352 results about "Double pass" patented technology

An apparatus and method for performing optical coherence domain reflectometry. The apparatus preferably includes a single output light source to illuminate a sample with a probe beam and to provide a reference beam. The reference beam is routed into a long arm of an interferometer by a polarizing beamsplitter. A reflected beam is collected from the sample. A 90.degree. double pass polarization rotation element located between the light source and the sample renders the polarizations of the probe beam and reflected beam orthogonal. The polarizing beamsplitter routes the reflected beam into a short arm of the interferometer. The interferometer combines the reference beam and the reflected beam such that coherent interference occurs between the beams. The apparatus ensures that all of the reflected beam contributes to the interference, resulting in a high signal to noise ratio.

A spectrometer, or a spectral instrument using multiple non-interfering optical beam paths and special optical elements. The special optical elements for use with the instrument are used for directing the optical beam and / or altering the form of the beam. The instrument has the potential, depending upon the totality of the optical components incorporated into the instrument, to be a monochromator, a spectroradiometer, a spectrophotometer and a spectral source. The spectral instrument may further be a part of the spectral system. The system may include the spectral instrument, a power module and means for remote control of the instrument. Such remote control may be by use of a personal computer or a control system dedicated to the control, measurement and analysis of the collected information. The multiple non-interfering beam paths are created using specially designed optical elements such as a diffraction grating, a splitter box, a zero back-lash drive system for movement of the grating element. The orientation of and a physical / spatial relationship between the field lenses, slits, return mirror, reflecting prism, turning lenses all define the multiple, preferably two paths. Particularly, there is a double pass through the grating to increase dispersion, reduce scatter while maintaining a perfect temperature independent spectral match for the second pass. Using the same grating twice reduces scatter by about a factor of 1000, increases the dispersion by a factor of two, and eliminates any temperature-related mechanical spectral drift which often is present with two separate monochromators. Because of the specially designed grating structure, the grating can cause the concurrent diffraction of a plurality of incident optical beams, each of which beams have different angles of incidence and different angles of reflection. The path of the incident and the reflected beam to and from the grating is "off-axis". That is, the beams going to and from the grating do not use the optical axis of the grating structure.

Methods and apparatus for enhancing the performance of a reflective liquid crystal display system. The high-contrast color splitting prism system utilizes a "double-passed" prism assembly. Polarized light enters the prism assembly, is color-split and emitted as separate colors to spatial light modulators which reflect each color in accordance with a desired image. The reflective light is passed, once again, through the prism assembly where the separate colors converge and propagate to a projection lens for display of the image on a screen. A waveplate retarder is positioned between the liquid crystal display and the polarizing element. The waveplate retarder is tilted with respect to the optical axis to eliminate the deleterious effects of the Fresnel reflections at the interfaces of the waveplate retarder.

A fuel filter assembly (10) has a head portion (12) and an element portion (14) enclosing a replaceable cartridge (18). The assembly has a first inlet port (22) which accepts fuel from a tank (90) and filters it by passage through a screen (43) supported on a tube (36). The fuel that has been filtered by passage through the screen is delivered from the assembly through a first outlet port (24) for delivery to a lift pump (96). Fuel from the lift pump is returned to the fuel filter assembly through a second inlet port (26). The fuel is finely filtered by passage through a loop of filter media (60). Clean fuel is delivered from a second outlet port (28) to an engine (104). Contaminants separated from the fuel by passage through the screen and the media loop are collected in first-and second sump areas (78), (80) of the filter housing respectively. An alternative embodiment (110) includes a prefilter screen (158) integral with a replaceable cartridge (118).

The present invention relates to an instrument and method for measuring the optical quality of an eye in a human subject. The instrument, which can be of either a single or double pass design and may include three-separate channels, permits real-time, simultaneous measurement of optical aberrations in the eye, retro-illumination of tear film to assess tear film stability, and scoring of psychophysical measures of visual performance. The simultaneous measurement of these parameters of optical quality and visual performance with the present instrument enables the operator to more accurately assess conditions and diseases of the eye, including dry eye disease (DED).

An apparatus and method for performing optical coherence domain reflectometry. The apparatus preferably includes a single output light source to illuminate a sample with a probe beam and to provide a reference beam. The reference beam is routed into a long arm of an interferometer by a polarizing beamsplitter. A reflected beam is collected from the sample. A 90.degree. double pass polarization rotation element located between the light source and the sample renders the polarizations of the probe beam and reflected beam orthogonal. The polarizing beamsplitter routes the reflected beam into a short arm of the interferometer. The interferometer combines the reference beam and the reflected beam such that coherent interference occurs between the beams. The apparatus ensures that all of the reflected beam contributes to the interference, resulting in a high signal to noise ratio.

A back support comprising a back support belt having flaps with fastening material for releaseably securing the flap ends in overlying relationship. Side pulls extend from the back portion of the support belt and also are provided with fastening material for securing the ends of the side pulls to the support belt and to each other. The side pulls are formed of overlying inner and outer portions in a known manner. The support belt has mounted thereon quick lock release buckles for attaching to the back support accessories, such as a standard apron having waist ties. The quick lock release buckles have male and female halves and pass through type securements on the separable halves. Preferably one of the securements is a double pass through type on the male halves in order to provide adjustability in securing the waist ties of a standard apron. Another feature of the invention is the provision of a means for holding the side pulls adjacent the secured flaps when the back support belt is mounted on a wearer. To this end vertical strips are provided on the outside surface of the flaps between the positions where the side pulls are secured to the belt and their ends. These strips pass between the overlying elements of the side pulls.

A two-channel spectrometer has a shared objective and a pair of slits at a common image plane. Each of the slits receives a portion of the output beam of the shared objective and is optimized for transmitting different wavelengths. A shared double-pass reflective triplet receives the output beams of the slits. The output of the reflective triplet is incident upon a beamsplitter, which sends a collimated first reflective triplet output of a first wavelength to a first dispersive element, and a collimated second reflective triplet output of a second wavelength to a second dispersive element. The outputs of the dispersive elements are directed back to the beamsplitter and the reflective triplet to imaging detectors located at two different locations of the common image plane.

Systems, arrangements and methods for obtaining three-dimensional imaging data are provided. For example, a broadband light source can provide a particular radiation. A first electro-magnetic radiation can be focused and diffracted, and then provided to at least one sample to generate a spectrally-encoded line. A second electro-magnetic radiation may be provided to a reference, which may include a double-pass rapidly-scanning optical delay, where the first and second electro-magnetic radiations can be based on the particular radiation. An interference between a third electro-magnetic radiation (associated with the first electro-magnetic radiation) and a fourth electro-magnetic radiation (associated with the second electro-magnetic radiation) can be detected. The spectrally-encoded line may be scanned over the sample in a direction approximately perpendicular to the line. Image data containing three-dimensional information can then be obtained based on the interference. The exemplary imaging methods and systems can be used in a small fiber optic or endoscopic probe.

A catadioptric projection optical system for forming an intermediate image of a first object twice and for forming an image of the intermediate image onto a second object, said catadioptric projection optical system comprising, in order from the first object side and along an optical axis of said catadioptric projection optical system, a first dioptric group that does not form a reciprocating optical system (double-pass optical system) that an incidence light and reflected light pass, said first dioptric group including a first lens group that has a positive refractive power and a second lens group that has a positive refractive power, a catadioptric group that forms the reciprocating optical system (double-pass optical system), said catadioptric group including a third lens group that forms the reciprocating optical system (double-pass optical system), a second dioptric group that does not form the reciprocating optical system (double-pass optical system), a first deflective reflector that arranges between the first lens group and the second lens group, and a second deflective reflector that arranges between the second lens group and the third lens group or between the second dioptric group and the third lens group.

A projection exposure lens has an object plane, optical elements for separating beams, a concave mirror, an image plane, a first lens system arranged between the object plane and the optical elements for separating beams, a second double pass lens system arranged between the optical elements for separating beams and the concave mirror, a third lens system arranged between the optical elements for separating beams and the image plane. The second lens system has a maximum of five lenses.

The invention provides spectroscopy apparatuses and methods allowing precise overlapping between circularly polarized pump beam and a counter propagating linearly polarized probe beams in a sample which presents unique advantages for precision spectroscopy. In general, the apparatus comprises a phase retarding element with which by double pass by retro reflection of an incident beam turn linearly polarized light to circular and vice versa. This unique configuration enable to design a compact and miniature apparatus which may be applied for measuring polarization spectroscopy, nonlinear optical rotation and coherent population trapping phenomena with certain advantages resulting from the unique optical arrangement. The design of the apparatus further facilitates integration and scaling to produce arrays of units which may be particularly useful for magnetometry applications. Other important applications of the invention include laser frequency stabilization and atomic clocks.

A fiber amplifier module for amplifying a signal pulse includes an optically pumped double-pass fiber amplifier in which a fiber Bragg grating reflects an amplified pulse in between the first and second amplification passes, and transmits most forward-propagating amplified spontaneous emission (ASE) generated by the optical pumping. The reflected amplified pulse from the double-pass amplifier, and reverse-propagating ASE generated by the optical pumping are reflected from another fiber Bragg grating that again reflects the amplified pulse and transmits most of the ASE. The twice-reflected amplified pulse can be delivered from the amplifier as an output pulse or passed to another amplifier module for further amplification. The amplifier fiber is operated in a saturated or near saturated mode. This reduces amplification of any portion of the forward-propagating ASE that is reflected into reverse propagation by the fiber Bragg grating of the double-pass amplifier.

A compact wavelength dispersing device and a wavelength selective optical switch based on the wavelength dispersing device is described. The wavelength dispersing device has a folding mirror that folds the optical path at least three times. A focal length of a focusing coupler of the device is reduced and the NA is increased, while the increased optical aberrations are mitigated by using an optional coma-compensating wedge. A double-pass arrangement for a transmission diffraction grating allows further focal length and overall size reduction due to increased angular dispersion.

An optical switch uses a polarization insensitive spatial light modulator operating by a double pass through a liquid crystal cell. The switch includes two such modulators in a cross bar arrangement. Different embodiments employing techniques for reducing cross talk are described.

A reduced polarization-dependent loss optical device utilizing two or more dispersive elements or a single dispersive element and a turning mirror, wherein the optical signal makes two passes through said single dispersive element when reflected from said turning mirror, and wherein the two or more dispersive elements or double pass single dispersive element has lower dispersion compared to a functionally equivalent single dispersive element, resulting in lower polarization dependent loss, reduced chromatic dispersion and increased wavelength dispersion. Moreover, a wavelength selective switch incorporating the optical device utilizing aperture-shared optics and functionally distinct planes of operation that enables high fiber port counts, such as 1×41, and multiplicative expansion, such as to 1×83 or 1×145, by utilizing elements optimized for performance in one of the functionally distinct planes of operation without affecting the other plane.

During two-pass sliding compaction, a heap may first be logically divided into fixed-sized segments, or chunks, and information regarding each chunk, known as per-chunk metadata, may be saved for use during the second, sliding phase. In addition to the per-chunk information, information regarding the location and size, called object extent information, may also be saved during the marking phase of two-pass sliding compaction. In the sliding phase of two-pass sliding compaction, live objects are moved to their respective destinations in the heap after first updating any object references in the objects. The order of objects being moved may be maintained across heap compaction. By relying upon the per-chunk and object extent information saved during the marking phase, objects may be processed individually and independent of each other during the sliding phase, according to some embodiments.

A pulse-stretcher has an optical delay loop including a beamsplitter. The beamsplitter divides an input pulse into a temporal sequence of pulse replicas, a first of which is transmitted by the beamsplitter and the remainder of which are reflected by the beamsplitter along the path of the transmitted replica. The sequence of replicas form an initially stretched pulse having a longer duration and lower peak power than the input pulse. A prism cooperative with the delay loop reflects the initially stretched pulse back into the delay loop along a path laterally displaced from the replica path. The beamsplitter divides the initially stretched pulse into a temporal sequence of pulse replicas propagating along a common path to form a finally stretched pulse, having a longer duration and a lower peak power than the initially stretched pulse. The finally stretched pulse has a sequence of power peaks. Peak power in the pulse is minimized when the beamsplitter reflectivity is selected such that the power of the first two of these peaks is equal.

The invention relates to a video coding method based on an adaptive frame / field encoding mode. In order to avoid an impairment of the image quality and of the compression efficiency when a video sequence comprises a lot of motion or on the contrary quasi-motionless images, an improved real time double pass encoding scheme is proposed: during the first pass, no video stream is generated, but statistical results are computed and then provided to the second pass in order to optimize during said second pass the bit rate allocation and the buffer management. This improved double pass encoding method leads to an increase of the compression efficiency of about 10%.

A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The MZ interferometers, having free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. The PLC chip, including a zero-dispersion lattice-filter interleaver stage, a switchable fine-resolution stage and, or a retroreflector for double passing the filter, is packaged into a hot-pluggable XFP transceiver package. A compensation heater is used to keep constant the amount of heat applied to the PLC chip inside the XFP package, so as to lessen temperature variations upon tuning of the PLC optical filter.

The invention relates to fiber-optic wavelength dispersive devices incorporating a wavelength dispersive reflector that provides auto-compensation of variations of output spectral characteristic with temperature and includes a transmissive dispersion that is followed by a beam-folding reflecting surface in a double-pass configuration grating and is coupled to a wedged shaped prism.

An optical device for rerouting and modifying an optical signal that uses a double pass through a liquid crystal modulator is disclosed. The optical device includes a first polarizer for providing polarized light, a liquid crystal modulator for selectively modifying the polarized light, a second polarizer for analyzing the light passed through the liquid crystal modulator, and a reflector for reflecting the analyzed light back through the second polarizer, the liquid crystal modulator, and the first polarizer. This arrangement provides a double pass through the liquid crystal modulator, thus significantly improving the attainable extinction ratio.

The invention discloses a single-power clock clocked transmission gate ternary heat insulating circuit and a T computing circuit. The heat insulating circuit adopts a single-power clock technology to combine the high-information density characteristic of a multi-value logic circuit and the low-power consumption characteristic of a heat insulating circuit and is designed by utilizing a switch-signal algebraic system. The operation of the heat insulating circuit comprises two stages, wherein in the first stage, under the control of a clocked clock, a clocked NMOS (N-Mental-Oxide-Semiconductor) tube is used for sampling an input signal; and in the second stage, under the working rhythm of the single-power clock, a bootstrap-operation NMOS tube and a crossing storage structure are used for charging and discharging a load, and an NMOS tube grid leak parallel connection technology is utilized to ensure that the circuit realizes ternary input and output. The circuit has simpler structure and lower power consumption compared with a gate level circuit. When the working frequency is 16.7MHz, within 1.4 microseconds, the ternary heat insulating can averagely save the energy by about 66.4 percent compared with a DTCTGAL (Double Power Clock Ternary Clocked Transmission Gate Adiabatic Logic) circuit and averagely save the energy by about 85.1 percent compared with a ternary DPL (Double-Pass-Transistor Logic) circuit. The T computing circuit is designed on the basis of the heat insulating circuit, and any ternary logic circuit can be constructed through the T computing circuit.

A laser system comprises: a seed oscillator, having a seed output; dispersive optics, operative to receive the seed output and divide the seed output into spectrally separate seed components; an array of individually addressable, phase adjustable laser amplifiers corresponding to the spectrally separate components, each laser amplifier receiving as its seed one of the spectrally separate seed components and producing one of the spectrally separate amplified components; and phase actuators controlling the individually addressable, phase adjustable laser amplifiers. A method of operating a laser system comprises: generating a seed signal; dividing the seed signal into spectrally separate component signals; amplifying the spectrally separate component signals; recombining the spectrally separate component signals into an amplified output; and controlling phases of the amplified spectrally separate component signals. Both single-pass and double-pass amplifier array versions are disclosed.

Systems, arrangements and methods for obtaining three-dimensional imaging data are provided. For example, a broadband light source can provide a particular radiation. A first electro-magnetic radiation can be focused and diffracted, and then provided to at least one sample to generate a spectrally-encoded line. A second electro-magnetic radiation may be provided to a reference, which may include a double-pass rapidly-scanning optical delay, where the first and second electro-magnetic radiations can be based on the particular radiation. An interference between a third electro-magnetic radiation (associated with the first electro-magnetic radiation) and a fourth electro-magnetic radiation (associated with the second electro-magnetic radiation) can be detected. The spectrally-encoded line may be scanned over the sample in a direction approximately perpendicular to the line. Image data containing three-dimensional information can then be obtained based on the interference. The exemplary imaging methods and systems can be used in a small fiber optic or endoscopic probe.

The invention relates to a press type external spring perfume sprayer and a round trip press method thereof. The perfume sprayer and the round trip press method are designed to solve the technical problem of poor structural designs of like products. A valve needle component comprises a piston, a valve needle, an inner piston, long springs, short springs and a valve rod; a pump body component is composed of the valve needle component, a pump body and a glass bead; a pump head component is composed of an aluminum oxide press cap, a spray slice and a head cap, wherein key points are that the piston sleeves the valve needle of the valve needle component in an interference manner, the inner piston sleeves the piston in an interference manner, the pump body is buckled with the inner piston, and the valve needle is buckled with the valve rod; the long springs are arranged between the inner piston and the valve rod, the short springs are arranged between the valve rod and the valve needle, and the long springs are arranged on the outer diameters of the short springs; the valve needle component enables that round trip press is realized through the long springs and the short springs, and the piston is limited through terrace terminal angles on the inner diameter of the pump body. The press type external spring perfume sprayer and the round trip press method thereof have reasonable structural designs, high leak tightness, good convenience in assembly and use, and sound effect of round trip press spray, and are suitable for perfume and the like products, as well as structural improvement of the like products.

It is a wavelength-adjustable optics filter, which comprises fiber calibration couple module, polarization process module, optics thin film and plane reflection lens. It provides the total linear polarization beam through fiber calibration couple module and polarization process module to the optics thin film filter and then rotate the optics thin film filter to realize the adjusting functions of wavelength. The light path design adopts double-pass style, which comprises front and back beams in light path transmission.

A method for obtaining an incision in an embossing roller using a hob, with a low-cost technique that enables protuberances that are rounded on top to be obtained, which improve the quality of the embossed material and reduce the wear of the mechanical components of the embossing units. The shape of the protuberances is obtained by machining the cylindrical surface of the roller that is placed between the tailstocks of the lathe using a hob that has teeth, the profile of which in cross-sectional view is complementary to that of the cross-section of the protuberances illustrated in FIG. 6. FIG. 6 shows schematically in cross-sectional view a portion of the surface of the roller with protuberances in the machining step and a portion of the hob with the teeth that are generating the grooves that define the side faces of the protuberances. As seen in FIG. 6A, the grooves between the teeth of the hob have a profile that is curvilinear in a cross-sectional view. With a double pass at two different inclinations of the surface of the roller, the protuberances of FIGS. 5 and 6 are generated.

A thermal birefringence compensator for a double pass laser system, which includes a polarization or conventionally outcoupled laser resonator, a gain medium and a compensator optically coupled to the gain medium. In one implementation, the compensator, which acts as an end reflector, includes a Benson prism, a first quarter waveplate with its principle axes aligned to the fold axis of the Benson prism, and a second quarter waveplate with its principle axes at 45° to the fold axis of the Benson prism. Alternatively, the compensation's prism can be a Porro prism.