Laser Interferometer Optical Axis Shift for Return Light
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Solution Overview
Problem
Existing laser vibrometers face issues with unstable laser oscillation due to return light, leading to decreased signal-to-noise ratio and measurement accuracy of vibration speed.
Innovation Solution
A laser interferometer design that includes a laser light source, a collimator, an optical modulator, and a light receiving element, where the optical axes of the collimated light and return light are shifted to prevent return light from entering the laser light source, thereby stabilizing laser oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser light source is used to emit laser light for measurement, then the measurement function is achieved, but return light enters the laser light source causing unstable laser oscillation
Solution Approach 1:
The patent introduces a new spatial dimension by shifting the optical axis of the reference light path relative to the incident light path. The optical axis shift amount is specifically designed to be 0.01 mm or more, separating the return light path from the laser light source in the spatial domain. This dimensional separation allows the measurement function to continue while preventing return light from destabilizing the laser oscillation.
2Device complexity
If the optical axis of reference light is aligned with the incident light path, then the optical system is simple, but return light enters the laser light source causing phase discontinuity
Solution Approach 1:
The patent applies local quality by creating a localized optical axis shift only in the reference light path where return light is generated. The optical axis of the reference light is shifted by 0.01 mm or more relative to the incident light path, while other parts of the optical system maintain their original configuration. This localized modification prevents phase discontinuity without significantly increasing overall system complexity.
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 design effectively reduces the light intensity of return light, stabilizes laser oscillation, and improves the measurement accuracy of vibration speed by maintaining a high signal-to-noise ratio.
Implementation Method 1
an optical modulator configured to modulate the collimated light into reference light having a different frequency
Implementation Method 2
a light receiving element configured to receive object light generated by reflecting the collimated light by an object to be measured and the reference light and output a light receiving signal
Implementation Method 3
a collimator configured to collimate the laser light to generate collimated light
Data Source
AI summary
A laser interferometer includes a laser light source, a collimator generating collimated light, an optical modulator modulating the collimated light into reference light having a different frequency, and a light receiving element receiving object light and the reference light and outputting a light receiving signal. An optical axis of the collimated light is a first optical axis. When return light is generated, an optical axis of the return light is a second optical axis. A position at which the collimated light is generated is a reference position. The first and second optical axes at the reference position has a shift width Δy. The collimator has an effective diameter κ. The collimated light has a light diameter R. The reference position is away from the optical modulator by a distance L. The collimated light has a wavelength λ. These properties satisfy a specific equation (A).