Liquid Crystal Shutter Assembly for Dynamic Long-Pass Filtering
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Solution Overview
Problem
Existing liquid crystal shutters in multi-spectral imaging systems are limited by the polarizing extinction ratio of polarizing filters and the limited transmission of liquid crystals, restricting the spectral range of effective shuttering.
Innovation Solution
A liquid crystal assembly with a polarizer configured to have a light cut-off outside its range of polarization, combined with a liquid crystal that toggles between open and closed states using bi-polar square waves, allowing high and low electric fields to enhance light transmission and block unwanted wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional polarizing filters are used in liquid crystal shutters, then the spectral range of effective shuttering is limited by the polarizing extinction ratio, but the结构简单性 (structural simplicity) is maintained
Solution Approach 1:
The patent inverts the conventional approach by positioning the polarizer after the liquid crystal shutter rather than before it. This reversal allows the liquid crystal to first modulate the light spectrum, and then the polarizer to filter the remaining wavelengths, thereby extending the effective spectral range beyond the limitations of polarizer extinction ratios alone
Solution Approach 2:
The patent combines liquid crystal material with polarizing filters in a composite optical assembly where each component performs a specific function: the liquid crystal provides spectral modulation and the polarizer provides wavelength filtering. This composite structure achieves broader spectral control than either component could achieve alone
2Illumination intensity
If liquid crystal transmission is increased to allow more light through, then the signal-to-noise ratio improves, but the contrast ratio between blocked and transmitted states deteriorates
Solution Approach 1:
The patent introduces a polarizing filter as an intermediary element between the liquid crystal shutter and the detector. This polarizer acts as a mediator that enhances the contrast ratio by blocking unwanted wavelengths while allowing the liquid crystal to control the intensity of transmitted light, thus resolving the trade-off between light transmission and contrast
3Speed
If video rate switching speeds are achieved, then motion blur is reduced, but the energy consumption increases
Solution Approach 1:
The patent employs periodic switching of the liquid crystal shutter at video rates (typically 30-60 Hz) to achieve temporal multiplexing of spectral bands. This periodic action allows the system to capture multiple spectral images sequentially and combine them, reducing motion blur while managing energy consumption through efficient duty cycling
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 solution increases the ratio of transmitted light available for imaging, enabling high-speed video rate switching and improved signal-to-noise ratio, reducing motion blur, and enhancing contrast-to-noise ratio in fluorescent imaging.
Implementation Method 1
a polarizer disposed in a path of light from the light source. The polarizer is configured to have a light cut-off in a range outside of its range of polarization
Implementation Method 2
a liquid crystal disposed in a path of light transmitted through the polarizer and a drive voltage source configured to apply a first voltage and a second voltage to the liquid crystal. The first voltage and the second voltage achieve high and low electric fields across the liquid crystal
Implementation Method 3
the second voltage induces a backflow in the liquid crystal
Data Source
AI summary
The present disclosure relates to a novel liquid crystal assembly for use in multispectral imaging systems. In particular, the liquid crystal assembly includes an engineered polarizer and a liquid crystal. In various aspects, the liquid crystal assembly takes advantages of short-comings found in conventional polarizers and liquid crystals requiring complex temperature regulation.