low cost microscopes

1. smart design https://www.osapublishing.org/DirectPDFAccess/73B7846B-A422-B22A-AA38B1E6131DE5F9_429869/boe-11-5-2447.pdf?da=1&id=429869&seq=0&mobile=no 2. not fancy https://www.instructables.com/ARPM-Another-raspberry-pi-microscope-made-from-Ple/ control of motion (for adujustment of focus): https://www.robotshop.com/community/forum/t/retracting-linear-actuator-with-raspberry-pi/43024/6 Since you want to control the speed and the position of the actuator, I would recommend using a linear actuator including a potentiometer like this one: https://www.robotshop.com/en/l16-linear-actuator-351-50mm-12v-w--potentiometer-feedback.html 89 This will allow you to track the position of the actuator. Note that you will need a microcontroller to read the value of the potentiometer. To control the speed of the actuator I would recommend any regular DC motor driver depending on the specifications of the actuator.