Hi-Speed DM277-15 deformable mirror
The ALPAO Hi-Speed DM277-15 mirror features all the benefits of voice-coil actuators: linearity, large stroke, no hysteresis with a large bandwidth and large inter-actuator stroke (>1.5µm, mirror surface). All these performances are obtained with a compact mirror thanks to a pitch of 1.5mm between two actuators.
This is the ideal mirror for applications requiring large strokes, fitting accuracy and fast temporal response such as astronomy, free space optics and all adaptive optics without wavefront sensors.
|
|
Stroke performances
Thanks to its know-how, ALPAO engineers have designed an adaptive optics with optimized influence functions: a large stroke when all actuators are pushing/pulling in the same directions (more than 20.0µm on the mirror surface with a 3x3 pattern) and in waffle mode (more than 1.8µm on the mirror surface).
 |
 |
| Typical stroke (mirror surface) obtained while applying currents on 3x3 actuators (only 20µm of the total stroke). |
Typical inter-actuator stroke obtained by poking all actuators with the same absolute command (only 20% of the full stroke). The image shows the wavefront value. |
The image on the right shows the typical wavefront amplitudes (peak-to-valley) that are achievable with the Hi-Speed DM277-15.
|
|
The figure on the right shows an
high resolution interferometric measurement (436x436 pixels) showing the residual best flat error in closed loop (mirror surface, 5.7nm RMS, 60.3nm Peak-to-Valley). This level of performance warrants a high quality point-spread-function.
|
Courtesy of Dr. Olivier Lardière from the AO Group of University of Victoria (BC, Canada). Units are in µm.
|
Temporal performances
|
The large bandwidth of the Hi-Speed DM277-15 is shown on the left. The figure shows the typical step response featuring a low overshoot and a quick stabilization time. Thanks to a settling time lower of 1 milli-second, it is possible to compensate fast phenomenon encountered such as in astronomy and free space optics. Furthermore, thanks to a quick stabilization, adaptive optics without wavefront sensors are possible using iterative algorithms. |
Drive electronics
The Hi-Speed DM277-15 deformable mirror comes with high precision drive electronics (called CODE320). The new ALPAO drive electronics controls the currents (not the voltages) sent to the deformable mirror in order to increase the control precision. Furthermore, thanks to its 14 bits DAC and its high frame rate (>7 kHz), all the benefits of the deformable mirror are used. It features built-in monitoring functions for diagnostic or calibration purposes.
|
|
As this high precision drive electronics is scalable up to 1024 channels, a single drive electronics might be used to control multiple deformable mirrors such as needed in most demanding applications (Multi-Conjugate Adaptive Optics, Multiple Objects Adaptive Optics).
|
ALPAO Hi-Speed DM277-15 |
| Clear aperture size |
24.5 mm |
| Number of actuators |
277 |
| Distance between two actuators |
1.5mm |
| Geometry of the actuators |
Square Grid |
| Mirror surface quality in closed loop |
Error < 7.0 nm RMS |
| Wavefront tip/tilt stroke (Peak-to-Valley) |
>+/- 60µm |
| Wavefront astigmatism and focus (Peak-to-Valley) |
> +/- 45µm |
| Wavefront inter-actuator stroke |
> 3.0 µm |
| Non linearity errors |
< 3% |
| Settling time (at +/- 5%) |
1 ms |
| Coating |
Silver Protected |
| Operating Temperature |
15 - 35 °C |
| Software interface available for: |
C/C++, Matlab, Labview |
| Hardware interface |
PCI I/O Board |
> Click here for more information
|
