DOE Performance Monitoring via Side Surface Detection
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Solution Overview
Problem
Diffractive optical elements (DOEs) face efficiency variations due to manufacturing tolerances and operational changes, leading to increased zero diffraction order intensity, which can cause performance degradation and safety hazards.
Innovation Solution
An optical apparatus with a diffractive optical element and a side surface that receives high-order diffracted radiation, monitored by an optical detector, which signals a controller to adjust or inhibit the radiation source operation based on intensity changes, minimizing additional hardware and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DOE efficiency varies due to manufacturing tolerances and operational changes, then the zero diffraction order intensity increases, but this causes performance degradation and safety hazards
Solution Approach 1:
The patent implements a feedback mechanism where an optical detector continuously monitors the intensity of diffracted radiation and provides signals to a controller. The controller adjusts or inhibits the radiation source operation based on real-time DOE efficiency changes, preventing harmful increases in zero diffraction order intensity and maintaining safe operating levels throughout the DOE's lifetime
Solution Approach 2:
The system uses the DOE's own diffracted radiation as the monitoring signal source. The optical detector receives radiation that has already interacted with the DOE, allowing the system to self-monitor its performance without requiring external reference beams or separate test equipment
2Measurement precision
If an optical detector is positioned to monitor high order diffracted radiation, then DOE performance can be monitored, but additional hardware is required
Solution Approach 1:
The patent combines the monitoring function with the existing optical structure by positioning the optical detector in proximity to the side surface of the DOE. The detector utilizes the same optical path and radiation source as the main DOE function, merging monitoring capabilities into the existing system rather than adding completely separate monitoring equipment
Solution Approach 2:
The patent monitors DOE performance by detecting radiation in a different spatial dimension - specifically through the side surface of the DOE rather than through the entrance or exit surfaces. This side-surface detection approach allows monitoring without interfering with the primary optical path and projection function
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
Effectively monitors DOE performance with minimal impact, preventing eye safety hazards by controlling radiation source operation and maintaining system performance by detecting efficiency changes and inhibiting operation when thresholds are exceeded.
Implementation Method 1
A grating is formed on at least one of the optical surfaces so as to receive radiation entering the DOE via the entrance surface and to diffract the radiation into a predefined pattern including multiple diffraction orders
Implementation Method 2
The optical surfaces of the DOE are configured so that the high order of the diffracted radiation reaches the side surface after reflecting internally within the DOE
Data Source
AI summary
Optical apparatus includes a diffractive optical element (DOE), which includes multiple optical surfaces, including at least an entrance surface and an exit surface, and a side surface, which is not parallel to the optical surfaces of the DOE. A grating is formed on at least one of the optical surfaces so as to receive radiation entering the DOE via the entrance surface and to diffract the radiation into a predefined pattern comprising multiple diffraction orders that exit the DOE via the exit surface. An optical detector is positioned in proximity to the side surface so as to receive and sense an intensity of a high order of the radiation diffracted from the grating that passes through the side surface of the DOE.