Title :
A simple microcontroller based digital lock-in amplifier for the detection of low level optical signals
Author :
Dorrington, Adrian A. ; Künnemeyer, Rainer
Author_Institution :
Dept. of Phys. & Electron. Eng., Waikato Univ., Hamilton, New Zealand
Abstract :
Traditionally digital lock-in amplifiers sample the input signal at a rate much higher than the lock-in reference frequency and perform the lock-in algorithm with high-speed processors. We present a small and simple digital lock-in amplifier that uses a 20 bit current integrating analogue-to-digital converter interfaced to a microcontroller. The sample rate is set to twice the reference frequency placing the sampled lock-in signal at the Nyquist frequency allowing the lock-in procedure to be performed with one simple algorithm. This algorithm consists of a spectral inversion technique integrated into a highly optimised low-pass filter. We demonstrate a system with a dynamic range of 103 dB recovering signals up to 85 dB below the interference
Keywords :
analogue-digital conversion; demodulation; low-pass filters; signal sampling; 20 bit; Nyquist frequency; current integrating analogue-to-digital converter; dynamic range; high-speed processors; input signal; lock-in algorithm; low level optical signals; low-pass filter; microcontroller based digital lock-in amplifier; reference frequency; sampled lock-in signal; spectral inversion technique; Frequency; High speed optical techniques; Low pass filters; Microcontrollers; Optical amplifiers; Optical filters; Optical modulation; Optical noise; Semiconductor optical amplifiers; Stimulated emission;
Conference_Titel :
Electronic Design, Test and Applications, 2002. Proceedings. The First IEEE International Workshop on
Conference_Location :
Christchurch
Print_ISBN :
0-7695-1453-7
DOI :
10.1109/DELTA.2002.994680
