On-Chip Silicon LED Calibration for Laser Range Finder Phase Offset
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser range finders in mobile devices face challenges in achieving high accuracy due to factors like temperature variations, component drift, and internal gain settings, requiring frequent calibration and a self-calibrating mechanism that is highly integrated and power-efficient, while also needing to be compact and independent of object surface reflectance and optical component variations.
Innovation Solution
The implementation of an on-chip silicon LED for calibration, which generates a reference light signal to correct phase offset settings of photodetectors and IF filters, ensuring accurate distance measurement by compensating for component mismatches and environmental effects, and using an avalanche photo diode with variable gain control to maintain signal quality across varying distances and reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent calibration is performed to maintain measurement accuracy, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements a self-calibrating mechanism using an integrated silicon LED that automatically compensates for phase offset errors caused by temperature variations and component drift. The system performs self-calibration by comparing the phase of light signals at different temperatures and automatically adjusting the phase offset, eliminating the need for external calibration equipment and manual intervention.
Solution Approach 2:
The patent changes the operating temperature parameter to induce controlled phase offset variations, then uses these variations to calibrate the system. By deliberately varying temperature and measuring the corresponding phase changes, the system extracts calibration data to compensate for environmental effects during normal operation.
2Measurement precision
If frequent calibration is performed to maintain measurement accuracy, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The self-calibration mechanism uses the existing laser and photodetector components to perform calibration without requiring additional high-power components. The silicon LED is integrated into the existing circuitry and operates at low power, enabling calibration to be performed efficiently during normal device operation.
3Object-affected harmful factors
If the laser emitting power is limited to Class 1 safety level, then safety is improved, but measurement range and signal strength deteriorate
Solution Approach 1:
The patent replaces direct high-power laser measurement with an optical heterodyne detection system that uses low-power Class 1 laser combined with local oscillator light. The phase information is extracted through optical mixing rather than direct time-of-flight measurement, enabling accurate detection with safe laser power levels.
4Length of moving object
If the lens diameter is limited to 4mm to fit mobile phone form factor, then device compactness is improved, but optical signal collection capability deteriorates
Solution Approach 1:
The patent makes the lens serve multiple functions: it focuses both the outgoing measurement light and the incoming reflected light, and also collects light for the silicon LED calibration source. This multi-functionality maximizes the utility of the limited optical path space within the compact lens assembly.
Solution Approach 2:
The patent enhances the optical signal strength not by increasing lens aperture but by utilizing the temporal and spectral dimensions through coherent optical mixing. The heterodyne detection technique amplifies the weak reflected signal through interference with the local oscillator, compensating for the limited light collection area.
5Length of moving object
If the height of range finder assembly is limited to 3mm, then device compactness is improved, but integration of calibration components becomes difficult
Solution Approach 1:
The patent merges the calibration LED, photodetector, and laser components into a single integrated chip or closely coupled module. The silicon LED is positioned in close proximity to the photodetector, sharing the same optical path and electronic circuitry, which enables the entire range finder assembly to be compressed to 3mm height while maintaining calibration functionality.
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 solution enables a laser range finder to achieve sub-millimeter resolution and accuracy, independent of environmental and component variations, with reduced power consumption and size, ensuring consistent phase information and improved signal-to-noise ratio.
Implementation Method 1
an on-chip silicon LED for calibration, which generates a reference light signal to correct phase offset settings of photodetectors
Implementation Method 2
using an avalanche photo diode with variable gain control to maintain signal quality across varying distances and reflectance
Data Source
AI summary
Embodiments of the present disclosure use an “on chip” silicon LED to generate a light signal for calibration of a range finder. The light signal from the silicon LED may be detected by photo detectors in a reference path and a receive path of the range finder to generate a calibration phase offset, which may be subtracted out from a phase offset measurement of the range finder to correct the phase offset measurement for component mismatch due to, for example, environment, process variation, aging, etc.