SBIG AO-X Adaptative Optics for STX & STXL Cameras
The SBIG AO-X Adaptative Optics is a large aperture AO designed to be compatible with all STX and STXL series cameras, including the STX-16803, STXL-16200, STXL-11000 and STXL-6303. The AO-X requies minimal backfocus while offering a large 3″ aperture optical element, which is large enough to cover the KAF-16803 CCD sensor.
The SBIG AO-X requires an off-axis guide camera behind the device. For STXL cameras, we recommend using the FW8G-STXL filter wheel. For STX cameras, the AO-X stacks on top of the FW7-STX and STX Guider. The AO-X can also be used with a Remote Guide Head if you have a custom Off-Axis Guider setup.
AO-X Design Yields a Thin Package
The main advantage of this new technique is that it is thin, with a body only 1.05 inches
The light passes through a 10 mm thick plane parallel BK-7 glass plate that is supported on a two axis gimbal mount. The gimbal can be tilted +/- 2.4 degrees by the action of four sets of magnets and coils around the periphery of the gimbal. The tilt in each direction produces a deflection of about +/- 144 microns in each direction, which is +/- 16 pixels using an STX-16803 or STXL-11K. This tilt has no significant focal shift, distortion, rotation, or change in magnification associated with it. The smallest move increment is 1/7th pixel. The window has an anti- reflection coated specified to be less than 1% reflection per surface from 400 to 900 nm wavelength.
The images below are actual star images showing the effect of image wander corrected at 1 Hz and 10 Hz:
And the resulting size of the star image in a long exposure:
Other data gathered by Brad Wallis of JPL (Brad Wallis and Benoit Schillings developed the prototype for the original AO-7) show the the effect of rapid corrections on poor seeing. At 1 Hz the larger, slower component is reduced, but the amplitude of the jitter remains about the same:
However, at a 5Hz correction rate, the faster jitter is reduced:
And at a 10 Hz correction rate, significant improvement is seen:
The improvement in stellar profiles can also be seen at corrections above 1 Hz. First by looking at the non-AO guided image:
And comparing the non-AO guided image to the AO guided image there is again significant improvement in the FWHM of the star profile:
Telescope mounts cannot correct faster than about once per second. The 10Hz rate of the SBIG AO-X will clearly result in improved resolution under the right conditions.