In this paper, some key techniques on development of on-line MR urine analyzing system based on AOTF (Acousto -
Optics Tunable Filter) are introduced. Problems about designing the optical system including collimation of incident light
and working distance (the shortest distance for separating incident light and diffracted light) are analyzed and researched.
DDS (Direct Digital Synthesizer) controlled by microprocessor is used to realize the wavelength scan. The experiment
results show that this MR urine analyzing system based on. AOTF has 10000 - 4000cm<sup>-1</sup> wavelength range and O.3ms
wavelength transfer rate. Compare with the conventional Fourier Transform NIP. spectrophotometer for analyzing
multi-components in urine, this system features low cost, small volume and on-line measurement function. Unscrambler
software (multivariate statistical software by CAMO Inc. Norway) is selected as the software for processing the data.
This system can realize on line quantitative analysis of protein, urea and creatinine in urine.
In this paper, the basic dispersion principle of AOTF (Acousto - Optic Tunable Filter) and the configuration of on-line auto gas detection system based on it are generally described. The off-axial reflection paraboloid mirror employed as the collimation system of light source avoids the light energy loss and spherical aberration. The filament length of infrared light source is limited to 5.2mm for separating incident light beam from diffracted light beam spatially. In this paper, DDS (Direct Digital Synthesizer) measure to be used to realize wavelength scan, an interface circuit between DDS and DSP (Digital Signal Processor) is introduced. Experiment results show that this system based on AOTF has 4000 - 2000cm<sup>-1</sup> wavelength range with 15cm<sup>-1</sup> spectral resolution and 0.3ms wavelength transfer rate. This system has already been satisfactory for detecting auto gas on-line.
The principle of AOTF (Acousto-Optic Tunable Filter) is first described. Some design problems of the monochromatic system using AOTF as dispersive element is in detail discussed. These design problems include the design of AOTF driver and the design of optical system. In AOTF driver system, the DSP (Digital Signal Processor) is used as a controller, the DDS (Direct Digital Synthesizer) is used as frequency scanner. In the optical system, the paralic cylinder is used as collimating reflector.