Data digitization and display for an imaging system

Abstract

A system and method for digitizing data from an imaging system includes sampling a signal from an optical detector with a first circuit having a first attenuation and with a second circuit having a second attenuation different than the first attenuation. The system and method further includes digitizing the sampled signal at a predetermined number of bits desired for an analog to digital conversion of the sampled signal by allocating a first portion of bits to digitizing a signal from the first circuit and allocating a second portion of bits to digitizing a signal from the second circuit. The system and method further includes encoding the first and second portion of bits into one monotonic digital word corresponding to a range of the sampled signal.

We claim: 
     
         1 . A method for digitizing data from an imaging system, comprising;
 sampling a signal from an optical detector with a first sample and hold, S/H, for a first sample time t s/h2  and with a second S/H for a second sample time t s/h2  where t s/h1 >t s/h2 ,   producing a digital counter signal and a ramp signal wherein the counter and the ramp are timed such that the counter counts from  0  to a predetermined number of bits, C max -x, wherein C max  corresponds to the number of bits desired for an analog to digital conversion of the detector signal, in approximately the time taken for the ramp to ramp from 0 to a predetermined voltage, v s1 ,   sending the first S/H output to a comparator and comparing it to the ramp signal,   starting the counter and the ramp, after a time>t s/h ,   latching the count value if the ramp signal meets a threshold defined by the output of the first S/H before the counter counts to C max -x,   sending the second S/H signal to the comparator if the latching does not happen before C max -x is reached,   resetting the ramp to zero and restarting the ramp at a slope sufficient to ramp from 0 to a predetermined voltage v s2  in the time required for x counts, and   latching the count value if the output of the ramp signal meets a threshold defined by the output of the second S/H, wherein the count latched is a digitization of the detector signal.