Reduction of laser speckle noise by using particle-dispersed liquid crystals

54‐1: Laser Speckle Reduction using Nanoparticle‐Embedded Liquid Crystals

“…There is no external voltage applied on the liquid crystal cell during observation, which indicates that it is a zero-power consumption laser speckle reduction device. The similar results were reported by Furue et al [16] with the NPs of fumed silica NPs Aerosil R-812(EVONIK). The benefit of using PγCyD-ZrO 2 NP is that there is a large refractive index discrepancy between NPs and liquid crystal host.…”

P‐222:Late‐News‐Poster:Mechanically‐Static Laser Speckle Reduction Solution

“…Comparing the cells at the field-off state (Figure 2(a) vs. Figure 2(c)), the NP-doped LC cells shows a slight speckle reduction effect, which matches the phenomenon that was observed and reported in references [18,[25][26]. However, the laser speckle is reduced more significantly by inducing the electro-convection effect in LCs [27].…”

“…Several solutions are proposed based on the temporal decoherence approach, for example, mechanically vibrating or rotating an optical component such as diffuser, microlens array, phase matrix and/or optical fibers [8][9][10][11][12]. Motionless approaches have also been demonstrated by using a polymer dynamic diffraction grating, colloidal suspension, spatial light modulator, ferroelectric liquid crystal (LC), LC with chiral dopant, and nanoparticle (NP)-doped LC devices [13][14][15][16][17][18]. While the solution of using a moving diffuser is mostly selected due to its low cost and effectiveness, motionless approaches are of high interest, since they eliminate the risk of mechanical failure in products.…”

Laser Speckle Reduction Using a Liquid Crystal Diffuser Enhanced with Redox Dopants

“…By virtue of their electro‐optic properties, liquid crystals (LCs) are appealing for the reduction of the speckle contrast and as a result have been considered for this purpose by numerous research teams. [ 6–15 ] An example of previous research in this area involved the use of a nematic LC device with a controllable alignment layer consisting of polyvinyl alcohol (PVA) and an azo dye. [ 6 ] Exposing the device to ultraviolet (UV) light resulted in a reorientation of the LC director through the PVA/azo dye alignment layer enabling access to two orthogonal polarization states and thus giving rise to a reduction in the speckle contrast of .…”

“…[ 10,11,13 ] Other techniques have included the addition of nanoparticles to LC materials. [ 14,15 ] Alternatively, LC spatial light modulator (SLM) technology has been used to generate multiple random phase masks corresponding to the Hadamard orthogonal functions. [ 12 ] This approach has been shown to reduce speckle contrast by 1/ when using 64 cyclic phase patterns.…”