Re: ATM Off axis mask

[espector@mlswc.uk.lucent.com]

>From: Buck Childers <buckchil@sound.net>
>Subject: Re: ATM Off axis mask
>
>It seems to me that you could do an off-axis mask with 2 holes - much like
>a hartmon(sp?) mask and increase your light gathering and still not have
>to deal with spikes.

I've wondered about this. If one hole is good, because it avoids the spider 
legs and central obstruction, then how about four holes?

And then put smaller holes between the bigger holes etc.

I eventually concluded that the resulting image would be diffraction-limited
by the smallest hole. 

Note: I haven't proved this, but I'd expect to see the large Airey disc due
to the small aperture, but with the brightness of a large aperture.

Conclusion: no free lunch (this time).

Edwin.