VAP Image Stabilizer

Atmospheric turbulence and vibration in a telescope degrade the quality of images taken with the telescope. Image stabilizers are schemes to compensate for the motion of images due to air turbulence or telescope vibration. The most popular scheme is to use the so-called tip-tilt mirror. We have been developing an original scheme which makes use of deformable prisms. This scheme has the advantage of keeping the original optical configuration almost intact; tip-tilt mirrors make the optical path off from the original path.

The prism we selected is the product of CANON, which they call 'the Vari-Angle Prism (VAP)'. This prism is used in the anti-vibration scheme of handy VCRs. The prism is made of two glass plates sandwiching a liquid of high refractive index. The two glass plates can be tilted in horizontal and vertical directions, respectively, by solenoid coils. By changing the driving voltage applied to the solenoids, we can achieve a prism of variable apex angle.

The image stabilizer based on a deformable prism is now used on the Solar Flare Telescope.

References

• T. Sakurai et al.: "A Flexible Prism Used as an Image Stabilizer", Solar Phys., 205, 201-208, 2002