A flexibly reconfigurable data acquisition system for tunable diode laser absorption spectroscopy

In the tunable diode laser absorption spectroscopy, the intensity profile over an absorption spectrum is captured to extract the temperature and gas concentration of the target species. A real-time spectral scanning yields a quick response of the temperature and gas concentration measurement but requires a high-speed data acquisition system. In this work, a reconfigurable data acquisition system was proposed for the spectral profile detection. The proposed system was implemented on a field-programmable gate array (FPGA) and flexibly reconfigurable via modular design and running different commands. It enabled the mass data storage and real-time readings at the same time. The sampled data from the analog-to-digital converter (ADC) was mainly stored in the arrays of the Double Data Rate Synchronous Dynamic RAM (DDR3). Some of the sampled data were transferred to the host PC for real-time display. The proposed system in this way enabled online uploading of the spectral profile as well as the offline analysis possible in one system. It consisted of four channels of data acquisition at 20 MSPS and the data was transferred to the PC through USB and UDP network protocols. These interfaces of data transfer awarded the system a versatile ability for further deployment with more channels and large spaces. Preliminary results validated the performance of the proposed system.