| The photothermography is a new technology of medical film hard-copy field, which emerges at tremendous pace.It uses laser beam to expose the special film, then develops by heating the film. The photothermographic system does not use chemic liquid to develop and fix the film. It has many virtues, such as saving water, preventing the pollution of the environment and easy operation. At the present time, the price of import photothermographic systems is very high, and domestic products aren't mature enough, so it can not be widely used in our country. The most important problems to be solved are reducing the cost and improving performance of it.How to design and implement a photothermographic system was introduced in the dissertation, mainly including four aspects: the design scheme, realized method, performance test and result discussion. The system would be reasonable cost, good performance. From the view of practicality, we did some meaningful work and made an experimental prototype. In this prototype, the wavelength of laser is 785nm and the film is Kodak's Dry view series film. One dimension scanning of the film was performed by a telecentric f-theta objective with a moving coil optical scanner; the other dimension was scanned through a stepping motor driving the rollers. The dates of the image transmitted from PC to this prototype through the USB 2.0 interface. The features and specifications of the system, such as the resolution, nonlinear deviation, uniformity of film density and characters of density conversion, were analyzed based on the actual parameters. In the dissertation, we also corrected the characters of density conversion, so that the image of film could accurately correspond to the original gray image. The resolution of this prototype exceeded 300 dpi. The minimal film density was 0.4 and the maximal density was 2.1. It took 18 seconds to scan a film (10" ×8" ).In conclusion, the performance of this prototype can meet the demand of photothermographic system.
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