Angular aperture

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

Parabolic Mirror and Air-Coupled Transducer for Multimodal Plate Wave Detection

Abstract: A conventional contact piezoelectric transducer, excited by a broadband burst (chirp) that covers its whole frequency bandwidth, is used as a transmitter to simultaneously generate several Lamb waves in a plate Throughout the propagation, these modes leak energy into the ambient air, producing bulk waves in many directions The association of a parabolic mirror and an air‐coupled transducer (PMAT) allows these waves to be received in air with a large angular aperture By displacing the PMAT in a direction parallel to the plate, but without changing its orientation like when standard air‐coupled receivers are used, a series of temporal waveforms are captured Signal processing then allows the phase velocity of the several Lamb waves to be measured in large wave number and frequency domains These resulting data are used to identify the moduli of elasticity for composite plates made of long glass fibers and polymer matrix

Simplified sector scan ultrasonic imaging system

Abstract: A curved transducer array or a flat array with an acoustic converging lens functions as a fixed focus physical lens and is focused near maximum range. At longer ranges the full aperture is utilized for good resolution, and at shorter ranges up to a specified fraction of maximum range improved resolution is achieved by a dynamic aperture control which increases the array aperture by steps by switching in more transducer elements. This simplified sector scanner does not require dynamic electronic focusing.

Image display device provided with condensing element

Abstract: PROBLEM TO BE SOLVED: To increase an effective numerical aperture and to make an exit angle small by means of a structure for independently determining the effective numerical aperture and the exit angle in an image display device for displaying an image and having a part, preventing a light beam from passing through it, in each pixel representing the image signal. SOLUTION: A micro-mirror 17, whose cross sectional shape is a triangle and front surface is a reflection surface, is formed on a light shielding layer 6. Incident light beams 10, 11 are made incident, directly or after reflected by the micro-mirror 17, on an aperture part 8. At this time, since an effective numerical aperture E and an exit angle ψ are independently designed, an image display device with a converging elements is provided suitable for a system. By facilitating the manufacture by making the cross sectional shape a trapezoid and forming the structure for refracting a light beam after reflection, the smaller exit angle is obtained.

A new type of quadrupole correction lens for electron-beam lithography

Abstract: A new type of quadrupole correction-lens system with lower aperture aberration coefficients has been developed for an electron-beam lithography system. The new lens is called a self-aligned quadrupole correction lens and consists of three-stage electrostatic quadrupoles, and aperture electrodes placed between quadrupoles. An octupole field for correction of aperture aberration is automatically created and aligned with a quadrupole field by supplying a voltage to the aperture electrode, and it has its peak near the edge portion of the quadrupole. A new mechanical construction of the quadrupole correction-lens system is developed for realizing high-precision alignment of the multistage lens electrodes. The optical properties of the new correction lens are exactly calculated by using simulated potential distributions. Aperture aberration coefficients of the new correction lens can be corrected to less than 0.1 mm. It is confirmed experimentally that the probe size is improved remarkably by excitations of the aperture electrodes.

Improved 3D Imaging System using Reflectors

Abstract: An improved 3D Imaging System Using Reflectors is provided. The device includes a beam splitter system comprising an even number of mirrors. The device also includes a lens panel that has two independent image forming lenses, and an aperture panel with a pair of apertures. The aperture panel is positioned between the beam splitter and lens plane to project dual images of the subject onto a film exposure or ground glass. The alignment of lens, aperture and beam splitter mirrors creates a pair of divergent light paths from lens pair to exposure plane, which simulates a single lens, permitting accurate light metering and a bright viewfinder image when the device is used with a Single Lens Reflex (SLR) camera.