Showing papers on "Beam splitter published in 1974"

Coherent Optical Adaptive Techniques

Abstract: The theory of multidither adaptive optical radar phased arrays is briefly reviewed as an introduction to the experimental results obtained with seven-element linear and three-element triangular array systems operating at 0.6328 μm. Atmospheric turbulence compensation and adaptive tracking capabilities are demonstrated.

11. Fourier Spectrometers

Abstract: Publisher Summary This chapter examines the theory and applications of Fourier transform spectroscopy. A Michelson interferometer is ideally suited for work in high-resolution infrared spectroscopy of astronomical objects. In this application the available signal-to-noise ratio limits the number of observable objects and, therefore, any gain in signal-to-noise is of tremendous importance. The Michelson interferometer is a device for interfering two beams of light. Light entering the interferometer is divided into two separate beams by a beam splitter and is recombined after a controllable phase delay has been applied to one of the beams The use of digital computers in performing the Fourier transform of the interferogram, implies that the data be supplied in digital form. The effect of the slow-beat frequency is to make the contributions from spectral elements near the calculated element essentially positive rather than averaging to zero. The dispersive properties of the beam splitter can cause wave number-dependent phase shifts. The data recording and processing systems are as important as the optical and mechanical systems of the interferometer.

Measuring device for the measurement of fluid flow rates

Abstract: This disclosure relates to an apparatus for measuring flow rates in gas sams and includes an optic component and an electronic component. The optic component starts with a focussed laser beam which is passed through a beam splitting prism so as to define two partial beams which, in turn, pass through a lens system so as to have two adjacent remote focal points. Particles in the gas stream passing through the focal points, which are located therein, reflect light in the form of reflected light beams which pass through a further lens system to pulse generators which, when actuated, generate a start pulse and a stop pulse with these pulses controlling the formation of a saw toothed wave controlling the amplitude of the generated wave, and the generated wave being directed to binary converter means and collector means which, in conjunction with an oscilliscope provides a visual wave having an amplitude indicative of a flow rate. The beam splitter is rotatable so as to selectively position one of the focal points within the gas stream with respect to the other so as to obtain a directional vector of the flowing gases.

Catadioptric projection printer

Abstract: An improved projection printer prints a circuitry pattern from a reticle onto a wafer by using a mercury arc source, a beam splitter, and a focusing mirror. The beam splitter is a polarizing beam splitter, and a polarization altering means is arranged between the polarizing beam splitter and the focusing mirror, allowing the radiant energy reflected from the focusing mirror to pass straight through the polarizing beam splitter to the wafer being printed. A system for optically registering the wafer and the reticle includes a source of visible radiant energy of a longer wavelength range and a microscope arranged for observing the reticle. The visible radiant energy is polarized and directed to the polarizing beam splitter in an orientation to pass straight through the beam splitter and be incident on the wafer. The visible radiant energy reflected from the wafer to the focusing mirror and back to the polarizing beam splitter has its polarization altered to be split be the polarizing beam splitter for imaging the wafer on the reticle for viewing through the microscope.

Wide-angle on-axis projection system

Abstract: The invention provides a wide-angle common axis projection system wherein a reflector and a see-through beam splitter reflector are combined with a projector means having a wide angle lens and a display screen of spherical shape to develop on-axis image projection for wide-angle display in relation to a viewer''s point located on the non-reflective side of the beam splitter reflector.

Optical system for objective refractor for the eye

Abstract: An optical system for an objective refractor for the eye uses a source of light and a reticle for forming the light in a pattern, and a polarizing beam splitter directs a polarized portion of the light along a light path including a quarter-wave plate. Light reflected from the retina of the eye is directed back along the light path to the polarizing beam splitter, and a polarized portion of the reflected light is oriented by the quarter-wave plate to pass through the polarizing beam splitter on an output path directed away from the source. A light responsive device in the output path produces a usable output as a function of the focus of the reflected pattern, and the optical system can be applied to both manual and automatic refractors.

Apparatus for reading a record carrier on which information is stored in an optically readable structure

Abstract: An apparatus is described for reading a record carrier on which information is stored in an optically readable structure. Between a radiation source and an objective system, a polarization-sensitive beam splitter and a λ/4 plate are disposed. The optic axis of the λ/4 plate is perpendicular to the end faces, so that the plate may be thick and may be rotated in its own plane.

Laser apparatus employing mechanical stabilization means

Abstract: A laser includes a lasing medium and two Porro prism end reflectors with the roofline of each prism being at an angle between about 5* -85* with respect to the plane of polarization and optically perpendicular to each other, to provide mechanical stability. A beam splitter is provided to direct a portion of the energy out of the system, the output power being determined by the angle of rotation of the Porros.

Instrument responsive to back-scattered or back-reflected radiation having passive system for range correction

Abstract: An instrument for responding to backscattered or backreflected radiation from a path through a medium in which a beam of electromagnetic radiation is transmitted along the path, and a receiver system is arranged to receive backscattered radiation returning along the path substantially coaxially with the beam, the receiver system including detection means for the backscattered radiation and equalizing means for producing a substantially equal response regardless of the point of backscatter along the path. The equalizing means comprises a passive radiation transmission structure interposed in the path of return prior to the detection means, the passive structure having a substantially constant acceptance solid-angle for the returning radiation from points over the range of the path whereby radiation reaching the detection means from various points along the path does not vary in intensity due to the different distances of the points from the detection means. The passive structure is shown in the form of a full circular hole and a doughnut-shaped hole in an opaque plate, with the return beam focused to fill the hole out to a range of interest. Other passive structures are illustrated by a Fabry-Perot filter combined with a telescope and a bundle of opaque walled tubes. Transmissivity of a medium out to a point r is determined by the ratio of the integral of power from r to an outer limit range L in which the passive structure is still functional, as numerator, over the integral from the instrument to limit L as denominator. The coaxial array is shown achieved by use of a beam splitter, the beam from the source proceeding via the beam-splitter outwardly, the beamsplitter sized so that all return signal reaching the detector is treated equally by the beam-splitter. A multiple beam-splitter is shown by which multiple beams from a single source are produced, with the respective returns concentrated on a single detector.

Optical system for angle measurement by interferometry

Abstract: An optical system for angle measurement by interferometry comprises four retroreflectors arranged in pairs as beam pathlength multipliers, with two adjacent ones of the retroreflectors rigidly mounted and the other adjacent ones mounted for rotation together about a common axis. A beam of electromagnetic energy, for example a laser beam, is directed towards a beam splitter by which means it is split into two secondary beams, one secondary beam being directed to pass back and forth between one pair of the retroreflectors while the other secondary beam is similarly directed by a beam folder to pass back and forth between the other pair of retroreflectors. Both reflected beams are redirected by retroreflectors along similar paths between their respective retroreflectors to the beam splitter where interference between the secondary beams occurs. The angular displacement of the movable retroreflectors is deduced from the distance between their ridges and the number of fringes generated at the beam splitter.

Uni-directional viewing system

Abstract: A uni-directional viewing system with an obliquely disposed mirror defining a beam splitter for partial reflection and partial transmission of a light beam that is generated by a source and having an absorber disposed at one side of the mirror for absorbing the beam that is transmitted through the mirror. The reflected beam is directed towards a viewing port, which is disposed at the other side of the mirror. An eye port, which is disposed on the absorber side of the mirror, is provided for observing a subject at the viewing port. The observed subject views only the image of the source and the observer views the observed subject.

Polarized continuous wave crystalline laser

Abstract: A beam splitting polarizer is positioned in a laser cavity consisting of a laser rod and two highly reflecting mirrors. The laser rod is continually pumped, producing thermally induced stress birefringence in the laser rod, which performs a polarization rotation which is used to couple energy via the polarizer from inside the laser cavity. The stress pattern in the laser rod can be changed by rotation of the plane containing the pumping lamp and laser rod axes while keeping the beam splitter polarizer stationary. Two cavity configurations are shown, one in which the HR mirrors are arranged in opposed facing relationship, and the other with the mirrors being arranged orthogonally with respect to each other, and the beam splitting polarizer which is utilized for obtaining the polarization component with the largest gain. The gain of each of these configurations can be controlled by the aforesaid rotation of the pump lamp and laser rod with respect to the beam splitting polarizer.

Optical measuring apparatus

Abstract: A smoke meter or a visibility meter comprises a light source in operative association with an optical system forming a light beam traversing a measuring distance at the end of which there is a reflex-reflector on which the light beam impinges. A beam splitter is positioned in the path of rays of the light beam and inclined with respect to the optical axis thereof, for example at a 45* angle, to direct light, reflected by the reflex-reflector, laterally of the optical axis as a measuring light flux. A photoelectric detector is positioned in the path of the light directed laterally of the optical axis by the beam splitter. A rotatable sector disc intersects the light beam between the beam splitter and the reflex-reflector, and is divided into sectors which are alternately transparent and diffusely reflecting. The sector disc produces a reference light flux from the light source and which impinges on the detector in alternation with the measuring light flux. In a preferred modification, a perforated disc, modulating the light beam, is secured on a common shaft with the sector disc, with the beam splitter being located between the perforated disc and the sector disc. The sector disc, in this case, is formed with two pairs of arcuate slots each extending through 90*, with the two pairs being angularly offset by 90* and the slots of one pair being diametrically opposite each other and offset radially with the corresponding slots of the other pair. Respective photoelectric detectors are positioned adjacent the two pairs of slots and are illuminated from the light source by a light conducting pipe or tube having an exit end aligned with the arcuate slots. Electronic evaluation circuits are connected to the outputs of the photoelectric detector receiving the measuring and reference light fluxes, and in the preferred embodiment, the electronic circuitry is also connected to the two photoelectric detectors associated with the arcuate slots in the sector disc.

Monolithic beam splitter mirror arrangement

Abstract: A beam splitter is incorporated as one of the mirrors in a three mirror folding array in a projection system for exposing wafers used in making micro circuits. Through the use of the beam splitter, it is possible to view the wafer for alignment purposes while avoiding the drawbacks of viewing through the back of the master which is being imaged on the wafer.

Optical beam splitter

Abstract: A pair of beam splitters for an optical instrument wherein one beam splitter is used to divide source radiation into a sample and reference beam while the second beam splitter recombines the sample and reference beams prior to their entering a monochromator. In order to reduce schlieren effects, each beam splitter is provided with stripes of alternating reflective and transmitting portions. The edges of the stripes of each beam splitter lie wholly within the optical aperture while the ends of the stripes extend outwardly of the optical aperture. The beam splitters are oriented in such a manner that the stripes are orthogonal.

Picosecond infrared holography on bismuth film

Abstract: Thin films of bismuth provide a holographic recording medium that requires no development and is sensitive into the infrared. At a spatial frequency of 1730 lines/mm the diffraction efficiency is 5% for an exposure of 50 mJ/cm2 at 1.06 μm. Interference holograms using a diffusive beam splitter for a picosecond Nd:YAG laser show sufficiently high resolution for plasma holography applications.

Hologram recording device

Abstract: A hologram recording device for recording information from any position on a hologram recording material as elemental holograms along the circular periphery of a hologram recording material comprising A LASER LIGHT SOURCE; A BEAM SPLITTER FOR SPLITTING A LASER LIGHT BEAM FROM THE LASER LIGHT SOURCE INTO A FIRST LASER LIGHT BEAM AND A SECOND LASER LIGHT BEAM; MEANS FOR DIRECTING THE FIRST LASER LIGHT BEAM FROM A PREDETERMINED DIRECTION TOWARD A PREDETERMINED POSITION ON A HOLOGRAM RECORDING MATERIAL; AN OPTICAL FIBER HAVING AN OPTICAL ELEMENT ROTATABLE AROUND TWO AXES AT ONE END THERE OF FOR DIRECTING THE SECOND LASER LIGHT BEAM FROM ANY POSITION TOWARD THE PREDETERMINED POSITION ON THE HOLOGRAM RECORDING MATERIAL; AND MEANS FOR ROTATING THE HOLOGRAM RECORDING MATERIAL AT ANY ANGLE IN THE PLANE OF THE HOLOGRAM RECORDING MATERIAL.

Very high resolution radiometer

Abstract: A primary sensor used in environmental and earth-resource observation, the Very High Resolution Radiometer (VHRR) was designed for use on the ITOS D series spacecraft. The VHRR provides a 0.47 mile resolution made possible with a mercury-cadmium-telluride detector cooled to approximately 105 K by a passive radiator cooler. The components of this system are described. The optical subsystem of the VHRR consists of a scanning mirror, a Dall-Kirkham telescope, a dichroic beam splitter, relay lenses, spectral filters, and an IR detector. Signal electronics amplify and condition the signals from the infrared and visible light detector. Sync generator electronics provides the necessary time signals. Scan-drive electronics is used for commutation of the motor winding, velocity, and phase control. A table lists the performance parameters of the VHRR.

Rotating beam splitter for the extreme vacuum ultraviolet

Abstract: We have built a rotating-mirror beam splitter at grazing incidence which was used to measure directly (with minor corrections) the transmissivity of thin films in the 20-280 eV photon energy region. The intensity fluctuations usually encountered when using electron accelerators as light sources were efficiently eliminated. The same instrument could be used to measure differential transmissivities DeltaT/T with a sensitivity of a few tenths of a percent. In another arrangement a deflecting mirror which is incorporated as the photocathode into an open electron multiplier served as a very efficient beam monitor against intensity fluctuations.

Thermooptic sonar system

Abstract: A means of generating usable sonar beams in water comprising, a high powered laser, a standpipe for conducting a beam from the laser to a predetermined depth in the water, a beam splitter for directing the laser beam along two paths in the water, the laser beam being absorbed in the water and the energy contained therein converted to acoustical energy by the expansion of the water along the paths thereby generating a coherent acoustic beam perpendicular to the two paths.

Fluorescence spectrophotometer for absorption spectrum analysis

Abstract: A fluorescence spectrophotometer having a beam splitter placed between an exit slit of an excitation monochromator and a specimen. Part of the excitation radiation is conducted to a first light quantum meter by said beam splitter and a reference photomultiplier is provided for receiving fluorescence from said first light quantum meter. A second light quantum meter is placed at the position normally occupied by a specimen cell and first and second absorbing cells are disposed in front of said first and second light quantum meters, respectively.

The Theory of the Optical Wedge Beam Splitter

Abstract: Report discussing optical wedge beam splitters and the basic theory for computing the ratio of the intensity of the incident beam to the intensity of any selected emerging beam and also for computing the direction of the emerging beam, assuming that the wedge angle, index of refraction, angle of incidence, and number of reflections are known.

Thin-film waveguide laser with a distributed feedback and gain modulation

Abstract: Laser action was produced in a polymethylmethacrylate film activated with rhodamine 6F and deposited on a quartz substrate. The film was pumped with two converging second-harmonic neodymium laser beams, which formed an interference pattern. The rectangular edge of the quartz substrate acted also as a beam splitter of the pumping radiation. The output frequency of the film laser was tuned by altering the angle which the quartz plate made with the direction of the pumping radiation.

Apparatus for measuring the proportion or quantity of a component in a radiation-transparent mixture

Abstract: For measuring the proportion or quantity of a component in a radiation-transparent mixture, a beam is passed through the mixture and subsequently split by a beam splitter into a measuring beam and a reference beam. The measuring beam is passed through a narrow-band interference filter which has a transmitting wavelength that corresponds to a discrete absorption wavelength of the component. This filter is oscillated in a range of oscillation which traverses the absorption maximum. The reference beam is passed through a narrow-band interference filter which has a transmitting wavelength that differs from the absorption wavelength of the component. Subsequently, the radiation intensities of the measuring beam and the reference beam are separately detected and their difference is formed. This difference is a function of the proportion or quantity of the component.