Optomechanical Assembly With Flexible Coupling for Thermal Beam Stability
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Solution Overview
Problem
Temperature-induced changes in the environment affect the spatial properties of laser beams, causing issues such as laser beam pointing error, loss of collimation, and changes in convergence/divergence, which are critical for stable laser-based technologies like flow cytometry.
Innovation Solution
The use of optomechanical assemblies with materials having low coefficients of thermal expansion and mechanical decoupling between subassemblies and a supporting baseplate to prevent thermal expansion or distortion, maintaining stable laser beam focus and combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials and rigid mounting are used, then the device structure is simple, but temperature-induced thermal expansion causes laser beam pointing error and focus shift
Solution Approach 1:
The patent changes the physical parameters of the mounting system by introducing compliant elements with specific mechanical properties (low stiffness in thermal expansion direction, high stiffness in optical alignment direction) and selecting materials with matched coefficients of thermal expansion. This allows the system to accommodate thermal expansion while maintaining optical stability without complex active control mechanisms.
Solution Approach 2:
The patent introduces compliant mounting elements as intermediary components between the rigid optical components and the baseplate. These intermediaries absorb thermal expansion stresses through their compliance while maintaining rigid optical alignment, effectively decoupling the thermal expansion of the baseplate from the optical train.
2Reliability
If materials with low coefficients of thermal expansion are used, then temperature-induced distortion is reduced, but material selection and manufacturing become more difficult
Solution Approach 1:
The patent changes the approach from selecting exotic low-CTE materials to using conventional materials with matched CTEs. By carefully selecting materials whose thermal expansion coefficients are compatible with each other (e.g., aluminum baseplate with aluminum optics, or stainless steel with stainless steel components), the system achieves thermal stability using readily manufacturable materials.
Solution Approach 2:
The patent promotes homogeneity in material selection throughout the optomechanical assembly. By using materials with similar thermal and mechanical properties across different components, the system minimizes differential thermal expansion and simplifies manufacturing, as the same or similar materials can be used for multiple parts.
3Strength
If the baseplate is rigidly connected to optical subassemblies, then structural support is strong, but thermal expansion of the baseplate forces expansion or distortion of the subassembly
Solution Approach 1:
The patent segments the mounting system into distinct functional zones: rigid optical mounting regions that maintain precise optical alignment, and compliant transition regions that accommodate thermal expansion. This segmentation allows the baseplate to expand freely while isolating the optical components from expansion stresses.
Solution Approach 2:
The patent applies different mechanical properties to different parts of the mounting system. The compliant elements have low stiffness in the thermal expansion direction to absorb expansion stresses, while maintaining high stiffness in directions critical for optical alignment. This local differentiation of mechanical properties resolves the contradiction between structural strength and thermal stability.
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 assemblies maintain stable laser beam focus and combination, even in the presence of temperature changes, ensuring accurate cell identification and composite laser beam formation in spectral flow cytometers.
Implementation Method 1
The flexible coupling allows for a thermally induced change in distance between the first and second anchor points in the presence of dissimilar thermal expansion of the optics plate and the baseplate
Data Source
AI summary
An optomechanical assembly for temperature-robust laser beam processing includes a baseplate and an optics plate. The baseplate includes a source area for accommodating a source of the laser beam, and a light-processing area located away from the source area and including first and second anchor points. The optics plate is disposed in the light-processing area and includes first and second portions and a flexible coupling interconnecting the first and second portions. The first and second portions are fixed to the baseplate at the first and second anchor points, respectively. The flexible coupling allows for a thermally-induced change in distance between the first and second anchor points in the presence of dissimilar thermal expansion of the optics plate and the baseplate. The assembly further includes a series of optical elements for manipulating a laser beam from the laser source. Each of the optical elements is rigidly bonded to the first portion.