Showing papers on "Depth of focus published in 1977"

Method of and apparatus for the expansion of the range of the depth of focus beyond the limit given by conventional images

Abstract: A method of and apparatus for increasing the range of depth of focus when optically imaging three dimensional objects having different depth ranges corresponding to desired image levels wherein the object is focused through at a plurality of levels to produce a plurality of images. At each level, the image produced has sharp details and unfocused details. Each image is filtered with a high pass filter to suppress unfocused details and to pass sharp details. The images are then summed to produce a composite image containing only the sharp details passed by the filtering step. If desired, the filter may be selectively by-passed in order to sum unfiltered images. By utilizing the method of an apparatus for practicing the instant invention more meaningful visual displays of three-dimensional objects are obtained.

Switchable depth of focus pulse-echo ultrasonic-imaging display system

Abstract: An ultrasonic transducing unit comprising a central section, which cooperates with only a small portion of the relatively large aperture of an acoustic lens, and an annular section, which cooperates with the remainder of the aperture, can be selectively operated by switch means to utilize the relatively large depth of focus detected signal of the central section alone or to utilize the relatively small depth of focus detected signal of both the central and annular sections together.

Sonar controlled two focal position lens system

Abstract: A photographic camera in which a two-position lens is focused automatically on subjects located within "near" and "far" distance ranges from the camera. The lens is normally positioned in one of the two positions and movable to the other of the two positions in response to a signal generated by an electronic ranging circuit upon the detection of subject location in the focus range to which the other position corresponds.

Microscope with great depth of focus - prevents image contrast reversal and has filter with high transmission coefficient decreasing towards edge and exit pupil objective

Abstract: The microscope, which has a great depth of focus prevents several of the image contrast and has a filter with a high transmission coefficient on the optic axis (A). Towards the edge of the filter (F) the transmission coefficient continuously decreases. An objective (O) is located at or near the exit pupil. With an additional lens, the filter lies at or near the plane of the image (corresp. to the exit pupil of the objective) projected by the additional lens. The transmission coefficient of the filter is specified by formulae. The formulae involves a weakening factor and the distance measured from the optic axis.

Automatic focussing for camera - is coupled to viewfinder and monitors contrast of image on retina of user

Abstract: The automatic focussing camera has the viewfinder optics in parallel to the main optics. A secondary optic system is used to monitor the image on the retina of the camera user and to determine the contrast of that image. A feedback control operates a servo motor (11) to adjust the focus of the lens for optimum sharpness, without any additional control. The system sets the focus on that part of the image which the camera user is looking at. This enables the camera to provide sharp images with a variable focal length lens, without having to compute depth of focus. The scanning of the retina can be most suitably performed with an infrared beam from e.g. LED.

Increased Depth Of Focus In Scanning Microscope

Abstract: A technique is described which yields an increased depth of focus in a scanning microscope system. The technique's utility for certain types of objects is demonstrated experimentally.

Imaging natural materials with a quasi-microscope

Abstract: A Viking lander camera with auxilliary optics mounted inside the dust post was evaluated to determine its capability for imaging the inorganic properties of granular materials. During mission operations, prepared samples would be delivered to a plate positioned within the camera's field of view and depth of focus. The auxiliary optics would then allow soil samples to be imaged with an 11 pm pixel size in the broad band (high resolution, black and white) mode, and a 33 pm pixel size in the multispectral mode. The equipment will be used to characterize: (1) the size distribution of grains produced by igneous (intrusive and extrusive) processes or by shock metamorphism, (2) the size distribution resulting from crushing, chemical alteration, or by hydraulic or aerodynamic sorting; (3) the shape and degree of grain roundness and surface texture induced by mechanical and chemical alteration; and (4) the mineralogy and chemistry of grains.