Four optical designs.
Here are four alternate optical designs, based on new design work done since the 13 December 2006 design review, and including suggestions from Steve Shectman. The ZEMAX files can be found here. The SAFE8.AGF glass catalog is needed for these ZEMAX designs—this is the Ohara catalog with the obsolete glasses deleted, the glasses with low transparency at 4000Å deleted, and a few additional glasses added in.
All the designs meet PISCO optical and mechanical specifications.
This design is a lightweighted version, with thinner lenses, of the design shown at the 13 Dec 2006 design review.
Attached to a Magellan model where Magellan has no Atmospheric Dispersion Compensator (ADC), the image quality is high.
This design is a development of Steve Shectman's design. It's been modified to fit it into the PISCO physical configuration, and to reduce the size of the lenses using a field lens.
Here is a spot diagram:
This design is basically the same as Design B, but uses a low-dispersion, high-CTE glass, S-FPL53, instead of CaF2. A variant with S-FPL51 works nearly as well. In this example, the two triplet objectives are air spaced, so there is no gluing of grossly different CTEs. It might also be possible to glue the triplets together as in Design B.
This design is nearly diffraction limited.
Uses a more readily-obtainable low-dispersion, high-CTE glass, S-FPL51, instead of S-FPL53. Two lenses fewer than Design C, and the image is nearly as good. The first objective is now a cemented doublet, the second a cemented triplet.