Is it possible to use a set of cylindrical mirrors and software correction to build an optical reflector telescope, instead of using a paraboloid reflector? By 'cylindrical' I actually mean a planar mirror curved to a parabolic profile.

In other words, rather than focusing light in 360 degrees in one step, is it possible to focus it in two steps -- first along one axis and then using a perpendicular 'cylindrical' mirror to focus it along the other axis?

Does this introduce optical distortions, and if so, can software correction be used?

The reasoning is that 'cylindrical' reflectors are far easier and cheaper to fabricate (either using sheet metal techniques or linear grinding methods) than traditional ones. They are also easier to stack together, launch into orbit and deploy once it reaches stable orbit (for space telescopes).

A Google search revealed only a single document with an attempt to describe such a setup, but it is over a decade old: http://www.bruno.postle.net/2001/telescope/

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1 Answer 1


Since this has remained unanswered for over an year, I went searching for answers myself. Recently I came across an acceptable one: http://www.iceinspace.com.au/forum/showpost.php?p=869520&postcount=6

This is the most important part of the explanation:

...parabolic cylindrical mirror produces a line focus (not a point) from a distant point object (star or the sun). If you use two cylindrical mirrors with the axes at 90 degrees, what you will get is two lines crossed, not a point.

So a purely optical solution is not possible. However, it should be possible to use a single cylindrical reflector with a parabolic profile to focus light on a linear array of sensors and derive an image through software.


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