FILM THICKNESS PROBE CARD.

A number of applications require the processing of photodiode signals from a linear photodiode array. Because of random noise, multiple readings of the data from the photodiode array are required, after which the data must be averaged to eliminate the random noise component. Virtually any control computer using a 'dumb' interface card to acquire the photodiode data can be used; however, it is easier and usually faster to use a microprocessor on a 'smart' interface card to pre-process the photodiode data before transmitting them to a host computer. The implementation of this technique involves a microprocessor-based printed circuit card (compatible with the host system being used) to acquire, digitize, and average the photodiode signals from the array. In this manner the host computer only has to receive the condensed data from the microprocessor card, which frees the host computer to do other tasks, thus improving the host computer system throughput.