摘要:
An apparatus including a cavity optical length actuator to vary a cavity optical path length of a laser in response to an excitation signal having varying frequencies. The cavity optical length actuator induces intensity perturbations in an optical beam of the laser corresponding to the excitation signal. A sensor senses the intensity perturbations in the optical beam and generates a response signal corresponding to the intensity perturbations. A combiner combines the excitation signal and the response signal to generate an error signal.
摘要:
A laser apparatus and method that uses active thermalization of a reflective element to minimize losses and provide wavelength stability. The laser comprises first and second reflectors defining an external cavity, and a compensating member coupled to at least one of the reflectors and configured to thermally position one reflector with respect to the other reflector. The compensating member may be coupled directly to the first reflector and configured to position first reflector with respect to said second reflector. The thermal positioning may be carried out by a thermoelectric controller operatively coupled to the compensating member and configured to thermally adjust the compensating member by heating or cooling thereof. The laser apparatus may comprise a gain medium having first and second output facets and emitting a coherent beam from the first output facet along an optical path. The first reflector is positioned in the optical path, with the second output facet and first reflector defining an external cavity. The compensating member may be thermally conductive and have a high coefficient of thermal expansion.
摘要:
A servo technique for concurrently providing wavelength locking and stimulated Brillouin scattering (SBS) suppression in an external cavity laser. Respective wavelength locking and SBS suppression signals are generated by a controller and combined into a composite drive signal. The composite drive signal is used to drive an optical path length adjustment element to modulate the optical path length of the laser cavity. The wavelength locking and SBS suppression portions of the drive signals produce concurrent modulations of the laser optical path length having different modulation frequencies and causing different frequency (wavelength) excursions. These modulations produce corresponding wavelength and intensity amplitude modulations in the laser's output. A feedback signal indicative of the intensity amplitude modulations is filtered to attenuate the portion of the signal due to the SBS suppression modulation, and is received as a tuning feedback signal by the controller. In response, the control provides a tuning adjustment signal to adjust the frequency of the laser.
摘要:
A holding device includes a mesh container having a closed end and an opposite open end defining an interior. A tassel may hang from the container proximate the closed end. The mesh container may be formed by a plurality of strands braided and tied together in a series of knots such that a diamond-shape weave appears. A drawstring is inserted through the interstices of the mesh at the open end of the container. A cinching mechanism, such as a draw bead, slidably engages the drawstring for opening and closing the open end of the container. The drawstring may have a connecting ring for enhancing safety.
摘要:
Some implementations feature a mast stabilizing device that includes a mast comprising a first portion and a second portion, a sensor coupled to the first portion of the mast, and a pivot structure coupled to the mast. The pivot structure is configured to allow the mast to pivot in the mast stabilizing device. The mast is coupled to the pivot structure so as to pivot along a pivot portion of the mast. The mast stabilizing device also includes a mass coupled to the second portion of the mast. The mass is configured to counteract a force applied to the first portion of the mast. The mast stabilizing device further includes a platform coupled to the pivot structure, the platform configured to operate on a body of water. In some implementations, the pivot structure is a gimbal device.
摘要:
Some implementations feature a mast stabilizing device that includes a mast comprising a first portion and a second portion, a sensor coupled to the first portion of the mast, and a pivot structure coupled to the mast. The pivot structure is configured to allow the mast to pivot in the mast stabilizing device. The mast is coupled to the pivot structure so as to pivot along a pivot portion of the mast. The mast stabilizing device also includes a mass coupled to the second portion of the mast. The mass is configured to counteract a force applied to the first portion of the mast. The mast stabilizing device further includes a platform coupled to the pivot structure, the platform configured to operate on a body of water. In some implementations, the pivot structure is a gimbal device.
摘要:
A method for tuning a laser via a temperature control loop that linearizes a non-linear characteristic of a thermal electric cooler (TEC) element used to adjust the temperature of tuning components and corresponding laser apparatus. One or more TEC elements are thermally coupled to respective tuning components, such as etalon filters. The TEC elements provide a heat transfer function (cooling rate) in response to a received electrical input (drive signal), wherein the relationship between the cooling rate and the drive signal is non-linear. An un-compensated drive signal produced by the control loop is compensated such that the open loop gain of the control loop is linearized via a linearizer control block. In effect, the non-linear transfer function of the TEC element is cancelled out by the linearizer control block to produce a linear relationship between the cooling rate and the drive signal. This open loop gain linearization enables tuning events such as channel slewing, and laser start-up operations to be performed with reduced tuning overshoots and undershoots that would otherwise result from the non-linear TEC transfer function characteristic.
摘要:
A laser apparatus and method that uses active thermalization of a reflective element to minimize losses and provide wavelength stability. The laser comprises first and second reflectors defining an external cavity, and a compensating member coupled to at least one of the reflectors and configured to thermally position one reflector with respect to the other reflector. The compensating member may be coupled directly to the first reflector and configured to position first reflector with respect to said second reflector. The thermal positioning may be carried out by a thermoelectric controller operatively coupled to the compensating member and configured to thermally adjust the compensating member by heating or cooling thereof. The laser apparatus may comprise a gain medium having first and second output facets and emitting a coherent beam from the first output facet along an optical path. The first reflector is positioned in the optical path, with the second output facet and first reflector defining an external cavity. The compensating member may be thermally conductive and have a high coefficient of thermal expansion.
摘要:
A marine vessel for amphibious operations carries a land military vehicle which is secured by a cable and winch arrangement to the deck of the vessel and also positioned by means of a torsion bar. The military vehicle can be moved fore and aft to vary the longitudinal center of gravity of the vessel as a function of water speed so as to a transition the hydrodynamic hump of the vessel to obtain maximum speed with minimum power. The movement of the vehicle is controlled by the vehicle operator who manipulates the recovery winch. The vessel is under the control of the vehicle operator by means of a flexible control cable and a control box which is disposed within the vehicle.