Re: [ATM] Luri-Houghton prescriptions.

["Ukyo Chen" <ukyochen888@hotmail.com>]

Hi Bob,

Ofcouse equal radius curves is not the best in L/H system design, but it is 
the best way to make and test, you can only make and test 2 radius, also the 
result is not too far away from the best result, for example if total error 
of the equal mode is 0.000466, then the best result's total error is 
0.000381.

Best Regards,
Ukyo Chen


>From: "Bob May" <bobmay@nethere.com>
>To: <atm@atmlist.net>
>Subject: [ATM] Luri-Houghton prescriptions.
>Date: Wed, 12 Oct 2005 17:52:15 -0700
>
>I've been playing with the Lurie-Houghton prescription on the two
>lenses and seem to find that the equal radius pairs of curves
>doesn't seem to do the best job.  The equal radius curves seem to
>do some inverse coma along with more astigmatism than doing
>different radius curves for each surface.
>What I've come up with is the following set of curves for the
>typically specified lens set:
>Object
>0 12.5
>Refraction
>BK7 0 -96.3
>Refraction
>Air -0.81 275.9
>Refraction
>BK7 -0.96 96.3
>Refraction
>Air 1.457 -275.9
>Mirror
>-61. 119 0 13
>FocalPlane
>-1.69403
>WAVELENGTH
>0.643 0.54 0.486
>while a much better result is:
>Object
>0 12.5
>Refraction
>BK7 0 -107.09
>Refraction
>Air -0.745 201.726
>Refraction
>BK7 -0.78739 94.3063
>Refraction
>Air -1.27146 -271.735
>Mirror
>-61 119 0 13
>FocalPlane
>-1.57512
>WAVELENGTH
>0.486 0.54 0.582
>ANGLE
>0 0.0066 0.01
>FOV
>0.0005
>the format is in Dave Rowe's TRACE program where the first number
>is the distance and the second is the ROC of the surface.
>The first data set gives a spot size of 0.00024" in diameter
>while the second gives a spot size of 0.00012" in diameter.  The
>images of the spots on the first show that the off-axis spot has
>a bit of inverse coma and the size of the spot is about twice the
>size of the second set of spot diagrams where the way off-axis
>spot shows a nice oval which indicates only astigmatism.
>Any comments?  I've got a guy that is about to build the scope
>and I'd want to make sure that he builds the best possible.
>Bob May
>bobmay at nethere.com
>http: slash /nav.to slash bobmay
>http: slash /bobmay dot astronomy.net
>Addresses have been munged up to keep spammers from bothering me.
>replace the obvious words with the proper character.
>Thank you for your understanding!
>
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