In many applications, such as remote sensing of atmospheric trace gases, monochromatic radiation with multiple discrete wavelengths is required. To date, there no instrument or technique that measures the wavelength jitters and fluctuations in real time.
NASA Langley has developed a rapid and precise technique for continuously monitoring and measuring the absolute wavelength of monochromatic radiation sources, such as lasers, irrespective of the temporal profile of the source (i.e., continuous wave, modulated, or pulsed). The technology relies on high-speed, low-noise detection. A valuable byproduct of this technique is the ability to measure radiation power or energy.
Such high-precision wavelength and power measurements could be used to monitor radiation source jitters and fluctuations without relying on frequency transforms or dispersive optics. Further, both wavelength and power could be measured simultaneously or sequentially.
This novel technique provides simple and accurate real-time wavelength monitoring by obtaining two independent measurements using two different wavelength-dependent conditions to solve for both radiation power and wavelength simultaneously. These conditions could include operating a single detection system at different settings as well as using two different detection systems.
The technique requires initial calibration for the detection systems being used, specifically around the expected detection wavelength.