Rapid Scan Absorption Spectroscopy with Applications for Remote Sensing
Abstract
Our objective is to develop accurate and reliable methods for quantifying distributed carbon sources and sinks to support both mitigation efforts and climate change research. The presentation will describe a method for rapid step-scan absorption spectroscopy in the near-infrared wavelength range for the measurement of greenhouse gases. The method utilizes a fiber coupled laser system and a free space confocal cavity to effectively scan the laser system over a bandwidth of 37.5 GHz (1.25 cm-1), with a step size of 300 MHz (0.01 cm-1) and a scan rate of 40 kHz. The laser system is scanned with microwave precision over a full absorption lineshape profile. Measurements have been demonstrated in a 45 m long multipass cell for detection of carbon dioxide near 1602.4 nm (6240.6 cm-1) and for methane near 1645.5 nm (6077.2 cm 1). Ambient level detection is demonstrated using the multipass cell with a signal-to-noise ratio of ~5:1 in a 5 ms integration time. The scan speed, resolution and bandwidth are well suited for remote sensing using integrated path and differential absorption LIDAR techniques.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A24B..06D
- Keywords:
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- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE Instruments and techniques;
- 0345 ATMOSPHERIC COMPOSITION AND STRUCTURE Pollution: urban and regional;
- 3360 ATMOSPHERIC PROCESSES Remote sensing;
- 0312 ATMOSPHERIC COMPOSITION AND STRUCTURE Air/sea constituent fluxes