Summary

This is a powerful scientific tool that is able to visualize even the slightest density gradients within a fluid. This can be very useful when working with thermal systems as well as with supersonic flow. This setup that I designed should allow anyone with a 3D printer to replicate some of the fascinating footage found in some of my other videos. Alignment is the most difficult part of any complex optical device so be patient and make sure to use very slight movements on the adjustment screws.

(correction) - If the aperture of the camera is used to block deflected light instead of a knife edge, this setup is technically a shadowgraph that shows the second derivative of fluid density. As a shadowgraph this setup is more sensitive to shockwaves which is what I primarily use it for. If directional density gradient visualization is needed, you may need to place the camera further away and carefully position a knife edge to block roughly half of the light passing through the focal point.

Materials:
1x D114F900mm telescope mirror
2x SP-9703 springs (or similar)
2x #8-32 x 1-1/2 in machine screws
1x #8x1 in sheet metal screw
≈ 280g of filament

Printing:
Mirror base, Mirror cover, & extender block: 1mm top/bottom 0.8mm wall 20% gyroid infill no support
Mirror holder: 1mm top/bottom 1.2mm wall 40% gyroid infill support recommended
Cell Phone Holder: 1mm top/bottom 0.8mm wall 20% gyroid infill support recommended

See the assembly video: https://youtu.be/piGYryly5Bw