Angular aperture

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

Method of Determining a Focal Point or Beam Profile of a Laser Beam in a Working Field

Abstract: In a method for determining the focal point or the beam profile of a laser beam, which can be deflected in the x and y directions by a scanner optic or an x-y-movement unit and can be displaced in the z direction by a focusing optic or a z-movement unit, at a plurality of measurement points in the two-dimensional working field or three-dimensional working space of the laser beam. An aperture diaphragm, followed by a detector, is arranged at each measurement point. At each measurement point, for x-y-focal point or beam profile measurements, the laser beam is moved by the scanner optic or the x-y-movement unit in an x-y-grid over the measurement aperture in the aperture diaphragm, and, at each grid point, the laser power is measured by the detector, the scanner axis of the scanner optic or the x-y-movement unit being stationary. For z-focal point measurements, the laser beam is displaced by the focusing optic or the z-movement unit in the z direction within the measurement aperture in the aperture diaphragm. The laser power is measured by the detector at each grid point. The focal point and/or the beam profile of the laser beam is then determined at each measurement point from the measurement values.

Fixed-focus lens system

Abstract: A fixed-focus lens system includes, in order from an object side to an image side along an optical axis thereof, an aperture stop, a first positive lens, a second negative lens, a third positive meniscus lens, and a fourth negative lens having increasing negative refractive power from the optical axis toward the periphery. The fixed-focus lens system satisfies the following condition: 0.1

Reflection type optical apparatus

Abstract: A beam splitter, a first polarizing plate and a quarterwave plate are provided in that order on the optical axis of an image formation lens between an image formation plane and an objective lens. The first polarizing plate comprises a non-polarizing region for transmitting illuminating light and reflected light and a polarizing region provided to enclose the non-polarizing region for transmitting the illuminating light but limiting the reflected light which is rendered out of phase with the illuminating light by the quarterwave plate. Thus, the angular aperture of the illuminating light can be increased and an irradiated plane can be observed with no hindrance even if the same is inferior in flatness, while illuminance of the irradiated plane can be sufficiently ensured. At the same time, the angular aperture of the objective lens can be reduced, and the depth of focus Q is increased.

A method of transforming Fresnel field to far field for circular aperture antennas

Abstract: A method of transforming Fresnel-region fields to far-region fields for circular aperture antennas consisting of arbitrary aperture field distributions is presented. In addition, this method can be directly applied to a planar antenna of any shape by defining the aperture diameter as the largest dimension of the antenna. The accuracy of this technique was demonstrated on a 32-element planar array. >