Adaptive Laser Intensity Control for Nonlinear Display Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser beam scanning display technologies face challenges in accurately controlling light intensity due to non-linear optical-electrical responses of semiconductor lasers, which are influenced by factors such as temperature, unit-to-unit variability, and aging, leading to inaccuracies in image display.
Innovation Solution
A dual-control system comprising a primary and secondary control system is employed to calibrate the laser intensity-to-current curve, where the primary system uses a PID controller for single-drive condition feedback, and the secondary system iterates through multiple drive conditions with a multiple-input multiple-output controller to update the laser model, minimizing errors through time multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single control system is used to control laser intensity, then the device complexity is low, but the light intensity control accuracy deteriorates due to non-linear optical-electrical response and varying operating conditions
Solution Approach 1:
The control system is divided into two independent control loops: a inner control loop that operates at a single drive condition with high bandwidth for rapid error correction, and an outer control loop that iterates through multiple drive conditions to maintain accuracy across varying operating conditions. This segmentation allows each loop to be optimized for its specific function, resolving the contradiction between accuracy and complexity.
Solution Approach 2:
The outer control loop performs preliminary calibration by measuring and storing the actual light output at multiple drive conditions before normal operation. This pre-characterization of the laser's non-linear response creates lookup tables that the inner control loop uses during real-time operation, eliminating the need for complex real-time calculations and enabling accurate intensity control across all conditions.
2Adaptability or versatility
If the laser model is updated for multiple drive conditions, then the adaptability to varying operating conditions improves, but the calibration time and processing complexity increase
Solution Approach 1:
The outer control loop operates periodically to update the laser model at multiple drive conditions, while the inner control loop continuously operates at the current drive condition. This periodic updating strategy balances the need for adaptability across conditions with the constraint of calibration time, refreshing the model only when necessary rather than continuously for all conditions.
Solution Approach 2:
The system performs preliminary calibration measurements at multiple drive conditions and stores the results in lookup tables before normal operation begins. During real-time operation, the system simply retrieves pre-computed correction values from these tables rather than performing complex calculations, significantly reducing processing time while maintaining adaptability.
3Manufacturing precision
If a dual control system with multiple drive condition calibration is implemented, then the grayscale and color fidelity improve, but the device complexity and control algorithm complexity increase
Solution Approach 1:
The control algorithm is segmented into two distinct functions: the inner loop handles rapid error correction using simple proportional control at the current drive condition, while the outer loop performs periodic model updates using steepest descent optimization across multiple conditions. This segmentation simplifies the real-time control algorithm while maintaining high fidelity through periodic comprehensive calibration.
Solution Approach 2:
The system performs preliminary characterization of the laser's non-linear response at multiple drive conditions and stores correction data in lookup tables. During normal operation, the control algorithm simply retrieves and applies pre-computed correction values, avoiding complex real-time calculations and significantly reducing algorithmic complexity while maintaining grayscale and color fidelity.
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 provides more accurate light intensity control, ensuring improved image quality by compensating for variations in laser behavior over time and environmental conditions, thereby enhancing the fidelity of grayscale and color reproduction in laser-driven displays.
Implementation Method 1
The actual light intensity can be determined by a photodiode that receives a portion of light generated by the laser
Data Source
AI summary
Systems, devices, methods, and computer-readable media for driving a laser of a laser-driven display. A method includes determining a first error between a first expected light intensity and a first actual light intensity from the laser at a specified control light intensity and specified control pulse spacing, determining a second error between a second expected light intensity and a second actual light intensity from the laser at a specified second light intensity and specified second pulse spacing, updating, by the secondary control system and based on the second error, a laser model resulting in an updated laser model, the laser model indicating respective driving currents to generate respective light intensities by the laser, and driving, by a driver and at a driving current determined based on the first error and the updated laser model, the laser to generate a pixel of the laser-driven display.