Abstract: This invention relates to retrievable measuring cell for optical measurements in gas, the cell being defined by a gas conducting pipe having an input end adapted to be connected to a gas flow input intruding gas into the cell and an output end adapted to be connected to a gas flow output. The pipe ends also being adapted to be coupled to optical components including an optical transmitter transmitting light into said cell and an optical receiver adapted to receive light having passed through said cell, the optical beam in said cell having a predetermined shape, the optical components including a light source, at least two minors and a light receiver being mounted in known positions on an external frame covered by the pipe ends. The cell has an elongated shape corresponding to the optical beam shape.

Abstract: The present invention relates to a Fabry-Perot interferometer including two plane mirror surfaces mounted in a frame and a system including the interferometer. The mirrors have a known distance between them, and at least one of the mirror surfaces is both partially reflective and partially reflective, where there are at least two actuator units, each including at least one actuator. The first actuator unit is adapted to adjust said distance between said mirrors and the second actuator unit is adapted to modulate said distance at a chosen frequency, both thus providing a variation over a range of mirror distances corresponding to a range of filtered wavelengths in said Fabry-Perot interferometer. At least one of said mirrors is related to the frame through a silicon membrane, at least one of said actuator units comprising a piezoelectric material on said membrane, thus constituting a bimorph or unimorph actuator unit.

Abstract: An optical pressure sensor, such as a microphone, is constituted by two membranes, but where the sound does not arrive perpendicular to the membrane, but comes in from the side. The membranes may be parallel as in a Fabry-Perot or slightly skew as in an Air-wedge shearing interferometer. The pressure sensor uses interferometric readout, and consists of two membranes with essentially equal characteristics, where at least one of the membranes is partially transmitting and partially reflective and the other membrane is at least partially reflective, the membranes being separated by a cavity defined by a spacer part, where the distance between the membranes is variable to provide a shift sensitive Fabry-Perot resonator, and where the two membranes have a common back volume being sealed or essentially sealed in the frequency one wish to measure, and where a pressure increase results in that the distance between the membranes move in opposite directions.

Abstract: The present invention relates to a Fabry-Perot interferometer including two plane mirror surfaces mounted in a frame and a system including the interferometer. The mirrors have a known distance between them, and at least one of the mirror surfaces is both partially reflective and partially reflective, where there are at least two actuator units, each including at least one actuator. The first actuator unit is adapted to adjust said distance between said mirrors and the second actuator unit is adapted to modulate said distance at a chosen frequency, both thus providing a variation over a range of mirror distances corresponding to a range of filtered wavelengths in said Fabry-Perot interferometer. At least one of said mirrors is related to the frame through a silicon membrane, at least one of said actuator units comprising a piezoelectric material on said membrane, thus constituting a bimorph or unimorph actuator unit.

Abstract: The invention relates to an optical pressure sensor, such as a microphone, being constituted by two membranes, but where the sound does not arrive perpendicular to the membrane, but comes in from the side. The membranes may be parallel as in a Fabry-Perot or slightly skew as in an Air-wedge shearing interferometer. The pressure sensor uses interferometric readout, and consists of two membranes with essentially equal characteristics, where at least one of the membranes is partially transmitting and partially reflective and the other membrane is at least partially reflective, the membranes being separated by a cavity defined by a spacer part, where the distance between the membranes is variable to provide a shift sensitive Fabry-Perot resonator, and where the two membranes have a common back volume being sealed or essentially sealed in the frequency one wish to measure, and where a pressure increase results in that the distance between the membranes move in opposite directions.

Abstract: A liquid crystal lens cell comprises a pair of flat layers with the liquid crystal lens supported between the layers. One of the layers supports a planar electrode made of ITO. The other electrode, also formed of ITO, is supported in the center of the opposing substrate and projects downwardly toward the center of the liquid crystal layer. A power supply creates a potential difference between the two electrodes and accordingly imposes a non-uniform electric field on the liquid crystal modules which aligns them in which a way as to act as a lens. By varying the voltage between the two electrodes the focal length of the lens may be controlled. A central electrode may be in the form of a beam or of a pointed tip. In other embodiments of the invention an electrode having a central hole may be associated with the central electrode or the planar electrode.

Abstract: A system for photographing an object and generating a three-dimensional display of the object without the need for the observer to wear special glasses employs a camera having an electronically tunable liquid crystal lens in which the focal plane of the lens may be adjusted by controlling the voltage on the lens. An operator of the camera focuses the camera on the scene to be imaged and the camera records a series of images at closely spaced focal lengths by varying the voltage applied to the lens between the images. The digitally recorded images are then used to generate a display on a multilayer transparent display substrate with pixel addressing capabilities. Each of the recorded images at the differing focal lengths are displayed on one of the layers of the display screen, with the closest focal length recorded being displayed on the top screen, the one most proximate to the observer, and with successive images on other screens. A three-dimensional image is produced.

Abstract: To provide an image of a scene having three-dimensional characteristics, without the use of special glasses, a special camera employing an electrically controllable LCD lens which may be changed as to focal length by varying an applied voltage is used to record a plurality of images of the scene at each of a plurality of closely spaced focal lengths. All of the recorded images are simultaneously displayed on a device employing a stack of transparent LCD screens with one image being provided to each screen in the same order as the focal lengths used during the recording step.

Abstract: An electrically controlled liquid crystal zoom lens system for a camera or the like is set to a desired zoom by an operator. The desired zoom signal is provided to an image signal processor which also receives the output of an image sensor at the output of the lens. The process generates a control signal for a power supply which adjusts the voltage between electrodes sandwiching the liquid crystal module. By rapid, iterative adjustment the actual zoom is brought to the desired zoom level. The liquid crystal module is combined in series with conventional lenses which may be integrated with the liquid crystal.

Abstract: An optical disc storage system employs a read/write pick-up head assembly in which the optical path between the disc and the read/write light source, usually a laser diode, includes both a conventional objective lens formed of glass or plastic, with a fixed focus, and a liquid crystal lens which is electrically tunable to vary its refractive index and focal distance. The optical signal reflected from the disc is passed through this hybrid pick-up head assembly and demodulated to detect errors in the focus of the pick-up head and the tracking, and to adjust the focus by modifying the electrical signals applied to the LCD lens, and move the pick-up head in the plane of the disc to address the appropriate track.

Abstract: A system and method is provided to calibrate a transmission laser, such as a widely tunable laser (WTL), within a dense wavelength division multiplexer (DWDM) for transmission through an optic fiber. The WTL is tuned to the ITU grid using an etalon and a gas cell. The absolute transmission wavelengths of the WTL are calibrated by routing a WTL output beam through the etalon and through the gas cell while varying tuning parameters of the WTL to generate an etalon spectrum and a gas absorption spectrum, both as functions of the tuning parameters. The etalon and gas absorption spectra are compared, along with input reference information specifying gas absorption as a function of absolute wavelength, to determine the absolute transmission wavelength for the WTL as a function of the tuning parameters. The WTL is then tuned to align the transmission wavelength of the WTL to an ITU transmission grid line.

Abstract: The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM) and to lock the laser to a selected transmission wavelength. In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a set of transmission lines for detection by a detector. Another portion of the beam is routed directly to another detector. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line.

Abstract: The method and system operate to maintain a widely tunable laser (WTL) at a selected transmission wavelength. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a transmission line for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector to determine the power of the beam. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line. The wavelength-locking controller thereafter monitors the temperature of the etalon and keeps the temperature constant to prevent any wavelength drift attributable to the etalon.

Abstract: The semiconductor laser has a resonance cavity composed of a gain chip, a Mach-Zehnder wide tuning port, and a wavelength-selective mirror component formed either as a ring resonator or a reflective Fabry-Perot etalon. Optical signals generated by the gain chip propagate through the wide tuning port and into the wavelength-selective mirror component and are then reflected back to the gain chip. The wavelength-selective mirror component is configured to reflect only those optical signals having wavelengths within a set of sharp peaks so that the laser cavity resonates only within the sharp peaks. The wavelength-selective mirror component is heated to adjust internal dimensions to maintain one of the sharp peaks at a selected emission wavelength. As optical signals pass through the wide tuning port, the signals are split between two channels of differing lengths resulting in optical interference.

Abstract: A semiconductor laser is provided having a cavity including a gain chip, a Mach-Zehnder wide tuning port, and a ring resonator mirror. Optical signals generated by the gain chip propagate through the Mach-Zehnder wide tuning port and into the ring resonator mirror where the optical signals are reflected back through the Mach-Zehnder wide tuning port to the gain chip. The ring resonator is configured to reflect only those optical signals back into the laser cavity having wavelengths within a set of sharp peaks and the laser cavity therefore can resonate only within one of the sharp peaks. The ring resonator mirror is heated to adjust its dimensions so as to maintain one of the sharp peaks at a selected emission wavelength. As optical signals reflected from the ring resonator pass through the Mach-Zehnder wide tuning port, the signals are split between two channels of differing lengths resulting in optical interference.