the measurement object are affected. That is, when the object to be measured is a transmissive substance, an error occurs if the measurement result of the scattered light intensity distribution by the scattered light information processing system is BSDF even if the measurement surface is flat. This is a particular problem when the object to be measured is a permeable material. Further details will be described below.

Here, the definition of BSDF will be described again.
In the optical design software, the BSDF is defined as a function of the angle of the scattered light from the surface normal as described above. In some cases, the radiance of the scattered light is expressed as a function of the angle of the incident light applied to the scattering surface, and the scattered light intensity distribution is flat.

For this reason, the external shape and optical properties of the object to be measured are not considered. That is, when the object to be measured is a transmissive substance, the shape of the surface to be measured (spherical surface, aspherical surface, free-form surface, etc.), outer diameter, surface interval (thickness), flange, chamfered part, edge part and refractive index Therefore, the result of simply measuring scattered light deviates from the definition of BSDF.
As a result, according to the conventional procedure, the BSDF cannot be obtained for the measurement object of the permeable material. This will be described in more detail.

  In the case where the object to be measured is a transmission material, a specific phenomenon when measuring scattered light will be described. FIG. 15 is a diagram for explaining the behavior of the scattered light Sf and Scr of the parallel plate 20 having a transmission part in the object to be measured. In the parallel plate 20, first, the incident light Lin enters the first surface 20 b before reaching the second surface 20 a that is a scattering surface, and passes through the inside of the parallel plate 20 that is an object to be measured. Further, reflection occurs due to the difference in refractive index at the boundary surface between the first surface 20b and air. Furthermore, light absorption and fluorescence occur inside the substance of the parallel plate 20, and the amount of incident light Lin reaching the second surface 20a changes.

  In the scattered light beam Scr generated by the second surface 20a, the light originally emitted rearward (incident side) hits the first surface 20b and causes refraction and total reflection at the boundary surface between the air and the first surface 20b. A part of the totally reflected light beam S1 travels in the forward direction. Further, a part of the refracted light beam S2 is emitted at a wide angle according to Snell's law. Thus, the behavior of the scattered light generated by one surface changes under the influence of the other surface.

  Furthermore, since the light flux S1 and the light flux S2 are transmitted through the parallel plate 20 as the object to be measured, the light absorption of the substance and the influence of fluorescence are added according to the traveling distance, and as a result, the scattered light intensity distribution is increased. Will change.

  In particular, it can be seen that the greater the intensity and spread angle of the scattered light generated by one surface, the higher the degree of influence on the measurement result. Up to this point, the object to be measured has been described with respect to the parallel plate 20. However, when the first surface and / or the second surface are curved like a lens, the behavior of light becomes more complicated, and the incident light Lin is initially Reaches the second surface at an angle different from the angle of incidence on the first surface, and the behavior of the backscattered light on the second surface changes under the influence of the surface shape of the first surface. These are all problems specific to permeable materials.

  In this way, when it is desired to measure the behavior of scattered light generated by one surface of the object to be measured, when the object to be measured is a transmissive substance, not only the surface shape of the object to be measured but also the back surface Surface shape, outer diameter, surface interval (thickness), outer shape such as ribs, chamfers, edges, etc., and effects inside the measured object such as refractive index, transmittance, reflectance, light absorption rate, and fluorescence The scattered light intensity distribution is received.

  Thus, when the object to be measured is a transmissive substance, the above-described conventional technique cannot take into account the behavior of scattered light inside the substance, and as a result, the BSDF cannot be calculated. As described above, conventionally, even if the intensity distribution of scattered light is measured in a transmissive material, the result cannot be simply used as BSDF which is a parameter of optical design simulation. Further, even if it is used, an error occurs and an accurate optical design simulation cannot be performed.

  The embodiment described below can solve such a problem of errors included in the scattered light intensity distribution measurement result of the conventional transmission material, and the BSDF, which is a parameter input to the optical design simulation, is obtained from the scattered light intensity distribution measurement result. It can be calculated with high accuracy.

(First embodiment)
FIG. 1A is a functional block diagram showing an outline of the scattered light information processing system 100 according to the first embodiment of the present invention. FIG. 1B is a functional block diagram for explaining the scattered light information processing system 100 in more detail.

  As shown in FIG. 1A, the scattered light information processing apparatus 200 exchanges signals with the light irradiation unit 101, the light receiving unit 102, and the information storage unit 103 via the control unit 110.

  As shown in FIG. 1B, the scattered light information processing apparatus 200 includes a scattered light measurement information acquisition unit 104, a function parameter setting unit 105, a model generation unit 106, a scattered light intensity distribution calculation unit 107, and a function. A parameter calculation processing unit 108.

  In FIG. 1B, the scattered light information processing device 200 surrounded by a dotted line is connected to the light irradiation unit 101, the light receiving unit 102, and the information storage unit 103 via the control unit 110 as described above. Yes.

The scattered light measurement processing device 200 provided in the scattered light information processing system 100 of this embodiment will be described in more detail.
Here, the object to be measured is an optical element composed of a substance that at least partially transmits light. The optical element is, for example, a parallel plate 300 shown in FIG.

  In FIG. 1B, the scattered light information processing apparatus 200 includes a scattered light measurement information acquisition unit 104 that acquires information on a scattered light intensity distribution of light irradiated at a predetermined angle with respect to an object to be measured, and a measured object. Based on the measurement conditions of the shape, optical properties, and scattered light intensity distribution of the object, the model generation unit 106 that creates the object model to be measured, and the scattering reflected on the incident side of the measurement surface of the optical element with respect to the object model A function parameter setting unit 105 that sets parameters of a function that represents light information and scattered light information on the exit side that has passed through the object to be measured, and scattered light that calculates a scattered light intensity distribution calculation result by calculation based on the object model to be measured. The intensity distribution calculation unit 107, the scattered light intensity distribution information acquired by the scattered light measurement information acquisition unit 104, and the scattered light intensity distribution calculation result calculated by calculation based on the measured object model match. And a function parameter calculation unit 108 for calculating the power sale function parameters.

  Next, the configuration and components of the scattered light information processing system 100 of this embodiment will be described.

  The scattered light information processing apparatus 200 is disposed integrally with the scattered light information processing system 100 or inside one separate computer or another computer.

  The control unit 110 controls the light irradiation unit 101, the light receiving unit 102, and the information storage unit 103 in addition to the control of the scattered light information processing apparatus 200.

  In the present embodiment, the light irradiation unit 101 does not particularly define an LD (Laser Diode), an SLD (Super Luminescent Diode), an LED (Light Emitting Diode), or a halogen that is a white light source. Here, it is desirable that the characteristics such as the wavelength of the incident light, the polarization state, and the light intensity distribution are known.

  The light receiving unit 102 continuously or intermittently moves two-dimensionally or three-dimensionally around the measurement surface of the object to be measured based on the control information of the control unit 110 sent from a computer (not shown). The mechanism can receive scattered light.

  Here, the light receiving unit 102 is rotated around the measurement surface of the object to be measured. However, the present invention is not limited to this, and the light receiving unit 102 may be moved around another place different from the center of the object to be measured or a part other than the object to be measured. It is only necessary that the relative positional relationship between the rotation center position of the light receiving unit 102 and the position of the object to be measured is known.

In addition, the light receiving unit 102 has a mechanism that can acquire information on scattered light transmitted through the object to be measured and / or information on scattered light reflected.
Furthermore, the light receiving unit 102 is not particularly limited as long as it is a device that can observe the intensity of light, such as a power sensor or a high sensitivity camera. Furthermore, it is desirable that the type of the light receiving unit 102 can be properly used depending on the light intensity and angular resolution desired to be measured.
When it is desired to change the angle of the incident light on the object to be measured, the light irradiation unit 110 or the object to be measured can be relatively changed in position.

The information storage unit 103 manages storage of “measurement condition information”, “measurement object information”, and “scattered light measurement information”. Detailed description regarding the information of the measurement conditions and the information of the object to be measured will be described later.
As described above, the scattered light information processing apparatus 200 performs processing related to the scattered light information for calculating the BSDF from “measurement condition information”, “measurement object information”, and “scattered light measurement information”. Detailed description regarding the processing of the scattered light information will be described later.

  As described above, the scattered light information processing system 100 that measures the scattered light of the object to be measured and processes the scattered light information, in addition to the scattered light information processing apparatus 200, further emits light at a predetermined angle with respect to the object to be measured. The light irradiation unit 101 for irradiating the light, the light receiving unit 102 for receiving the scattered light transmitted through the measurement object and / or the reflected scattered light, and the measurement conditions of the shape, optical properties, and scattered light intensity distribution of the measurement object. And an information storage unit 103 that stores the information.

  Thereby, as will be described below, the BSDF, which is scattered light information of one surface, is converted into a front and back surface shape and outer diameter, a surface interval (thickness), a rib portion, a chamfered portion, It can be calculated accurately by taking into account the effects inside the measured object such as the edge portion and optical properties such as refractive index, transmittance, reflectance, light absorption rate, and fluorescence. . For this reason, when it sets as a parameter in optical design software, it becomes possible to simulate with high precision compared with the past.

Next, a method for measuring scattered light in the present embodiment will be described with reference to FIG.
Measurement by the scattered light information processing system 100 is started. In advance, in step S101, measurement condition information is stored in the measurement condition and measurement object information storage unit 103a via the control unit 110.

  Information on measurement conditions includes the positional relationship between the light irradiation unit 101, the object to be measured, and the light receiving unit 102, the wavelength of incident light, the incident angle to the object to be measured, the polarization state, NA (directivity), the irradiation diameter, and the irradiation region. Information on detailed measurement such as intensity distribution, environmental variables (external refractive index), temperature, atmospheric pressure, carbon dioxide concentration.

  At the same time, in step S101, information on the measurement object is also stored in the measurement condition and measurement object information storage unit 103a. The information of the object to be measured includes the outer and front and back shapes and outer shapes, surface spacing (thickness), ribs, chamfers, edges, and optical properties such as refractive index, transmittance, reflectance, and light absorption. If the object to be measured, such as a lens, is provided with an antireflection coating, it is a design requirement such as coating conditions. In particular, when the object to be measured is a transmissive material, the above-described optical property setting is an essential requirement.

  That is, it is desirable that the shape and optical properties of the measurement object include at least the radius of curvature, the optical thickness, and the refractive index of the optical element that is the measurement object.

  Further, it is desirable that the information about the object to be measured be input in more detail. Thereby, the process by the scattered light information processing apparatus 200 is performed with high accuracy.

  The information on the object to be measured may be either information such as a design formula obtained from the drawing or information on the result of actual measurement. The information obtained by actual measurement includes the surface shape errors of the front and back surfaces, surface distance errors, eccentricity errors, outer diameter errors, refractive index distribution, reflectance, transmittance, light absorption rate, fluorescence, etc. Items relating to the optical properties of the object to be measured are listed.

  The information on the measurement conditions and the information on the object to be measured are sent to the computer. Then, it is stored in the information storage unit 103a of the measurement condition and measured object via the control unit 110 that is integral with or separate from the computer.

  Next, in step S102, measurement by the scattered light information processing system 100 is performed to obtain measurement information of scattered light. A state of receiving scattered light will be described with reference to a specific system configuration.

  The drive unit 305 shown in FIG. 3 moves the light receiving unit 102 based on control information sent from the control unit 110 of the computer. In FIG. 3, the light receiving unit 102 selectively describes two states, position A and position B. The driving unit 305 is not limited to this, and it goes without saying that the light receiving unit 102 can be moved to an arbitrary position. When the object to be measured is the parallel plate 300, the driving unit 305 is continuous in two dimensions or three dimensions around the measurement surface 300a. It can move intermittently and receive scattered light from the surface to be measured. At this time, the fluorescence emitted from the object to be measured is preferably removed by a filter or the like.

Then, the measurement information of the scattered light received by the light receiving unit 102 is sent to the computer and stored in the scattered light intensity distribution measurement data storage unit 103b via the control unit 110.
At this time, the measurement information of the scattered light may be sent to the computer together with the measurement condition information and the measurement object information.

The information storage unit 103 (see FIG. 1A) is configured by the measurement condition and measurement object information storage unit 103a and the scattered light intensity distribution measurement data storage unit 103b.
Here, it goes without saying that the contents of the measurement condition / measurement object information storage unit 103a and the scattered light intensity distribution measurement data storage unit 103b may be collectively stored in a text file or the like.

  The object to be measured is not limited to a parallel plate, and a lens element having a curved surface can also be measured.

  Moreover, although the procedure was shown using FIG. 2 about the measuring method of scattered light information, this order may be mixed. For example, after measuring scattered light, information on the measurement conditions may be input in accordance with the actual measurement conditions. Further, after measuring the scattered light, information on the object to be measured may be obtained.

  For example, when a contact-type shape measuring machine is used to obtain information on the shape of the object to be measured, the surface of the object to be measured may be damaged by the measurement probe. For this reason, there exists an effect that the direction which measures a shape after measuring scattered light can measure scattered light accurately.

Next, a data processing method in the scattered light information processing apparatus 200 will be described.
FIG. 4 is a diagram for explaining a data processing method in the scattered light information processing apparatus 200. The scattered light information processing apparatus 200 performs a predetermined process using the measurement condition information, the measurement object information, and the scattered light measurement information, and performs a process for calculating the BSDF with high accuracy.

  First, the information processing unit 109 starts data processing. In step S201, a virtual measurement object measurement simulation model is generated by the computer based on the “measurement condition information” and the “measurement object information”. The measured object measurement simulation model in this state assumes that when a light beam is passed through the measured object, the light beam is transmitted and reflected geometrically optically. Hereinafter, in all the flowcharts, simulation is appropriately abbreviated as “Sim.”.

In step S202, BSDF, which is scattered light information, is temporarily set on the measurement surface of the measurement object. As described above, the BSDF includes an incident light angle (θ _i ), an incident azimuth angle (φ _i ), a light receiving angle (θ _r ), a light receiving azimuth angle (φ _r ), and a wavelength of incident light (λ ) And five variables. That is, the position of the BSDF in the three-dimensional space is expressed in two directions on the incident light side and in two directions on the light receiving side.

  The distribution shape of the scattered light intensity can be applied to several mathematical model functions. For example, examples of the model function include a Gaussian function, a CosN power function, and a Lambertian function. In any function, the scattered light intensity distribution can be expressed as a function of angle. Here, the Gaussian model function will be described. The Gaussian function can be expressed by Equation 2 below.

The parameters θ and φ in Equation 2 above represent the angle of the scattered light intensity distribution. The parameters σ _θ and σ _φ indicate the half width of the Gaussian function. By changing the parameter, the distribution shape in each angular direction also changes.
P ₀ corresponds to the light intensity at the center. That is, the scattered light intensity distribution can be expressed by three parameters (variables) of P ₀ , σ _θ , and σ _φ with respect to an incident angle (θ _i , φ _i ) of certain incident light.

  Various other functions can be set as model functions. For example, a Pearson 7 function known as a peak fit function, a Voice function, or the like can be set.

  Further, for example, when the surface scattering is small like an optical element, the peripheral light intensity distribution is smaller than the central light intensity distribution. FIG. 5 is a diagram showing the intensity distribution of scattered light when the scattering of the surface of the object to be measured is small. It is also possible to arbitrarily create a model function such as the following Expression 3 suitable for such a scattered light intensity distribution. Here, α is a coefficient.

The BSDF is provisionally set by selecting one of the above model functions. Returning to FIG. 4, the description will be continued. In step S203, initial values of parameters are set for the temporary installation of the BSDF on the specific measurement surface (specific surface) set in step 202. For example, when the BSDF is a Gaussian function, initial values are set for three parameters P ₀ , σ _θ , and σ _φ . The initial value is set as appropriate according to user instructions and system requirements. Further, it is preferable that the range for changing the parameter, the change width, etc. can be set at the same time.

  In the present embodiment, since the object is to calculate the scattered light intensity distribution of the transmissive substance as the object to be measured, steps S202 and S203 are a bidirectional transmittance distribution function (BTDF) and a bidirectional reflectance that are BSDFs. It must be set for both the distribution function (BRDF). The settings of BTDF and BRDF may be different or the same.

  In step S204, ray tracing is performed on the virtual measurement object measurement simulation model set in steps S201 to S203 by computer processing. In the ray tracing, since the BSDF is set in step S202, ray tracing using random numbers such as the Monte Carlo method is performed in addition to the normal geometric ray tracing. Then, the scattered light intensity distribution of the object to be measured is calculated.

Here, in step S204, the movement of the scattered light will be described again with reference to FIG.
In the ray tracing in step S204, when incident light is incident on the measurement surface of the object to be measured, backscattered light is generated. A part of the light S1 of the backscattered light is reflected and totally reflected in the parallel plate 20 which is a transmission material, and is incident on the surface to be measured again. In this internal reflection, it is rare that the light is incident at the same angle as the light incident angle by the light irradiation unit. As for the scattering by the incident light by the backscattered light, the concept of shift-invariant scattering angle is applied except for the Lambertian function.

  The concept of the shift invariant scattering angle is a calculation method that assumes that the shape of the scattered light intensity distribution does not change even if the incident angle changes. The details of the theory behind this process are described in “Light-Scattering Characteristics of Optical Surfaces” by James E. Harvey (Doctoral Dissertation, University of Arizona, 1976).

  The shift-invariant scattering angle concept means that the BSDF distribution shape of light incident perpendicularly to the measurement surface of the object to be measured and the BSDF distribution shape of light obliquely incident on the measurement surface are the same. . Under such assumption, the scattered light intensity distribution can be calculated in step S204.

  In step S205, the degree of coincidence at each angle of the scattered light intensity distribution is calculated using the scattered light intensity distribution calculated in step S204 and the “scattered light intensity measurement information” stored in the information storage unit 103 of the computer. To do.

  For the calculation of the degree of coincidence of the values, the difference between the calculated scattered light intensity distribution and the measurement information of the scattered light is used, and the PV (Peak-Valley) value and the RMS (Root-Mean-Square) value are evaluated values. And

  In step S206, the evaluation value calculated in step S205 is compared with a preset threshold value to determine whether or not the values match. When the evaluation value is larger than the threshold value, it is determined to perform a process of changing the initial value of BSDF temporarily set. When the evaluation value is smaller than the threshold value, it indicates that the set BSDF well represents the BSDF of the measurement surface of the measurement object.

If it is determined in step S206 that the evaluation value is greater than the threshold value, that is, if the determination result is false (No), the process proceeds to step S207.
In step S207, the parameter of the initial value of BSDF is changed. Then, the process returns to step S204, and ray tracing is performed by computer processing.

  The processing from step S204 to step S207 is repeated until the evaluation value becomes smaller than the threshold value. That is, convergence calculation is performed. By repeating this step, it is possible to calculate BSDF parameters that well represent the BSDF of the surface to be measured of the object to be measured.

Here, the evaluation value may not converge even if the calculation is repeated. In this case, the BSDF model function set in step S202 may be different.
Therefore, if the evaluation value does not converge, the process returns to step S202, and a process of changing the BSDF model function is performed.

  That is, if the evaluation value does not converge to the threshold value in the repeated calculation from step S204 to step S207, the BSDF model function is changed by a step not shown. Then, a new convergence calculation is added in which the step of changing the model function of BSDF is repeatedly calculated from step S202.

If the determination result in step S206 is true (Yes), the data processing ends.
With the above processing, the BSDF model function that best represents the scattered light information on the surface to be measured of the object to be measured and the parameters that determine the model function are determined.

  In the example of this embodiment, incident light is irradiated onto the measurement surface of the measurement object. However, it is not particularly limited, and for example, it may be incident on another part of the surface to be measured, or the entire object to be measured may be irradiated. Needless to say, there is no need to regulate the light if it is clear how the light enters the object to be measured.

  As described above, according to the scattered light information processing apparatus, the scattered light information processing method, and the scattered light information processing system including the apparatus and performing the method according to the present embodiment, the optical design is performed in the transmission material. It becomes possible to obtain BSDF which is one of the parameters input to the software.

  In the optical design software, it is possible to perform an optical design simulation for ghosts and flares generated when unnecessary light other than regular light reaches the image plane.

Further, according to the present embodiment, both the bidirectional transmittance distribution function (BTDF) and the bidirectional reflectance distribution function (BRDF) can be acquired in the BSDF of the transmissive material.
Furthermore, according to the scattered light information processing method of the present embodiment, the BSDF, which is scattered light information of one surface, is obtained from the measurement result of the scattered light, from the front and back surfaces, outer diameter, and surface spacing that are the outer shape of the object to be measured. (Thickness), ribs, chamfers, edges, and optical properties such as refractive index, light absorption, fluorescence, etc. The BSDF can be calculated accurately. For this reason, when it sets as a parameter in optical design software, it becomes possible to simulate with high precision compared with the past.

  Regarding the present embodiment, depending on the shape of the object to be measured and the characteristics of the BSDF, the scattered light information processing apparatus for scattered light information, the scattered light information processing method, and the simplified scattered light information processing system that includes this apparatus and performs this method. Alternatively, high accuracy can be achieved.

A method for realizing simplification and high accuracy will be specifically described. First, it is assumed that the following prediction conditions are satisfied.
The prediction condition is a scattered light intensity distribution having the same model function and parameters of the scattered light intensity distribution shapes of BTDF and BRDF and axisymmetric with respect to incident light.

When the above prediction conditions hold, the scattered light intensity distribution specified in step S202 of the flowchart of FIG. 4 has the same model function of BTDF and BRDF, and the measurement and calculation parameters can be reduced.
This prediction condition is not only when the object to be measured is a transmissive substance, but also when the object to be measured is rotationally symmetric with respect to the incident light and when the incident light is perpendicularly incident on the surface to be measured. There are assumptions that stand well.
In addition, this model is accurate when the surface roughness is small asperities less than or equal to the wavelength of the irradiation light.

  As a specific example, a case where a Gaussian function is used as a model function in Equation 4 to represent BTDF and BRDF is shown.

  Here, assuming an axially symmetric scattered light intensity distribution, the following Expression 5 is established.

  Further, from the prediction condition that the parameters of BTDF and BRDF are the same, the following formulas 6 and 7 are established.

That is, the only real parameters are P _t , P _r , and σ. The relationship between P _t and P _r is expressed by the following formula 8. Here, x represents an item that does not contribute to scattering, such as a light absorption coefficient.

  Here, L is the light intensity of the incident light and becomes an indispensable input value in step S201 of the flowchart. Further, as described above, BTDF and BRDF are generally values normalized by the light intensity of incident light. For this reason, the parameter L can be set to 1.

  That is, in the scattered light measurement information acquisition unit 104, at least the scattered light intensity distribution transmitted through the object to be measured or the scattered light intensity distribution reflected from the object to be measured is normalized by the light intensity of the incident light on the object to be measured. It is desirable to obtain an intensity distribution.

The information acquisition of the scattered light intensity distribution may be either transmission or reflection normalized by incident light, and the other can be calculated from one. For this reason, there are only two finally calculated parameters, P _t and σ. That is, the processing time of the scattered light intensity distribution can be shortened. In addition, since the driving range of the light receiving unit may be only one of transmission or reflection, the measurement apparatus can be simplified.

  Further, under the assumption based on the above prediction condition, the scattered light intensity distribution in the forward direction is a scattered light intensity distribution that is axisymmetric with respect to the incident light. For this reason, as shown in FIG. 6A, the light receiving range of the light receiving unit may be measured in the range of 0 to 90 degrees in the θ direction or the φ direction.

  As described above, in the present embodiment, in the case of an object to be measured in which conditions and assumptions are satisfied, the scattered light information processing apparatus, the measurement method, and the scattered light information processing method can be simplified. Alternatively, if measurement data in all directions has been acquired, it is possible to increase the accuracy by averaging the measurement error and noise by performing an averaging process.

  If the model function and parameters of the scattered light intensity distribution shapes of BTDF and BRDF are different among the assumptions based on the above prediction conditions, the light receiving range of the light receiving unit is θ direction or φ direction as shown in FIG. The range of 0 to 180 degrees may be measured.

(Second Embodiment)
Next, the scattered light information processing apparatus, measurement method, scattered light information processing method, and scattered light information processing system of the second embodiment will be described.
FIG. 7 is a functional block diagram showing the scattered light information processing system of the second embodiment. Here, the configuration of the scattered light information processing apparatus 250 surrounded by a dotted line is different from that of the first embodiment.
About the scattered light information processing apparatus 250 of 2nd Embodiment, the same code | symbol is attached | subjected to the same structure as the scattered light information processing apparatus of 1st Embodiment, and the overlapping description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 7, the scattered light measurement information acquisition unit 104 acquires information on the scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured.
Furthermore, function parameters for each incident angle are used as temporary function parameters so that the scattered light intensity distribution information acquired by the scattered light measurement information acquisition unit 104 matches the scattered light intensity distribution calculation result calculated from the measured object model. Using at least a part of the temporary function parameters for each incident angle with respect to the measured object model and the information on the scattered light intensity distribution acquired by the temporary function parameter calculation unit 251 to be calculated, the scattered light measurement information acquisition unit 104 And a function parameter determination unit 252 that adjusts the temporary function parameters so as to match the calculated scattered light intensity distribution calculation result to determine a final function parameter.

  Thereby, as described below, using the scattering measurement information at a plurality of incident angles, the BSDF which is the scattered light information of one surface is not only the surface shape of the object to be measured but also the surface shape and outer diameter of the back surface. , Surface spacing (thickness), outer shape of ribs, chamfers, edges, etc., optical properties such as refractive index, transmittance, reflectance, light absorptivity, fluorescence, etc. Since it can be calculated in consideration, it is possible to calculate the scattering information with high accuracy from the BSDF calculated using one incident angle. For this reason, when it sets as a parameter in optical design software, it becomes possible to simulate with high precision compared with the past.

  Compared to the first embodiment, the scattered light measurement method and the scattered light information processing method are different. Specifically, the second embodiment is different from the first embodiment in that the scattered light measurement method changes a plurality of incident angles of incident light and acquires measurement information of scattered light at each incident angle. . Further, the scattered light information processing method is different in that the BSDF is calculated using the measurement information of the scattered light acquired by changing the incident angle of the incident light.

Next, the configuration of the scattered light information processing system 150 will be described.
The scattered light information processing apparatus 250 is arranged integrally with the scattered light information processing system 150 or inside one separate computer or another computer.

The control unit 110 controls the light irradiation unit 101, the light receiving unit 102, and the information storage unit 103 in addition to the control of the scattered light information processing apparatus 250.
The information storage unit 103 manages storage of “measurement condition information”, “measurement object information”, and “scattered light measurement information”. The scattered light information processing apparatus 250 performs control related to the scattered light information for calculating the BSDF from “measurement condition information”, “measurement object information”, and “scattered light measurement information”.

  In the present embodiment, there is an effect that the BSDF can be calculated with higher accuracy than in the first embodiment.

Next, the procedure of the scattered light information processing method of this embodiment will be described.
FIG. 9 is a flowchart illustrating a procedure for measuring scattered light in the scattered light information processing method according to the second embodiment.

  In the present embodiment, in step S301 in FIG. 9, as in the first embodiment, information on measurement conditions is set in the control unit 110 of the computer when measurement by the scattered light information processing apparatus 250 is started. Here, in the second embodiment, the setting of the incident angle range of incident light and the number of divisions within the range are newly added to the information stored in the first embodiment as measurement condition information. Is set.

  In the present embodiment, as shown in FIG. 8, the light irradiation unit 101 and the light receiving unit 102 are driven by the drive unit 305 so that the relative position with respect to the object to be measured changes.

For example, a condition for measuring by dividing the range where the incident angle θ _i is 0 degree (normal incidence) to 89 degrees by 5 degrees is set. Further, similarly to the first embodiment, information on the object to be measured is set at the same time.
The measurement condition information and the measured object information are sent to the computer and stored in the information storage unit 103a.

  In step 302, the light receiving unit 102 moves two-dimensionally and / or three-dimensionally around the measurement surface of the object to be measured based on the control information sent from the computer, and receives scattered light from the surface to be measured. To do.

Next, the measurement information of the plurality of scattered lights received by the light receiving unit 102 is sent to the computer and stored in the scattered light intensity distribution measurement data storage unit 103b.
Here, the measurement information of the scattered light in the measurement range (0 to 89 degrees) of the incident angle of the incident light is expressed as follows.

FS (θ _ni ) ・ ・ ・ ○ Measurement data BS (θ _ni ) ・ ・ ・ △ Measurement data

Here, FS indicates the forward scattered light intensity distribution with respect to the surface to be measured, and BS indicates the backward scattered light intensity distribution with respect to the object to be measured. Both FS and BS are functions of θ, θ _ni represents the incident angle of incident light on the surface to be measured, ni is ni = 1, 2, 3,..., Θ _ni = 0, 5, 10, 15, 20, ... 85.

  In step S303, the incident angle of the incident light is compared with information on measurement conditions set in advance. If the determination result in step S303 is true, the scattering measurement is terminated.

  If the determination result in step S303 is false, the process proceeds to step S304. In step S304, the incident angle of incident light is changed. Then, steps S301, S302, and S303 are repeated.

As described above, in the present embodiment, the measurement from S301 to S304 is repeated until the incident angle of the incident light to the object to be measured is acquired for the number of divisions within a predetermined range.
Here, the measurement information of the scattered light indicates the state when measured in one section for the sake of simplicity. That is, it is assumed that the incident angle of the incident light and the angle of the light receiving unit are moved only in the θ direction.
Next, in the computer, using the above “information on measurement conditions”, “information on the object to be measured”, and “measurement information on scattered light”, the scattered light information processing apparatus 250 performs predetermined processing, BSDF is calculated.

A data processing method in the scattered light information processing apparatus 250 will be described. FIG. 10 is a flowchart for explaining a data processing method in the scattered light information processing apparatus 250. The scattered light information processing apparatus 250 performs processing for the purpose of calculating the BSDF.
This embodiment is different from the first embodiment described above in that “scattered light measurement information” measured at a plurality of incident angles is used.

The procedures of steps S401, S402, S403, S404, S405, S406, and S407 perform the same processing as steps S201, S202, S203, S204, S205, S206, and S207 in the flowchart of FIG. For this reason, the overlapping description is omitted. In step S401, the incident angle of the measurement light is θ _ni . The incident angle θ _ni is input from a small value (acute angle) with the measurement light.

In step S408, the BSDF at the calculated plurality of incident angles is referred to as “temporary BSDF”. Specifically, the temporary BSDF is calculated from the ○ measurement data and the Δ measurement data.
Provisional BSDF (θ _ni ) (ni = 1, 2, 3,..., Θ _ni = 0, 5, 10, 15, 20,... 85)

In step S409, it is determined whether or not the incident angle θ _ni is the largest angle. That is, it is determined here that (temporary) BSDFs are calculated for all incident angles set in the measurement conditions.
If the determination result of step S409 is false (No), the process proceeds to step S410.

  In step S410, the incident angle is changed to the next angle, and the processing from step S402 to step S408 is performed.

  Next, after step S411, the BSDF at each incident angle is calculated again. At this time, the “temporary BSDF” calculated at each incident angle is set in the measured object measurement simulation model, and the calculation for calculating the BSDF at each incident angle is performed again.

  Here, in this embodiment, the calculation accuracy is further improved as compared with the first embodiment described above. The reason will be described.

  As described above, the steps S401, S402, S403, S404, S405, S406, and S407 are the same as those in the first embodiment. Here, the concept of shift invariant is applied in the calculation within the object to be measured.

  Here, actually, the scattered light intensity distribution varies depending on the incident angle to the object to be measured. In particular, it is known that the deviation from the shift / invariant concept increases as the incident angle increases.

  Therefore, in steps S411 to S419, the BSDF is obtained using the temporary BSDF calculated at each incident angle without using the concept of shift invariant. Thus, the calculation accuracy is improved by performing recalculation in consideration of the scattered light intensity distribution at each incident angle.

In step S411, provisional BSDFs at all calculated incident angles are set. In step S412, the scattered light intensity distribution is calculated.
In step S413, the scattered light intensity distribution calculated in step S412 is compared with the “scattered light measurement information” stored in the scattered light intensity distribution measurement data storage unit 103b of the computer. In step S414, the degree of coincidence of the scattered light intensity distribution at each angle is calculated and determined.

  In calculating the degree of coincidence, the difference between the calculated scattered light intensity distribution at each angle and the measurement information of the scattered light is used. Then, a PV (Peak-Valley) value or an RMS (Root-Mean-Square) value is used as an evaluation value.

  In step S414, the evaluation value calculated in step S412 is compared with a preset threshold value. If the evaluation value is larger than the threshold value in step S414, that is, if the determination result is false, the process proceeds to step S415.

  In step S415, the process of changing the provisional BSDF temporarily set in advance is performed in order from an angle with a small incident angle (acute angle). When the evaluation value is smaller than the threshold value, it indicates that the set temporary BSDF represents the BSDF of the surface to be measured of the object to be measured with good accuracy.

  If it is determined in step S414 that the evaluation value is greater than the threshold value, the process proceeds to step S415. In step S415, processing for changing the parameters of the temporary BSDF is performed. Then, the process returns to step S412, and ray tracing is performed.

The processes up to steps S412, S413, S414, and S415 are repeated until the evaluation value becomes smaller than the threshold value. That is, convergence calculation is performed.
Through this repeated step, it is possible to calculate a parameter of the temporary BSDF that well represents the BSDF of the surface to be measured of the object to be measured.

In step S416, using the new temporary BSDF determined in step S414, it is determined whether or not the incident angle θ _ni is the largest angle. If the determination result in step S416 is false, in step S417, the temporary function parameter calculation unit 251 (FIG. 7) changes the incident angle θ _ni to the next angle, and calculates the temporary BSDF at the next incident angle θ _ni. Set. And after changing to the next angle, the process of step S411, S412, S413, S414, S415, S416, S417 is performed.

  If the determination result in step S416 is true, in step S418, the processing from step S411 to step S417 is repeated, and calculation is performed until the value of the temporary BSDF at each incident angle converges. Then, in step S418, it is determined whether or not the temporary BSDF value has converged. The convergence determination is made based on whether or not the change of each temporary BSDF is minimized.

  If the determination result of step S418 is false, the process proceeds to step S419. In step S419, the function parameter determination unit 252 (FIG. 7) changes and determines the parameter of the BSDF function.

  If the determination result in step S418 is true, the data processing ends. Through the above procedure, the BSDF model function that best represents the scattered light information of the surface to be measured of the object to be measured and the parameters that determine the model function are determined.

  According to this embodiment, according to the scattered light information processing system 150, the scattered light information processing apparatus 250 provided in the system 150, and the scattered light information processing method executed by the apparatus 250, the transmission material is input to the optical design software. It becomes possible to obtain BSDF which is one of the parameters.

In the optical design software, it is possible to perform an optical design simulation for ghosts and flares generated when unnecessary light other than regular light reaches the image plane.
Further, according to the present embodiment, both the bidirectional transmittance distribution function (BTDF) and the bidirectional reflectance distribution function (BRDF) can be acquired in the BSDF of the transmissive material.

  Furthermore, according to the scattered light information processing method of the present embodiment, BSDF, which is scattered light information of one surface, can be used not only for the surface shape of the object to be measured, but also for the surface shape, outer diameter, surface interval (thickness of the back surface). ), BSDF is accurately applied by taking into account the effects inside the specimen such as refractive index, transmittance, reflectance, light absorption rate and fluorescence such as the outer shape and optical properties of the ribs, chamfers, edges, etc. Can be calculated. For this reason, when it sets as a parameter in optical design software, it becomes possible to simulate with high precision compared with the past.

(Modification of the second embodiment)
Next, a modification of the second embodiment will be described. FIG. 11 is a flowchart showing the procedure of the scattered light information processing method of the present modification.

  This modification is different from the second embodiment described above in that the temporary BSDF is calculated by sequentially using the measurement information of the scattered light at each incident angle. A data processing method in the scattered light information processing apparatus 250 will be described.

First, from steps S501 to S506, substantially the same processing as steps S201 to S207 in the first embodiment is performed. The incident angle θ _ni is input from a small angle (acute angle).

In step S507, the BSDF calculated at the incident angle θ _ni is referred to as “temporary BSDF”.
In step S508, it is determined whether or not the incident angle θ _ni is the largest angle based on the information on the incident angle θ _ni of the incident light. If the determination result of step S508 is false, the process proceeds to step S509.

In step S509, the incident angle θ _ni of the measurement light is changed to the next angle using all the provisional BSDFs (θ _ni ) calculated so far. Then, the processing from step S501 to step S507 is performed.

At this time, in step S504, the temporary BSDF of the next incident angle is calculated using the temporary BSDF calculated up to that time. That is, in the measurement light information processing method of the second embodiment, the temporary BSDF (θ _ni ) at each incident angle is individually calculated in steps S402 to S410.

In contrast, in this modification, when calculating the temporary BSDF (θ _ni ), the temporary BSDF (θ _(ni−1) ) of the incident angle calculated so far is changed to the temporary BSDF (θ _{(ni). = 0) The} difference is that the temporary BSDF for each incident angle is calculated in consideration of the above ₎ )).

  As a result, the BSDF can be calculated with high accuracy by calculating in consideration of the scattered light intensity distribution at each incident angle. Furthermore, with respect to the measurement light information processing method of the second embodiment, a provisional BSDF calculated in consideration of the scattered light intensity distribution at each incident angle can be acquired up to step S507. For this reason, the processing from step S501 to step S509 is made more efficient, and the processing speed is increased.

  The above-described first and second embodiments have been described on the assumption that there is no place for generating scattered light other than the surface to be measured of the object to be measured. However, the present invention is not limited to this, and there may be a plurality of places where scattered light is generated other than the surface of the object to be measured.

  For locations other than the surface to be measured where scattered light is generated, BSDF may be calculated in advance by another method and input as information on the object to be measured. Further, it may be set as one of the calculation parameters in the repeated calculation.

  Moreover, about 1st Embodiment and 2nd Embodiment, the parallel plate is used as a to-be-measured object. Needless to say, the present invention is not limited to this, and it is needless to say that it is possible to measure even a sample made of a transparent material with both surfaces having a radius of curvature, such as an optical element used in an imaging device such as a camera or an endoscope. In this case, the radius of curvature may be set in the information of the object to be measured in the information processing unit for scattered light. In addition, when an object to be measured such as a lens is provided with an antireflection coating, the coating conditions may be added to the information on the object to be measured. Furthermore, the present invention can be similarly applied to a rib portion, a chamfered portion, an edge portion, and the like.

  As described above, the present invention provides a scattered light information processing method, a scattered light information processing apparatus, and a scattered light information processing system capable of measuring with high accuracy the scattered light intensity distribution of an optical element having a transmission part as a measurement object. Is suitable.

DESCRIPTION OF SYMBOLS 100 Scattered light information processing system 101 Light irradiation part 102 Light receiving part 103 Information storage part 104 Scattered light measurement information acquisition part 105 Function parameter setting part 106 Model generation part 107 Scattered light intensity distribution calculation part 108 Function parameter calculation process part 110 Control part 200 Scattered light information processing equipment

Claims (24)

A scattered light information processing method for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition step for acquiring information on the scattered light intensity distribution of light irradiated at a predetermined angle to the object to be measured;
From a measurement condition of the shape and optical properties of the object to be measured and the scattered light intensity distribution, a model generation step for creating a object model to be measured;
A function parameter setting step for setting a parameter of a function representing scattered light information on the exit side that has passed through the object to be measured, with respect to the object model to be measured;
A scattered light intensity distribution calculating step for calculating a scattered light intensity distribution calculation result by calculation considering reflection of scattered light inside the substance of the measured object and refraction of the scattered light based on the measured object model;
The function parameter is calculated so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition step matches the scattered light intensity distribution calculation result calculated by calculation based on the measured object model. A function parameter calculation process;
A scattered light information processing method characterized by comprising:   The function for setting a parameter in the function parameter setting step includes the scattered light information reflected on the incident side of the measurement surface of the optical element and the emission side transmitted through the measured object with respect to the measured object model. The scattered light information processing method according to claim 1, wherein the scattered light information is a function representing scattered light information. The scattered light intensity distribution information acquired in the scattered light measurement information acquisition step is at least a scattered light intensity distribution transmitted through the object to be measured or a scattered light intensity distribution reflected from the object to be measured,
2. The measurement condition of the scattered light intensity distribution input in the model generation step includes at least the light intensity of light incident on the object to be measured at the time of measuring the scattered light intensity distribution. Or the scattered light information processing method according to 2;   In the scattered light measurement information acquisition step, at least a part of the scattered light intensity distribution transmitted through the object to be measured or a part of the scattered light intensity distribution reflected from the object to be measured is acquired. The scattered light measurement information processing method according to claim 3.   In the scattered light measurement information acquisition step, at least a scattered light intensity distribution transmitted through the object to be measured or a scattered light intensity distribution reflected from the object to be measured is normalized by the light intensity of incident light on the object to be measured. The scattered light information processing method according to claim 1, wherein a light intensity distribution is acquired.   The scattered light intensity distribution information acquired in the scattered light measurement information acquisition step is a scattered light intensity distribution of light transmitted through the object to be measured and a scattered light intensity distribution of light reflected from the object to be measured. The scattered light information processing method according to any one of claims 1 to 5.   The shape and optical properties of the object to be measured include at least a radius of curvature, an optical thickness, and a refractive index of the optical element that is the object to be measured. The scattered light information processing method described in 1. A scattered light information processing method for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition step for acquiring information on a scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured;
From a measurement condition of the shape and optical properties of the object to be measured and the scattered light intensity distribution, a model generation step for creating a object model to be measured;
A function parameter setting step for setting a parameter of a function representing scattered light information on the exit side that has passed through the object to be measured, with respect to the object model to be measured;
A scattered light intensity distribution calculating step of calculating a scattered light intensity distribution calculation result by calculation based on the measured object model;
The information on the scattered light intensity distribution acquired in the scattered light measurement information acquisition step and the scattered light intensity distribution calculation result calculated by calculation based on the measured object model match each incident angle. A temporary function parameter calculation processing step of calculating the function parameter as a temporary function parameter;
Information of the scattered light intensity distribution acquired in the scattered light measurement information acquisition step, and the scattered light intensity distribution calculation result calculated using at least a part of the provisional function parameter of each incident angle with respect to the measured object model, A scattered light information processing method comprising: a function parameter determination step of adjusting a temporary function parameter so as to match each other and determining a final function parameter. A scattered light information processing apparatus for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition unit that acquires information on a scattered light intensity distribution of light irradiated at a predetermined angle on the object to be measured;
Based on the measurement conditions of the shape and optical properties of the object to be measured and the scattered light intensity distribution, a model generation unit for creating an object model to be measured;
A function parameter setting unit that sets parameters of a function representing scattered light information on the exit side that has passed through the device to be measured;
A scattered light intensity distribution calculation unit for calculating a scattered light intensity distribution calculation result by calculation in consideration of reflection of scattered light inside the substance of the measured object and refraction of the scattered light based on the measured object model;
The function parameter is calculated so that the scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit and the scattered light intensity distribution calculation result calculated by calculation based on the measured object model match. A function parameter calculation processing unit;
The scattered light information processing apparatus characterized by having.   The function for setting a parameter in the function parameter setting unit includes the scattered light information reflected on the incident side of the measurement surface of the optical element and the emission side transmitted through the measured object with respect to the measured object model. The scattered light information processing apparatus according to claim 9, wherein the scattered light information processing apparatus is a function representing scattered light information. The scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit is at least a scattered light intensity distribution transmitted through the object to be measured or a scattered light intensity distribution reflected from the object to be measured,
10. The measurement condition of the scattered light intensity distribution input in the model generation unit includes at least the light intensity of light incident on the object to be measured at the time of measuring the scattered light intensity distribution. Or the scattered light information processing apparatus according to 10;   The scattered light measurement information acquisition unit acquires at least a part of the scattered light intensity distribution transmitted through the object or a part of the scattered light intensity distribution reflected from the object. The scattered light measurement information processing apparatus according to claim 11.   In the scattered light measurement information acquisition unit, at least a scattered light intensity distribution transmitted through the measurement object or a scattered light intensity distribution reflected from the measurement object is normalized by the light intensity of incident light on the measurement object The scattered light information processing apparatus according to claim 9, wherein a light intensity distribution is acquired.   The scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit is a scattered light intensity distribution of light transmitted through the object to be measured and a scattered light intensity distribution of light reflected from the object to be measured. The scattered light information processing apparatus according to any one of claims 9 to 13.   The shape and optical properties of the object to be measured include at least a radius of curvature, an optical thickness, and a refractive index of the optical element that is the object to be measured. The scattered light information processing apparatus described in 1. A scattered light information processing apparatus for processing scattered light information of an object to be measured,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A scattered light measurement information acquisition unit that acquires information on a scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured;
Based on the measurement conditions of the shape and optical properties of the object to be measured and the scattered light intensity distribution, a model generation unit for creating an object model to be measured;
A function parameter setting unit that sets parameters of a function representing scattered light information on the exit side that has passed through the device to be measured;
A scattered light intensity distribution calculation unit for calculating a scattered light intensity distribution calculation result by calculation based on the measured object model;
The information on the scattered light intensity distribution acquired by the scattered light measurement information acquisition unit and the scattered light intensity distribution calculation result calculated by calculation based on the measured object model are matched with each incident angle. A temporary function parameter calculation processing unit for calculating the function parameter as a temporary function parameter;
Information on the scattered light intensity distribution acquired in the scattered light measurement information acquisition unit, and the scattered light intensity distribution calculation result calculated using at least a part of the provisional function parameter of each incident angle with respect to the measured object model, A scattered light information processing apparatus, comprising: a function parameter determination unit that determines a final function parameter by adjusting a temporary function parameter so that the two match. A scattered light information processing system for measuring scattered light of an object to be measured and processing scattered light information,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A light irradiation unit that irradiates light at a predetermined angle to the object to be measured;
A scattered light measurement unit that receives at least light scattered by the object to be measured;
Based on information received by the scattered light measurement unit, a scattered light measurement information acquisition unit for acquiring information on the scattered light intensity distribution of the object to be measured;
An information storage unit for storing measurement conditions of the shape and optical properties of the object to be measured and the scattered light intensity distribution;
From the stored shape, optical properties, and measurement conditions, a model generation unit that creates an object model,
A function parameter setting unit that sets parameters of a function that represents at least the scattered light information on the exit side that has passed through the object to be measured, with respect to the object model to be measured;
A scattered light intensity distribution calculating unit for calculating a scattered light intensity distribution calculation result by calculation in consideration of reflection of scattered light and refraction of the scattered light inside the substance of the measured object from the measured object model;
A function parameter for calculating the function parameter so that the scattered light intensity distribution information acquired by the scattered light measurement information acquisition unit matches the scattered light intensity distribution calculation result calculated from the measured object model. A calculation processing unit;
The scattered light information processing system characterized by having. The scattered light measurement unit has a light receiving unit that receives light scattered and reflected by the object to be measured,
The function for setting a parameter in the function parameter setting unit includes the scattered light information reflected on the incident side of the measurement surface of the optical element and the emission side transmitted through the measured object with respect to the measured object model. The scattered light information processing system according to claim 17, wherein the scattered light information system is a function representing scattered light information. The scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit is at least a scattered light intensity distribution transmitted through the object to be measured or a scattered light intensity distribution reflected from the object to be measured,
18. The measurement condition of the scattered light intensity distribution input in the model generation unit includes at least the light intensity of light incident on the object to be measured at the time of measuring the scattered light intensity distribution. Or the scattered light information processing system according to 18.   The scattered light measurement information acquisition unit acquires at least a part of the scattered light intensity distribution transmitted through the object or a part of the scattered light intensity distribution reflected from the object. The scattered light measurement information processing system according to claim 19.   In the scattered light measurement information acquisition unit, at least a scattered light intensity distribution transmitted through the measurement object or a scattered light intensity distribution reflected from the measurement object is normalized by the light intensity of incident light on the measurement object The scattered light information processing system according to any one of claims 17 to 20, wherein a light intensity distribution is acquired.   The scattered light intensity distribution information acquired in the scattered light measurement information acquisition unit is a scattered light intensity distribution of light transmitted through the object to be measured and a scattered light intensity distribution of light reflected from the object to be measured. The scattered light information processing system according to any one of claims 17 to 21.   23. The shape and optical properties of the object to be measured include at least a radius of curvature, an optical thickness, and a refractive index of the optical element that is the object to be measured. The scattered light information processing system described in 1. A scattered light information processing system for measuring scattered light of an object to be measured and processing scattered light information,
The object to be measured is an optical element composed of a substance that at least partially transmits light,
A light irradiation unit that irradiates light at a predetermined angle to the object to be measured;
A scattered light measurement unit that receives at least light scattered by the object to be measured;
Based on the information received by the scattered light measurement unit, the scattered light measurement information acquisition unit for acquiring information on the scattered light intensity distribution of light irradiated at a plurality of different incident angles on the object to be measured;
An information storage unit for storing measurement conditions of the shape and optical properties of the object to be measured and the scattered light intensity distribution;
From the stored shape, optical properties, and measurement conditions, a model generation unit that creates an object model,
A function parameter setting unit that sets parameters of a function that represents at least the scattered light information on the exit side that has passed through the object to be measured, with respect to the object model to be measured;
A scattered light intensity distribution calculating unit for calculating a scattered light intensity distribution calculation result by calculation from the measured object model;
The information on the scattered light intensity distribution acquired by the scattered light measurement information acquisition unit and the scattered light intensity distribution calculation result calculated by calculation based on the measured object model are matched with each incident angle. A temporary function parameter calculation processing unit for calculating the function parameter as a temporary function parameter;
Information on the scattered light intensity distribution acquired in the scattered light measurement information acquisition unit, and the scattered light intensity distribution calculation result calculated using at least a part of the provisional function parameter of each incident angle with respect to the measured object model, A scattered light information processing system comprising: a function parameter determining unit that adjusts the temporary function parameters so as to match each other and determines a final function parameter.

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