Step-by-step instructions for building an SFDI system
The original version of the website contained a link to an old version of the Arduino code that isn’t correct. You can download the new version that should work here. Or if you’d rather update it yourself, you just need to copy and paste the following code inside the “loop” function:
serialCheck(); //Check for new serial input
if (stringComplete){ //Check if string is complete
parseInput(); //Run parseInput function
} //end if
Thanks to Ben Mellors for noticing the error
The original version of the guide recommended using condenser lenses with built in diffusers. The idea was that the diffusers would prevent the LED emitter from being imaged onto the DMD leading to inhomogeneities in illumination. What we found was that the built in diffusers don’t work very well for the long beam paths associated with openSFDI. Too much light is lost around the edges which can lead to low light throughput and long exposure times.
We now recommend using aspheric condenser lenses without diffusers. Specifically the Thorlabs 16 mm focal length aspheric condensing lens ( ACL25416U-B ).
To align this lens first image the emitter on the DMD surface. You should see a series of stripes. Then move the lens toward or away from the LED until the image of the emitter is blurred and the illumination on the DMD is uniform. This should increase throughput and allow for shorter exposure times and faster imaging.
As this project evolves, we’ll be making changes to the guide. This includes changing the recommended components, updating software, and adding pages. My plan is to use the “Blog” page to document any changes that are made to the site and try to provide some rationale for why. If you visit the site often, I’d recommend checking out the blog first to see if there have been any updates since last time you checked-in.
This will also be the place where we’ll post openSFDI news. If you successfully build a system, send pictures! We’ll post them here. Hopefully as more systems get built in the community we’ll also be able to post links to publications that use the openSFDI platform.