Wavelength Tuning Source Using Rotating Polygon Scanner
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Solution Overview
Problem
Current optical wavelength filter systems are limited by slow tuning speeds, typically less than 100 nm/s, which restricts their application in high-speed biomedical imaging and optical coherence tomography, requiring faster wavelength tuning rates for video-rate imaging.
Innovation Solution
An optical wavelength filter system incorporating a diffraction grating and a rotating polygon scanner, capable of tuning at speeds greater than 15 kHz over a wide spectral range, combined with a laser gain medium to achieve high-speed wavelength tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional intra-cavity filters (acousto-optic filter, Fabry-Perot filter, galvanometer-driven diffraction grating filter) are used, then narrow line width and wide-range tuning can be achieved, but the tuning speed is limited to less than 100 nm/s
Solution Approach 1:
The patent replaces the mechanical galvanometer-driven diffraction grating filter with a polygon scanner system. The polygon scanner uses a rotating polygon mirror to deflect the laser beam across the diffraction grating, eliminating the need for mechanical rotation of the grating itself. This substitution enables much faster tuning speeds while maintaining the wavelength selection functionality.
Solution Approach 2:
The patent introduces dynamic control of the polygon scanner rotation speed to achieve variable tuning rates. By controlling the rotation speed of the polygon scanner, the system can dynamically adjust the wavelength tuning speed to match the requirements of different imaging applications, achieving speeds greater than 15 kHz repetition rate.
2Speed
If mechanical apparatus is used for mode-hop-free tuning, then single-frequency laser operation can be achieved, but the maximum tuning speed is limited to less than 100 nm/s
Solution Approach 1:
The patent replaces the slow mechanical apparatus with a polygon scanner system that uses optical deflection instead of mechanical grating rotation. This enables fast tuning while maintaining mode-hop-free operation through precise control of the beam deflection angle across the diffraction grating.
Solution Approach 2:
The patent changes the operational parameters by using a rotating polygon mirror with multiple facets to deflect the beam. Each facet position corresponds to a specific wavelength, and the rapid switching between facets enables fast tuning without mode hopping, achieving repetition rates greater than 15 kHz.
3Productivity
If conventional filters with sweep frequency less than 1 kHz are used, then narrow line width can be achieved, but the repetition rate is insufficient for video-rate imaging
Solution Approach 1:
The patent implements dynamic control of the polygon scanner rotation to achieve high repetition rates. By increasing the rotation speed of the polygon scanner and optimizing the beam deflection geometry, the system achieves tuning repetition rates greater than 15 kHz, enabling video-rate optical imaging applications.
Solution Approach 2:
The patent utilizes the periodic rotation of the polygon scanner to achieve rapid wavelength tuning. Each rotation cycle of the polygon scanner produces a complete wavelength sweep, and by synchronizing this periodic action with the imaging requirements, the system achieves high repetition rates suitable for video-rate imaging.
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
Enables video-rate optical imaging with a tuning speed more than an order of magnitude higher than conventional filters, providing a wide spectral range and instantaneous line width suitable for applications like optical coherence tomography and spectrally encoded confocal microscopy.
Implementation Method 1
The filter includes a diffraction grating
Implementation Method 2
The filter includes a rotating polygon scanner
Data Source
AI summary
An apparatus and source arrangement for filtering an electromagnetic radiation can be provided which may include at least one spectral separating arrangement configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus and source arrangement may also have at least one continuously rotating optical arrangement which is configured to receive at least one signal that is associated with the one or more components. Further, the apparatus and source arrangement can include at least one beam selecting arrangement configured to receive the signal.