Tunable Filter Spectral Response Speed Testing
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Solution Overview
Problem
Current methods for testing the spectral response speed of high-speed tunable filters lack the necessary temporal precision, as they can only measure wavelength changes at the millisecond level, which is insufficient for filters with microsecond-level wavelength output changes.
Innovation Solution
A system comprising a collimating light source, a tunable filter, a beam splitting element, and a high-speed or rolling shutter camera, where the tunable filter is continuously tuned, and the image recording device captures the displacement of light spots to calculate the response time, effectively converting spectral changes into spatial movements for precise timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spectrometer is used for testing rapidly changing portions of wavelength, then the testing can be performed, but the temporal precision can just reach the millisecond level which is insufficient for microsecond-level wavelength output changes
Solution Approach 1:
The patent transforms the spectral dimension (wavelength) into the spatial dimension (light spot position) using a diffraction grating. Different wavelengths are diffracted at different angles, creating spatially separated light spots on the detector. This allows the high-speed spectral output of the tunable filter to be converted into high-speed spatial movement of light spots, which can be captured by a camera with microsecond-level temporal precision.
Solution Approach 2:
The patent replaces the traditional spectrometer's mechanical scanning system with a static diffraction grating and camera system. Instead of mechanically moving components to measure wavelength changes over time, the system uses the diffraction grating to spatially separate wavelengths and a high-speed camera to capture the temporal evolution of light spot positions, achieving microsecond-level temporal precision.
2Speed
If the tunable filter continuously changes output wavelength at microsecond level, then the spectral response speed is high, but the measurement becomes difficult with conventional millisecond-level testing equipment
Solution Approach 1:
The patent converts the difficult-to-measure spectral dimension (wavelength changes at microsecond level) into an easier-to-measure spatial dimension (light spot position changes). The diffraction grating maps different wavelengths to different spatial positions, and the camera captures these position changes with high temporal precision, making the measurement of fast spectral responses feasible.
Solution Approach 2:
The patent changes the measurement parameter from wavelength (spectral domain) to light spot position (spatial domain). By using the diffraction grating's angle-wavelength relationship, the system measures position changes instead of directly measuring wavelength changes, enabling high-speed spectral response measurement with standard camera equipment.
3Measurement precision
If a beam splitting element with diffraction grating is used to separate different wavelength bands, then the spectral resolution is improved, but the device complexity increases
Solution Approach 1:
The patent uses a single diffraction grating to perform multiple functions: it separates different wavelength bands spatially, enables spectral resolution through angle-wavelength mapping, and works with standard camera equipment. This multi-functional approach achieves high spectral resolution without requiring complex specialized measurement systems.
Solution Approach 2:
The patent creates a spatial copy of the spectral information using the diffraction grating. Instead of directly measuring wavelength, the system captures a spatial distribution pattern (copy) of different wavelengths at different positions on the camera sensor, which can then be analyzed to determine spectral response characteristics.
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 approach allows for high-precision testing of tunable filters by recording the time required for light spots to move across the image sensor, achieving temporal precision in the range of microseconds, thereby accurately measuring the spectral response speed of high-speed wavelength output changes.
Implementation Method 1
the beam splitting element employs a diffraction grating or a refractive prism
Implementation Method 2
the beam splitting element employs a diffraction grating or a refractive prism
Implementation Method 3
the focusing lens being used to focus the diffracted beams or refracted beams
Data Source
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AI summary
A system for testing a spectral response speed of a tunable filter is disclosed, which includes a collimating light source, a beam splitting element, a focusing lens, and an image recording device of light spot position arranged successively. The tunable filter is disposed between the collimating light source and the beam splitting element and configured to be continuously tuned within a certain wavelength range during testing. The beam splitting element is used to form light beams of different wavelength bands passing through the tunable filter into diffracted beams or refracted beams corresponding to different wavelength bands. The focusing lens is used to perform focusing. The image recording device of light spot position is used to record change information about positions where the diffracted beams or refracted beams corresponding to different wavelength bands are imaged. A testing method is further disclosed. Different diffraction angles or refraction angles are generated by the beam splitting element, resulting in light spot position distributions of corresponding wavelengths at the spatial receiving end. Change information in the spectral dimension is converted into that in the spatial dimension to obtain the wavelength response speed of the tunable filter.