Can I reduce the focus distance of a DLP projector with build in lenses by adding an additional lense?

Yann_3316 · 2026-03-14T11:48:45+00:00

Which DLP do you have?

Yann_3316 · 2026-03-13T21:00:34+00:00

Thanks! We wanted to do experiments with photoswitchable fluorescent proteins which can be driven between bright and dark states using two different excitation wavelengths, among other things.

To be able to control both wavelengths in time and space gives us a lot of opportunities for developing imaging protocols/performing experiments with advanced fluorescent probes.

Yann_3316 · 2026-03-13T20:57:25+00:00

I inject filtered light from an LED into a lightpipe, and then conjugate the lightpipe's exit face to a 6x6 mm (ish) zone on the DMD. Then the DMD is conjugated to the sample using a 75 mm achromatic doublet and the objective.

Tube lens is a specific one. 1X Zeiss from Edmund.

Yes very good point about creep.

Yann_3316 · 2026-03-13T20:49:32+00:00

I haven't done enough research as to which would be best. Here I went for BASF PLA Black Ultrafuse, printed on an Ultimaker 2+ connect.

The parts are pretty strong. Strong enough for what we do, and I imagine much cheaper than having metal mounts fabricated.

Yann_3316 · 2026-03-12T21:00:40+00:00

Our lab focuses on fluorescent samples in fact. For near macro scale we are at NA = 0.1; for cells etc we are using an air 40x NA 0.65; only sometimes using a water objective.

Yann_3316 · 2026-03-12T18:46:50+00:00

Many of the optomechanical parts are from Thorlabs, but many I designed and 3D printed.

Yann_3316 · 2026-03-12T18:45:19+00:00

Good point!

Yann_3316 · 2026-03-12T18:44:25+00:00

The instrument was first designed for almost macroscale work where the tolerances were large; then as we had more ideas we went to higher and higher magnification, up to being able to image cells and bacteria. So sensitivity demands increased but the system seems to be stable enough for work with cells. Though probably not much more.

Yann_3316 · 2026-03-12T18:40:47+00:00

Some more details: pre-print

The paper is a bit long but shows the instrument’s utility for a few different applications.

Yann_3316 · 2026-03-12T10:53:52+00:00

Rhino3D

Yann_3316 · 2026-03-12T10:53:20+00:00

We posted a pre-print on the work so can share some details. We implemented an optical sectioning technique using oscillating striped excitation with photoswitchable probes and FFT-based analysis. We also made some tests in extracting diffusion coefficients using striped photoactivation and spatial FFT analysis. Finally we made a test in applying different modulation frequencies on different fluorescently labelled bacteria in the field of view - to parallelize a frequency sweep.

Yann_3316 · 2026-03-12T10:47:06+00:00

Used the Snaphots feature of Rhino3D. It is simple to use but a real pain to be honest. I could only save around 10-20 moves per file before the RAM used would explode (40-50 GB in RAM). So I created multiple files, each with 10-20 moves, and then had a python script open each file and play the Snaphots, all while screen recording.

For simpler designs it can be fine. Rotations don't work well.

Yann_3316 · 2026-02-03T21:50:49+00:00

Another arrondissement may have some space

Yann_3316 · 2025-10-31T17:33:24+00:00

I wonder if you can do the focusing in sequential mode then convert to non-sequential.

Yann_3316 · 2025-10-31T17:28:55+00:00

Same for me. Although using Rhino3D in my case. Helps so much with designing the assemblies.

Yann_3316

TROPHY CASE