Microscopes generally employ shutters to limit light exposure for the safety of the samples or the user. Most commercial microscopes come with integrated shutters. For home-built instruments you can purchase external shutters (there are many options out there, but they can be quite expensive) or assemble your own. We have just published an open source, low-cost, general purpose shutter system based on various actuators (RC servos or solenoids). Several shutters are connected to an Arduino-based controller and the shutters can be controlled via a display, by serial commands via USB, or by electrical control lines.
We described this design in our open-access HardwareX paper. The associated design files are in the Github repo and include 3D print files for the actuator holders and cases, software for the Arduino, libraries for serial communication (C and python), and example graphical user interfaces for testing.
In the paper we provided instructions for a design with RC servos (very cheap, quiet, but relatively slow with a bit of timing jitter) and linear solenoids (faster and more deterministic, but quite a bit noisier). Since the paper came out, we have also tested the controller with rotary solenoids like these:
These perform quite a bit better then servos:
However, rotary solenoids are a bit more expensive (~$60) compared to RC servos (~$5) and are a bit harder to get (only a few types of rotary solenoids are available in small quantities through distributors). In the Github repo we include a document that describes the operation with rotary solenoids in a bit more detail. Happy to answer questions here 