Angular aperture

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

Wide angle photographic lens

Abstract: A small, light weight wide angle photographic lens has attachment size of less than approximately 3.5 times the focal length and has a field angle of approximately 100°. The wide angle photographic lens includes a first lens L 1 having a negative refractive power and a concave surface facing the image side; a second lens L 2 with a positive refractive power having the convex surface facing the object side; a third lens L 3 having a negative refractive power cemented to the second lens L 2 and having a surface with a larger absolute value of index of refraction on the image side; a fourth lens L 4 having a positive refractive power cemented to the third lens L 3 and having a surface with a larger index of refraction on the object side; and a plurality of lenses on the image side of the fourth lens L 4 , wherein the concave surface of the first lens L 1 is an aspherical surface with a conical constant κ greater than 0.3 and less than 0.3 with a curvature of the concave surface decreasing monotonically with increasing distance from the optical axis. The wide angle photographic lens also satisfies conditions 0

Varying a numerical aperture of a laser during lens fragmentation in cataract surgery

Abstract: Some embodiments disclosed here provide for a method fragmenting a cataractous lens of a patient's eye using an ultra-short pulsed laser. The method can include determining, within a lens of a patient's eye, a high NA zone where a cone angle of a laser beam with a high numerical aperture is not shadowed by the iris, and a low NA zone radially closer to the iris where the cone angle of the laser beam with a low numerical aperture is not shadowed by the iris. Laser lens fragmentation is accomplished by delivering the laser beam with the high numerical aperture to the high NA zone, and the laser beam with the low numerical aperture to the low NA zone. This can result in a more effective fragmentation of a nucleus of the lens without exposing the retina to radiation above safety standards.

Confocal line sensor

Abstract: Disclosed is a sensor device for measuring distances according to the principle of confocal microscopy, comprising an approximately punctiform first aperture for a transmitted light beam and at least one second aperture as a receiving aperture arranged concentrically to the first aperture. Both apertures use a joint lens provided with a collimator and a focussing element. By positioning the second aperture away from the optical axis and positioning the first aperture exactly on the optical axis, the light received via the second aperture and reflected by the object to be measured contains a minimum of intensity when the object surface 2 is exactly in the focal point of the viewed light wavelength. The wavelength of the light that is not received by the second aperture acts as an identifier for the distance between the sensor and the measuring point of the object surface when multichromatic light is used and the lens provided with the collimator and the focussing element has sufficient longitudinal chromatic aberration.

The solid angle (geometry factor) for a spherical surface source and an arbitrary detector aperture

Abstract: It is proved that the solid angle (or geometry factor, also called the geometrical efficiency) for a spherically symmetric outward-directed surface source with an arbitrary radius and polar angle distribution and an arbitrary detector aperture is equal to the solid angle for an isotropic point source located at the center of the spherical surface source and the same detector aperture.