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This is a more efficient process than optical parametric oscillation, and in principle can be thresholdless. In order to change the output wave frequencies, one can change the pump frequency or the phasematching properties of the nonlinear optical crystal. This latter is accomplished by changing its temperature or orientation or quasi ...
The original scoring system was developed before the invention of pulse oximetry and used the patient's colouration as a surrogate marker of their oxygenation status. A modified Aldrete scoring system was described in 1995 [2] which replaces the assessment of skin colouration with the use of pulse oximetry to measure SpO 2.
The coherence time, usually designated τ, is calculated by dividing the coherence length by the phase velocity of light in a medium; approximately given by = where λ is the central wavelength of the source, Δν and Δλ is the spectral width of the source in units of frequency and wavelength respectively, and c is the speed of light in vacuum.
Laser surgery is a type of surgery that cuts tissue using a laser in contrast to using a scalpel. [ 1 ] Soft-tissue laser surgery is used in a variety of applications in humans ( general surgery , neurosurgery , ENT , dentistry , orthodontics , [ 2 ] and oral and maxillofacial surgery ) as well as veterinary [ 3 ] surgical fields.
ASE is produced when a laser gain medium is pumped to produce a population inversion. Feedback of the ASE by the laser's optical cavity may produce laser operation if the lasing threshold is reached. Excess ASE is an unwanted effect in lasers, since it is not coherent, and limits the maximum gain that can be achieved in the gain medium. ASE ...
Laser linewidth from high-power high-gain pulsed laser oscillators, comprising line narrowing optics, is a function of the geometrical and dispersive features of the laser cavity. [29] To a first approximation the laser linewidth, in an optimized cavity, is directly proportional to the beam divergence of the emission multiplied by the inverse ...
In this case the loss of coherence is described as a "static dephasing". T2* is a measure of the loss of coherence in an ensemble of spins that includes all interactions (including static dephasing). T2 is a measure of the loss of coherence that excludes static dephasing, using an RF pulse to reverse the slowest types of dipolar interaction.
Nevertheless, the intuitive pure-frequency heterodyne concept still holds perfectly for the wideband case provided that the signal and LO are mutually coherent. Crucially, one can obtain narrow-band interference from coherent broadband sources: this is the basis for white light interferometry and optical coherence tomography.