One and Two-photon Excited Optogalvanic Spectra of Argon in the Wavelength Region of 735 – 850 nm

Abstract

Optogalvanic (OG) spectra of argon in the visible to near-infrared spectral region between 735 and 850 nm were investigated using a Grimm-style glow-discharge tube, which has been widely used to obtain depth profiles of the elemental composition on various film-like samples. About 49 lines of one-photon and two-photon OG peaks were observed with a pulsed Ti:sapphire laser; these peaks were precisely assigned. Two-photon OG spectra of argon were easily observed without focusing the pulsed laser irradiation to more than 1 mJ. The excitation mechanisms of the observed argon OG spectra could be classified into 3 types: single-photon transition, two-photon transition, and twophoton stepwise transition. In addition, a pseudo-resonant effect was also found to be effective. The argon lines observed in this experiment are suitable as convenient calibration wavelength markers of pulsed tunable laser radiation.

Spectral measurement of picosecond optical pulses by optogalvanic spectroscopy

“…We assume that the OG signal is presented by (2) where s(v) is the OG signal when the laser frequency is tuned to v, ε(v) is the pulse energy, I(v) is the spectral profile of the laser, F(v) is the spectral profile of the absorption line of argon, and v 0 is the center frequency of the absorption line. If F(v) is much narrower than I(v), Eq.…”

“…There are many strong transition lines of argon in the wavelength region of 700-850 nm [2], which covers most of Ti:Sapphire wavelength range. The OG spectroscopy can be performed with a commercial hollow cathode lamp and a simple electric circuit, which are much less expensive than optical spectrum analyzer.…”

Influence of Welding Current and Focal Position on the Resonant Absorption of Laser Radiation in a TIG Welding Arc

“…In fact, Hermsdorf et al (2009b) could not distinguish the effect of an interaction of the laser beam and the arc from the effect of an additional heating of the melting pool. Matsuta et al (2010) demonstrated that resonant absorption of laser radiation is causing a change of the discharge current in an argon filled glow-discharge tube.…”