The discrete Fourier transform algorithm for determining decay constants—Implementation using a field programmable...

Area of Science:

• Spectroscopy
• Analytical Chemistry
• Physical Chemistry

Background:

• Cavity ringdown spectroscopy (CRDS) is a sensitive technique for measuring analyte concentrations.
• Traditional CRDS data acquisition can limit throughput due to processing speed.
• Accurate determination of the exponential decay constant is crucial for quantitative analysis.

Purpose of the Study:

• To develop a high-throughput data acquisition system for CRDS.
• To enable near real-time determination of the decay constant.
• To improve the speed and efficiency of CRDS measurements.

Main Methods:

• Utilized a field-programmable gate array (FPGA) for real-time signal processing.
• Implemented the discrete Fourier transform (DFT) algorithm to calculate the decay constant.
• Adapted a commercial analog-to-digital converter (ADC) evaluation board for the system.

Main Results:

• Achieved a maximum decay constant output rate of 4.4 kHz.
• Demonstrated successful implementation using an 8192-point fast Fourier transform (FFT).
• Validated system performance both as a stand-alone unit and integrated into an existing CRDS setup.

Conclusions:

• The developed FPGA-based system significantly enhances CRDS throughput.
• Near real-time analysis is achievable, enabling faster experimental results.
• The modified ADC evaluation board provides an effective platform for high-speed CRDS data acquisition.