摘要:
Laser apparatus is disclosed in which fundamental-wavelength optical pulses delivered from a mode-locked laser resonator at a pulse-repetition frequency (PRF) are converted to harmonic-wavelength pulses in an optical delay loop. One example is disclosed in which the harmonic-wavelength pulses are delivered directly from the delay loop. Another example is disclosed in which the harmonic-wavelength pulses are divided by the delay loop into a number of temporally spaced-apart replicas thereof, and the delay loop delivers bursts of replicas of different one of the harmonic wavelength pulses at a burst-repetition frequency equal to or a multiple of the PRF of the resonator.
摘要:
Apparatus for attenuating an unpolarized laser beam includes a polarizing beamsplitter for separating the laser beam into two plane-polarized beams following separate paths. The two plane-polarized beams are polarization rotated by a single polarization rotator. Each of the polarization-rotated beams is separated by a polarizing beam-combiner into two plane-polarized portions. One of the portions of one polarization-rotated beam is combined by the beam-combiner with one of the portions of the other polarization-rotated beam to provide an attenuated output-beam. In certain examples of the apparatus the separate paths are made equal in length so that combined beam portions are equal in diameter.
摘要:
A laser resonator includes an OPS gain-structure that is pumped with optical pulses repeatedly delivered at a pulse-repetition frequency corresponding to a resonant frequency of the laser resonator. The laser resonator additionally includes a passive mode-locking arrangement such that the resonator delivers mode-locked optical pulses. In one example the laser resonator further includes a CW optically pumped OPS gain-structure for increasing the power of the mode-locked pulses delivered from the resonator.
摘要:
An amorphous silicon layer on a glass substrate is crystallized by concentrating CW radiation from a number of OPS-lasers into a line of light on the layer. The layer is moved with respect to the line of light to control the dwell time of the line on any location on the layer and to crystallize an extended area of the layer.
摘要:
A frequency-tripled laser-resonator has three resonator-branches. The branches are optically connected with each other by one or more polarization-selective devices. Unpolarized fundamental radiation is generated by optically pumping a gain-element in one branch of the resonator. The polarization-selective device provides that radiation in the other branches is plane-polarized, with the polarization planes of radiation entering the branches perpendicular to each other. Two optically nonlinear crystals are located in one of the branches of the resonator in which the fundamental radiation is plane-polarized and arranged to generate third-harmonic radiation. Three-branch resonators including two gain-elements having a optical relay therebetween, and a three-branch ring-laser-resonator are also disclosed.
摘要:
An optical pulse-shaper includes a prism, a delay line having positive optical power and a reflective spatial light modulator. In one arrangement the delay line has a selectively variable optical path length for accommodating pulses of different spectral bandwidth and positive optical power is provided by a concave mirror. In another arrangement, the delay line includes a zoom-mirror arranged to provide selectively variable optical power for accommodating pulses of different spectral bandwidth.
摘要:
In traveling-wave ring-resonator an optically nonlinear crystal for converting visible radiation to ultraviolet (UV) radiation has an input face and two output faces. The visible light propagates through the crystal from the input face to one of the output faces. That output face is coated with a dichroic optical coating that transmits unconverted visible light and reflects the ultraviolet light. The reflected ultraviolet light exits the optically nonlinear crystal via the other output face and is coupled out of the resonator at an angle to the resonator axis.
摘要:
Apparatus for attenuating an unpolarized laser beam includes a polarizing beamsplitter for separating the laser beam into two plane-polarized beams following separate paths. The two plane-polarized beams are polarization rotated by a single polarization rotator. Each of the polarization-rotated beams is separated by a polarizing beam-combiner into two plane-polarized portions. One of the portions of one polarization-rotated beam is combined by the beam-combiner with one of the portions of the other polarization-rotated beam to provide an attenuated output-beam. In certain examples of the apparatus the separate paths are made equal in length so that combined beam portions are equal in diameter.
摘要:
A multilayer semiconductor laser includes a substrate on which is formed a semiconductor multilayer heterostructure divided into a plurality of electrically pumped regions and an elongated optically pumped region. The electrically pumped regions generate and delivering optical pump radiation laterally into the elongated optically pumped region. Output radiation is generated and delivered by the optically pumped region.
摘要:
Fluence monitoring apparatus is disclosed for a system for modifying curvature of the cornea of an eye by selective laser photoablation of corneal tissue by delivery of pulses of laser radiation to the cornea in an overlapping pattern. The system includes a scanner for directing the pulses to form the overlapping pattern, the movement of which is modified by an eye-tracker. A beamsplitter is located between the scanner and the cornea for directing a fraction of each of the pulses to a fixed monitor plate, which emits fluorescent light on being irradiated by each pulse-fraction. A video camera 100 images the monitor plate. Processing circuitry periodically records the image which includes images of pulse-fractions delivered during the period between recordings. These recordings are electronically integrated and processed to form a composite image representative of spatial distribution of laser fluence on the cornea.