Projection Diffuser Monitoring via Exit Pupil Light Sampling
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Solution Overview
Problem
Existing projection systems fail to accurately detect minor damages to diffusers, such as pinhole defects, which can lead to unsafe laser light levels due to inconsistent detection methods that do not account for varying light distribution patterns across the diffuser surface.
Innovation Solution
A system that samples and analyzes the light distribution in the exit pupil of a projection system using a sampler and detectors to identify anomalies in light intensity ratios or FWHM changes, allowing for precise detection of diffuser failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor detects reflected light from a diffuser to shut off laser power, then safety is improved, but detection precision deteriorates because the detector cannot distinguish between minor damages (pinhole defects) and normal variations in light distribution
Solution Approach 1:
The detection system divides the aperture plane into multiple sampling regions (central region and peripheral regions) to independently monitor different characteristics of light distribution. This segmentation allows the system to detect anomalies by comparing light intensity ratios between regions, thereby improving detection precision for minor diffuser damages while maintaining safety monitoring
Solution Approach 2:
The system applies different detection strategies to different regions of the aperture plane. The central region monitoring detects overall light intensity changes, while peripheral region monitoring detects angular distribution changes. This local quality approach enables precise detection of pinhole defects by analyzing regional differences in light distribution patterns
2Device complexity
If electrical, thermal or magnetic sensors are used to monitor diffuser state, then device complexity is reduced, but measurement precision deteriorates because optical characteristic changes do not guarantee significant changes in electrical, thermal or magnetic characteristics
Solution Approach 1:
The system replaces electrical, thermal, or magnetic sensors with an optical detection system that directly measures light distribution characteristics in the aperture plane. This substitution uses optical fields instead of other physical fields, enabling precise detection of diffuser damages by measuring changes in light intensity and angular distribution that directly reflect optical characteristic changes
3Device complexity
If a detector monitors overall reflected light intensity, then device complexity is minimized, but measurement precision deteriorates because the detector cannot detect pinhole defects that affect only small portions of the diffuser active area
Solution Approach 1:
The detection system segments the aperture plane into multiple sampling regions with different detectors, allowing localized detection of light intensity variations. This segmentation enables the system to detect pinhole defects that affect only small portions of the diffuser by monitoring regional differences rather than overall intensity alone
Solution Approach 2:
The system transitions from monitoring only light intensity (one dimension) to monitoring both light intensity and angular distribution (adding spatial dimension). By sampling light distribution across different angular regions in the aperture plane, the system can detect pinhole defects through changes in the spatial pattern of light distribution, not just overall intensity
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 differentiation between safe and unsafe operating conditions by generating alarm signals to shut down or reduce laser power, thereby reducing the risk of eye damage from unsafe laser light levels.
Implementation Method 1
a diffuser illuminated by a coherent light source
Implementation Method 2
a sampler configured to sample the at least one light beam exiting the diffuser and to redirect the light beam sample toward a detection system
Implementation Method 3
The detection system comprises a photosensor, a linear array of photosensors or an array of N columns and M lines of photosensors
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The invention provides an optical system configured to monitor a state of a diffuser, the system comprising the diffuser, a light source configured to emit at least one light beam, a transmissive or reflective spatial light modulator, a sampler a detection system, and an analyzer, wherein the light source is configured to illuminate the diffuser, wherein the aperture is configured to be filled with light and the optical system is configured to have all rays of light that exit the diffuser with a same angle ending up at a same point in the aperture. The invention further provides a method of monitoring a state of a diffuser in the optical system.