Conventional Lens System Research Articles

レーザ照射処理におけるカライドスコープによるパワー密度分布の変換 角管のカライドスコープを用いた焼入処理

The kaleidoscope is a device to convert the power density distribution of the laser beam. Rectangular pipe kaleidoscopes are applied to laser hardening experiments in the present research in order to show their effectiveness in the laser processing. The shapes and the dimensions of the kaleidoscopes are determined based on the theoretical analysis of the power density distribution of the laser beam converted by the kaleidoscopes. Laser hardening experiments are carried out for graphite-coated steel plates by applying both the kaleidoscopes and the conventional lens system. The heat affected zones of the processed materials are observed and compared from the viewpoints of the depths, the widths and the shapes. The following remarks are concluded from the experimental results. The heat affected zones of the workpieces generated by the laser beam converted by the kaleidoscopes are flatter and wider than those obtained by applying the conventional lens system. The surface deformation of the heat affected zone is relatively smaller in the case of the rectangular pipe kaleidoscopes than the conventional lens system.

Design study of an infrared panoramic optical system

A design study was undertaken on an infrared, 3-5-μm, panoramic optical system for a particular monitoring application. The different types of systems investigated covered the conventional fish-eye lens system, a panoramic block arrangement, and a new type of configuration based on a panoramic shell. Examples of these systems are included, and their advantages and disadvantages are discussed.

Pupil exploration and wave-front-polynomial fitting of optical systems

Pupil exploration and wave-front-polynomial fitting algorithms are tools that are often employed in image-quality evaluation techniques, such as optical-transfer-function and point-spread-function calculations. These techniques require that aberration data be determined for a large number of points across the pupil. With optical systems increasing in complexity, it is necessary that these algorithms become more sophisticated to ensure that the proper pupil shapes and aberration maps are used to represent the wave fronts. Such algorithms are described. These algorithms can handle systems that not only lack the symmetry found with the more conventional lens systems but those that also have apertures with unusual shapes. As practical demonstrations the treatments employed in the pupil exploration and the wave-front-polynomial fitting have been applied to various lens arrangements and the results discussed.

Praktische Erfahrungen bei der Umstellung auf die Weitwinkelbeobachtungssysteme für Glaskörperchirurgie BIOM, SDI, VPF

The wide-angle observation system for vitreous surgery introduced by Spitznas und Reiner has the following advantages: Wide angle of view. Large depth of field. Good view to the periphery even with narrow pupil. Easy gas fluid exchange in a phacic eye. Free mobility of the eye when working in the periphery. Changing from the conventional vitrectomy lens system to the BIOM an experienced surgeon is familiar with the new system in a very short time.

Scanning tunneling microscope microlens with magnetic focusing

We describe a design for a low-energy scanning tunneling microscope microlens with magnetic focusing, to achieve several improvements over conventional lens systems and previously reported microlens systems. First, scaling of the lens dimensions yields corresponding scaling of spherical and chromatic aberration coefficients. Second, magnetic focusing avoids the difficulty inherent in electrostatic microlenses of withstanding large potential differences over short distances, which can lead to dielectric breakdown in insulating elements of the lens, although magnetic focusing has an analogous problem with maximum achievable fields. Third, a low-energy (100–200 eV) electron beam offers a significant advantage in lithography, where proximity effect and scattering within the resist from conventional high-energy (>1 keV) electron beam systems act as serious limitations on pattern fidelity. Calculations indicate that for reasonable values of lens parameters (aperture potential=60–200 V, Bz=1.4–2 T, tip radius=300 Å, aperture diameter=0.25–0.5 μm, and convergence semi-angle=20–100 mrad), aberration coefficients on the order of 40–80 μm and beam diameters down to 150 Å are obtained, with beam current up to several μA.

Gradient-Index Optical Imaging Systems: A New Efficient Technique for Design and Analysis

The analysis and design of the gradient index (GRIN) lens systems, like those of conventional homogenous lens systems, involve extensive raytracing. However, in GRIN lenses the rays are curved and the ray paths are generally obtained by a numerical solution of the ray equation. We have developed new techniques for each of the steps involved in the analysis and design of GRIN systems, ie, the transfer of ray, ray-surface intersection and the optical path length (OPL) computation for the calculation of optical transfer function which gives the overall performance of a system. In particular, we have been able to obtain a new form of the ray equation which makes the transfer of ray very efficient and fast. The ray-surface intersection point has hitherto been obtained by iterative raytracing which often requires more computations than the transfer of ray itself. The method that we have developed reduces these computations to simple analytical ones. For OPL computations, our method is at least two orders of mag...

Book Reviews

The soft x-ray region covers wavelengths longer than those of medical x rays, where vacuum is required for propagation (A ^ 5 A). Absorption of all materials increases with increasing wavelength in this region, and the absorption length of, the most transparent specimens is around 1 pm for A « 50 A. Conventional lens and mirror systems cannot be built for soft x rays (due to absorption in lenses and low reflectivity of normal incidence mirrors), and only three types of imaging systems remain possible for soft x rays: grazing incidence reflectors, multilayer mirrors, and diffractive elements such as zone plates. Soft x-ray optics has advanced dramatically during the last decade.

ASTIGMATIC DECOMPOSITION: AN ALTERNATIVE SUBJECTIVE REFRACTION TEST EMPLOYING CONVENTIONAL INSTRUMENTATION

The Humphrey Vision Analyser introduced the refractive technique of astigmatic decomposition with the aid of Alvarez continuously variable sphere-cylinder lenses. The adaptation of astigmatic decomposition to conventional trial lens systems and a Stokes' lens is described. Refractive errors measured by this technique and by crossed cylinder are compared in 33 optometric patients (one eye each) to assess the relative validity of the method, which compares well with data published on the Humphrey Vision Analyser. Astigmatic decomposition can be considered as an alternative subjective refraction test to more conventional methods.

Astigmatic decomposition: An alternative subjective refraction test employing conventional instrumentation

Abstract The Humphrey Vision Analyser introduced the refractive technique of astigmatic decomposition with the aid of Alvarez continuously variable sphere-cylinder lenses. The adaptation of astigmatic decomposition to conventional trial lens systems and a Stokes'lens is described. Refractive errors measured by this technique and by crossed cylinder are compared in 33 optometric patients (one eye each) to assess the relative validity of the method, which compares well with data published on the Humphrey Vision Analyser. Astigmatic decomposition can be considered as an alternative subjective refraction test to more conventional methods.

Recording of one-dimensionally dispersed holograms in white light

A conventional lens system is incorporated into a three-grating interferometer, producing a system for making 1-D dispersed holograms in white light. A hologram of a 2-D transparency was made so that in 1-D the object was imaged onto the hologram, whereas in the orthogonal dimension, the image formed some distance from the hologram plane.

Matrix lens electron-beam recording systems

State-of-the-art achievements of matrix lens recording systems are presented in this paper. Also the primary beam limiting aberrations and physical constraints of matrix lens electron-beam recording systems are discussed. A new concept in matrix lens optics, known as the short focus plus relay with improved performance over conventional matrix lens systems is presented. Analytical projections of the beam current and spot size for this configuration are shown indicating significant performance improvements in matrix lens capabilities. Preliminary experimental data for the short focus plus relay matrix optics is presented.

A cassegrain collector with unusually high light grasp

AbstractThe design and performance characteristics of a Cassegrain mirror system suitable for Raman spectroscopy are described. This system has a number of outstanding advantages over more conventional lens systems, including its unusually high speed and achromaticity.

Comparison of optical-waveguide lens technologies

Various materials, lens structures, and processes are examined relative to the lens requirements of an RF spectrum-analyzer implemented through the use of an integrated-optics format. Factors which distinguish optical-waveguide lenses and reflectors from conventional imaging lens systems are enumerated. It is concluded that a thin-film Luneburg lens is the most viable planar approach based upon the use of oxides and, when high refractive-index materials must be employed, the spherical depressed geodesic becomes a feasible alternate.

Mesh-initiated large area detonators

Inexpensive large area detonators are described which utilize a mesh of etched copper brigewires to detonate PETN. Breakout simultaneity within 100 nsec is achieved on the surface of a PBX-9407 booster at discrete initiation points originating from the individual bridgewires. Initiation point densities as high as 3.1×105 m−2 are achieved by printed circuit manufacturing techniques. Electrical requirements are established from threshold burst current experiments. Two initiators are described; a general purpose 200-mm diam detonator, employing 750 or 10 000 bridgewires (depending on the mesh pattern used), and a 150×600 mm detonator employing 2300 that was developed for a fast explosive generator. These detonators achieve simultaneous detonation of large surface areas at lower cost and with much less explosive than conventional lens systems. They can also be applied to singly curved surfaces.

Red filters in the esophagoscopic diagnosis of esophageal varices.

The accuracy of the endoscopic diagnosis of esophageal varices is limited by difficulty in distinguishing esophageal varices from mucosal folds. This study was undertaken to determine whether the use of a red filter would make esophageal varices more easily recognizable by esophagoscopic examination. Two experienced endoscopists examined 17 cirrhotic patients independently for the presence of esophageal varices with the Eder-Hufford esophagoscope, using both conventional and red-filter lens systems. Fifty-four additional cirrhotic patients were examined by 1 endoscopist who used the red filter after dark adaptation and, subsequently, the conventional lens system. Esophageal varices appeared darker and more readily distinguishable from mucosal folds with use of the red-filter lens system after dark adaptation than with conventional esophagoscopy. Without dark adaptation, however, the red filter did not appear to influence favorably the endoscopic diagnosis of varices. Although these preliminary observations require confirmation, they suggest that the use of red filters may improve the precision of the endoscopic diagnosis of esophageal varices.

Introduction to Acoustical Holography

The principle of reconstructed wavefronts is extended to the formation of visual pictures of acoustical waves. The important relationships used in conventional optical holography that also apply to acoustics are briefly reviewed. It is shown that image formation using the principles of acoustical holography yields better results than do conventional acoustical lens systems, particularly in the presence of turbulence and turbidity. Experiments are described in which coarsely sampled acoustical holograms, made with sound wavelengths of 0.64 in. and longer, have successfully reconstructed images of acceptable quality. The signal-to-noise ratio in a sampled acoustical hologram is shown to increase with the number of sampled points as well as with the reduction in the size of the sampling probe. Applications of acoustical holography in different fields are discussed.

Design and Construction of Fresnel Optics for Photoelectric Receivers*†

The design and construction of Fresnel-type optics particularly suitable for use with area-type photoelectric receivers are described. Such optics have several advantages over conventional lens and mirror systems; large aperture systems may be constructed cheaply and are light in weight, the radiant energy can be distributed uniformly over the sensitive surface to avoid local saturation, and the optics can be economically custom-made for each application. The design procedure is explained and a method given for the construction of these Fresnel-type lenses from plastic in a modestly equipped machine shop. The design predictions and experimental performance data are compared for lenses designed for three different applications.