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 zoom lens with high zoom ratio

Abstract: A two lens group type of miniaturized zoom lens system having a minimum wide end viewing angle of 76° and a zoom ratio at least 2.3. The first or object side lens group includes at least two positive and two negative lenses with the image side lens being positive. The second or image side lens group includes at least two positive lenses facing the object. The variable aperture is mounted in front of the second lens group and the fixed aperture, which may be proportionally movable, is mounted behind the second lens group. The overall lens system satisfies the following conditions: ##EQU1## wherein: Z is the zoom ratio (Z=fT /fW), f1 is the focal length of the first lens groups, f2 is the focal length of the second lens group, fW is the focal length in the wide angle position, fT is the focal length in the telescopic or narrow angle position, and rI is the radius of curvature of the lens surface facing the object of the positive lens nearest to the image in the first lens group.

Development of Microlens for High-Density Small-Form-Factor Optical Pickup

Abstract: A microlens of numerical aperture (NA) 0.85 a small-form-factor optical pickup, following the specifications of the Blu-ray disc (BD), was designed, fabricated and evaluated. To avoid difficulties in the fabrication of a high-NA objective lens and to obtain a low chromatic aberration, a new hybrid lens unit was designed to have a refractive lens and a diffractive lens. The micro-plano-aspheric refractive lens was fabricated using glass molding technology, and the diffractive lens was fabricated in a two-dimensional array using the electron beam mastering and consecutive UV embossing process. For the evaluation of the developed lens unit, diffraction efficiency was measured with the proposed diffraction efficiency measurement method, and the wavefront error of the lens unit was evaluated using a modified Mach–Zehnder interferometer. The measured average efficiency of the diffractive lens was approximately 85% and the RMS wavefront error of the lens unit was 0.0376 λrms.

Intensity, Brightness and ´ Etendue of an Aperture Lamp

Abstract: Phosphor molecules are excited by ultraviolet light emitted during the steady electrical discharge of the low-pressure gas inside the lamp, and subsequently de-excite via emission of visible light. Some of this light is absorbed and re-emitted by the phosphor. In this problem, assume that there are no losses in this absorption/re-emission. Compare the intensity, brightness and etendue of the light from an ordinary fluorescent lamp (with no reflector and phosphor over the full azimuth) with that of an aperture lamp, with small angular aperture Δφ, with the same power output in the visible light. You may assume that the phosphor surface emits radiation according to Lambert’s cosine law [2]. Note that the principle of this problem applies equally well to a lamp consisting of an array of light-emitting diodes (which also absorb and re-emit light with little loss). Show that the effect of the phosphor/reflector (optical insulator) is to increase the intensity/brightness/temperature of the light inside the lamp (and the light emitted by it) for a given input power. The phosphors are typically metal oxides with a PO4 radical, often with rare-earth elements. The first variant of an aperture lamp may be from 1936 [1]. See, for example, sec. 4.8 of [3]. The principle also applies to an incandescent lamp in which a reflector (mirrorlike or diffuse) directs some of the light back onto the filament. The small size of tungsten filaments makes this a small effect, which apparently went unnoticed until (2000) [4]). Subsequently it was noted that the principle (there called “light recycling”) applies to extended light sources [5], such as LEDs, and that these sources can also serve as diffuse reflectors as in the fluorescent aperture lamp. The effect of the “light recycling” by the phosphor/reflector is similar to that of insulation of the walls of a house in permitting a higher internal temperature for a given heat input.

Wide Angle Imaging Lens System with Two Positive Lenses

Abstract: A wide-angle imaging lens system with two positive lenses is revealed. The imaging lens system includes a first lens with positive refractive power that is a biconvex aspherical lens and a second lens having positive refractive power that is a meniscus lens with concave surface facing the image side. In the concave surface of the second lens, the effective diameter range from the lens center to the edge includes at least one inflection point that changes the refractive power of the second lens from positive to negative. Moreover, the following conditions are satisfied by the imaging lens system: 2  ω ≥ 70 ° ; 0.3 ≤ bf TL ≤ 0.6 wherein bf is back focal length, TL is distance from an aperture stop to an image plane, and 2ω is maximum field angle. Thus, the imaging lens system of the present invention has wide angle effects, short back focal length, and reduced overall length.

Displacement Measurement Sensor Using the Confocal Principle

Abstract: A displacement measurement sensor using the confocal principle for measuring small changes in distance to a specular target surface comprises a monochromatic light source such as a laser diode 12, an aperture, 31 an objective lens system 44 possessing spherical aberration that separates the monochromatic light at different focal distances according to the magnitude of angular deviation from the optical axis. Each distance of the target surface from the objective lens will select specific angular rays able to retrace the path through the objective lens and aperture. Each angle then will correspond to specific distance. The angle measurement is determined by detecting the light impinging on a light sensitive electronic detector array 36.