Speckle reduction is important in interferometry-based arrangements in order to improve the accuracy and precision of the measurement as such speckle patterns can obscure the underlying fringes, making it difficult to analyze or interpret the results. In the present work, we demonstrate the implementation of a chiral nematic liquid crystal (LC) based diffuser as a tool to mitigate the influence of speckles in an interferometry arrangement. Such LC based diffusers are controlled by adjusting the applied voltage to modulate the phase of the incident light dynamically to create a temporally varying random phase mask that can reduce the impact of spatially varying speckle noise. Proof-of-concept experimental results are included to demonstrate the reduction of speckle in an interferometric arrangement using chiral nematic LC materials. Quality metric parameters are also defined to analyse and quantify the amount of reduction for different values of the applied voltage to the LC diffuser.
A well-known issue when dealing with lasers as illumination sources is the formation of speckle, which results in an intensity interference pattern that appears superimposed on an image. To combat the formation of speckle, we have been developing tunable liquid crystal (LC) diffusers that can reduce the appearance of speckle in a range of different display and imaging applications. Not only does this approach provide direct control of the speckle contrast, allowing it to be reduced from C = 0.7 to C = 0.07, but it does so without the need for bulky mechanical parts, moving components or expensive elements.
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