Angular aperture

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

Focal properties of geodesic waveguide lenses

Abstract: The focal properties of uncorrected geodesic lenses in ion‐exchanged glass waveguides are reported. A 13.8‐mm‐focal‐length lens resolved by beams with an angular separation of 27.6 mrad, while a 28‐mm‐focal‐length lens resolved beams with an angular separation of only 3.3 mrad. Intensity profiles of the focal region of the former lens revealed a 40‐μ spot size when the input aperture was 5 mm, and a spot size of 7.7 μ when the aperture was reduced to 1 mm. This value is close to the diffraction‐limited spot size of 5.7 μ.

An optical method for direct determination of the radiometric aperture area at high accuracy

Abstract: An optical method for calibration of the aperture area is described and studied both theoretically and experimentally. A spatially uniform, known irradiance is formed over the aperture by overlapping identical, parallel laser beams centred at constant spacing in an orthogonal lattice. The ratio of the throughput power and irradiance gives the area of the aperture. The method has several advantages compared with previous methods: it measures the area of the aperture directly, the shape of the aperture is not limited to a circle, it is relatively inexpensive to establish, it does not damage the edges of the aperture and the calibration set-up is similar to that for the actual use of the aperture. It is estimated that the relative standard uncertainty is in calibration of a circular 3 mm diameter aperture. The results that the present method gave for one aperture have been compared with the result of a mechanical calibration at the National Physical Laboratory (UK). The relative difference between the results was , with a combined standard uncertainty of .

Optical scanner with power efficient lens

Abstract: An optical scanner which employs a special lens to maximize the percentage of focused laser light that passes through a collimating aperture. The optical scanner also includes a laser diode and a housing containing the laser diode and having a wall with the aperture therethrough for collimating light from the lens. The lens may be a gradient index (grin) lens, a bi-zonal lens, or an axicon lens. Another scanner is disclosed which employs an axicon lens to focus light reflected from an article having a bar code label to a detector for a range of article distances from the scanner.

Optical beam shifts in graphene and single-layer boron-nitride

Abstract: Optical beam shifts from a free-standing two-dimensional atomic crystal are investigated. In contrast to a three-dimensional crystal the magnitude of the Goos-H$\rm \ddot{a}$nchen shift depends on the surface susceptibility of the crystal and not on the wavelength of the incident light beam. The surface conductivity of the atomically thin crystal is less important in this context because it enters in the expression of the shifts only as a second order parameter. In analogy to a three-dimensional crystal the magnitudes of the Imbert-Fedorov shift and of the angular shifts depend respectively on the wavelength and on the square of the beam angular aperture.

High energy laser-to-waveguide coupling devices and methods

Abstract: Laser-to-waveguide coupling devices and methods are disclosed employing an aperture, and an imaging lens. The aperture clips the beam edges to flatten the spatial intensity profile, and the lens mirror-images the plane of the aperture onto the waveguide face with appropriate magnification or demagnification to match the input beam dimensions to those of the waveguide. In one preferred embodiment, a first focusing lens is also employed in conjunction with a pinhole aperture and a second imaging lens. The first focusing lens focuses the laser beam onto the aperture and thereby reduces the optical path length. The second imaging lens images the plane of the aperture onto the waveguide.