Abstract: A microdensitometer arranged to scan an exposed film is coupled to a programmed computer. The computer analyses images captured through a microscope by a digital camera and to ‘map’ and indicate the optical density of the exposed film and distribution of density levels at any visible wavelength. This information, recorded in the exposed film, can be used to determine the actual exposure to which a patient has been subjected during X-ray treatment, where the film has been exposed to the X-rays during the treatment. If a film is sensitive to mechanical stress, the microdensitometer can also be used to yield mechanical stress distribution that has been applied to the film.

Abstract: A spectroscopy system having enhanced noise reduction that comprises (i) an arc lamp light source of emitted light, which emitted light is projected as an image of the light source; (ii) a slit aperture through which the emitted light is projected; and (iii) a detector operably associated with the slit aperture for detecting the emitted light. The slit aperture, the arc lamp, and the image of the arc lamp each have a major axis. The major axis of the slit aperture is oriented essentially orthogonally to the major axis of the image of the arc lamp, so that the signal-to-noise ratio of the spectroscopy system is improved as compared to the signal-to-noise ratio of the spectroscopy system when the major axis of the slit aperture is oriented essentially parallel to the major axis of the image of the arc lamp.

Abstract: For calibrating a spectrophotometer having a monochromator with a rotary mechanism to rotate a diffraction grating for producing a monochromatic beam of light of a specified target wavelength, transmission errors by the rotary mechanism are preliminarily measured to obtain an error curve having peaks corresponding to feed angles. A smallest angular interval, greater than an allowable limit, between a pair of feed angles corresponding to a mutually adjacent pair of peaks in the error curve is selected. One or more lamps emitting bright lines with wavelength interval which corresponds to motion of the rotary mechanism by less than one half of the selected smallest angular interval are used as a light source. Control values to be supplied to the rotary mechanism for obtaining monochromatic beams of light from the bright lines emitted from the selected lamps are determined by measurements.

Abstract: In the monochromator, when measured beam which is diffracted by a plane diffraction grating is collected by a collimator to be returned, the measured beam is displaced by a displacement member in a direction parallel to rulings of the plane diffraction grating and is passed through a first cut-off slit having a slit of a predetermined width formed in a direction perpendicular to the direction of the rulings.

Abstract: Fiber Bragg grating coupled light sources can achieve tunable single-frequency (single axial and lateral spatial mode) operation by correcting for a quadratic phase variation in the lateral dimension using an aperture stop. The output of a quasi-monochromatic light source such as a Fabry Perot laser diode is astigmatic. As a consequence of the astigmatism, coupling geometries that accommodate the transverse numerical aperture of the laser are defocused in the lateral dimension, even for apsherical optics. The mismatch produces the quadratic phase variation in the feedback along the lateral axis at the facet of the laser that excites lateral modes of higher order than the TM00. Because the instability entails excitation of higher order lateral submodes, single frequency operation also is accomplished by using fiber Bragg gratings whose bandwidth is narrower than the submode spacing. This technique is particularly pertinent to the use of lensed fiber gratings in lieu of discrete coupling optics.

Abstract: A system for translating applied linear motion into a slit width present between facing edges of two "Knife-blade" elements. In its preferred embodiment, two slide assemblies are firmly affixed to a frame such that loci of motion of slide elements thereof form an acute angle therebetween. Lower ends of each slide element, as viewed in vertically oriented frontal elevation, allow horizontal motion therebetween when said slide element lower ends are caused to simultaneously move vertically. An alternative embodiment provides that the slide elements be oriented such that said loci of motion of said slide elements are, for instance, horizontally directed. In its preferred embodiment the simultaneous motion of the slide elements is effected by a motor, preferably a precisely controlled computer driven stepper motor, which motor causes a threaded shaft therein to move vertically as a result of screw thread translation of motor imparted rotational motion to said threaded shaft.

Abstract: A spectrometer slit switching mechanism includes a slit plate having a plurality of entrance slits and exit slits formed at prescribed positions, parallel support rods for supporting the slit plate so as to be movable along the support rods, a screw portion formed on at least one support rod for transmitting forced to the slit plate, and a driving motor for transmitting rotational energy to the support rod provided with the screw portion, wherein the entrance slits are arranged on a line that runs parallel to the direction of movement of the slit plate and the exit slits are arranged on a line that is both parallel to and spaced a prescribed distance from the line on which the entrance slits are arranged. In accordance with this structure, the driving motor is operated in the clockwise and counterclockwise directions to raise and lower the slit plate in order to align a desired entrance slit and exit slit with the light path of the spectrometer.

Abstract: A scanning monochromator system which uses a directly coupled stepper motor to drive a spectral-dispersion element. The spectral-dispersion element is directly coupled to the output shaft of the motor. The movement of the motor is controlled with an electronic circuit that controls the motor winding current. The circuit includes a power driven section, a pulse-width modulator section and a computer section. The power driven section switches electrical current through the motor windings and can produce a variable pulse-width ranging from 0 to 100 percent modulation. The pulse-width modulator section accepts values from the computer section and converts these values into variable pulse-width signals for use by the power driver section. The computer section supplies values to the pulse-width modulator section based upon requirements for the motor movement and position. The required motor position is determined by the type of spectral-dispersion element and the desired wavelength selection of the monochromator.

Abstract: A spectrometer comprises a tunable interferometer for producing a monochromatic continuous image at an image plane and including two mirrors having substantially parallel surfaces and an adjustable spacing therebetween, a radiation detector located at the image plane for recording the image, a filter arrangement for allowing at least one predetermined range of wavelengths to pass to the detector, and a lens arrangement for collecting radiation and limiting radiation incident on the interferometer to an angle which is substantially perpendicular to the substantially parallel surfaces of the two mirrors.

Abstract: A slit is disposed as diaphragm in the beam path of a mass spectrometer. The slit width is to be variable in the simplest possible manner. Manual, electric motor-driven, thermoelectric or piezoelectric adjustment devices are known. According to the invention a pneumatic adjustment is provided. A Bourdon tube (12) moves a lever (14), at one end (18) of which slits (19, 20, 21) of differing slit widths are disposed. The lever movements are limited by abutments (22, 23).

Abstract: A laser radiation detection system using a spatial/wavelength filter to "ulate" the response of a detector as a function of wavelength, allowing discrimination of laser sources against broad spectral sources, as well as wavelength determination.

Abstract: A device for the spectral dispersion of light suitable for use in a spectrographic mode with arrays of solid state photo-detectors. Light from an entrance aperture passes through a dispersing prism with two curved, refracting surfaces both operating near their aplanatic conjugates. After being reflected by a concave mirror located behind the prism, light returns through the prism in the opposite direction, the refractions at each face again being nearly aplanatic. Spectrally dispersed images of the entrance aperture are formed on a plane well separated from the entrance aperture and nearly normal to the incident light rays. Good image quality is maintained over a broad range of operating wavelengths simultaneously, allowing large spectral intervals to be surveyed without moving any of the elements of the system.

Abstract: A monochrometer having a stray light trap which substantially directs stray light away from light of wavelength of interest and/or absorb the stray light so as to substantially reduce the stray light component in the light of interest. The monochrometer has internal surfaces each having one of several optical characteristics.

Abstract: Iterative compensation of drift of peak positions of spectral lines is effected in a spectral monochromator including a grating, a detector of spectral fractions of a spectral band, a stepper motor for varying relative orientation of the grating and the detector, and a computer. Computer-defined spectral windows each encopasses a spectral band and has an initial spectral center. Each window is scanned to determine a peak spectral position. Calculation is made for determining a spectral position error of the peak position from the initial center for each corresponding window. A functional average of the offsets for the peaks is calculated as a linear function of window position, and a revised spectral center for each window is calculated as being equal to the initial center plus the functional average for the window position determined from the linear function. Each window is shifted correspondingly.

Abstract: A multi-element optical detector having a planar array of detector elements is focused at the focal plane of an optical spectrometer by placing the detector with the detecting surface of the array facing the optical spectrometer and being substantially perpendicular to the axis of the path of the light from the optical spectra to the focal plane. Relative movement is provided between the detector and the focal plane along said axis so that the detector array is placed at several different positions with respect to the focal plane. At each position the output values of the detector elements of the array are measured and the second difference of the output values is determined by the equation (-F1+2.times.F2-F3), where F1, F2, and F3 are the output values of three of the elements. The optical detector is placed at the position which provides the maximum value of the second difference, which is the position of the focal plane.

Abstract: An optical relay having a pair of simple lenses and an opaque barrier defining an aperture. In a spectrometer, the optical relay is positioned between a light source and an opaque barrier defining a slit to focus light of a reference wavelength w.sub.r onto the slit. The location of the aperture and the choice of w.sub.r are selected so that the flux of light through the slit is substantially flat as a function of wavelength.

Abstract: A slit changing device for a monochrometer comprises a slit disc forming a plurality of pairs of slits each having different widths, a pulse motor for rotating the slit disc, a control circuit for activating the pulse motor, so that any pair of the pairs of slits can be selected, and a keyboard operated to enter target slit information into the control circuit. The coupling between the slit disc and the pulse motor is slipless and backlashless. The control circuit comprises a present slit pulse counter for storing the pulse number of a presently selected slit pair and a target pulse counter for storing the pulse number of a target slit pair.

Abstract: A slit mechanism for use in a monochromator which is capable of changing not only the slit width but also the slit height. The slit mechanism is provided with a plurality of pairs of slits formed in a disk rotatable about an axis. The two slits in each pair have the same width and the same height, and each pair of slits have a different width from those of the other pairs of slits. The slit mechanism is further provided with at least one additional pair of slits having the same width as the width of, and a different height from the height of, a predetermined pair of the plurality of pairs of slits. All the pairs of slits are arranged circumferentially of a circle on the disk concentric with the axis of rotation of the disk, so that each pair of slits are positioned diametrically opposite to each other on the circle so as to serve as an entrance and an exit slit, respectively, for the monochromator.

Abstract: Disclosed is an optical system used in a spacecraft to observe a remote surface and provide a spatial and spectral image of this surface. The optical system includes aspheric and spherical mirrors aligned to focus at a first focal plane an image of the surface, and a mirror at this first focal plane which reflects light back on to the spherical mirror. This spherical mirror collimates the light and directs it through a prism which disperses it. The dispersed light is then focused on an array of light responsive elements disposed at a second focal plane. The prism is designed such that it disperses light into components of different wavelengths, with the components of shorter wavelengths being dispersed more than the components of longer wavelengths to present at the second focal plane a distribution pattern in which preselected groupings of the components are dispersed over essentially equal spacing intervals.

Abstract: At least one of the entrance slit and the exit slit of a monochromator is capable of being opened or closed. The light issued from the exit slit when the slit width is changed is detected by a light detector. The slit width is calibrated when the ratio between the maximum value of the output of the light detector and the output of the light detector with the slit being gradually closed subsequently reaches a predetermined value, in other words, when a predetermined narrowness of the slit is attained. The slit width is controlled by a pulse motor or the like. The pulses supplied to the pulse motor are counted by a counter. At the time of slit width calibration, a value corresponding to the particular slit width is set in the counter, thus performing the slit width calibration.

Abstract: A cam and follower arrangement in which the cam consists of a track carried by a rotatable member. The track has one or more abrupt directional transitions (17) and the follower (17) is biassed to engage one wall or the other (21) of the track (21) appropriate to the direction of rotation of the member by means including a direct-current electric motor operated in a stalled condition. The arrangement may be employed in a monochromator for spectrophotometric apparatus to drive a filter-holder to position one of a number of optical filters arranged in the incoming beam of light.

Abstract: Various vacuum ultraviolet monochromators embodying a rotatable diffraction grating and fixed entrance and exit slits, and working at a predetermined magnification are disclosed which provide improved optical performances by a correction of the odd terms of the wavefront aberration. In one group of instruments the fixed angle 2.theta. between the entrance and the exit beams is 90.degree. and the magnification 1. In another group, grazing incidence instruments are considered, 2.theta. being equal to 166.degree..