• Measuring Laser On/Off Time

    Alan Green • 01/03/2021 at 23:00 • 0 comments

    We plan to measure galvo position over time by precisely controlling laser on and off times. To get accurate results, we should know how long it takes to turn the laser on and off.

    The Plan

    To do this, we're going to use a constant current driver for the laser, and then toggle it on and off using a signal generator. We'll detect the laser producing light with a photodiode.  


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  • This Project Will Be a Saga

    Alan Green • 01/03/2021 at 22:36 • 0 comments

    The aim here is to be able to control a cheap laser galvo to produce laser shows effects such as drawing complex figures.  To do this, I plan to characterize one set of galvos, to understand what affects the position of the laser beam and thus how to control the inputs to produce the desired output.

    I plan to do this by commanding both the mirrors and the laser and capturing the resulting picture with a camera.  Let's say we scan the x-axis mirror from left to right, starting from t=0. This will move the dot across the projection screen from left to right. We can then find the x-axis position at time t=1 and time t=2 by turning the laser on between t=1 and t=2 (red section in diagram below) and using a camera to capture the resulting drawn line.

    I'm pretty sure I can capture this accurately with an RPi camera