RE: ATM Spider Design

[andydtg@alpha1.phoenix.net]

Re posts from Brastislav & Neil Levin re spider diffraction:

I'll concede that secondary support structure area may affect
the amount of diffraction seen in the image, in a theoretical
sense. As Bratislav points out, there are other effects like
thermal etc. We might also consider that, on the scale of 
the size of a wavelength of light, that these obstructions are
probably not very smooth, also increasing the amount of scatter
and diffraction. Neil's expanded explanation also makes a lot of 
sense, although I probably have forgotten everything I ever
knew about Fourier transforms many moons ago. 

I'm not set up to do this right now, but some tests with an
apo with various simulated spider obstructions & a CCD camera
imaging a bright star might yield some useful results.

Thanks for the enlightenment, guys!





Andy Saulietis / DTG Alt-Az-Fp Drive Systems
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax