Showing papers on "Image resolution published in 1973"

Three dimensional pictures and method of composing them

Abstract: A stereoscopic picture is produced by providing an image array, or sheet, containing vertical image bands, each of which bands includes a number of adjacent lineiform images of the object field, i.e., the scene, being depicted. A lenticular screen overlying the image sheet and located such that each lenticule covers one of the image bands allows left and right eye observations of two different images of the same scene, wherein such two images are a steroscopic pair. In the embodiments illustrated, the stereoscopic pairs of images are obtained by simultaneously photographing a scene with a multilens camera, or with a number of conventional cameras located in side-by-side spaced relation, or by moving a single camera or the object field relative to one another. Preferably the optical axes of the cameras, or of the single camera in its various positions, are parallel. Alternatively, the image sections may all be produced from a single two dimensional image of the object field. Novel techniques for substantially covering the area of the image sheet beneath each lenticule with lineiform images of the object field are also disclosed.

An examination of an iterative method for the solution of the phase problem in optics and electron optics: II. Sources of error

Abstract: In the evaluation of an iterative scheme that determines the amplitude-phase distribution of an image from two image intensity distributions recorded at two different lens defocus values, the effects of various sources of error on the solution for the phase distribution are examined, namely, a background signal superimposed on the image intensity, a mismatching of the two images and an error in determining the defocus difference between the two images. In electron optics, a background intensity, arising from (say) inelastic electron scattering, corresponding to 10% of the maximum image intensity has a significant effect on the calculated phase distribution. In high-resolution electron microscopy, achieving a potential image resolution of 01-03 nm, a mismatching of the two images by 01 nm is acceptable, corresponding to a misalignment of the two electron micrographs by 50 μm at an electron-optical magnification of 500 000; and a defocus error of 10 nm, in a total defocus difference of 100 nm between the two images, does not severely distort the solution for the phase distribution. The combined effect of photographic noise (10-20% of the maximum intensity), mismatching (01 nm), defocus error (10 nm) and a background (6% of the maximum intensity) on the calculated phase distribution gives an indication of the maximum error that can be tolerated in an experimental test of the method. The magnitude of the maximum error that can be tolerated may be scaled to the resolution required in the phase solution and the wavelength of the radiation used; in optics with a potential image resolution of 10 μm, a mismatching of images by 5-10 μm (at unit magnification or 05-10 mm at an optical magnification of 100) is acceptable and a corresponding defocus error of 100 μm for a defocus difference of 1 mm (depending on the numerical aperture of the objective lens).

Microscope with Enhanced Depth of Field and 3–D Capability

Abstract: In the summer of 1969, R. L. Gregory was working at Bell Labs, and suggested one might be able to increase the effective depth of field of a microscope if, instead of making the objective achromatic, one arranged that the different spectral colors come to foci at different distances from the lens. J. S. Courtney-Pratt suggested that one might then be able to view the image in 3-D by use of a simple binocular eyepiece modified to give a convergence of the images that varied with the spectral color. A 16-mm NA 0.4 objective has been made that gives a lateral resolution of 1 μ and a depth of field of 100 μ. 3-D displays present sharp images of objects with dark field illumination with depth magnification at any chosen value up to ± 10,000×.

Fresnel Zone Plate Imaging in Radiology and Nuclear Medicine

Abstract: X-ray tubes and gamma ray cameras have traditionally involved trade-offs between spatial resolution and radiation flux. Recently we have shown that the use of a Fresnel zone plate as a spatially-coded source or aperture can avoid this trade-off. In radiology, this technique can eliminate the need for a rotating anode and give higher resolution, while in nuclear medicine it can be used either to decrease patient dose or exposure time, or to increase resolution and greatly simplify the apparatus. With a coded source or aperture, the image is also coded, like a hologram and can be reconstructed optically. The system is tomographic with information about all planes contained in a single film.

Imaging in Nuclear Medicine with Incoherent Holography

Abstract: One of the principal concerns in nuclear medicine is imaging the spatial distribution of tracer amounts of gamma emitting radiopharmaceuticals which have been intravenously administered to patients. These images are customarily formed on a gamma ray detector by means of lead pinholes or multichannel collimators. In practice these apertures yield only 1 cm spatial resolution and geometric efficiencies of 10-4. This paper describes the use of a lead Fresnel zone plate aperture in conjunction with an image intensifier camera to produce coded images of gamma sources. These images possess properties similar to holograms. This method shows promise of a factor of 4 or 5 improvement in resolution, a factor of 10 improvement in efficiency and gives 3 dimensional information about the object.

On the correction of hot wire turbulence measurements for spatial resolution errors

Abstract: Hot wire anemometers have found widespread use in the measurement of turbulence for many years. Recently, considerable improvements in the signal to noise ratio of these instruments has facilitated measurements in the high wavenumber region of the energy spectrum, where the turbulent energy level is usually relatively low. Of major concern in the measurement of very small scale turbulent fluctuations by the hot wire method is the error introduced by the spatial averaging effect of the wire. Clearly, for fluctuations with wavelengths of the same order of magnitude as the wire length, or less, the line integration of the wire results in measured amplitudes which deviate considerably from those which would be recorded by a probe of infinitely small size.

Fresnel zone plate imaging in radiology and nuclear medicine.

Abstract: X-ray tubes and gamma ray cameras have traditionally involved trade-offs between spatial resolution and radiation flux. Recently we have shown that the use of a Fresnel zone plate as a spatially-coded source or aperture can avoid this trade-off. In radiology, this technique can eliminate the need for a rotating anode and give higher resolution, while in nuclear medicine it can be used either to decrease patient dose or exposure time, or to increase resolution and greatly simplify the apparatus. With a coded source or aperture, the image is also coded, like a hologram and can be reconstructed optically. The system is tomographic with information about all planes contained in a single film.

High spatial resolution photographs of the Sun in L$alpha$ radiation.

Abstract: Photographs of the Sun in predominantly Lα radiation (centered at 1215.67 A) with 3″ spatial resolution were taken from an Aerobee rocket shortly after fourth contact by the Moon on the eclipse day of 1972 July 10. This preliminary reporting of the results describes the instrument and shows two of the photographs taken. The supergranulation is manifest and active regions and filaments are well resolved over the entire disk. Densitometer traces across the disk are presented giving the flux incident on the Earth from active regions, cell boundaries, and filaments.

On the electron microscopy of biological specimens

Abstract: Calculations are presented for the elastic and inelastic image profiles for the transmission electron microscopy of amorphous (biological) materials, corresponding to objective lens defocus values, 0 to -2000 nm for an incident electron energy of 100 keV, used in the electron microscopy of biological specimens. These calculations are relevant to image analysis procedures which neglect the contribution of the inelastic electron scattering to the image intensity for these large underfocus values. For small defocus values, 0 to -200 nm, the inelastic contribution can be described as an unstructured background in the electron micrograph. However, corresponding to the larger underfocus values, -500 to -2000 nm, the elastic image resolution is inferior to that of the inelastic image. The inelastic image resolution is less dependent on the objective defocus value than the elastic image resolution, and in dark-field microscopy at defocus values -500 to -2000 nm, the inelastic image is of primary importance. In bright-field microscopy the dominance of the high-resolution elastic component is evident only for small underfocus values, but at the larger underfocus values the inelastic image is relevant.

Infrared laser addressing of media for recording and displaying of high-resolution graphic information

Abstract: Projection display systems which use a scanned infra-red laser beam to thermally record graphic information on different media may offer a useful alternative to CRT and other display systems. Three different types of thermal-recording projection display systems are reviewed. Laser micromachining of thin bismuth film has proved to be a very simple and efficient way to obtain instant high-quality images which are also permanent. Variable amplitude light pulses produced by an intracavity modulated laser beam were used to write these images. With an average laser power of 20 mW, 8×10 mm2facsimile type continuous-tone images, with a resolution of 1300×2000 resolvable elements, were recorded in 4 s. Thermal writing on liquid crystals offers a unique and simple way to record and display high-quality high-resolution graphic images with the capabilities of fast total or local erase. A CW Nd:YA1G laser was used to write graphic and alphanumeric-type information on cholesteric and smectic-type liquid-crystal light valves. High quality black and white images with a resolution of 2000×2000 picture elements were recorded within 30×30 mm2of liquid-crystal cell frames. With 4 mW of laser power, images were recorded at a rate of 104resolvable elements per second. A contrast ratio of 7:1 was obtained with the cholesteric-type liquid-crystal light valve. The stored image was electrically erased in about 0.1 s. In smectic-type light valves, the contrast ratio was better than 10:1 and local erase was achieved by the application of an electric field while the laser beam locally heated the erased area.

High Resolution and Spectroscopic Cathodoluminescent Images in Scanning Electron Microscope

Abstract: It was shown that the radiation collection system collecting the transmitted radiation through the specimen from the back side (i.e., the side opposite the surface struck by the electron beam) was effective for the formation of cathodoluminescent (CL) images in SEM. This system provided an image resolution of the order of the electron beam spot size (~500 A) for a CaWO4 crystal at an accelerating voltage of 20 kV. This collection system was also especially useful for the formation of spectroscopic CL images with a monochromator. The spectroscopic images of the mixed powder specimen of CaWO4 and ZnS were obtained separately in consequence of differences in their characteristic spectral components.

Comparison and Performance of Anger Cameras

Abstract: Measurements of sensitivity, spatial resolution, dead time, and field uniformity, as well as imaging of phantoms, provide a satisfactory means of evaluating and comparing Anger camera systems. The authors recommend that these parameters be measured periodically to detect deterioration of performance. A clinical evaluation of images depends upon the type of cathode-ray tube display and associated film response. Thus, given an optimized camera system, an appropriate display format is also required for best results.

Image resolution and image contrast in the electron microscope. I. Elastic scattering and coherent illumination

Abstract: The present work evaluates the effect of lens aberrations on image resolution and image contrast in the transmission electron microscope for the elastic component of the electron beam; coherent illumination of the specimen is assumed. The effects of lens aberrations on the image resolution are evaluated in terms of a resolution function in preference to the use of the transfer function. Although no precise figures can be given for image resolution, it is found that the condition for maximum contrast corresponds to the best resolution in the image. The fundamental limit in resolution, due to diffraction at the objective aperture, should be avoided by increasing the objective aperture size with a subsequent correction for the increased lens aberrations. For coherent illumination these corrections can, in general, only be made in bright field microscopy and not in dark field microscopy.

Basics Of Detection, Recognition And Identification In Electro-Optical Formed Imagery

Abstract: Electro-optical sensors can be of significant aid to our law enforcement agencies particularly if their capabilities and limitations are fully understood. In the following, the imaging process is discussed as it applies to the needs and requirements of security, surveillance and law enforcement. Our approach is to associate quantitative signal-to-noise ratios with simple geometric images as developed by electro-optical sensors, to determine the observer's SNR needs through psychophysical experimentation and then, through further psychophysical experimentation, to correlate the detectability of these simple images with the visual discrimination of the images of real objects. The visual discrimination tasks we consider are simple image detection and the higher order tasks of recognition and identification. The concepts developed form a rational basis for the selection of electro-optical equipments which have a reasonable expectation of actually performing a desired function.

Image resolution in high-voltage electron microscopy

Abstract: An examination is made of the effect of lens aberrations on image resolution for electron microscopy in the 200-1000 keV energy range. In particular a new assessment is made of the effect of chromatic aberration on the inelastic image resolution neglecting relativistic effects. At the optimum lens defocus for the elastic image, the inelastic image contributes mainly as an unstructured background displaying a resolution in the range 0·3-1·0 nm, when the resolution of the elastic image is 0·10-0·26 nm, the lower limit corresponding to an incident electron energy of 1000 keV. At the optimum defocus for the inelastic image, -CcEmp/E0, for a most probable energy loss Emp and an incident electron energy E0, the inelastic image resolution is in the range 0·2-0·4 nm, and the corresponding elastic image resolution is inferior to this. A comparison is made for a specimen thickness of 50 nm, corresponding to a typical section thickness of an amorphous biological section, of the inelastic image and the dark- and bright-field elastic images. Although the ratio of elastic to inelastic scattering is significantly less than unity, the elastic dark-field and inelastic image intensities are comparable at the elastic optimum defocus. In bright-field microscopy, phase contrast effects, which increase with incident electron energy, for the elastic component are significant, and the contribution of the inelastic image to the total image intensity is only as a slowly varying background, again considered at the optimum elastic defocus. The relevance of these calculations to practical high-voltage electron microscopy is discussed.

Longitudinal Magnification in Radiologic Images of Thick Objects: A New Concept in Magnification Radiography

Abstract: New concepts which are useful for evaluating image resolution and distortion in magnification radiography are introduced. It is shown theoretically and experimentally that “longitudinal magnification” defined as the ratio of the magnified image size to the conventional image size for objects located in a plane perpendicular to the film, is given approximately by the square of the conventional magnification. Resolution in the radiographically magnified image of such objects is much higher than that obtained by optical magnification. This is confirmed experimentally by radiographs of square-wave test objects. The related image distortion is also discussed.

Quantization Errors In Calculation Of Volumes Areas And Coordinates In Medical Images

Abstract: In the computer processing of dynamic images (cinefilm, TV) data volume and rates are usually excessively high. This is because of the addition of two spatial demensions to the normal time-domain processing problem. It has therefore been necessary to reduce the spatial and intensity resolution of the converted images. This paper examines the errors resulting from these quantization trade-offs, as applied to several medical image processing problems.

A High Resolution, High Efficiency Proportional Counter X-Ray Camera

Abstract: A high-resolution, high-efficiency, gas-filled, position-sensitive x-ray camera for diagnostic Nuclear Medicine will be described. The simple integral parallel hole collimator allows a spatial resolution of less than 1 mm. and holds down the front foil allowing the counter to be pressurized to greater than 10 atmospheres for high efficiency.

The Spatial Resolution of Visual System

Abstract: 従来から視覚の空間分解能特性は輝度や網膜照度の関数として測定するのが常であった.筆者らは, これら測光学的立場を離れ, 視覚系の情報処理機構を明らかにする立場から, 刺激光の物理的量の輝度や照度ではなく, 光刺激が網膜上でひき起す反応の大きさの関数として, さらに5種類の単色光を用いて空間分解能を測定した.この結果, 特性が, きわめて単純な形で表現された.また色によって同じ明るさ感覚でも空間分解能が異なることがわかった.

High resolution observations of the extragalactic radio sources 3C 52 and 3C 192

Abstract: 3C 52 and 3C 192 have been mapped at 2.7 and 5 GHz with the Cambridge One-Mile telescope. 3C 52 is a double source with evidence of misaligned structure in the components; with lower resolution 3C 192 appeared to have complex structure but the present observations show two compact components linked by extcnsive regions of low brightness. (auth)