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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.
An optical parametric amplifier, abbreviated OPA, is a laser light source that emits light of variable wavelengths by an optical parametric amplification process. It is essentially the same as an optical parametric oscillator , but without the optical cavity (i.e., the light beams pass through the apparatus just once or twice, rather than many ...
The resulting gas flow is analyzed in the mass spectrometer with a mass range of 2–535 daltons. [1] [5] The tunable laser spectrometer (TLS) performs precision measurements of oxygen and carbon isotope ratios in carbon dioxide (CO 2) and methane (CH 4) in the atmosphere of Mars in order to distinguish between their geochemical or biological ...
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.
The difference is the choice of the laser wavelength, which must be selected to match the energy of an electronic transition in the sample. A tunable laser is thus often used for resonance Raman spectroscopy, since a single laser can be used to generate many possible excitation wavelengths to match different samples. [8]