Heterodyne Laser Interferometer with Integrated Beam Splitter
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Solution Overview
Problem
Existing heterodyne laser interferometers with spatially separated optical paths face limitations in achieving both good thermal stability and a large tolerance angle, which restricts the improvement of measurement accuracy and resolution.
Innovation Solution
A heterodyne laser interferometer based on an integrated secondary beam splitting component, where the measurement and reference beams are spatially separated and balanced in length, with multiple reflections from a target plane mirror to enhance signal contrast and thermal stability, using isosceles right-angled prisms and polarizing or non-polarizing beam splitting films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a measurement beam is deflected by a target plane mirror only once, then the device structure is simpler, but the contrast of interference signal is easily affected by angular swing of the target plane mirror, resulting in a small tolerance angle
Solution Approach 1:
The patent segments the optical path into multiple reflection segments. Instead of a single reflection, the measurement beam reflects off the target plane mirror multiple times (at least twice), with each reflection segment contributing to the total optical path length. This segmentation allows the system to maintain a larger tolerance angle for angular swing while keeping the overall device structure manageable through modular optical component arrangement.
2Device complexity
If optical lengths of measurement beam and reference beam are unbalanced, then the device structure is simpler, but thermal stability is poor
Solution Approach 1:
The patent applies equipotentiality by balancing the optical path lengths of the measurement beam and reference beam. Both beams traverse equal total distances through the optical system, ensuring that thermal expansion or contraction affects both paths equally. This balanced configuration eliminates differential thermal drift, significantly improving thermal stability without requiring overly complex optical path management.
3Measurement precision
If spatially separated optical paths are used to reduce optical aliasing, then periodic nonlinear errors are reduced, but the device becomes more complex and difficult to integrate and assemble
Solution Approach 1:
The patent merges multiple beam splitting functions into a single integrated secondary beam splitting component. This component simultaneously performs spatial separation of measurement and reference beams, balances their optical path lengths, and enables multiple reflections off the target plane mirror. By combining these functions into one unified component rather than separate elements, the patent reduces periodic nonlinear errors through spatial separation while keeping the overall device composition manageable and easier to integrate and assemble.
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 design significantly reduces periodic nonlinear errors, improves thermal stability, and increases the tolerance angle, making the interferometer simpler to integrate and assemble while maintaining high measurement accuracy and resolution.
Implementation Method 1
a first input beam enters an integrated secondary beam splitting component and is then divided into a first measurement beam and a first reference beam; a second input beam enters the integrated secondary beam splitting component and is then divided into a second measurement beam and a second reference beam
Implementation Method 2
at least one of the first measurement beam and the second measurement beam is reflected by a target plane mirror at least once
Implementation Method 3
at least parts of the first measurement beam and the second reference beam overlap in an output travel path and form a first interference signal, and at least parts of the first reference beam and the second measurement beam overlap in an output travel path and form a second interference signal
Implementation Method 4
using isosceles right-angled prisms and polarizing or non-polarizing beam splitting films
Data Source
AI summary
Disclosed is a heterodyne laser interferometer based on an integrated secondary beam splitting component, which belongs to the technical field of laser application; the disclosure inputs two beams that are spatially separated and have different frequencies to the heterodyne laser interferometer based on the integrated secondary beam splitting component, wherein the integrated secondary beam splitting component includes two beam splitting surfaces that are spatially perpendicular to each other; and the two beam splitting surfaces are plated with a polarizing beam splitting film or a non-polarizing beam splitting film, and a measurement beam and a reference beam are the same in travel path length in the integrated secondary beam splitting component. The heterodyne laser interferometer of the disclosure significantly reduces periodic nonlinear errors, has the advantages of simple structure, good thermal stability, large tolerance angle and easy integration and assembly compared with other existing heterodyne laser interferometers with spatially separated optical paths, and meets the high-precision and high-resolution requirements of high-end equipment on heterodyne laser interferometry.