Self-Mixing Laser Sensor Module With Photocurrent Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser sensor modules using modulated laser currents face issues with large intensity variations in photocurrent, leading to clipping of photodiode signals and requiring complex electronic compensation, which is not always effective in reducing these variations.
Innovation Solution
A laser sensor module with two laser sources, where the circuitry adapts the amplitude of the driving current of one laser source based on the detected modulated light from the other laser source to compensate for photocurrent variations, ensuring stable detection without additional complex electronic provisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a modulated laser current is used to enable wavelength variations for improved detection, then measurement precision is improved, but large intensity variations in photocurrent occur causing signal clipping and requiring complex electronic compensation
Solution Approach 1:
The patent converts the harmful large intensity variations in photocurrent into a useful compensation mechanism by using a second laser source. The second laser source is modulated to generate photocurrent variations that are equal in magnitude but opposite in phase to those from the first laser source, thereby canceling out the harmful effects and eliminating the need for complex electronic compensation circuits
2Measurement precision
If a modulated laser current is used to enable wavelength variations for improved detection, then measurement precision is improved, but photodiode signals are clipped due to large photocurrent variations
Solution Approach 1:
The patent applies preliminary anti-action by using the second laser source to pre-compensate for the intensity variations before they cause signal clipping. The second laser source is modulated in advance to generate counter-phase photocurrent variations that cancel out the harmful effects from the first laser source, preventing signal clipping before it occurs
3Reliability
If special electronic provisions are added to compensate photocurrent variations, then reliability is improved, but device complexity increases and variations cannot be significantly reduced
Solution Approach 1:
The patent replaces the complex electronic compensation system with an optical solution. Instead of using elaborate electronic provisions to compensate photocurrent variations, the invention uses a second optical source (laser) whose photocurrent variations naturally cancel those from the first laser source, thereby simplifying the overall system while maintaining signal stability
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 approach effectively compensates for photocurrent variations, reducing signal clipping and enhancing the reliability of distance and velocity measurements in self-mixing interferometry applications by maintaining stable photocurrent without requiring elaborate electronic compensation.
Implementation Method 1
a detector configured to detect said first modulated laser light which induces a photocurrent
Implementation Method 2
a first laser source configured to emit first modulated laser light wherein the circuitry is configured to drive the first laser source with a first modulated driving current
Implementation Method 3
a well-known technique used for said purpose of sensing is self-mixing interferometry, where a detector, such as a photodiode, is positioned behind a laser or may be part of the laser structure itself
Data Source
AI summary
The present invention relates to a laser sensor module (150). The laser sensor module (150) comprises a first laser source (152) configured to emit modulated laser light, a circuitry (159) configured to drive the first laser source (152) with a first modulated driving current to cause the first laser source (152) to emit modulated laser light, a detector (156) configured to detect said modulated laser light which induces a photocurrent with variations resulting from the modulation of said modulated laser light, and a second laser source (154) configured to emit modulated light. The circuitry (159) is configured to drive the second laser source (154) with a second modulated driving current to cause the second laser source (154) to emit modulated light. The detector (156) is configured to detect said modulated light, wherein the circuitry (159) is configured to adapt the amplitude of the second modulated driving current to induce a contribution to the photocurrent which compensates for the variations of the photocurrent induced by the laser light of the first laser source (152). A device comprising the laser sensor module (150) and a method for compensating for the variations of a detected photocurrent of a detector (156) of the laser sensor module (150) and a corresponding computer program are further described.