Photoelastic Polymer Disc Chopper for High-Frequency Modulation
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Solution Overview
Problem
Existing mechanical chopper-based light modulation systems struggle to achieve modulation frequencies above 10 kHz due to mechanical and electronic challenges, and are limited by acoustic and vibrational implications.
Innovation Solution
A chopper system utilizing a transparent disc with an inner and outer opaque pattern, where the inner pattern is used for high-frequency light chopping and the outer pattern synchronizes and controls the chopper's rotation, allowing for broadband optical modulation at frequencies up to 100 kHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical chopper rotation frequency is increased to achieve higher modulation frequencies, then modulation frequency is improved, but mechanical strength and stability deteriorate due to severe acoustic and vibrational implications
Solution Approach 1:
The patent replaces the traditional mechanical blade chopper system with a photoelastic polymer disc system. The modulation is achieved through optical properties (birefringence) rather than mechanical blade rotation, eliminating the mechanical strength limitations. The polymer disc can be rotated at ultra-high speeds without the mechanical failure risks that plague traditional blade choppers.
Solution Approach 2:
The patent changes the fundamental parameter from mechanical blade geometry to optical material properties. By using photoelastic polymer materials with specific birefringence characteristics, the system achieves light modulation through optical anisotropy rather than physical blade obstruction, enabling frequencies above 10 kHz without mechanical strength compromises.
2Speed
If mechanical chopper rotation frequency is increased to achieve higher modulation frequencies, then modulation frequency is improved, but acoustic and vibrational noise increases
Solution Approach 1:
The patent substitutes mechanical blade chopping with optical modulation using photoelastic materials. The light modulation occurs through changes in optical birefringence rather than mechanical obstruction, dramatically reducing acoustic and vibrational noise even at ultra-high rotation frequencies.
3Speed
If acousto-optic modulators are used to achieve extremely high modulation frequencies, then modulation frequency is improved, but wavelength range applicability deteriorates
Solution Approach 1:
The patent creates a universal chopper system using photoelastic polymer materials that can modulate light across a broad wavelength spectrum. Unlike acousto-optic modulators that are wavelength-specific, the polymer-based system maintains effectiveness across UV, visible, and infrared ranges, providing multi-functional applicability.
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 system achieves high-frequency light modulation with minimal increase in control electronics complexity, enabling reduced noise and access to high-frequency sample responses, which is particularly beneficial for fast imaging and pump-probe schemes.
Implementation Method 1
The chopper comprises a photoelastic polymer disc
Data Source
AI summary
A system for evaluating a sample, the system includes (i) a chopper that includes (i.1) a disc that is made of a transparent material that bears an inner opaque pattern and outer opaque pattern, the outer opaque pattern surrounds the inner opaque pattern, and (i.2) a rotating unit that is configured to rotate the disc during a modulation period, (ii) first optics, (iii) second optics, (iv) a control unit that is configured to detect a second modulated beam from the second optics, and control the rotating unit based on at least one parameter of the second modulated beam.