Static and dynamic micro deformable mirror characterization by phase-shifting and time-averaged interferometry

Wavefront shaping is of main interest in the field of Adaptive Optics for Astronomy, wide-field imaging in Microscopy and live cells/tissues imaging in Biology. We propose an innovative technology for a new type of membrane deformable mirror, made by coupling a reflective polymeric membrane with a monolithic non-pixelated photoconductive substrate. The device is called continuous photocontrolled deformable mirror (PCDM), actuated by sending a light flux with given shape and intensity distribution, on the back side of the photoconductor, opposite to the reflective side. Unlike the other actuation mechanisms, this allows to obtain a continuous actuation field, without the typical segmented actuators pattern. Furthermore, it leads to a strong simplification to the driving electronics, for example by eliminating hundreds of cables used for the deformation control. Fundamental is the role played by the photo-excitation dynamics of the photoconductive material, in fact the deformation is obtained through the electrostatic pressure exerted by the photo-generated charge carriers, on the thin reflective membrane.We have developed a device with a single crystalline semiconductor photoconductor wafer, either Silicon or Cadmium Sulfide. The actuation is controlled by a light pattern modulated by a DMD (Digital Micromirror Device) chip, generating a reprogrammable actuator pattern projected on the photoconductor. In order to test the performance of the PCDM, we are addressing two deformation regimes: static behavior and dynamical response. We are then able to measure the response with light actuation, as the influence function matrix with respect to the number of projected virtual actuators; the response with frequency, including response time, resonance frequency, with respect to the different applied patterns, and with respect to the number of virtual actuators; finally, the response in open/close loop.

show abstract

“…Range is increased without loosing accuracy by using two-wavelength phase-shifting interferometry authorizing large steps measurements. 14…”

Section: Interferometric Benchmentioning

confidence: 99%

Photo-controlled deformable mirror for wavefront shaping

Zamkotsian

Cabona

Redaelli³

et al. 2021

MOEMS and Miniaturized Systems XX

Self Cite

View full text Add to dashboard Cite

show abstract

“…The 10µm thick mirrors are covered with a 60nm thick gold layer for IR operation, whereas gold has a different CTE than silicon. For characterising the surface quality and the performance of our MMA's at low temperature, we have developed a cryo chamber optically coupled to a high-resolution Twyman-Green interferometer [9]. The interferometer provides a sub-nanometer accuracy, and the cryo-chamber allows pressure down to 10 -6 mbar and temperatures down to 60 K. The MMA device is packaged in PGA chip carrier.…”

Section: B Micromirror Array Operation At Cryogenic Temperaturementioning

confidence: 99%

Micromirror arrays for multi-object spectroscopy in space

Zamkotsian¹,

Lanzoni²,

Tangen³

2019

International Conference on Space Optics — ICSO 2010

Self Cite

View full text Add to dashboard Cite

“…Range is increased without loosing accuracy by using two-wavelength phase-shifting interferometry authorizing large steps measurements. Dynamic analysis like vibration mode and cut-off frequency could be also measured with time-averaged interferometry [ 12 ].…”

Section: Cryogenic Interferometric Test Set-upmentioning

confidence: 99%

Operation of a MOEMS Deformable Mirror in Cryo: Challenges and Results

et al. 2017

View full text Add to dashboard Cite

Micro-opto-electro-mechanical systems (MOEMS) Deformable Mirrors (DM) are key components for next generation optical instruments implementing innovative adaptive optics systems, both in existing telescopes and in the future ELTs. Characterizing these components well is critical for next generation instruments. This is done by interferometry, including surface quality measurement in static and dynamical modes, at ambient and in vacuum/cryo. We use a compact cryo-vacuum chamber designed for reaching 10–6 mbar and 160 K in front of our custom Michelson interferometer, which is able to measure performance of the DM at actuator/segment level and at the entire mirror level, with a lateral resolution of 2 µm and a sub-nanometer z-resolution. We tested the PTT 111 DM from Iris AO: an array of single crystalline silicon hexagonal mirrors with a pitch of 606 µm, able to move in tip, tilt, and piston (stroke 5–7 µm, tilt ±5 mrad). The device could be operated successfully from ambient to 160 K. An additional, mainly focus-like, 500 nm deformation of the entire mirror is measured at 160 K; we were able to recover the best flat in cryo by correcting the focus and local tip-tilts on all segments, reaching 12 nm rms. Finally, the goal of these studies is to test DMs in cryo and vacuum conditions as well as to improve their architecture for stable operation in harsh environments.

show abstract

Static and dynamic micro deformable mirror characterization by phase-shifting and time-averaged interferometry

Cited by 4 publications

References 9 publications

Photo-controlled deformable mirror for wavefront shaping

Photo-controlled deformable mirror for wavefront shaping

Micromirror arrays for multi-object spectroscopy in space

Operation of a MOEMS Deformable Mirror in Cryo: Challenges and Results

Contact Info

Product

Resources

About