What are caustics as they apply to optics?

[solarblast]

I've searched the web for caustics and optics, but mostly see pictures of them. They seem to have some positive use. In some fashion they seem to magnify. They seem to be somehow related to critical curves, whatever they are. Both seem to be helpful in gravitational lensing. How?

 

[Drakkith]

Have you read this article?

http://en.wikipedia.org/wiki/Caustic_(optics)

 

[solarblast]

Yes, but it skims the surface. Nor am I that familiar with ray tracing or optics to see below the surface. As far as I can tell, it does not speak to the usefulness of these two ideas, caustics and critical curves.

 

[Andy Resnick]

Nye's book, referenced in the wiki article, is the 'gold standard' for caustics. Sir Michael Berry's website has pdf versions of his relevant papers (which are also excellent):

http://www.phy.bris.ac.uk/people/berry_mv/research.html
http://www.phy.bris.ac.uk/people/berry_mv/publications.html

 

[solarblast]

Let me simplify this. Of what use are caustics and critical curves?

 

[Andy Resnick]

Of use to whom?

 

[Spinnor]

Let me simplify this. Of what use are caustics and critical curves?

This may be of no use, but the price was low.

https://www.google.com/webhp?hl=en#...98,d.dmQ&fp=14c9918464cb48e3&biw=1093&bih=491

Looks like you got a good answer here,

https://groups.google.com/forum/?fromgroups=#!topic/sci.optics/9IEDt0CFOSY

Good luck.

 

[solarblast]

Of use to engineers, physicsts, astronomers, optical scientists.

 

[solarblast]

Well, this pretty well nails it for me, since my original interest is how it is used in gravitational lensing.

"Caustic and critical lines have important properties regarding the number and parity of the images. For instance, if we consider a source far away from the line of sight to the lensing distribution, there will be just one image of the source if the lens are non-singular. However, if were to displace the background source towards the center of the lensing distribution, additional images will appear in pairs whenever the source crosses a caustic."

This goes on for a 1/2 page. It's from the book Grav Lensing and Microlensing by Silvia Mollerach"

Look at it on Amazon. You can Look at pages or search for words. This material is on page 43f.