Angular aperture

About: Angular aperture is a research topic. Over the lifetime, 1771 publications have been published within this topic receiving 27257 citations.

A desktop X-ray monochromator for synchrotron radiation based on refraction in mosaic prism lenses.

Abstract: Focusing planar refractive mosaic lenses based on triangular prism microstructures have been used as an alternative approach for wide-bandpass monochromatization of high-energy X-rays. The strong energy dependence of the refractive index of the lens material leads to an analogous energy dependence of the focal length of the lens. The refractive mosaic lens, in comparison with the refractive lens of continuous parabolic profile, is characterized by a higher aperture because of reduced passive material. In combination with a well defined pinhole aperture in the focal plane, the transmittance of photons of an appropriate energy can be relatively high and photons of deviating energy can be efficiently suppressed. The photon energy can be tuned by translating the pinhole along the optical axis, and the bandwidth changed by selecting appropriate pinhole aperture and beam stop. This method of monochromatization was realised at the ANKA FLUO beamline using a mosaic lens together with a 20 µm pinhole and beam stop. An energy resolution of 2.0% at 16 keV has been achieved.

Aperture stop assembly for a laser beam optical system

Abstract: An aperture stop assembly is shown which may be utilized within a laser beam optical system whose laser beam has been split into zero, first and second order beams. A lens is provided to focus the split beams upon a focal plane where an aperture stop is mounted having an aperture aligned with the desired first order beams. The reflective surface of the aperture is arranged at an angle to reflect the unwanted zero and second order beams into a series of absorption baffles found within the aperture stop housing or the aperture stop may absorb unwanted beams directly.

Toward one nanometer X-ray focusing: a complex refractive lens design

Abstract: We report a design for one nanometer X-ray focusing by a complex refractive lens, which is capable of focusing 20 keV X-rays down to a lateral size of 0.92 nm (full-width at half-maximum (FWHM)) and an axial size of 98 nm (FWHM) with intensity gain of 49050. This complex refractive lens is comprised of a series of kinoform lenses, whose aperture is gradually matched to the converging trace of the X-ray beam so as to increase the numerical aperture (NA). The theoretical principle of the proposed complex refractive lens is presented. The NAs of these lenses are calculated. The numerical simulation results demonstrate that the proposed design can focus the X-ray beam into sub-nanometer while remaining high gain.

Rod lens array for line scanning

Abstract: A rod lens array for line scanning is provided that can reduce the degradation of image quality (i.e., vertical stripes (streaks) in the sub-scanning direction of an output image) caused by a periodic irregularity in the light quantity, considering an angular aperture and the positional deviation of an image line in the sub-scanning direction. A rod lens array for one-to-one imaging is used as the rod lens array for line scanning, including a plurality of columnar rod lenses having a refractive index distribution in the radial direction that are arranged in one row in the main scanning direction with their optical axes in parallel. The effective overlapping degree m is in the range defined by (1.55+0.5 j ) D/d≦m≦ (1.80+0.5 j ) D/d Eq. 37 where d is the lens diameter of the rod lens and D is the array pitch of the rod lenses.