Photodetection Device Spatial Resolution via Heterodyne Mixing
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Solution Overview
Problem
Existing photodetection devices and ranging devices struggle with achieving high spatial resolution due to limitations in the mixing of optical signals and the use of single photodetectors, which restricts the ability to sample spatial frequency components effectively.
Innovation Solution
The proposed solution involves a photodetection device and ranging device configuration that includes multiple photodetectors with separated light-receiving elements, a cross-correlation section to mix optical signals from any two photodetectors, and a heterodyne correlation section to perform heterodyne mixing with a reference signal, enabling the calculation of distance information based on difference frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single photodetector is used for detection, then the device complexity is low, but the spatial resolution is insufficient
Solution Approach 1:
The patent divides the detection system into multiple photodetectors with separated light-receiving elements instead of using a single photodetector. This segmentation allows the system to sample multiple spatial frequency components simultaneously, thereby improving spatial resolution while maintaining manageable device complexity through modular architecture
Solution Approach 2:
The patent transitions from single-point detection to multi-point spatial distribution detection by arranging light-receiving elements at different positions. This dimensional expansion in spatial sampling enables the system to capture spatial frequency information that cannot be obtained with a single detector, resolving the contradiction between simplicity and resolution
2Measurement precision
If optical signals are not mixed with reference signal, then the processing is simpler, but the distance measurement capability is lost
Solution Approach 1:
The patent introduces a reference signal as an intermediary that mixes with the optical signals from photodetectors. This reference signal acts as a carrier that enables the extraction of distance information through heterodyne mixing, allowing precise distance measurement while keeping the processing architecture systematic and manageable
Solution Approach 2:
The patent utilizes frequency modulation of the reference signal and optical signals to encode distance information. By changing the frequency parameters and performing heterodyne mixing, the system can extract precise distance measurements, resolving the contradiction between measurement precision and processing complexity
3Measurement precision
If multiple photodetectors are used with separated light-receiving elements, then the spatial resolution is improved, but the device complexity increases
Solution Approach 1:
The patent combines the functions of multiple photodetectors and their signal processing paths into a unified system architecture. By merging the detection and processing functions while maintaining the spatial separation of light-receiving elements, the system achieves high spatial resolution without proportionally increasing overall device complexity
Solution Approach 2:
The patent designs the multiple photodetectors and signal processing circuitry to serve multiple functions: spatial frequency sampling, distance measurement, and imaging. This multi-functionality allows the system to achieve high spatial resolution without requiring separate dedicated components for each function, thereby controlling device complexity
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
This configuration enhances spatial resolution by allowing the sampling of spatial frequency components corresponding to the relative positional relationships between photodetectors, enabling high-resolution imaging and distance measurement.
Implementation Method 1
a laser light source that outputs coherent light
Implementation Method 2
two or more photodetectors including respective light-receiving elements, the light-receiving elements being disposed separated from one another, the two or more photodetectors detecting, via the light-receiving elements, reflected light from a subject irradiated with the coherent light
Implementation Method 3
a cross-correlation section that mixes two optical signals detected by any two photodetectors out of the two or more photodetectors
Implementation Method 4
a heterodyne correlation section that mixes, with heterodyne mixing, the optical signals after mixing by the cross-correlation section or one of the optical signals before mixing by the cross-correlation section and a reference signal obtained by dividing the coherent light from the laser light source
Data Source
AI summary
A photodetection device of the present disclosure includes: a laser light source that outputs coherent light; two or more photodetectors including respective light-receiving elements, the light-receiving elements being disposed separated from one another, the two or more photodetectors detecting, via the light-receiving elements, reflected light from a subject irradiated with the coherent light; a cross-correlation section that mixes two optical signals detected by any two photodetectors out of the two or more photodetectors; and a heterodyne correlation section that mixes, with heterodyne mixing, the optical signals after mixing by the cross-correlation section or one of the optical signals before mixing by the cross-correlation section and a reference signal obtained by dividing the coherent light from the laser light source.