You could use a solid or flexible fiber optic taper.

You could find it at Schott (http://www.schott.com/lightingimaging/english/defenseproducts/imaging/inverters.html under inverters) and also at incomusa.

It is possible to rotate the image with reflecting system. For example consisting of three mirrors.

But in fact it too most that the Dove prism, however, is not present dispersion in glass.

Thanks for your help,

Assaf

By glueing 3 mirrors in a tube (mimmicking the action of a Dove prism) you can make a dispersionless (as mentioned above) image rotator that is also variable in the rotation angle.