>>3721201In the case of my Scanmate 5000 it works like this.
1 PMT per channel. Per rotation on the drum 1 R,G,B is read. Once a full pixel row of the image has been scanned a stepper motor moves the drum another pixel so it's over the scanning area again.
Light comes from a simple spotlight which goes in to a light tube to produce somewhat collimated light but not really near a laser.
There is a physical aperture in the device but it only matters for low DPI scanning. From like 1500DPI or something up to 5000DPI it uses the same aperture setting.
Sampling at a higher rate isn't done, they spin the drum down as you expected. Scanning times go up drastically as you approach the minimum speed of the system.
The system uses one fancy ADC per channel, I guess if they really wanted to they could perhaps drop from 12 bit to a lower setting to gain some extra throughput but I have never observed that actually happening.
In general the optics and sensors are fine, it's vibrations in the machine which are more a worry to me when it comes to scan quality.
