Diffraction efficiency

About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.

Highly efficient spectrally encoded imaging using a 45° tilted fiber grating

Abstract: A novel highly efficient, fiber-compatible spectrally encoded imaging (SEI) system using a 45° tilted fiber grating (TFG) is proposed and experimentally demonstrated for the first time, to the best of our knowledge The TFG serves as an in-fiber lateral diffraction element, eliminating the need for bulky and lossy free-space diffraction gratings in conventional SEI systems Under proper polarization control, due to the strong tilted reflection, the 45° TFG offers a diffraction efficiency as high as 935% Our new design significantly reduces the volume of the SEI system and improves energy efficiency and system stability As a proof-ofprinciple experiment, spectrally encoded imaging of a customer-designed sample (96 mm x 30 mm) using the TFG-based system is demonstrated The lateral resolution of the SEI system is measured to be 42 μm in our experiment

Multi foci with diffraction limited resolution.

Abstract: The generation of multi foci is an established method for high-speed parallel direct laser writing, scanning microscopy and for optical tweezer arrays. However, the quality of multi foci reduces with increasing resolution due to interference effects. Here, we report on a spatial-light-modulator-based method that allows for highly uniform, close to Gaussian spots with diffraction limited resolution using a wavelength of 780 nm. We introduce modifications of a standard algorithm that calculates a field distribution on the entrance pupil of a high numerical aperture objective splitting the focal volume into a multitude of spots. Our modified algorithm compares favourably to a commonly used algorithm in full vectorial calculations as well as in point-spread-function measurements. The lateral and axial resolution limits of spots generated by the new algorithm are found to be close to the diffraction limit.

Optical system comprising a diffractive optical element, and method of designing the same

Abstract: The invention relates to a method of easily and quantitatively determining the diffraction efficiency of a relief type diffraction optical element, and provides a method of designing an optical system comprising a diffractive optical element using diffraction efficiency as at least one estimation index. The diffractive optical element is a transmission blaze grating constructed of a relief having a sawtooth shape in section. The transmission blaze grating having a side wall substantially vertical to a grating surface. The estimation index is given by a predetermined mathematical expression including at least a phase difference due to a relief discontinuity and shadow effects thereof. The mathematical expression includes as the shadow effects of said discontinuity at least a light attenuation effect dependent on an angle-of-incidence and a light attenuation effect independent on the angle-of-incidence in a separate manner.

Fringing-field minimization in liquid-crystal-based high-resolution switchable gratings

Abstract: A liquid-crystal (LC)-based high-resolution switchable grating is proposed by using a double-sided structure, where striped electrodes are patterned on both sides of the LC cell. A unique biasing configuration is employed to successfully minimize the distortion of the LC director profile due to the fringing-field effects under two-dimensional electric fields. A first order diffraction angle of 14.5° with a diffraction efficiency of 33% for transmission light at 1.55μm is experimentally achieved. This result approaches the theoretical upper limit of 33.8% for a sinusoidal phase grating. The device efficiency is enhanced 80 times compared to a conventional single-sided device. Experimental results indicate the tolerance of electrode misalignment is 2μm.

Wobble correction and focusing optical element with refractive toroidal surface and binary diffractive optical surface

Abstract: A wobble correction and focusing optical element for a raster optical scanner combines a toric lens, which provides most of the optical power for focusing the light beam to a scan line, with a binary diffractive optical surface, which corrects the field curvature of the toric lens and which also linearizes the scan. The diffractive surface will have a multi-level structure (binary diffractive optical surface) which possesses a diffractive phase function that will flatten the field curvature of the toric lens.