Abstract: Stray light produced in a monochromator by the diffuse reflection of the incoming light beam specularly reflected from the surface of the diffraction grating is practically eliminated by interposing a black glass "absorbent-reflector" in the path of the specularly reflected beam. The small percentage of radiation that is not absorbed by the absorbing glass is reflected to an opposite blackened wall which diffuse reflects an extremely small percentage of the beam back to the absorbent-reflector where a very negligible part is returned to the grating surface and eventually to the monochromator exit slit.

Abstract: A time-division multiplexed spectrometer (TMS) which can convert the output from a pulsed continuum radiation source into a time- and wavelength-division multiplexed pulse train is provided, by a single spectrometer (1, 2) when: (a) an input source (100) is terminated at the image plane of the spectrometer at a first position which is displaced from the symmetry plane, (b) the first end of a set of optical fibers (100-110), each having a different length, are determined at the image plane at positions which are displaced in the opposite direction from the symmetry plane as is the first position, whereby narrowband portions of the output spectrum are picked up and delayed by different amounts, (c) the second end of the set are terminated at the image plane at positions which are reflections of the terminations of the first end about the symmetry plane, whereby the signals are reinjected into the instrument and refocused onto a second position at the image plane corresponding to the reflection of the first posi

Abstract: An improved optical system is disclosed for rapid, accurate spectral analysis of the reflectivity or transmissivity of samples. A concave holographic diffraction grating oscillated at high speed is utilized to provide a rapid scanning of monochromatic light through a spectrum of wavelengths. The grating is positively driven at very high speed by a unique cam drive structure comprising identically shaped conjugate cams. The rapid scan by the grating enables the reduction of noise error by averaging over a large number of cycles. It also reduces the measurement time and thus prevents sample heating by excessive exposure to light energy. A filter wheel having dark segments for drift correction is rotated in the optical path and is synchronous with the grating. Source optics is employed to optimally shape the light source for particular applications.

Abstract: A photometric absorption detector, in particular for the use in liquid chromatography is provided, in which a test cell is penetrated by the rays emitted by a light source and in which the absorption of certain wave length ranges of the light by the sample is recorded by means of a photodetector arrangement. Means for the spectroscopical dispersion of the light emerging from the test cell are provided, and the photodetector arrangement can be displaced within the spectrum. There may be two independently displaceable photodetectors, one of which may be set to a measuring wave length, while the other one may be set to a reference wave length.

Abstract: A monochromator has three ports or slits including two entrance slits and an exit slit. A single mirror and a diffraction grating define a first, folded path between an entrance slit on one side of the housing and an exit slit on the opposite side of the housing. The mirror is movable in and out of a second path between the second entrance slit and the grating so that a second path may be completed from the second entrance slit to the grating and thence to the exit slit. Alternatively two of the ports may be used as exit slits and one as an entrance slit.

Abstract: An improved optical system is disclosed for rapid, accurate spectral analysis of the reflectivity or transmissivity of samples. A concave holographic diffraction grating oscillated at high speed is utilized to provide a rapid scanning of monochromatic light through a spectrum of wavelengths. The grating is positively driven at very high speed. The rapid scan by the grating enables the reduction of noise error by averaging over a large number of cycles. It also reduces the measurement time and thus prevents sample heating by excessive exposure to light energy. A filter wheel having opaque segments is rotated in the optical path and is synchronous with the grating. The filter wheel is divided into two arcuate segments separated by the opaque segments arranged approximately 180 degrees apart. One arcuate segment of the wheel transmits only first order light. The other arcuate segment transmits only second order light.

Abstract: The invention relates to a spectrometer including a rotatable dispersive element, a stepping motor for varying the angular position of said dispersive element, a program transmitter for controlling said stepping motor, a timing generator and a recording instrument.

Abstract: A slow scan, frequency limited spectrometer having a screw mechanism for driving a rotatable grating is improved by incorporating and interlinking the following new constituent members with the screw mechanism: a cylindrical cam member with a groove and a constraint to attain a predetermined pitch, so that rapid scanning of a preselected wavelength range is achieved with the grating; a high torque, variable speed, direct current electric motor, so that the rapid scanning may be varied in speed; and, a liner potentiometer with a sliding contact, so that a remote wavelength readout of the variable rapid scanning can be obtained. Cylinder cam members of various pitches are also disclosed for use in scanning different wavelength ranges. At a low cost for improvements, the resulting spectrometer provides a variable fast scan, and is frequency selective.

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..

Abstract: A spectrometer capable of providing a predetermined wavelength of output light in accordance with a control voltage signal applied to a scanning element is described. The scanning element located at the grating image of the spectrometer is a small mirror attached to the rotor of a galvanometer whose angular position is accurately controlled by a closed-loop electronic control. The spectrum reflected from the mirror is passed through a slit to provide the output light of a predetermined wavelength. Selection of the waveform of the control signal allows the spectrometer to be operated as a dual wavelength spectrometer, to use a linear wavelength scan, or other wavelength scan patterns for absorbance analyses of a sample.

Abstract: A spectrophotometer utilizing a multiple wavelength electromagnetic wave source which is intercepted and dispersed into a spectrum. The spectrophotometer includes a closed loop servo positioning mechanism for simultaneously directing selected portions of the electromagnetic spectrum to a detector which analyzes these portions of the spectrum for analytical purposes.

Abstract: A wavelength reading apparatus for a monochromator comprises a monochromator utilizing a dispersion element for dispersing light in accordance with its wavelengths, a dispersion element driver unit for rotating the dispersion element to effect the tuning wavelength scanning operation of the monochromator and a wavelength counter for adding or subtracting a pulse, which is produced each time when the tuning wavelength of the monochromator changes by a predetermined wavelength increment, depending on whether the wavelength increases or decreases. The wavelength counter is set to a predetermined counting value, in response to a wavelength calibrating pulse produced when the tuning wavelength of the monochromator reaches a predetermined value, so that any counting value of the wavelength counter correctly represents the instant value of the tuning wavelength of the monochromator.

Abstract: There is disclosed herein an aspheric grating which is operable to image local or distant point sources sharply in a designated wavelength, i.e. produce a perfectly stigmatic image in the given wavelength at grazing angles of incidence. The grating surface comprises a surface of revolution defined by a curve which does not have a constant radius of curvature but is defined by a non-linear differential equation specified in terms of the diffraction condition expressed as (m.lambda./.sigma.).sup.2 =A>O where m is the diffraction order, .lambda. is the wavelength and .sigma. is the grating surface ruling interval.