Laser Range Finder Using Multi-Wavelength Photo Detectors
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Solution Overview
Problem
Existing laser range finding techniques require complex structures and suffer from time delays due to feedback control for wavelength changes, making them unsuitable for applications like automobiles.
Innovation Solution
A laser range finding apparatus with a light emitting section, a light receiving section using multiple photo detectors with different transmission wavelength bands, and an identifying section that determines unsaturated photo detectors to calculate distance without wavelength changes, eliminating the need for complex structures and time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control of temperature is performed to change laser light wavelength, then saturation of reflected light reception is prevented, but device complexity increases and time delay occurs
Solution Approach 1:
The light receiving section is divided into multiple photo detectors, each equipped with bandpass filters having different transmission center wavelengths. This segmentation allows simultaneous reception of reflected light across multiple wavelength bands, eliminating the need for temperature feedback control while preventing saturation in at least one detector.
Solution Approach 2:
Instead of dynamically adjusting the laser wavelength through temperature feedback, the system uses multiple static photo detectors with different transmission characteristics. The identification section dynamically selects which photo detector's data to use based on saturation status, achieving adaptability without physical adjustment mechanisms.
2Measurement precision
If feedback control is used to change laser wavelength, then detection accuracy is maintained, but response time increases due to time delay
Solution Approach 1:
Multiple photo detectors with different bandpass filters are prepared in advance, covering a range of transmission center wavelengths. This preliminary configuration ensures that at least one detector is ready to receive reflected light without saturation, eliminating the need for time-consuming wavelength adjustment during operation.
Solution Approach 2:
The system creates multiple copies of the detection function using different photo detectors with varying transmission characteristics. Instead of modifying the laser wavelength, the system copies the reception function across multiple detectors, allowing immediate selection of an unsaturated detector without time delay.
3Measurement precision
If laser light wavelength is changed to prevent saturation, then detection accuracy is improved, but device complexity and control requirements increase
Solution Approach 1:
The system automatically identifies which photo detector is unsaturated based on the received signal levels and selects that detector's data for distance calculation. This self-service mechanism eliminates the need for external temperature feedback control while maintaining detection accuracy through automatic adaptation to saturation conditions.
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 distance measurement to detection objects without time delays and complex structures, improving the reliability and efficiency of the laser range finding process.
Implementation Method 1
a light emitting section that emits a laser light
Implementation Method 2
reflected laser light reflected from a detection object
Implementation Method 3
a light receiving section that receives reflected laser light reflected from a detection object, the light receiving section including a plurality of photo detectors for respectively receiving a plurality of different transmission wavelength bands of the laser light
Data Source
AI summary
A laser range finding apparatus includes a light emitting section that emits a laser light, a light receiving section that receives the reflected laser light from a detection object, the light receiving section including a plurality of photo detectors for respectively receiving a plurality of different transmission wavelength bands of the laser light, an identifying section that identifies each of the photo detectors each of whose output indicating signal waveforms of the received reflected laser light is not saturated as an unsaturated photo detector, and a distance calculating section that calculates a distance to the detection object based on a light detection timing at which the reflected laser light is received by the unsaturated photo detector.