Standoff Methods for the Detection of Threat Agents: A Review of Several Promising Laser-Based Techniques
Figure 4
High resolution scan obtained with an isobutylene vapor sample at a total pressure of 80 mTorr in a 75 m Herriott cell. The top trace is the signal channel containing the isobutylene sample. The middle trace is an interference pattern generated by a solid Ge etalon. The last trace is due to methyl chloride. Again the bottom two traces are collected for calibration purposes with the etalon being used to transform the time-based signal into cm−1/point and the reference gas channel providing an absolute position in frequency space.
