Re[6]: [ATM] Chromatic effects visibility

[Richard <cnc@cncservo.co.uk>]

Hi Vlad,

Wednesday, February 2, 2005, 2:37:21 PM, you wrote:

vs> One think that is unclear to me is why the system is only
vs> "diffraction limited" between (from the memory) 300nm and 1200nm, if the
vs> "worst case" blur size is only a small fraction of the Airy disc.

It is the RMS spot value over the F, d and C line wavelengths
that is a small percentage of the diffraction limit. That's
480nm to 644nm. A small number rays are more like 50% of the
disk at wider fields. At the field limit and at 320nm more
rays start falling outside the Airy disk, even though the RMS
spot size is smaller than it. 320nm is the worst, but that's
right at the edge of BK7. The design works nearly as well with
fused silica if UV is of interest.

There's some spot plots (splots?) here :

http://www.cncservo.co.uk/RC16_320.JPG    ; 320nm near UV
http://www.cncservo.co.uk/RC16_480.JPG    ; 480nm F line BLUE
http://www.cncservo.co.uk/RC16_546.JPG    ; 546.1nm d line GREEN
http://www.cncservo.co.uk/RC16_644.JPG    ; 643.8 C line RED
http://www.cncservo.co.uk/RC16_FdC.JPG    ; RGB combined
http://www.cncservo.co.uk/RC16_1200.JPG   ; 1.2um IR


-- 
Best regards,
 Richard             mailto:cnc@cncservo.co.uk

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