ABSTRACT
In this Letter, we report the application of planar liquid crystal (LC) devices in axial focus shaping, proving that LC diffractive optical elements (DOEs) can achieve continuous adjustment of a symmetrical axial light field by changing the ellipticity of the incident light and can flexibly and quickly achieve various axial light field designs through an axial iterative Fourier transform algorithm. The LC DOE achieves a quasi-continuous phase and an extremely high transmittance (98.6% at 1030â nm), which makes the focusing efficiency of the LC DOE with two segments of uniform focal depths as high as 84%. The experimental results demonstrate the accurate optical field shaping effect and the axial intensity adjustable ability of LC DOE, indicating potential applications in optical tomography and precision manufacturing, among others.
ABSTRACT
Photobiomodulation therapy (PBMT) is a non-invasive and pain-less treatment for hair loss. Researches on PBMT rarely considered the impact of different light structures. In this study, we irradiated shaven rats with both 650 nm, m = 32 vortex beams and ordinary Gaussian beams. The laser treatment was performed at 24-hour intervals for 20 days. The energy density was set to 4.25 J/cm2 . The results indicated that low-level vortex beam irradiation led to better stimulation of hair growth than the Gaussian beams, which might be related to deeper penetration. The underlying biological mechanisms are discussed in terms of the activation of Wnt/ß-catenin/sonic hedgehog pathway. Our results suggest that low-level vortex beam irradiation is advantageous to the treatment of hair loss because it is technically feasible, convenient and effective.
