In this article, we show a breadboard setup of a complete closed-loop adaptive optical system that can be used for educational purposes or as a test setup for deformalbe mirrors, wavefront sensors and control software.
The complete AO system is built on a 45x30 cm breadboard and includes point source, aberration simulator (optional), deformable mirror and Shack-Hartmann WF sensor.
Laser diode, pinhole and the lens L1 form a collimated laser beam. A dynamic aberration is introduced in the pupil, defined by the diaphragm D, by a rotating disc. The cut-out part of the disk is necessary for proper calibration of the deformable mirror. Telescope formed by the lenses L2 and L3 rescales the beam to the 10-mm working area of the deformalbe mirror. Beam splitter BS splits the beam to the imaging camera, and to the wavefront sensor. Telescope formed by the lenses L4 and L6 conjugates the Shack-Hartmann sensor with the mirror pupil.
The frame of the pinhole forms an object O observed by the camera, while the pinhole provides the reference for AO operation. For better visibilty of the object, it is illuminated by an additional light source LS .
The following short movie demonstrates the setup operartion. A longer, three part movie, is available from here. In the first part, "AO off", you can see the image without correction; in the second part, "AO on, static", you can see the results of correction of the static aberration present in the system; and in the last part, "AO on, dynamic", the system corrects for all aberrations. The aberration disk makes a couple of full turns in each part.
|Deformable mirror||15-mm 17-ch MMDM with built-in tip-tilt stage (used for this particular demo). A wide range of OKO membrane and piezo DM, up to 109 ch.|
|Wavefront sensor||S-H, wide range of CCD and CMOS cameras|
|Closed-loop speed||50 ... 1000 Hz, depends on the hardware used|