Tracking Laser Interferometer Optical Path Redirection
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Solution Overview
Problem
Conventional tracking type laser interferometers have limited measurement range and accuracy due to restrictions in the emission direction control and reflectable range of the retro-reflector, leading to dead angles in measurement space and reduced sensitivity in distance measurements, especially when the retro-reflector is displaced vertically.
Innovation Solution
Incorporating light reflecting means in the optical path between the main body and the retro-reflector allows for expansion of the measurement range and improvement in measurement accuracy by changing the optical axis directions of the measurement light and return light, enabling measurement beyond the original emission direction range and enhancing sensitivity by aligning the measurement light axis with the displacement direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the emission direction controlling means is used to track the retro-reflector, then the measurement light can be kept aligned with the retro-reflector, but the measurement range is restricted by the alterable range of emission direction
Solution Approach 1:
A light reflecting means (mirror) is introduced as an intermediary element in the optical path between the tracking type laser interferometer and the retro-reflector. This mirror reflects the measurement light to reach the retro-reflector, enabling measurement in directions that exceed the original emission direction range of the interferometer while maintaining precise tracking capability.
2Adaptability or versatility
If the retro-reflector is displaced vertically, then the measurement can cover more positions, but the measurement sensitivity is reduced due to cosine error
Solution Approach 1:
By changing the orientation angle of the light reflecting means, the optical axis direction of the measurement light is adjusted. This parameter change allows the measurement light to be incident on the retro-reflector at an angle that aligns with the displacement direction, thereby improving measurement sensitivity and reducing cosine error effects.
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 solution effectively expands the measurement range and improves accuracy without moving the interferometer, allowing for precise distance measurements even at specific points where sensitivity is typically low, and allows for virtual reference point adjustments to avoid installation limitations.
Implementation Method 1
a retro-reflector 20 attached to a measurement object 70, means (not illustrated) for emitting measurement light, light receiving means 30
Implementation Method 2
measures the distance to the recursive reflector by laser interference at high accuracy
Data Source
AI summary
A tracking type laser interferometer including: a retro-reflector 20 for reflecting incident measurement light and returning the same in the incident direction and a main body 10 having means for emitting measurement light, means 30 for receiving return light reflected by the recursive reflector and returned therefrom, and means 40 for controlling the emission direction of measurement light so that the distance between both optical axes of measurement light and return light becomes constant at all times, and the tracking type laser interferometer outputs a measurement value in response to an increase or a decrease in distance between the reference point in the main body and the recursive reflector, wherein at least one light reflecting means 80 is disposed in an optical path between the main body 10 and the retro-reflector 20, and the directions of the optical axes of the measurement light and return light are changed, whereby without moving the tracking type laser interferometer, the measurement range can be expanded, and the measurement accuracy at a specific point can be improved.