Showing papers on "Stray light published in 1984"

Spectral radiant power measurements of VUV and soft x-ray sources using the electron storage ring BESSY as a radiometric standard source.

Abstract: A method is described for measuring the spectral radiant power of VUV and soft x-ray sources using the electron storage ring BESSY as a radiometric standard source of calculable spectral radiant power and degree of polarization. An ellipsoidal grazing incidence mirror stigmatically images the stored electrons or the source under investigation in equal optical conditions into a toroidal grating monochromator. The monochromator can be rotated around its optical axis in UHV conditions to account for different degrees of polarization of the two sources. The accuracy presently available with this method is demonstrated by a measurement of the spectral concentration of radiant intensity of a laser-produced tungsten plasma in the wavelength range between 7 and 100 nm with an overall uncertainty of 10%. A detailed analysis of the contributions to this uncertainty shows that the major part of it is caused by the presently uncertain knowledge of the polarizing properties of the radiometric instrumentation and by the uncertainty of the correction procedure which accounts for the influence of higher diffraction orders of the monochromator grating. The results of the radiation measurements of the laser-produced tungsten plasma let us expect that this source type has the potential to serve as a radiometric transfer standard in the VUV and soft x-ray range below 100 nm.

Reflectance Measurements On An Improved Optical Black For Stray Light Rejection From 0.3 To 500 µm

Abstract: The Martin Black process has been used to coat baffles on a wide variety of visible and ultraviolet range instruments. Its infrared applications include baffles for the Infrared Astronomy Satellite and the Spacelab 2 Infrared Telescope. Because of the increased emphasis on stray light suppression in the infrared, the Martin Black process was modified with the objective of creating a better black surface for use in the near-, mid-, and far-infrared regions. These modifications resulted in the creation of an infrared absorbing surface, called Infrablack, which retains the excellent visible absorption properties of its predecessor and has increased infrared absorption. Hemispherical and specular reflectivity and bidirectional reflectance distribution function (BRDF) measurements were made on the Infra-black surface. The specular reflectance at 17° incidence ranges from less than 1% at 60 i.im to less than 15% at 450 /um. BRDF measurements made at the University of Arizona at 10.6 pm, at incidence angles of 10°, 30°, and 60°, indicate that the surface behaves in a nearly Lambertian manner at this wavelength. At 10 incidence the BRDF for Infrablack is about one-seventh that of Martin Black, and the curve is noticeably flatter.

Image reading device

Abstract: An image reading device, such as may be employed in a facsmile transmitter, laser beam printer, copying machine, or the like, in which assembly and alignment of optical components of the system is simplified and stray light is prevented from reaching a photoelectric conversion element. The optical system and the photoelectric conversion element are fixedly secured to a single supporting frame in a desired predetermined positional relationship. The supporting frame is detachably mounted on a mounting surface of an image reading device body. The optical system includes a filter or dust-proof transparent cover, an optical path changing mirror, and an image forming lens, all of which are secured to the supporting frame. A light-quantity-distribution correcting light-shielding plate may be provided in front of the image forming lens to provide an even distribution of image light on the photoelectric conversion element.

Bragg-cell spectral analyzer with prism-expansion system

Abstract: A Bragg cell spectral analyzer with a prism expansion system for a laser beam, which has a Gaussian cross-sectional distribution of light intensity, is generally superimposed with stray light, and is conducted along a path through the system to a Bragg cell characterized by an aperture diaphragm being positioned in the path before the prism expansion system with the diameter of the aperture being selected to be larger than the half-width value of the Gaussian cross-sectional distribution. The prism expansion system only expands the laser beam to such a degree that the half-width value of the Gaussian cross-sectional distribution is smaller than the diameter of an aperture of the Bragg cell. As a result thereof, the diffraction side lobes of the spectrum can be reduced by apodization relative to the principal maximum of the spectrum and stray light contained in the laser beam can be blanked out.

High density block oriented solid state optical memories

Abstract: A block oriented solid state optical memory having a distributed data storage architecture comprises a lens array including a plurality of laterally separated lenslets which have numerical apertures selected to cause them to focus essentially diffraction limited images of a photoemitter array in parallel onto laterally displaced sections of a data mask, so that the images optically align with respective photosensors. The lenslets are formed on the first surface of the lens array, and the data mask is supported on or very close to the last surface of the lens array to minimize the scattering of reflected light. An opaque light shield on the first surface of the lens array optically masks the area between the lenslets to eliminate unwanted stray light. Furthermore, in at least some embodiments of the invention, the light shield extends into the apertures of the lenslets to stop them down sufficiently to obtain substantially diffraction limited performance.

Folded optical large format photomicrographic camera system

Abstract: A photomicrographic camera system in which a mirror system is utilized to deflect the light beam emanating from the eyepiece (20) of a properly illuminated, compound optical microscope (10) horizontally outward to another mirror which then deflectsthe beam vertically downward to a film holder (36) containing a sensitized photographic film of paper material. An appropriate housing (32) confines the optical path and protects the film from stray light, while at the same time providing structural support for the mirrors and auxiliary photographic components, such as baffles (57), shutter (48), filters (46), polarizers (52) and/or analyzers, light meter, etc. The film or paper holder lies flat, and is supported by the same base (74) that is used to support the microscope. Since the projection distance is more than doubled, by going first upward to the first mirror and thence downward by the same amount or more, plus the length of the horizontal path, very large format images (e.g. 20" X 24") or larger can be achieved easily with a system sitting on top a standard desk in a room of conventional 8 foot ceiling height. Since the image falls onto the photographic material immediately beside the microscope, it is very easy for the worker to achieve critical focus by looking directly at the projected image while his hand controls the focus and/or mechanical stage translation knobs of his microscope. Provisions are also made to allow this system to couple the microscope to standard small format still or motion picture cameras, or video camera systems (77). As dictated by the optical requirements associated with the particular projection distance used, provisions are made by means of the appropriate eyepiece spacer (18) or contoured positive lens (for short systems) to insure that optimum resolution is achieved in the finished photograph. By reversing the optical path through the system, high resolution microphotographs, microdots, or images for microelectronic component fabrication can be obtained utilizing the same structure.

Apparatus for determining the thermal conductivity of a solid material

Abstract: The sample 1 is heated by means of a laser flash and the change in temperature at the surface of the sample 1 facing the differential temperature pyrometer 6 is measured. An optimum temperature resolution in a temperature range from 20 to 3000 DEG C is achieved by using three detectors 8, 9, 10 comprising different detector materials. To screen the pyrometer 6 from the laser flash, a second camera shutter 11 closes the beam path to the pyrometer 6 for 2 ms. A first camera shutter 7, which is inverted with respect to the second camera shutter 11, simultaneously opens the beam path from the laser apparatus to the sample 1 and then keeps any stray light from the sample 1 out of the laser apparatus 4. Advantages are the wide temperature range from 20 to 3000 DEG C accompanied by high temperature sensitivity, the short dead time prior to the start of the measurement, the fact that the measuring signal is free of radiation components from the laser apparatus 4, and the fact that the pyrometer 6 does not require screening from the stray laser light.

Epidark illumination device

Abstract: An epidark illumination device comprising an optical means whereby a light from a light source is rightly reflected within an entrance plane including an optical axis but is diffused within a plane vertical to the entering plane, a light interrupting plate preventing the light from the light source from directly entering an objective and an iris diaphragm provided near an object to be inspected so as to make a uniform epidark illumination possible and to prevent a stray light from entering an observing optical system.

Apparatus for measuring particle diameter

Abstract: PURPOSE:To measure light intensity distribution within an all scattered angle range to measure the particle diameter of a fine particle, by a method wherein laser beam is converted to parallel beam by a collimator lens system and scattered light from a specimen is measured by an optical fiber and a photodetector. CONSTITUTION:A specimen 8 is irradiated with parallel beam 3 molded by laser 1 and a collimator lens system and scattered light is guided to a photodetector 12 by an optical fiber 10 arranged in a scattering angle direction desiring the measurement of scattered light. A microlens 9 is arranged in front of the optical fiber in order to guide the parallel beam to the scattering angle direction and a filter is arranged in front of the photodetector 12 in order to remove external stray light. A plurality of optical fibers as mentioned above are arranged to measure scattered light intensity distribution which is, in turn, converted to particle size distribution by a scattered light intensity distribution-particle size distribution converting apparatus 7. By this method, even a fine particle low in the change of the scattered light intensity distribution can be measured.

Illumination device of copying machine

Abstract: PURPOSE:To prevent the deterioration of a photoreceptor, an original imposing plate, etc and to prevent overheating by virtue of the heat radiating property that a honeycomb structural body possesses by using said body as a guide thereby providing a longer distance between a light source and the irradiation position of an original CONSTITUTION:A honeycomb structural body 6a which guides the light from an illumination part consisting of a lamp 1 and a reflection plate 2 provided in a lamp housing is coupled by means of a joint part 8 to a honeycomb structural body 6b directed to the irradiation surface direction of the original The light from the light source 1 is condensed directly or by the plate 2 to the body 6 where the light repeats reflection on the inside wall surface in the honeycomb optical guide until it arrives at the outlet on the original surface side and irradiates the original surface The image thereof is formed on a photoreceptor 5 by a condensing optical system 3 Thus there is no leakage of the light in the route from the light source to the irradiation surface of the original and the generation of stray light, etc is prevented

Focal position detector

Abstract: PURPOSE:To obtain a simple, compact and excellent focal position detector by forming the same number of the secondary images with plural splitting reflecting mirrors which split the image of the exit pupil of a photographing lens to the sensors provided on the right and left or the top and bottom of a reflecting mirror for converting the optical axis of the luminous flux of the exit pupil image. CONSTITUTION:The exit pupil image of a photographing lens is passed through a filter 16 and a slit 10 from the upward, and is fed through a condenser lens 4 to a concave mirror 9 having two splitting reflecting mirror faces by a reflecting mirror 13 for converting the optical axis held by prisms 11, 12. The mirror 9 splits the light to two luminous fluxes, makes the light incident again to the lens 4 and forms the images thereof on two sensors 14, 15 through the upper and lower or right and left spaces of the mirror 13. The coincidence of the two formed images is detected and the focus detection is accomplished. The filter 16 corrects the spectral sensitivity of the sensors 14, 15, and the slit 10 prevents the crosstalk and stray light of the image. The prisms 11, 12 make the optical distance of the imaging light coincident and the mirror 9 eliminates harmful abberations. The excellent focus detector which is free from vignetting of lens, etc., is compact and can be incorporated into the bottom of the camera or the like is thus obtd.

Optical waveguide plate

Abstract: PURPOSE:To improve the contrast of an image and to improve durability, reliability, etc. by pressing a light absorptive material to the surface of multifibers facing a supporting material on the side forming an acute angle to the information image surface of said fibers. CONSTITUTION:An information image fiber 1 formed by bundling densely many optical fibers so as to have the optical axes thereof in parallel with each other is inclined to face an information image plane 3 at an acute angle. Both side faces thereof are grasped by supporting materials 4, 5 so that a surface 2 facing the information image plane and a surface 12 facing a photoelectric sensor are formed in parallel. A light absorptive material 8' dispersed and incorporated therein with a light absorptive dye is pressed to the surface of the fiber 1 facing the material 5 on the side forming the acute angle to the plane 3 thereby providing an intended optical waveguide plate 61. The incident of stray light from the lateral and bottom parts of the material 5 on the fiber 1 is thus obviated and the contrast, etc. of the information image are improved.

Multi-wavelength spectrophotometer

Abstract: PURPOSE:To perform accurate analysis, by arranging a diffraction grating and a photodiode array in a relatively oblique state to prevent multiple reflection due to both of them. CONSTITUTION:Monochromatic lights spectrally diffracted by a diffraction grating formed by providing a plurality of linear marks to a concave reflection surface by etching are received by a photodiode array 10 having a plurality of light receiving elements arranged to the same flat surface thereof. The diffraction grating 12 and the photodiode array 10 are arranged so as to cross the normal A of the concave surface at the concave surface center theta of the diffraction rating 12 and the normal B of the photodiode array 10. Even if monochromatic lights spectrally diffracted by the diffraction grating 12 are partially reflected at the surface of the transparent protective member of the photodiode array 10, multiple reflection is effectively prevented. By this method, inaccurate spectroscopic analysis due to stray light is prevented.

Plane optical waveguide with output-stabilized laser

Abstract: PURPOSE:To enable a laser power output to be controlled so as to be stabilized, by employing a plurality of plane lenses and a laser output stabilizing circuit. CONSTITUTION:When a light beam with a divergent angle alpha is radiated and made incident on plane lenses 31-33, only a portion of the light beam which enters the lens 32 at an incident angle beta becomes collimated light 34. Light beam portions with divergent angles gamma1, gamma2 enter the lenses 31, 32 and reach an unneccessary light beam absorbing and scattering end face areas 37, 38, respectively. When the areas 37, 38 are in a normal state, the unnecessary light beams 35, 36 emerge therefrom to the outside. In consequence, it is possible to remove any stray light which may cause malfunction. If the laser power output from the light source 43 is fluctuated by any shock, the fluctuated output can be restored by a loop consisting of a laser power output detector 39, a pre-amplifier 40, a controller 41, a driver 42 and the light source 43.

Polarized beam splitter for video disk player

Abstract: PURPOSE:To lead only a regular laser light to a detector, and to prevent stray light from being made incident to the detector by angling a stray light generating surface against an optical axis so that a reflected stray light from the stray light generating surface of a splitter is not inputted to the detector. CONSTITUTION:A stray light generating surface of a polarized beam splitter 1 for a video disk player is angled against optical axes X, Y. For instance, when a shape of the polarized beam splitter 1 is a rectangular, and the surface A is placed at 45 deg. against the optical axes X, Y, the surfaces B, C do not fall at right angles with the optical axes but have some angle, and stray light M1, M2 do not coincide with the optical axis Y, and are not made incident to a detector 4. In this way, it can be prevented that stray light is made incident to the detector 4, therefore, a deterioration of performance such as a deterioration of S/N ratio of a picture, etc. can be prevented.

Particle analysis instrument

Abstract: PURPOSE:To measure suspended particles with good accuracy by providing an optical flow cell into which a particle suspension is introduced, a means for condensing scattered light which extracts only the scattered light within a specified angle by shutting off direct transmitted light from a light source and a photodetecting means to which the focused light from the focusing means is conducted after said light is diffused. CONSTITUTION:A sample such as blood and electrolyte soln., for example, physiological salt soln. are supplied from a sample supply device 2 to a detector 1. The luminous flux from a light source 3 is irradiated on the central part at the top end of the detector 1 and the scattered light within the specified angle out of the scattered light generated by the particles in the sample is condensed. The change of the scattered light which is condensed is converted to an electric signal by a photoelectric converter 4. The output thereof is conducted to a data processing part 5, by which the particles are analyzed. The result is displayed on a display part 6 and is recorded in a printing part 7. The part 4 feeds only the scattered light 16 to a lens by a plate 11 for blocking the direct light from the light source. The lens images the condensed luminous flux at the center of an aperture plate 13. The scattered light past the plate 13 is diffused using an optical diffusion plate 14 and the diffused light is detected by a photodetector 15. The background light owing to the scattered light except the light scattered by the particles to be measured as well as stray light, etc. is thus removed and the particle analysis is efficiently executed.

Filter assembly for fluorescence spectroscopy

Abstract: Apparatus for conducting fluorescent spectroscopy which involves irradiating a test sample with light of a first wavelength which causes the test sample to fluoresce light of a second wavelength and measuring a portion of the fluorescent light; irradiating the test sample with light of the first wavelength at reduced intensity and measuring the light of the first wavelength transmitted through the test sample; and comparing the intensity of the flurescent light to the transmitted light comprises an improved filter assembly which is rotatable between a test position and a reference position. The filter assembly includes a pair of test filters, one passing excitation light at one wavelength and the other passing fluorescent light from a test solution at a second wavelength, a pair of reference filters, each passing light at the first wavelength, and light shielding means to block stray light and prevent it from optically coupling between the filters. A pre-filter minimizes the background transmitted light. Insertion of the filter assembly into a commercially available automated clinical photometer enables the instrument to be used as a filter fluorimeter.

Device for controlling the contrast of photographic images when shooting by means of stray light

Abstract: Devices for controlling the contrast of photographic images when shooting by means of stray light are intended to achieve results which are of qualitatively high values in conjunction with minimum structural outlay and the simplest operation, it being possible for said devices to be adapted to the most varied shooting conditions, and at the same time for them to expand the photographer's creative scope This is achieved here by means of a light-guiding device (911), which guides light into the interior of a camera (1) up to in front of the image plane (2) and has a light inlet (10) for the stray light which is located outside the camera (1)

A semiconductor light emitting device

Abstract: A semiconductor light emitting device, which may be an LED or a laser, is structurally combined with a photo- generating device which is energised by stray light within the structure to generate electrical energy which is coupled to the light emitting device. The arrangement improves the power conversion efficiency and provides low input modulation power operation for the light emitting device. The structure comprises a series of epitaxially grown layer. In a first embodiment regions 15 to 20 form an LED, the active layer being 16, energised by a current 2 from source 1. Part of the emitted radiation falls on the junction between regions 14 and 15 and generates a photocurrent 6 which is applied in series with a second source 11 to the LED. In a second embodiment a second photogenerating junction (17,18 Figure 6) is arranged above the LED and connected in series with the first junction (14,15) in place of second power source 11. Alternatively this second photogenerating junction (17,18 Figure 8) may be connected in series with a third source (29 Figure 8) to the LED so that a higher current is provided.

Refractive vs reflective correctors

Abstract: Improved designs of refractive correctors produce excellent images with fast telescopes such as those with an F/1.5 prime focus and F/3.5 secondary focus. The fields are flat and there is compensation for the chromatic effect caused by windows. Disadvantages of such correctors are that stray light is produced at the optical surfaces, the elements must be supported at their edges, prerequisite high quality glass is available in only limited sizes, and all wavelengths are not transmitted. Reflective correctors, on the other hand, can produce diffraction limited images at all wavelengths and the mirrors can be supported across their backs as well as at their edges. Disadvantages are that the images are degraded by any substantial window (such as a detector faceplate), there is more central obstruction, and the correctors are sometimes very large and heavy. Except, perhaps, for a specialized telescope, such as one devoted to multi-object slit spectroscopy using fibres, the refractive corrector is preferable at fast foci. A good combination is a Ritchey-Chretien (R-C) telescope with refractive correctors at the fast prime and secondary foci, and a reflective corrector-magnifier for the slow infrared focus.

Optical information processing device

Abstract: PURPOSE:To make a recording and reproducing into a high density and to improve an S/N of detecting a signal by shaping incident light flux from a semiconductor laser for the beam splitter and making a stray light by a separating surface into a shape which guides in a direction different from a detecting means CONSTITUTION:A surface F, on which alight flux Li from a semiconductor laser in a polarizing beam splitter 10 falls, is inclined to a prescribed angle B for a vertical surface to an optical axis (x) after falling Simultaneously, a falling light flux Li is also inclined and falls to a prescribed angle alpha to the incident light flux Li for (x) By the constitution, in the incident light flux Li, a beam cross section shape is shaped to a circular light flux Li' The incident light Li from a semiconductor laser is reflected to 30% at the D surface and the stray light such as a broken line is obtained The stray light is reflected on the E surface again, the surface E is inclined at a prescribed angle to the vertical surface to the optical axis of a signal Ls facing to the detector surface, and therefore, the stray light is reflected in the direction different from the detector surface and will not mix into signal light Thus, the recording and reproducing are made high in the density and an SN ratio of the signal detection is improved

Optical Design Of An Image Degradation Reducing Enlarging Camera For The Prime Focus Of The Canada-France-Hawaii Telescope

Abstract: To eliminate image motion and blur (caused by "seeing" effects of the Earth's atmosphere) it is necessary to introduce an optical system which produces a real image of the pupil (the primary mirror) followed by a reimaged portion of the field. For the Canada-France-Hawaii telescope (CFHT) at the prime focus, these optics are required to magnify the field from F/3.8 (which is the primary focal ratio of the telescope) to F/17 so that the electronic detector can adequately sample stellar images of 0.25 arcsec diameter. The image motion is removed at the pupil. A simple but wasteful method is to locate a shutter at the pupil which opens only when a guide star is in the mid position of its motion. The guide starlight is taken from the centre of the field before the light reaches the pupil and feeds an autoguider. An alternative is to locate a flat mirror at the pupil which is rapidly deflected to remove the seeing motion. Tests conducted by staff of the CFHT Corporation produced photographs showing 0.25 arcsec resolution using the prime focus corrector followed by an off-the-shelf lens. However this lens produced poor images off the centre of the 4 arcmin field within which the image motions might follow those of the guide star. Custom designed optical systems are described which produce sharp images over a wide spectral region and also provide the option of doing without the prime focus corrector resulting in higher transmission, less stray light and better resolution than in the trial arrangement.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Laser light irradiator for laser raman microprobe

Abstract: PURPOSE:To enable a highly sensitive measurement of Raman spectrum at a micropoint with a reduction in laser reflected light by providing a polarizing cube type beam splitter to improve the irradiation intensity of laser light and the focusing efficiency of Ramam scattered lights. CONSTITUTION:A laser light 3 with the polarization plane turned vertical to the paper of the drawing is focused with a condenser lens 4, deflected by 90 deg. at the efficiency of more than 99% with a separation plane 6 of a polarization cube type beam splitter 5 and then, irradiates a sample 8 via an object lens 7. Raman scattered lights 9 radiated from the sample 8 transmits with the splitter 5 at the efficiency of more than 90% and an image is formed on an incident slit 12 of a spectrophotometer with a condenser lens 11. A laser reflected light portion 10 reflected from the sample 8 is deflected at the efficiency of more than 99% in the incident direction on the separation plane 6 of the slitter 5. This elevates the intensity of the irradiation laser light and the efficiency of focusing Raman scattered lights thereby reducing reflected laser lights causing a stray light. Thus, the detection sensitivity can be improved significantly to enable a highly sensitive measurement of Raman spectrum at a micro-point.

Reproduction camera with system to correct exposure for stray light

Abstract: A reproduction camera for the production of contact screen prints from an original is provided with sensing means, such as a photoelectric cell, for obtaining a measure of the light reflected by the original under conditions of an imagewise main exposure through the contact screen and a signal representing the obtained measure is inputted to a computerized control system through which, by taking into account the effect of stray light caused by reflection from the original during the main exposure, a non-imagewise additional exposure through the contact screen is effected so as to reproduce the minimum and maximum optical densities of the original with the correct dot sizes.

Textile machine optical detector stray light dependent regulation

Abstract: The regulation is performed by a circuit used for optical systems applied to monitoring moving goods in textile machinery so that switching processes are not triggered by stray light. The light intensity of a light emitting function block is regulated according to stray light influences so that a defined constant quantity of light faces onto a light sensitive functional block. This is achieved by enabling the light sensitive functional block to regulate the intensity of the light emitting block via an amplifier. The arrangement detects objects wich do not fully interrupt the light beam or only partially absorb the emitted light.

Method and device for colorimetry of colored liquid

Abstract: PURPOSE:To enable instantaneous, direct and continuous measurement of a change in the color of a soln. by positioning the open ends of two optical fibers oppositely to each other to constitute a slit part and to form a light path, and connecting the other ends to a light source and a photoelectric tube. CONSTITUTION:Two multiglass fibers 2, 2', of which the ends on one side are gently bent to 90 deg. and are housed in three-dimensional cells 3, 3' and the open ends 4, 4' are positioned oppositely apart at 2-4mm. space from each other, are inserted into a colored soln. The light from a light source 5 is made incident to the other end of the fiber 2 and the other end of the fiber 2' is connected to a photoelectric tube 6. The outside of the cells 3, 3' is made black to shut off the incidence of stray light. Continuous measurement and continuous recording are made possible according to the above-mentioned constitution by measuring directly the change in the color of the colored soln. with the velocity of light.