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The emission wavelength of the tunable diode laser, viz. VCSEL, DFB, etc., is tuned over the characteristic absorption lines of a species in the gas in the path of the laser beam. This causes a reduction of the measured signal intensity due to absorption, which can be detected by a photodiode , and then used to determine the gas concentration ...
The dye laser is considered to be the first broadly tunable laser. A tunable laser is a laser whose wavelength of operation can be altered in a controlled manner. While all laser gain media allow small shifts in output wavelength, only a few types of lasers allow continuous tuning over a significant wavelength range.
Laser absorption spectrometry (LAS) refers to techniques that use lasers to assess the concentration or amount of a species in gas phase by absorption spectrometry (AS). Optical spectroscopic techniques in general, and laser-based techniques in particular, have a great potential for detection and monitoring of constituents in gas phase .
Part of a Ti:sapphire oscillator. The Ti:sapphire crystal is the bright red light source on the left. The green light is from the pump diode. Titanium-sapphire lasers (also known as Ti:sapphire lasers, Ti:Al 2 O 3 lasers or Ti:sapphs) are tunable lasers which emit red and near-infrared light in the range from 650 to 1100 nanometers.
A tunable laser could function at any wavelength, eliminating the cost of manufacturing and the logistics of maintaining up to 80 different parts. [6] This is the case since tunability offers a more flexible and less costly operation. Given the large venture capital investments of the time, dozens of approaches and technologies were proposed.
A frequency comb or spectral comb is a spectrum made of discrete and regularly spaced spectral lines.In optics, a frequency comb can be generated by certain laser sources.. A number of mechanisms exist for obtaining an optical frequency comb, including periodic modulation (in amplitude and/or phase) of a continuous-wave laser, four-wave mixing in nonlinear media, or stabilization of the pulse ...
Typical transmission of the probe beam as recorded on the photodiode for natural rubidium as a function of the laser's wavelength If, however, the laser is approximately on resonance, these two beams address the same atoms, those with velocity vectors nearly perpendicular to the direction of laser propagation.
For the former type of spectrometer, the pump beam is a visible wavelength laser held at a constant frequency, and the other (the probe beam) is a tunable infrared laser — by tuning the IR laser, the system can scan across molecular resonances and obtain a vibrational spectrum of the interfacial region in a piecewise fashion. [6]