Showing papers on "Angular aperture published in 1999"

Defect-review SEM, reference sample for adjustment thereof, method for adjustment thereof, and method of inspecting contact holes

Abstract: There is disclosed a defect-review SEM (scanning electron microscope) and method for inspecting contact holes having small aperture diameters (e.g., less than 0.05 μm) and high aspect ratios (e.g., 10 to 15) for defects with high throughput. An angular aperture control lens interlocks with an objective lens to control the convergence angle of the electron beam incident on a wafer sample to a small value (e.g., 10 −5 to 10 −6 rad). The beam is scanned across the sample by an upper-stage deflector and a lower-stage deflector. The beam is scanned in two stages to scan the surface of the sample vertically. The resulting secondary electrons or backscattered electrons are detected by a detector located near the back focal point of the objective lens.

Optical properties of a retroreflecting sheet

Abstract: The power reflection and polarization properties of a close-packed array of retroreflectors are modeled, and a commercially available sheet is measured to verify the predictions. The modeling technique is conceptually simple and applicable to a wide range of structures of this type. The close-packed sheet retroreflects over a range of angles of incidence of approximately -40 to 40 deg in both directions and returns the polarization that illuminates it largely unchanged. Predictions of returned power are within 10% for light incident within 15 deg of normal and within 20% for angles less than 20 deg. Angles of polarization rotation are predicted to within 10 deg over a similar range of input angles. The model predicts the angular aperture of the sheet and the major features of the angular response. Future research will focus on design of structures with wider angles of acceptance and responses optimized for specific applications.

Optical scanning touch panel

Abstract: Laser light emitted by a light emitting element is made parallel light by a collimation lens, passes through an aperture of an aperture mirror, and is then angularly scanned in a plane substantially parallel to a display screen by rotation of a polygon mirror and projected onto a recurrence reflection sheet. Then, after the reflected light from the recurrence reflection sheet is reflected by the polygon mirror and aperture mirror, the light is focused by a condenser lens to enter a light receiving element. The aperture mirror has an asymmetrical shape in the scanning direction and/or the vertical direction about the optical axis, according to a scanning surface opening width of the polygon mirror.

Wide-angle infrared lens and detector with internal aperture stop and associated method

Abstract: An infrared lens and detector system and associated method are disclosed that utilize infrared lenses to form an internal entrance pupil at which an internal aperture stop is placed to control the intensity of infrared radiation focused on the infrared detector. In more detailed respects, the infrared lens is an assembly including a first infrared lens, a second infrared lens spaced from the first lens to form a pupil between the first and second lenses, and an aperture stop disposed proximal the pupil. The aperture stop may have a fixed diameter or may have an aperture stop that is manually or automatically adjustable depending upon the intensity of the infrared radiation being viewed. Significantly, this lens assembly may be sealed for improved performance particularly in extreme conditions. In more detailed respects, the lens assembly forms a wide-angle lens and includes a diffractive surface on the second lens to reduce color aberrations and improve performance. In another respect, the infrared lens is part of a detector system that also includes an infrared detector, a signal processor, and a display.

Aperture for high density laser radiation minimizes absorption heating

Abstract: The aperture (1) absorbs between 0 and 1 per cent of the laser radiation for a defined aperture thickness. A region of the aperture surface deflects or couples out the unwanted part of the laser radiation. The aperture can have an opening (2) so that the part of the radiation absorbed for the given thickness is null. The aperture is highly transmissive and can be a dielectric, especially sapphire, glass or crystal. Independent claims are also included for use of an aperture for fiber coupling of radiation from high power diode lasers, characterizing radiation fields and stopping or spatial filtering in a laser oscillator or oscillator amplifier.

Diffraction Fields in the Focal Space of Symmetrical Hyperbolic Focusing Lens

Abstract: The fields refracted by circular symmetric hyperbolic lens illuminated by a linearly polarized plane wave are calculated from the induced surface currents. It is shown that the fields in the axial region approximate to the fields in the aperture of corrugated horn under balanced hybrid condition. The image structures for different focal ratio are compared with the classical Airy pattern, deduced by scalar analysis, of optical focusing systems. The coupling between the lens and a corrugated horn at different position on focal plane are presented. The lens resolution and pix numbers are evaluated.

Reflection type liquid crystal projector

Abstract: PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal projector in which a case in which contrast is prioritized and a case in which brightness is prioritized can be selected. SOLUTION: A slide shutter 150 is provided on a light beam emitting side near a 2nd fly-eye integrator 113 out of 1st and 2nd fly-eye integrators 107 and 113. When the contrast is prioritized, the shutter 150 is closed. In this case, it is desirable that the shape of a pupil satisfies an angular aperture PP > an angular aperture PI, wherein the angular aperture in a main incident surface direction formed by the normal of the splitter surface of a polarizing beam splitter 21 and the optical axis of a projection lens 139 is PI and the angular aperture in a direction perpendicular to the main incident surface is PP.

Objective lens for high-density optical recording medium

Abstract: An objective lens for a high-density optical recording medium, employed as an objective lens for an optical pickup for converging a luminous flux onto an optical recording medium, comprises, successively from the light source side, a first lens L 1 made of a biconvex lens having at least one surface formed as an aspheric, and a second lens L 2 made of a planoconvex lens having a convex surface directed onto the light source side, and satisfies the following conditional expressions (1) to (3): 0.588<β 2 ≦0.676 (1) NA 1 ≧0.45 (2) RMS 1 ≦0.07λ (3) where β 2 is the imaging magnification of the second lens L 2 ; NA 1 is the numerical aperture of the first lens L 1 ; RMS 1 is the RMS of the wavefront aberration of the first lens L 1 ; and λ is a reference wavelength.

Effects of Fresnel number in focusing and imaging

Abstract: The effects of a finite value for Fresnel number in focusing systems are discussed. For an aperture illuminated by a convergent spherical wave, a shift of the maximum intensity towards the aperture results, associated with a coordinate scaling with regions further from the aperture stretched. There is also a dependence on the numerical aperture of the system, the focal shift decreasing with apertures. For high apertures, the focal field can be expressed in terms of a scaled Debye integral. An alternative geometry is that of a focusing system with an aperture stop at an arbitrary position. If the stop is situated in the front focal plane of the lens, the amplitude in the back focal plane is given by the Fourier transform of the aperture amplitude, and the effective Fresnel number is infinite. For positions further from the lens it is negative, so that the maximum in intensity is shifted further from the lens, and the scaling is such that regions closer to the lens are stretched. A high aperture system can be modeled using the concept of the equivalent refractive locus. The field in the front focal plane is transformed into an angular spectrum of plane waves with an appropriate apodization term, so that if the aperture stop is in the front focal plane the effective Fresnel number is infinite.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Interferometric method for testing focal lengths using a digital Fourier transform

Abstract: We describe an interferometric method for measuring effective focal length of lenses. Measurement of the effective focal lengths of macroscopic refractive lenses and of a diffractive microlens are performed within the limit of paraxial approximation. The technique uses a reflective grating interferometer to produce a fringe pattern with a regular pitch. The lens under test is illuminated by the interference pattern and the focal length is obtained by the knowledge of the spatial frequency in a fixed aperture. Three imags of the interference pattern are stored by using a CCD camera: two of them are imaged by the lens under test placed at two different position, an one is the reference pattern with no lens inserted in the set-up. A 1D fast Fourier algorithm is applied to the digitized image and the phase modulo 2 (pi) is reconstructed. The phase is unwrapped and averaged to calculate the spatial fringe frequency inside the chosen aperture. The method has been applied for measuring the focal length of macroscopic refractive lenses and of a 1mm aperture diffractive microlens.

Symmetric blanking for high stability in electron beam exposure systems

Abstract: An electronic beam lithography tool providing dimensional stability. The tool includes three or more deflection plates above an aperture diaphragm which allows the beam to be deflected away from an aperture and along a two-dimensional locus on the aperture diaphragm which is approximately symmetrical around the aperture therein. By doing so, the aperture diaphragm is symmetrically heated by the power of the charged particle beam and the geometry of the charged particle beam device is stabilized against variance in geometry of the device to a very small tolerance.

Scanning lens antenna

Abstract: A method and a device is disclosed for the generation of a lens device including a plate of ferroelectric material, the transmission phase gradient of which is be varied over the lens by means of a controllable static electric field. The lens may involve an entire antenna aperture, e.g. a feeder horn or constitute a body covering a slotted wave-guide antenna, be a portion of an antenna aperture or an element in a conventional array aperture. The division of the aperture depends on the number of degrees of freedom to be controlled simultaneously. In a general case N lobes and M nulls are to be controlled at the same time. In the most simple case with N=1 and M=0 the lens should be the entire antenna aperture. The invention is based on the fact that the direction of the wires of the control grids (1, 2) in the lens device must run perpendicular to the direction of the E-field direction of a penetrating high frequency radio wave. To obtain a full steering capability of an antenna lobe both in the X-Z plane and the Y-Z plane static electric fields are created by means of voltage sources (26, 36) along the wires of one grid or across the wires of the other grid of the continuous scanning lens.

Attenuation and scattering of short-duration laser pulses in a strongly scattering medium

Abstract: The dependence of the optical density of a model strongly scattering medium-aqueous milk solution on its layer thickness was investigated. IR lasers generating pulses of various short (from nanosecond to femtosecond) duration were used as the radiation sources. There were determined the dependences of the attenuation coefficients of such pulses on the solution concentration in the areas of low and more high optical densities of the solution layer for different values of radiation detector angular aperture. A modification of the two-flux Kubelka-Munk model was used to derive an expression describing the dependence of the transmission of a solution layer on its parameters when radiation detectors with a finite angular aperture are used. The absorption and scattering coefficients of the medium were obtained. A comparison of the calculations and experiments revealed a forward scattering anisotropy of short-duration laser radiation in an aqueous milk solution characteristic for the Mie's scattering.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Improving echograms’ resolution by wideband pulse compression and dynamic focusing

Abstract: Improving the resolution of fisheries’ sounder echograms (i.e., reducing the confusion volume) can be achieved by improving either the axial or the angular resolution. On one hand, the range (i.e., time) resolution can be improved without any degradation of the signal‐to‐noise ratio by using frequency‐modulated signals associated with pulse compression. Axial resolution can be considerably enhanced by using wideband signals. On the other hand, due to the angular spreading of the sonar beam, the lateral resolution is proportional to the range. Improving the angular resolution can only be achieved by using a larger array (only possible on the receiving side). Nevertheless, such a solution has a severe limitation as it reduces the volumes sampled at short range, leading to an angular under‐sampling of the biomass. Dynamic focusing can be used to overcome this problem. Its principle is simple: the shorter the range, the smaller the array (i.e., the larger the angular aperture). The use of such a technique nee...

Multipass systems with large relative aperture for TDLAS

Abstract: Two types of the multipass systems with the large angular aperture for using in TDLAS are developed. The main purpose of these developments is best optical coordination multipass systems with a diode laser irradiation. Keywords: multipass system, diode laser, spectrometer, aperture. 1. INTRODUCTION For the last years in department of Diode Laser Spectroscopy some types of mirror systems of long length path for high- resolution absorption spectroscopy are developed. As compared to the classical White system [1], the new ones involve many new design features as well as improved optical and performance characteristics. Various principles of mirror systems design allowed their different scientific applications and, first, in high-resolution spectroscopy, for increasing measurement sensitivity at low concentrations of substances under investigation. In this respect, we should mention the multipass systems with the highest relative aperture specially developed for Fourier Transform Infra-Red (FTIR) and Tunable Diode Laser

X-ray diagnostic apparatus with aperture unit

Abstract: The device has an X-ray source (2), an aperture unit (4) with aperture plates (41) to form an X-ray beam (210) and a light source (42) to form a light beam through the aperture, using a mirror arrangement (43). Correction apertures (44) are provided, which are transparent to X-rays but opaque to light, to limit the light beam. An Independent claim is included for an aperture unit for an X-ray source.