It's a pleasure to
 acknowledge  'support' from the
home studios of

particularly Nathan Kopp and
Chris Colefax of the POVRAY TAG
 

  and the European agents for ZEMAX

Recommendations for optical designers
  Visit  Prof.Jensen
 & buy a copy of his book

IIn case of complaints or clarification, then
anidonu@ntlworld.com
ecoRecommebdations



Diamond, an allotrope of carbon, is a truly remarkable natural material.  It is the hardest, has the highest thermal conductivity and lowest thermal expansivity, the highest refractive index and dispersion and its spectral tranmission waveband extends from the ultra-violet to the long-wave thermal infrared.
The 'brilliant' cut is a  careful spacing and angling of the facets which creates maximum spectral 'fire' from the index and dispersion of the material.

Diamond.html

This is a POVRAY model of a brilliant cut diamond

Diamond.zip





The human eye is a remarkable  device.  It is an 'immersed' optical system in that it contains no air. The majority of the optical power is at the cornea, a hard shell of transparent refractive material. Behind the cornea is the aqueous humor, a watery  gel.  This is followed by the  'lens' whose purpose is 'accomodate' scene objects at a range of distances. This is achieved by muscles around the rim of the lens which alter, at constant volume. the shape of the lens and thus its refractive power.  Notice that the image is formed on a 'spherical' surface, the retina, in a second watery gel medium, the vitreous humor.
The 'iris' separates the humors, and forms the optical aperure stop of the system.
The refractive indices of the  four optical materials are in the range 1.33 to 1.45, very much lower than normal glasses.

This is a ZEMAX model of a human eyeball




The POVRAY topics:
    


  OPTICAL DESIGN AND MODELING WITH
  POVRAY AND ZEMAX 
                                                                              November 2005
 ( Rev. Jan 2006, June 22 2008, August 2008))

I was horrified yesterday (21 June 2008 ) when I attempted to  play the movies on my recent replacement PC ( Windows XP),   Media Player sent an error  message to the effect that it could not open the files ( avi and m1v).  Later that day, I went to a Vista PC, and found that that PC would play them OK.   Today, (22 June) I installed k1codec395f.exe and found that they did run, using the very much older version of Media Player.   

Although primarily of use for generating more visually attractive images of optical systems, POVRAY has a number of advantages in the visualisation of the primary and straylight images created by real optical systems.

An essential capability to exploit POVRAY is the conversion from the traditional optical prescription sequential notation of 'Radius, Thickness, Index, Aperture, Aspheric Data' to the POVRAY global co-ordinate notation of CSG objects.   I've placed at this site four 'include' files which allow this conversion to be performed, albeit manually.  It would be highly desirable if someone could create a code that performed this conversion automatically - but I have found that using a pre-programmed text in an include file even the most complex system can be  converted to POVRAY notation.
 
Also on this site are some examples of optical systems coded in the POVRAY script notation. The script files are shown both as html files for the casual user, or the complete scenes are shown as *.zip versions which can be used directly in POVRAY.

I have recently ( December 2005 ) come across another optical design program 'OpTaliX' at  www.optenso.de which does indeed feature an ability to export  traditional optical design prescriptions in POVRAY format.

At least a rudimentary familiarity with the POVRAY code, Version 3.6 is required.  With this installed on a PC, I'd expect that the zipped *.pov and *.inc files will run.









Just to show to a traditional optical designer what is possible in POVRAY, this is a movie of a  model of a 'brilliant'  cut  diamond. 

http://www.donzoptix.co.uk/funmovies/d1.avi

If you're willing to wait a lot longer  (for a 14MB file) 

http://www.donzoptix.co.uk/funmovies/nud1.avi

It shows POVRAY's  ability to create virtual chromatic images in the diamond volume and  real images on the tableNotice that the image is 'photorealistic' - no rays are present.   But POVRAY cannot create optical systems to meet a design aim.   Its purpose is to provide a pleasing  illusion of reality.  

And just to show to a POVRAY user, this is a ZEMAX raytrace lens design model of a highly stylised human eye.   Notice that the geometry of the lens object and the  paths of energy transport are shown as lines, or rays, on a 2-D representation of reality.  Although the image is not 'photorealistic' this is the design representation which is an essential part of the optical system creation process.



In reality, the eye is rather more complex than this model.   More detail on the lens itself, as it affects the treatment of cataract is shown here. http://www.crstoday.com/PDF%20Articles/0806/CRST0806_PR.pdf

And, if you're not squeamish, you might enjoy this movie of cataract surgery, in which the lens, clouded by age in my case,  or excessive ultra-violet radiation in sunlight, typical in the tropics, is destroyed by ultrasound and replaced with a plastic equivalent. http://www.youtube.com/watch?v=poGJSFLmrnc

I have
recently ( August 2008) had such surgery, very successfully, at the hands of Mr.Simon Horgan of Harley Street, London.  His website  http://www.iiiicare.com/profile.htm offers further information on the biology of the eye.














POVRAY is only of use for optical engineering assessment if it can be trusted to yield correct physical results.  This page compares results from the two programs when assessing an apparently simple 'non-sequential-components'  situation.

 








Many optical scenes are constructed by lens shaped objects.  Go to this page for a full description of the objects via html files. These 'include' files are used to create the objects in the three scenes.




The first scene is a four element lens zooming laser projector system constructed from three of the lens components, with the ray paths visualised both by traditional raypath diagrams from ZEMAX and by scattering in a POVRAY 'media'  atmosphere.








The second scene shows how a complex system with a zooming lens and an internal scanning mirror and a de-rotation prism can be animated.








The third scene shows a conversion of a Pro-Engineer CAD object to a POVRAY scene file using the SLP2POV conversion utility.






The technology of thermal infrared cameras has evolved over the last 65 years.  This page shows some results of modeling how the performances have improved over the last 30 years.  







© Don Barron 2005