Null Assembly Optical Alignment for Cryogenic Metrology
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Solution Overview
Problem
Metrology devices face performance degradation due to the use of optical windows in cryogenic environments, which can lead to varying measurement accuracy and alignment issues when multiple devices operate with different optical paths and are subjected to different vibrations.
Innovation Solution
A system and method utilizing a rangefinder with a null assembly to emit and reflect light beams for measuring distances to optical surfaces, which includes a fixed lens to collimate and focus light beams, and a null assembly with aspheric and spherical mirrors to compensate for distortion, allowing for precise measurement and alignment of optical surfaces in both ambient and cryogenic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical windows are used in cryogenic environments for metrology devices, then the devices can operate in pressure-tight enclosures, but the optical windows degrade measurement performance and cause alignment issues
Solution Approach 1:
The patent removes the optical window from the measurement path by using a port in the pressure-tight enclosure that allows direct optical access. The metrology device transmits light through the port without passing through optical windows, thereby eliminating window-induced degradation while maintaining the ability to operate in cryogenic environments.
Solution Approach 2:
The patent introduces a null assembly as an intermediary optical component that compensates for distortions. This assembly includes null lenses and other optical elements designed to counteract the effects of the cryogenic environment and maintain beam quality without requiring optical windows in the measurement path.
2Productivity
If multiple metrology devices operate through different optical windows, then each device can independently measure, but varying vibrations and window degradation cause alignment issues and reduced networked measurement performance
Solution Approach 1:
The patent eliminates optical windows from the measurement path by using ports in the pressure-tight enclosure. This removes the source of varying degradation and alignment issues that occurred when multiple devices operated through different windows, while still allowing multiple devices to perform simultaneous measurements.
Solution Approach 2:
The patent changes the operational parameters by removing the optical window interface and using direct optical access through enclosure ports. This parameter change ensures that all metrology devices operate under consistent conditions without the variable degradation introduced by different optical windows, improving alignment consistency across the network.
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
The system achieves high measurement accuracy, maintaining precision across different environments and reducing the impact of optical window degradation, enabling effective alignment and testing of optical surfaces with improved resolution and reliability.
Implementation Method 1
a fixed lens to collimate and focus light beams
Implementation Method 2
a null assembly with aspheric and spherical mirrors to compensate for distortion
Data Source
AI summary
A system for testing an optical surface includes a rangefinder configured to emit a light beam and a null assembly located between the rangefinder and the optical surface. The null assembly is configured to receive and to reflect the emitted light beam toward the optical surface. The light beam reflected from the null assembly is further reflected back from the optical surface toward the null assembly as a return light beam. The rangefinder is configured to measure a distance to the optical surface using the return light beam.