Diffraction efficiency

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

Diffractive lens fabricated with mostly zeroth-order gratings

Abstract: We demonstrate a spherical diffractive lens fabricated in fused quartz for use at the 632.8-nm wavelength. The lens is constructed by use of a modulated two-dimensional binary grating with a high transmitted zeroth-order efficiency. Rigorous eigenmode analysis is used to correlate the desired phase modulation with the fill factor. Fabrication requires only one lithography step. Using the lens, we were able to image a focal spot with a diffraction-limited spot size (FWHM).

Efficiency and Image Contrast of Dielectric Holograms

Abstract: The contrast and diffraction efficiency of a dielectric hologram made from a diffuse signal beam is calculated. Diffraction efficiency of 64% with acceptable image contrast is possible. Experimental results with holograms made by bleaching photographic emulsions are presented.

Demonstration of focus-tunable diffractive Moiré-lenses.

Abstract: In an earlier publication [Appl. Opt. 47, 3722 (2008)] we suggested an adaptive optical lens, which consists of two cascaded diffractive optical elements (DOEs). Due to the Moire-effect the combined optical element acts as a Fresnel zone lens with a refractive power that can be continuously adjusted by a mutual rotation of the two stacked DOEs. Here we present an experimental realization of this concept. Four designs of these Moire-DOEs (MDOEs) were fabricated in thin (0.7 mm) glass slides by lithography and subsequent etching. Each element was realized as a 16 phase level DOE designed for 633 nm illumination. Our experimental investigation shows that the Moire-lenses have a broad adjustable refractive power range with a high efficiency, which allows one to use them for flexible beam steering and for imaging applications.

First results from a next-generation off-plane X-ray diffraction grating

Abstract: Future NASA X-ray spectroscopy missions will require high throughput, high resolving power grating spectrometers Off-plane reflection gratings are capa- ble of meeting the performance requirements needed to realize the scientific goals of these missions We have identified a novel grating fabrication method that utilizes common lithographic and microfabrication techniques to produce the high fidelity groove profile necessary to achieve this performance Application of this process has produced an initial pre-master that exhibits a radial (variable line spacing along the groove dimension), high density (>6000 grooves/mm), laminar profile This pre- master has been tested for diffraction efficiency at the BESSY II synchrotron light facility and diffracts up to 55 % of incident light into usable spectral orders Fur- thermore, tests of spectral resolving power show that these gratings are capable of obtaining resolving powers well above 1300 (λ/�λ ) with limitations due to the test apparatus, not the gratings Obtaining these results has provided confidence that this

Femtosecond laser damage threshold of pulse compression gratings for petawatt scale laser systems

Abstract: Laser-induced femtosecond damage thresholds of Au and Ag coated pulse compression gratings were measured using 800 nm laser pulses ranging in duration from 30 to 200 fs. These gratings differ from conventional metal-on-photoresist pulse compression gratings in that the gratings patterns are generated by etching the fused silica substrate directly. After etching, the metal overcoating was optimized based on diffraction efficiency and damage threshold considerations. The experiment on these gratings was performed under vacuum for single-shot damage. Single-shot damage threshold, where there is a 0% probability of damage, was determined to be within a 400–800 mJ/cm2 range. The damage threshold exhibited no clear dependence on pulse width, but showed clear dependence on gold overcoat surface morphology. This was confirmed by electromagnetic field modeling using the finite element method, which showed that non-conformal coating morphology gives rise to significant local field enhancement near groove edges, lowering the diffraction efficiency and increasing Joule heating. Large-scale gratings with conformal coating have been installed successfully in the 500 TW Scarlet laser system.