Development of a microcomputer controlled data acquisition system for laser based instruments
Abstract
Laser based instruments are commonplace in research laboratories worldwide but remain
fairly expensive and out of reach for the average research/teaching laboratory in
developing countries. This work is an attempt to develop a cost effective microcomputer
controlled data acquisition system for use in a variety of laser-based instruments. The
system has been put together using standard components and is 'controlled by an
inexpensive 8-bit microcomputer.
The system uses a silicon detector to convert an incoming laser beam into a voltage
signal, which after conditioning, is digitized and stored on a 256Kbyte memory bank
external to the hostBBe microcomputer. The acquired data are available for display
and/or further processing by the host. A DMA circuit is implemented to ensure fast
transfer of data to and from the external memory. Software routines have been developed
to test, initialize and control the system as well as display the acquired data.
A 780nm modulated laser beam has been used to test and calibrate the system. The
system's amplitude response has been found, within the modulation limits possible, to be
linear for laser power modulation amplitudes lying between O.75mW to 2.4mW.
Modulated laser signals with frequencies between 50Hz and 1.2 kHz have also been
successively acquired. The data acquisition system should be suitable for use in a variety
of laser based teaching and research instruments
Citation
A thesis submitted in partial fulfillment of the requirement for the degree of Master of Science in Physics, University of NairobiPublisher
Science in Physics, University of Nairobi