A new type of space telescope

[Deane Clark]

This is a very interesting idea, although I’m still not sure exactly how it works.
https://uanews.arizona.edu/story/new-le ... _campaign=

[rjcegla]

Here is a link that describes it better: http://nautilus-array.space/

[Dale Smith]

The article said the design is patented, so I visited the U.S. Patent & Trademark Office website (www.uspto.gov). Unfortunately when I typed in the names in the article I did not get any hits that sounded specifically like a telescope. Tom Milster is listed as the inventor in several patents relating to other types of optical design. His patents are assigned to ARIZONA BOARD OF REGENTS ON BEHALF OF THE UNIVERSITY OF ARIZONA

I suspect that either:
1. The actual inventor is someone further down the organizational ladder in that lab
2. The patent was originally for some other application than telescopes, such as telecommunications or microscopy
3. The patent belongs to someone else and they are just licensees.
Maybe someone else can get further on the patent search.

[clayton]

Canon article: https://cpn.canon-europe.com/content/ed ... element.do

[Dick Jacobson]

I've been reading a little about diffractive lenses and I think I understand how they work. Basically they combine the ideas of the diffraction grating and the Fresnel lens, resulting in a very thin focusing element.

A diffraction grating is a transparent or reflective surface with tiny parallel grooves. The width of the grooves is comparable to the wavelength of light. Light that hits the surface gets transmitted or reflected at an angle that depends on the ratio of the wavelength to the groove spacing. This is based on the principle of the diffraction of light, where the light propagates only in directions where the waves are in phase with each other (an integral number of wavelengths). Since the angle of refraction/reflection varies with the wavelength of the light, diffraction gratings break the light up into colors just like a prism.

A Fresnel lens consists of a series of thin concentric ring-shaped lenses each of which has the same focal length. The overall lens can be much thinner and lighter than a conventional length of the same diameter and focal length. These are used in lighthouses and thin plastic "sheet" magnifiers.

A diffractive lens is a Fresnel lens where the width of the concentric lenses is reduced to the wavelength of light. It bends the light just like a diffraction grating, but in a radial direction just like a Fresnel lens. Different wavelengths would have different focal lengths so it would be useless for a white-light telescope, but apparently it is possible to combine multiple diffractive surfaces to make an achromatic lens.

Diffractive optics are already used in some Canon and Nikon camera lenses. Will we be able to ditch our heavy lenses and mirrors in telescopes? If they can use a thin Mylar sphere for focusing in the proposed space telescope, then maybe the quality will be high enough for our amateur telescopes.