Gas spectroscopy

A spectroscopy device, comprising:

• a laser diode emitting laser radiation, said laser radiation having only a first wavelength during a first time period, only a second wavelength during a second time period, and only a third wavelength during a third time period, said second wavelength being greater than said first wavelength but smaller than said third wavelength;
• a radiation detector operatively disposed to receive a portion of said laser radiation after said portion of said laser radiation has passed through a sample gas, said sample gas comprising at least a first gas and a second gas, said second wavelength being the wavelength of a peak of an absorption line of said first gas;
• and
• means for determining a value indicative of a concentration of said first gas, said value being substantially independent of line-broadening effects on said first gas due to said second gas.

A method, comprising:

• transmitting laser diode laser radiation through a mixture of a first gas and a second gas, said laser radiation having only a first wavelength during a first time period, only a second wavelength during a second time period, and only a third wavelength during a third time period, said second wavelength being greater than said first wavelength but smaller than said third wavelength;
• centering the second wavelength on the peak of an absorption line of said first gas by using absorption information obtained during said first and third time periods to indicate left and right skirts of said absorption line, absorption of said laser radiation during said first time period being substantially equal to absorption of said laser radiation during said third time period;
• and
• determining a concentration of said first gas by measuring absorption of said laser radiation during said second time period and using line width information obtained during said first and third time periods to correct for foreign gas line-broadening effects on said first gas due to said second gas.