Webb Space Telescope

[dtvmcdonald]

The Webb Space Telescope finished unfolding today. Next step
is aligning all those mirrors.

Speaking of mirrors ... have you noticed that NASA has a habit of making
it impossible for someone to find that actual specs of their things.

I wanted to find the specs of the mirrors in the main telescope (there are three). Official values are just not there. I did find one set of values
that somebody cooked up to make a published drawing, but in
a simulator they were not accurate enough to give the specced performance. I wanted to see what it was like .... optics used to be
the heart of my business, including ones cooled to liquid nitrogen
or liquid helium temperatures like the Webb.

This really ticks me off. I think its a conspiracy. So I got playing around.

They do give some good large scale drawings that all look alike.
They give the numbers for the exact diameters, and the overall focal length, so I have the scale. I measured the drawings and fed that into
my cheapie (i.e. free) simulator. I've had expensive (by academic standards, that is, like $10,000) optics made up using designs from that program and the devices work as specced.

I used the auto-optimize to get the curvatures and asphericities and tilts.
This is very highly overconstrained and resulted in a unique solution.

The results when simulated match their specs nicely.

Its interesting to note that the design is NOT diffraction limited at wavelengths shorter than 2 microns, at least not over
most of the field.

At long wavelengths the resolution is, of course, abysmal due to diffraction.

I hope this gizmo is more of a success than the European (CERN) LArge Hadron Collider, which really really disappointed lots of high energy physicists, as it works perfectly but showed that the particles they expected do not exist.