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Angular aperture

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


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Journal ArticleDOI
TL;DR: In this article, a new method for rapidly acquiring fluorescence spectra from optical probes using an acousto-optic tunable filter (AOTF) was developed, which consists of a piezoelectric transducer bonded to a birefringent crystal.
Abstract: A new method for rapidly acquiring fluorescence spectra from optical probes using an acousto‐optic tunable filter (AOTF) has been developed. The AOTF consists of a piezoelectric transducer bonded to a birefringent crystal. Acoustic waves are generated in the crystal by an applied radio frequency. For a given radio frequency, only a narrow band of optical frequencies will be diffracted. Unlike normal Bragg diffraction which can only be used with collimated light, the AOTF has a large angular aperture (up to 28 deg) and can therefore be coupled to an uncollimated broadband white light source, photomultiplier tube, or camera. Using the device and a xenon–mercury arc lamp, excitation and emission spectra of the fluorescent pH probe BCECF were acquired in 17 ms (spectral resolution=4 nm). Rapid wavelength switching or modulation of selected wavelengths was achieved at ∼105 Hz. The device is also capable of spectral imaging with a spatial resolution of greater than 100 lines/mm.

65 citations

Journal ArticleDOI
J.J. Maciel1, L.B. Felsen
TL;DR: In this article, the authors studied the high-frequency propagation of electromagnetic wavefields from an extended planar aperture distribution through a complicated environment, and showed that narrow-waisted beams can reconstruct the correct transmitted field in these cases, as established independently by numerical evaluation of an exact spectral integral.
Abstract: High-frequency propagation of electromagnetic wavefields from an extended planar aperture distribution through a complicated environment is addressed. Geometric optical ray tracing provides a versatile approximate approach to the class of problems, but it fails in transition regions surrounding shadow boundaries and caustics. The uniformity required there can be established by field tracking with Gaussian beams. The basic theory is summarized and applied to the two-dimensional test problem of transmission of radiation from a finite one-dimensional plane aperture through a planar dielectric layer. For a truncated uniform or focused aperture illumination, tracking the edge or caustic transition regions through the layer when it is located within the Fresnel zone of the aperture poses a problem of substantial complexity. It is shown that narrow-waisted beams, which can be propagated in their far zone as complex ray fields, reconstruct the correct transmitted field in these cases, as established independently by numerical evaluation of an exact spectral integral. >

65 citations

Journal ArticleDOI
TL;DR: Aperture guiding, as opposed to thermal waveguiding, is shown to be the dominant mechanism for cavity mode stabilization in a quasi-three-level Yb:YAG laser in a flat-flat resonator.
Abstract: Aperture guiding, as opposed to thermal waveguiding, is shown to be the dominant mechanism for cavity mode stabilization in a quasi-three-level Yb:YAG laser in a flat-flat resonator. Excellent agreement is obtained between the experimental and modeled spot sizes in this laser when aperture guiding is included in the model. The models show that the spot size is insensitive to the exact form of the dependence of the transmission of the aperture on the transverse dimension. This finding is expected to affect other quasi-three-level lasers.

64 citations

Journal ArticleDOI
TL;DR: It is shown that the focal length, F-number, and numerical aperture can be dynamically controlled by changing the shape of the fluidic adaptive lens without moving the lens position mechanically.
Abstract: High-performance fluidic lenses with an adjustable focal length spanning a very wide range (30 mm to infinite) are demonstrated. We show that the focal length, F-number, and numerical aperture can be dynamically controlled by changing the shape of the fluidic adaptive lens without moving the lens position mechanically. The shortest focal length demonstrated is less than 30 mm for a 20-mm lens aperture. The fluidic adaptive lens has a nearly perfect spherical profile and shows a resolution better than 40 line pairs/mm in a plano-convex structure and 57 line pairs/mm in a biconvex structure.

64 citations

Patent
05 Sep 1996
TL;DR: In this article, an objective lens system for an endoscope having an image transfer optical fiber bundle comprises from the object end a first lens of negative power having a concave image side surface, a second lens of positive power with a radius of curvature greater on an image side than on an object side, a third lens and a doublet lens with an aperture diaphragm interposed between the second and third lenses and satisfies the following relations: |d·f/f.sup.
Abstract: An objective lens system for an endoscope having an image transfer optical fiber bundle comprises from the object end a first lens of negative power having a concave image side surface, a second lens of positive power having a radius of curvature greater on an image side than on an object side, a third lens of positive power having a radius of curvature greater on the object side than on the image side, a doublet lens of positive power which comprises a forth lens element and a fifth lens element, and an aperture diaphragm interposed between the second and third lenses and satisfies the following relations: |d·f/f.sub.R.sup.2 |<0.11 v2<45.0 where f is the equivalent focal length of the entire objective lens system, f R is the equivalent focal length of the rear lens group including the third, fourth and fifth lens elements, d is the axial distance between the aperture diaphragm and the front focal point of the rear lens group, and v2 is the Abbe number of glass for the second lens.

64 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
20224
20217
20207
20195
201811