Optical Angle Sensor Using Diffractive Interferometry for Wavelength-Independent Detection
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Solution Overview
Problem
Conventional optical angle sensors face challenges in accurately detecting the change in angle due to rotation of a measurement target when the light source wavelength varies with environmental changes, leading to detection errors and instability in interference signal amplitude.
Innovation Solution
An optical angle sensor design that includes a diffraction unit with a diffraction grating attached to the measurement target, rotating in synchronization with the target, and a set of reflection units that stabilize the overlap of combined light at the light receiving unit by diffracting the light four times, canceling variations in traveling angle caused by wavelength changes, allowing for accurate angle detection regardless of wavelength changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical angle sensor uses a light source and lens to detect angle changes, then the detection can be performed, but the cost becomes high due to the need for high-quality and expensive optical components such as a lens to suppress noise
Solution Approach 1:
The invention extracts and eliminates the lens component from the optical system. By using a laser interferometer configuration with corner cubes and polarization beam splitters, the system achieves noise suppression and accurate angle detection without requiring a lens, thereby reducing cost while maintaining measurement precision.
Solution Approach 2:
The invention replaces the conventional optical detection mechanism (using lens for light focusing and noise suppression) with a laser interferometric measurement system. This substitution uses the interference of laser beams and polarization effects to achieve angle detection without mechanical or optical components like lenses, reducing cost and complexity.
2Device complexity
If the light source wavelength varies with environmental changes, then the detection system becomes simpler, but the detection accuracy deteriorates due to detection errors and instability in interference signal amplitude
Solution Approach 1:
The invention uses feedback by measuring the interference signal amplitude and using it to correct for wavelength variations. The system detects changes in interference pattern intensity caused by wavelength drift and compensates for these changes, maintaining measurement accuracy despite environmental variations in light source wavelength.
Solution Approach 2:
The invention accounts for parameter changes in light source wavelength by designing the optical path and interference measurement system to detect and compensate for these changes. By monitoring the interference signal characteristics and adjusting the measurement calculations, the system maintains precision despite variations in the wavelength parameter.
3Ease of manufacture
If a laser interferometer is used to measure angle changes, then the cost is reduced by eliminating the need for expensive lenses, but the system becomes sensitive to light source wavelength variations causing detection errors
Solution Approach 1:
The invention introduces feedback mechanisms to monitor and compensate for wavelength variations in the laser source. By continuously measuring the interference signal characteristics and using this information to correct for drift, the system maintains reliable and stable detection performance without requiring expensive wavelength-stabilized laser sources or high-quality optical components.
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 enables high-accuracy detection of angle changes with reduced cost and miniaturization, as it stabilizes the overlap of combined light and allows the use of semiconductor lasers, reducing the need for expensive He-Ne lasers.
Implementation Method 1
a first diffraction part that divides and diffracts light from the light source into a first light and a second light different from the first light
Implementation Method 2
a first reflection unit for reflecting the first light divided and diffracted by the first diffraction part toward the second diffraction part in a direction parallel to and opposite to the direction in which the first light is incident
Implementation Method 3
the laser beam emitted to the light receiving signal processing unit through the polarizing beam splitter for rotation angle detection causes interference at the irradiation surface
Data Source
AI summary
The optical angle sensor comprises a diffraction unit, a light source, a light receiving unit, and a plurality of reflection units. The diffraction unit includes a first diffraction part for generating combined light and a second diffraction part for diffracting a first light and a second light a plurality of times. The plurality of reflection units includes a first reflection unit, a second reflection unit, a third reflection unit that reflects the first light and the second light through the second diffraction part toward the second diffraction part, fourth reflection unit, and fifth reflection unit. The calculating unit, with the rotation of the diffraction unit, calculates the amount of change in the angle based on the change in the interference signal caused by the combined light generated on the light receiving surface.