Flexible lock-in detection system based on synchronized computer plug-in boards applied in sensitive gas spectroscopy

Summary, in English

We present a flexible and compact, digital, lock-in detection system and its use in high-resolution

tunable diode laser spectroscopy. The system involves coherent sampling, and is based on the

synchronization of two data acquisition cards running on a single standard computer. A

software-controlled arbitrary waveform generator is used for laser modulation, and a four-channel

analog/digital board records detector signals. Gas spectroscopy is performed in the wavelength

modulation regime. The coherently detected signal is averaged a selected number of times before it

is stored or analyzed by software-based, lock-in techniques. Multiple harmonics of the modulation

signal 1f, 2f, 3f, 4f, etc. are available in each single data set. The sensitivity is of the order of 10−5,

being limited by interference fringes in the measurement setup. The capabilities of the system are

demonstrated by measurements of molecular oxygen in ambient air, as well as dispersed gas in

scattering materials, such as plants and human tissue.

• Author: Mats Andersson; Linda Persson; Tomas Svensson; Sune Svanberg
• Department/s: Atomic Physics
• Publishing year: 2007
• Language: English
• Publication/Series: Review of Scientific Instruments
• Volume: 78
• Issue: 11
• Full text: - 497 kB; Download statistics
• Links: http://dx.doi.org/10.1063/1.2813346
• Document type: Journal article
• Publisher: American Institute of Physics (AIP)
• Topic: Atom and Molecular Physics and Optics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1089-7623