Photodetection Device Using Interference Element for Shape Measurement
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Solution Overview
Problem
Conventional photodetection devices face challenges in accurately measuring the shape of objects with steps beyond the wavelength of light due to limitations in downsizing and susceptibility to ambient environmental changes, such as air convection and vibrations, which affect the optical path and interfere with precise measurements.
Innovation Solution
A photodetection device with an optical system that utilizes an image sensor and an interference element with first and second incident regions, emitting light in two different wavelength bands, causing interference and guiding the resultant light to specific pixels, while using bandpass filters to separate and process the light, allowing for accurate phase difference determination and shape measurement even with steps beyond the wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photodetection devices are used for shape measurement, then measurement capability is provided, but the optical part is large in size and susceptible to ambient environmental influences
Solution Approach 1:
The patent merges the reference surface and object surface into a single integrated optical path, eliminating the need for separate reference and measurement optical paths. This integration reduces the overall optical part size while maintaining the interferometry function for shape measurement.
Solution Approach 2:
The patent transitions from traditional spatial separation of optical paths to a temporal or spectral dimension approach, using wavelength division to separate reference and object light. This allows compact integration while maintaining measurement capability.
2Measurement precision
If single-wavelength interferometry is used, then simple measurement is achieved, but steps beyond the wavelength cannot be measured accurately
Solution Approach 1:
The patent segments the measurement function into multiple wavelength channels, each capable of measuring different ranges. By dividing the measurement task across multiple wavelengths, the system can accurately measure steps beyond a single wavelength without requiring a completely complex system.
Solution Approach 2:
The patent changes the wavelength parameter to extend measurement capability. By using multiple wavelengths (e.g., 650 nm and 480 nm), the system can measure steps larger than what a single wavelength would allow, effectively extending the measurement range through parameter variation.
3Measurement precision
If two-wavelength interferometry is used to measure steps beyond wavelength, then measurement accuracy improves, but optical part size increases and environmental susceptibility increases
Solution Approach 1:
The patent combines multiple wavelength light sources and their corresponding interference paths into a single integrated optical detection area. This merging allows two-wavelength interferometry to achieve extended measurement capability while minimizing the optical part size and reducing environmental susceptibility.
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
The device achieves a compact optical design less susceptible to environmental influences, enabling precise measurement of object shapes with steps beyond the wavelength of light, providing accurate and reliable results.
Implementation Method 1
the interference element causes first interference of part of the light in the first wavelength band incident on two incident regions that are included in the incident regions and that are adjacent to each other
Implementation Method 2
using bandpass filters to separate and process the light
Data Source
AI summary
A photodetection device including an image sensor that includes first pixels and second pixels; an interference element that includes incident regions; and illumination that emits light in a first wavelength band and a second wavelength band. The interference element causes first interference of light in the first wavelength band incident on two incident regions, and guides resultant light of the first interference to any of the first pixels and guides another part of the light in the first wavelength band to any of the second pixels, and causes second interference of part of the light in the second wavelength band incident on the two incident regions, and guides resultant light of the second interference to any of the first pixels and guides another part of the light in the second wavelength band incident on the two incident regions to any of the second pixels.