In one application, the apparatus is used with unstable laser resonators which include a gain region defined by a concave mirror and a convex mirror. The apparatus includes a spectral line selection medium, such as a multiple band pass filter or a multiple diffraction grating, which is located so that the laser beam directed out of the laser gain region impinges thereon. A retroreflector is positioned so that the spectral lines selected by the line selection medium are reflected back into the laser gain region along the propagation path of the incident beam, resulting in a lockup of the laser at the selected spectral lines.
A laser system having an optically unstable cavity with a unique optical center axis longitudinally offset from the center axis of the cavity toward one side of the resonator to obtain an unobscured output beam from the opposite side. The resonator also has astigmatic magnification which provides for a greater volume utilization of the gain medium than otherwise possible. In a preferred embodiment, the off-axis astigmatic resonator employs spherical mirrors at off-normal incidence to provide for different magnification in two orthogonal planes.
An improved tunable diode laser is capable of fast digital line selection over a broad wavelength spectrum, and uses no moving parts. A focusing element, such as a mirror or a lens, used in combination with a micromirror array serves as the retroreflector in a typical Littman-Metcalf laser cavity. This configuration provides arbitrary, simultaneous, and/or sequential line selection capability over a very broad wavelength range. The use of an individually-controllable micromirror array eliminates the high precision mechanical motion of a grating element and improves the overall durability and ruggedness of the device. The present invention can be integrated into any diode laser and has significant application in spectroscopy.
An output gate means is provided which is capable of outputting individual signals selectively to an internal bus; the individual signals are interchanged among a plurality of functional modules connected to the internal bus which is interfaced with an external circuit. An input gate means is provided which is capable of supplying selectively a signal, input to the internal bus, to a specified functional module in place of an individual signal.
Very generally, the gas analyzer of the invention includes a source of infrared energy, a sample cell for containing an analyte gas mixture positioned in the path of infrared energy, and a monochrometer including a movable diffraction grating for producing a beam of infrared energy wherein the constituent wavelengths are spetrally separated. The device also includes a wide band interference filter for transmitting a predetermined wavelength band spanning the characteristic absorption wavelength of each of a plurality of constituent gases in the analyte gas mixture. A detector positioned to receive radiation passing through the filter produces an electrical response related to the infrared energy impinging thereon. The monochrometer includes provision for moving the diffraction grating to sequentially cause infrared energy of different wavelengths to impinge upon the detector, and for intermittently causing infrared energy directed toward the detector from the source to be blocked by the interference filter.
A tunable laser system where incoming light is separated into wavelength separated light; the separated light is focused into a plurality of single wavelength focal spots. The laser system includes a locally controllable reflectivity array having a plurality of individually controllable localized reflective elements corresponding to and reflecting one of the plurality of focal spots. A wavelength filter substantially allows wavelengths of the incoming light separated by a specified frequency to emerge as filtered light, while substantially barring other wavelengths. The separated light includes this filtered light. An elongation element for elongates the wavelength separated light into a plurality of elongated single wavelength focal spots. The locally controllable reflectivity array includes a plurality of sets of a plurality of individually controllable localized reflective elements, each set corresponding to and reflecting one of the elongated single wavelength focal spots.
