Lasers offer highly desirable characteristics for imaging and display applications, including high directionality, intensity, and potential for a wide color gamut. However, the coherence of laser light leads to the formation of speckle, a spatially distributed granular distortion caused by interference. In this presentation, we demonstrate novel liquid crystal (LC) active screens that enable a significant reduction in the speckle noise for RGB laser illumination sources. The advantages of the active screen approach are then highlighted in comparison to LC speckle reducers used in transmissive geometries. We conclude by considering the impact of the active screen configuration on image formation.
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.
Advances in vectorial polarization-resolved imaging are bringing new capabilities to applications ranging from fundamental physics through to clinical diagnosis. Imaging polarimetry requires determination of the Mueller matrix (MM) at every point, providing a complete description of an object’s vectorial properties. Despite forming a comprehensive representation, the MM does not usually provide easily interpretable information about the object’s internal structure. Certain simpler vectorial metrics are derived from subsets of the MM elements. These metrics permit extraction of signatures that provide direct indicators of hidden optical properties of complex systems, while featuring an intriguing asymmetry about what information can or cannot be inferred via these metrics. We harness such characteristics to reveal the spin Hall effect of light, infer microscopic structure within laser-written photonic waveguides, and conduct rapid pathological diagnosis through analysis of healthy and cancerous tissue. This provides new insight for the broader usage of such asymmetric inferred vectorial information.
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