Interferometer Semiconductor Laser Reference Source
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Solution Overview
Problem
The existing Michelson interferometer configurations using He-Ne lasers as reference light sources are large and prone to errors due to increased sensitivity to temperature and vibration, and the use of expansion lenses to reduce returning light destabilizes laser oscillation, making them unsuitable for compact and stable position detection of movable mirrors.
Innovation Solution
A semiconductor laser or laser light source is used as the reference light source, emitting collimated light that obliquely incidents on the stationary mirror, eliminating the need for expansion lenses and reducing the interferometer's size while preventing returning light from reaching the reference light source, thus stabilizing laser oscillation and enabling accurate position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a He-Ne laser is used as the reference light source, then wavelength stability is maintained, but the apparatus size increases and sensitivity to temperature and vibration errors increases
Solution Approach 1:
The patent changes the type of laser source from He-Ne laser to semiconductor laser, altering the physical parameters of the light source system. This enables miniaturization while implementing temperature compensation mechanisms to maintain wavelength stability despite the different laser characteristics
Solution Approach 2:
The patent replaces the mechanical/thermal management requirements of He-Ne lasers with electronic control systems suitable for semiconductor lasers. This includes using LED-based temperature control and electronic feedback mechanisms to stabilize the semiconductor laser wavelength, substituting complex mechanical stabilization systems with more compact electronic solutions
2Object-affected harmful factors
If an expansion lens is disposed on the light emission side of the reference light source to decrease returning light, then the influence of harmonic resonance is reduced, but the number of components increases and accuracy in detecting position deteriorates due to increased sensitivity to temperature and vibration
Solution Approach 1:
The patent extracts and removes the expansion lens from the optical system, eliminating the component that causes increased sensitivity to temperature and vibration. Instead of using the expansion lens to reduce returning light, the patent addresses the harmonic resonance issue through other means such as optical path design and beam direction control
Solution Approach 2:
The patent introduces a beam splitter and separate detection path as intermediary elements. The reference light is separated from the measurement light path, and the position detection is performed through a dedicated reference light detection system that is not affected by the measurement optical path variations, thereby maintaining detection accuracy without requiring expansion lenses
3Object-affected harmful factors
If returning light is reduced by expanding divergence angle, then harmonic resonance influence is reduced, but the number of components increases
Solution Approach 1:
The patent removes the expansion lens component entirely from the system. Instead of reducing returning light through divergence angle expansion, the patent uses alternative approaches such as controlling the beam path geometry and using the beam splitter to separate reference and measurement beams, thereby eliminating the need for additional optical components
Solution Approach 2:
The patent makes the beam splitter serve multiple functions: it not only divides the measurement light into reference and sample paths but also separates the reference light for position detection. This multi-functionality eliminates the need for separate components to manage returning light and maintain system simplicity
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 compact interferometer design using a semiconductor laser source allows for stable detection of the movable mirror's position without destabilizing laser oscillation, enhancing the accuracy and reliability of the interferometer's measurements.
Implementation Method 1
a beam splitter that splits incident light into two light beams
Implementation Method 2
the light beam reflected off the movable mirror and the light beam reflected off the stationary mirror are combined by the above-described beam splitter into measurement interference light
Implementation Method 3
a reference light source that emits reference light
Implementation Method 4
The reference optical system has a collimator optical system for reference light that converts laser light emitted from the reference light source into collimated light, and the collimated light becomes obliquely incident on the stationary mirror
Implementation Method 5
the light beam reflected off the movable mirror and the light beam reflected off the stationary mirror are combined by the beam splitter and guided as reference interference light to a reference light photodetector for position detection
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An interferometer (1) measures a measuring interference beam, while detecting the position of a moving mirror (16) on the basis of detection results obtained from a reference beam detector (25). In the interferometer, a reference beam source (21) is configured by including a light source (21a) composed of a semiconductor laser device. A reference optical system (20) has a collimating optical system (22) for a reference beam, said collimating optical system converting a laser beam outputted from the reference beam source (21) into a collimated beam, and the collimated beam is diagonally inputted to a fixed mirror (15).