Uniform Solid-Angle Inspection Lighting for 3D Surface Profiling
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Solution Overview
Problem
Existing inspection and measurement systems struggle to quantitatively capture the three-dimensional shape of an object surface, particularly in regions with varying incline angles and discontinuities, due to non-uniform irradiation and observation conditions, leading to difficulties in accurately determining incline directions and surface profiles.
Innovation Solution
An inspection and measurement system that uses a lighting device with a surface light source, lens, and shielding or filtering means to form uniform irradiation solid angles and divide them into regions with different optical attributes, allowing for quantitative capture of contrast and brightness variations in scattered and direct light components, even in discontinuous regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If irradiation light is applied from a plurality of different directions to produce a variation in illuminance on an inclined minute surface, then the incline angle of the inclined surface can be determined, but illuminance varies even on minute surfaces having the same incline direction and incline angle, making it difficult to quantitatively obtain incline information
Solution Approach 1:
The patent divides the irradiation light into multiple solid angle regions with different optical attributes (different wavelengths, polarizations, or intensities) and applies these segmented light components from multiple directions simultaneously. This segmentation allows the system to distinguish between variations in illuminance caused by surface inclination versus other factors, enabling quantitative determination of incline angles while maintaining accuracy for surfaces with the same incline characteristics.
Solution Approach 2:
The patent applies different optical attributes to different solid angle regions of the irradiation light. By assigning specific wavelengths, polarizations, or intensities to different directional light components, the system creates locally differentiated illumination patterns that preserve incline information across all surfaces while enabling quantitative measurement even when overall illuminance varies.
2Measurement precision
If the direct light component is mainly observed to acquire contrast information, then quantitative three-dimensional shape information can be acquired for continuous regions, but relative information such as height information cannot be obtained for regions isolated by discontinuities
Solution Approach 1:
The patent makes the observation optical system multi-functional by enabling it to detect both direct light components (for continuous region measurement) and scattered light components (for discontinuous region measurement). The system can switch between or combine these modes to universally measure three-dimensional shape information across all regions, including isolated areas where direct light alone would be insufficient.
Solution Approach 2:
The patent introduces scattered light as an intermediary mechanism that bridges the gap between continuous and discontinuous regions. Scattered light from discontinuous regions provides the necessary contrast information to determine relative height and shape information in isolated areas, mediating between the direct light measurements in continuous regions and the need for comprehensive three-dimensional shape data.
3Measurement precision
If irradiation solid angles are made uniform across the object surface, then quantitative capture of contrast and brightness variations is enabled, but the device complexity increases due to the need for shielding masks or filtering means
Solution Approach 1:
The patent merges the functions of multiple optical components (shielding masks and filtering means) into an integrated optical system. By combining these elements to work together in forming uniform irradiation solid angles with different optical attributes, the system achieves precise measurement capability while managing device complexity through functional integration rather than separate components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and quantitative acquisition of three-dimensional shape information, including incline directions and surface profiles, by ensuring uniform irradiation and observation conditions across the object surface, even in complex and discontinuous areas.
Implementation Method 1
a lens configured to form, on the inspection object, an irradiation solid angle of light that is emitted from the surface light source as the inspection light
Implementation Method 2
at least one of a first shielding mask configured to form irradiation solid angles of the inspection light applied to respective points on the inspection object by shielding light and a first filtering means configured to divide the inspection light into a plurality of solid angle regions having partially different optical attributes
Implementation Method 3
an imaging device configured to image light reflected, transmitted, or scattered by the inspection object
Data Source
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AI summary
Technical Problem In the case where object light returned from an object surface to be inspected has a low content of a direct light component that corresponds to regular reflection and regular transmission of irradiation light, and contrast information thereof is therefore acquired by mainly observing a scattered light component, if irradiation conditions, such as inclines of optical axes of irradiation light, at respective points on the object surface cannot be kept uniform, it is difficult to quantitatively reflect incline directions and incline angles of minute areas in the vicinity of respective points on the object surface in a variation in optical attributes, and in the contrast, of the scattered light. On the other hand, in the case where object light returned from an object surface to be inspected has a high content of the direct light component, and contrast information thereof is acquired by mainly observing the direct light component, when surface characteristics of the object surface include, for example, a three-dimensional shape containing a relatively large change, if an incline of a minute surface constituting the object surface is larger than or equal to a certain angle, the optical axis of direct light that is regular reflection of irradiation light, of object light returned from the object surface, is significantly inclined and thus located outside an observation solid angle formed by an observation optical system from above the object, and therefore, the observation optical system cannot capture direct light from that inclined surface, which means that gray level information of that portion cannot be obtained from the direct light returned from the object, and it is difficult to continuously and quantitatively obtain the surface profile of the object surface. Solution to Problem The present invention was made in view of the above-described problems, and it is an object thereof to provide an inspection and measurement system and an inspection and measurement method with which, in an observation area of an object to be inspected, an object surface is irradiated with irradiation light capable of forming identical irradiation solid angles at respective points on the object surface, and when mainly observing a scattered light component, of object light returned from the object surface, other than direct light corresponding to regular reflection or regular transmission of the irradiation light, and acquiring a surface profile of the object surface based on the thus obtained contrast information, inclines of minute surfaces in the vicinity of the respective points on the object surface can be quantitatively reflected as a variation in optical attributes, and in the contrast information, of the scattered light component, or when mainly obtaining contrast information generated by a variation in inclusive relations between solid angles formed by the direct light and observation solid angles formed by an observation optical system for observing the direct light, and thereby acquiring a surface profile of the object surface, a relative relation of three-dimensional shape information such as height, incline, and incline direction, for example, can be acquired with regard to a surface profile of a region that is adjacent to a region in which an incline of a minute surface in the vicinity of a respective point on the object surface is larger than or equal to 1/2 of the sum of half plane angles of the irradiation solid angle and the observation solid angle at that point, and the observation optical system cannot continuously obtain gray level information based on the direct light returned from the object surface. That is to say, the present invention was made based on the following new idea: when observing scattered light of object light returned from the inspection object when irradiated with irradiation light, irradiation solid angles of the irradiation light are formed such that the three-dimensional shape of an object surface can be acquired by causing illuminance on minute surfaces in the vicinity of respective points on the object surface to have the same illuminance distribution if the minute surfaces have the same incline direction and the same incline angle and by quantitatively varying optical attributes and contrast of the scattered light component of object light returned from minute surfaces having different incline directions and incline angles, according to the variation in incline direction and incline angle of the minute surfaces, or when observing direct light of object light returned from the inspection object, with attention being paid to the fact that, with respect to a discontinuous region in which the 3D shape of the object surface contains a large change and inclines of minute surfaces in the vicinity of respective points on the object surface cannot be continuously acquired as contrast information of object light returned from the respective points, there is a specific region in which irradiation solid angles of the irradiation light incident on respective points on the object surface in the vicinity of the discontinuous region are not reflected in solid angles of direct light corresponding to regularly reflected light of object light returned from those points, and with attention being also paid to a variation in the solid angles of the direct light relative to the irradiation solid angles and a variation in object light from the discontinuous region, the three-dimensional shape of the discontinuous region can be acquired based on contrast information of the object light.