Zygo Interferometry of Echelle Gratings

484347ce845b7236c4791348e0eed9ba?s=47 gully
November 10, 2013

Zygo Interferometry of Echelle Gratings

This deck illustrates the need to deproject interferometry of echelle gratings to understand the origin of instrumental artifacts in the device development process.

484347ce845b7236c4791348e0eed9ba?s=128

gully

November 10, 2013
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  1. zygo interferometry of gratings michael gully-santiago | grad student UT

    Austin Silicon Diffractive Optics Group
  2. who michael gully-santiago astronomer, engineer, bicycle rider amanda turbyfill astrophysicist,

    basketball enthusiast
  3. Interferometry tells us two things Where did we go wrong?

    Is it good enough?
  4. Interferometry tells us two things Where did we go wrong?

    Is it good enough? Astronomers care about this Engineers care about this
  5. There are two data products Where did we go wrong?

    Is it good enough? Astronomers care about this Engineers care about this PSF FULL MAP
  6. PSF FULL MAP The two data products are related to

    each other
  7. PSF FULL MAP The two data products are related to

    each other Sub aperture FFT € ∫∫
  8. Let’s talk about the full map. Since we’re engineers

  9. You have to de-project the full map.

  10. de-project

  11. We didn’t used to de-project

  12. We didn’t used to probably because astronomers don’t care. de-project

  13. We didn’t used to probably because astronomers don’t care. but

    now we’re learning something, because de-projected images look like what engineers see. shadow of grating holder Shadow of grating holder Photoresist thickening at edge Periodic structures resembling Newton’s fringes Comets from photoresist spin Photoresist thickening at edge de-project
  14. We can do even better with shadow of grating holder

    Shadow of grating holder Photoresist thickening at edge Periodic structures resembling Newton’s fringes Comets from photoresist spin Photoresist thickening at edge
  15. high pass* . We can do even better with shadow

    of grating holder Shadow of grating holder Photoresist thickening at edge Periodic structures resembling Newton’s fringes Comets from photoresist spin Horizontal artifact, probably from using the cart and slit. high pass filtering* is: way faster than fitting Zernike polynomials. k ~ 51 pixels is the median smoothing kernel d = d - median( d, k )
  16. But since we are astronomers and engineers, we want the

    best of both worlds™, so: We are proud to introduce… ZIGZAG: Zygo Interferometry of Gratings with Zernike Analysis by Gully
  17. None
  18. None
  19. None
  20. H! L! !" Silicon! Desired line edge position! Realized line

    edge position! Value measured by Zygo!
  21. I’m having a hard time getting the PSF to work.

    This is either hard or I am not smart enough to figure it out. Help!
  22. In summary: gully@astro.as.utexas.edu | astronomer and engineer You have to

    de-project the full map. and high pass filter and ZIGZAG™ does it all except PSFs… for now.