ERRATUM: Diffraction Effects in DMDs

I made a big mistake in the calculation of the DMD diffraction effects, it affects the following posts:

• A practical guide to Digital Micro-mirror Devices (DMDs) for wavefront shaping, and also the corresponding paper,
• Setting up a DMD: Diffraction effects,
• The online tool.

These will be edited shortly to reflect the corrections, as well as the paper A practical guide to digital micro-mirror devices (DMDs) for wavefront shaping (DOI, Arxiv) that will be retracted and resubmitted.

Long story short, the grating equation was wrong. It should not affect too much the results for low angles, but given the fact that the angles of each micro-mirror is already 12 degrees, it is not negligible at all.

The correct grating equation should be:

\[
  \text{sin}(2\theta_B-\alpha') + \text{sin}(\alpha')
  = 2 \,\text{sin}(\theta_B)  \,\text{cos}(\theta_B-\alpha')
  = p\frac{\lambda}{\sqrt{2}d} \, ,
\]

with the same notations as in the tutorial, so the blazed number then reads:

\[
  \mu =
  \left|
  \lfloor 2 \frac{\sqrt{2}d}{\lambda}
  \left[
    \text{sin}(\theta')\text{cos}(\theta'-\alpha')
    \right]
  \rfloor
  \mod{2} -1
  \right| \, .
\]

Big thanks to L. Malosse and @NiuYihan1999 for pointing out this error.

Call for papers on Wavefront Shaping Tutorials:
JPhys Photonics Special Issue

Guest Editors

• Ivo Vellekoop - University of Twente, Netherlands
• Joshua Brake - Harvey Mudd College, United States
• Sébastien Popoff - CNRS - Institut Langevin - ESPCI, France

In the past 15 years, wavefront shaping has emerged as a preferred tool for controlling and studying light propagation in complex media. Thousands of papers have been published, many of which present new and potentially exciting applications. However, wavefront shaping is a tool that requires experience, custom codes, and most importantly, specific tricks, which are often not published or shared. This special issue provides an opportunity to disseminate this information, thereby ensuring the reproducibility of the results and promoting the spread of techniques in this field.

More information here

Hey, we got a new website!

It was long overdue, but we now have a fully functional new website (written in Python!). The interface has been simplified and I added new cool features, like the possibility to run small Python apps directly from the site. See this new DMD tool app for instance, I plan to add more in the future as well as to add content more regularly, such as article highlights, talks, etc...

Please feel free to write comments or remarks, as I wrote the website myself, I am sure it is not bug-free...