TUNABLE DIFFERENCE FREQUENCY SPECTROMETER

ULTRASENSITIVE SPECTROSCOPIC TECHNIQUES THAT ARE BASED ON THE UNIQUE PROPERTIES OF TUNABLE DIODE LASERS ARE POTENTIALLY USEFUL FOR TRACE GAS ANALYSIS, TOXIC VAPOR DETECTION, INDUSTRIAL PROCESS MONITORING, AND OTHER REMOTE SENSING APPLICATIONS. UNFORTUNATELY, DIODE LASERS WITH OUTPUT WAVELENGTHS CORRESPONDING TO THE FUNDAMENTAL ABSORPTION BANDS OF MANY MOLECULAR GASES MUST BE OPERATED AT CRYOGENIC TEMPERATURES. THIS FACT SIGNIFICANTLY LIMITS THEIR USE OUTSIDE THE RESEARCH LABORATORY. ROOM TEMPERATURE, DIODE-BASED, DIFFERENCE FREQUENCY GENERATORS OPERATE AT WAVELENGTHS BETWEEN 2.0 MICRON AND 10 MICRON AND HAVE OUTPUT PROPERTIES THAT ARE SIMILAR TO THOSE OF TUNABLE DIODE LASERS. RESEARCHERS ARE DETERMINING THE FEASIBILITY OF USING DIFFERENCE FREQUENCY GENERATORS IN LIEU OF TUNABLE DIODE LASERS FOR ULTRA-HIGH RESOLUTION INFRARED SPECTROSCOPY.