Abstract
The use of a liquid crystal Lyot filter as a simple and compact switchable laser protection system is demonstrated. The system OFF state exhibits a wavelength-independent transmission and switches to an ON state, which rejects a selected wavelength. The response time of the switchable system is <110 ms, depending on the rejected wavelength, with the ability for faster switching of <5 ms when using a lower-order rejection band. A rejection tuning range between 480 and 640nm is demonstrated, and the potential to operate outside of the visible spectrum is discussed. In the ON state, the transmission at the rejected wavelength was found to be effectively limited by the polarizer extinction ratio, while transmission at other wavelengths allows for partial observations through the system even when in protection mode.
Highlights
High-powered handheld laser with high intensity and coherent radiation can dazzle and cause permanent damage to sensor and surveillance systems
Tuneable liquid crystal Lyot filters can select a specific wavelength by applying a wavelength-dependent retardance to light passing through aligned polarizers
The ability to directly control the transmission spectrum through application of an electric or magnetic field to the liquid crystal element led to many further developments and applications of the Lyot filter to astronomical spectral observations [4,5,6,7,8], remote sensing [9, 10], laser tuning [11], and biological imaging [12, 13]
Summary
High-powered handheld laser with high intensity and coherent radiation can dazzle and cause permanent damage to sensor and surveillance systems. Lyot filters were first developed in 1933 by Lyot [1], and their initial implementation into astronomical observations was widespread [2] It was not until 1990 that a liquid crystal component was implemented as the birefringent material. The ability to directly control the transmission spectrum through application of an electric or magnetic field to the liquid crystal element led to many further developments and applications of the Lyot filter to astronomical spectral observations [4,5,6,7,8], remote sensing [9, 10], laser tuning [11], and biological imaging [12, 13]. Switching speed [16], contrast ratio [17], and spectral resolution [16] and reducing the passband size [14] or the appearance of side lobes [18]
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