[Raytrace] Where To Start?

[Wayne Churchill]

Hi John, Hello List Members,
A question concerning surfaces:
When considering optically flat reflecting surfaces, how is a change in the 
angle of the direction of the light cone usually denoted?
And thickness:
When considering the thickness of a lens, is the on axis thickness of the 
center of the lens the thickness value used?
For those of us who haven't kept up or brushed up on optical terminologies, 
should we develope a short list of common optical terms and meanings so 
we're able to communicate effectively?
Thankyou,
Wayne Churchill


>From: "John D. Upton" <jd-upton@texas.net>
>To: raytrace@blackhole.idcomm.com
>Subject: [Raytrace] Where To Start?
>Date: Thu, 06 Dec 2001 18:46:13 -0600
>
>List,
>
>     Our membership seems to be pretty stable now at about 35.  Let's get
>going.
>
>     Where do you want to get started on this list?  I don't know exactly
>what level of knowledge already exists, so I am unsure.  What do you want
>to discuss?  One possible starting point is to discuss things common to all
>ray-tracing programs -- or whether there is anything in common.
>
>     For starters, do all programs use the same conventions for data entry?
>
>     OSLO uses a "spreadsheet" format.  If you draw out a design on paper
>with light starting from the left, the following rules apply.  Are these
>basic rules the same for all other programs we might be interested in 
>using?
>
>1.  Each surface encountered by the light is numbered in the order that the
>incident light transverses it.  If the light is reflected back onto a
>previous surface, it is numbered again, but the parameters can be picked up
>from the original specification.
>
>2.  If light is travelling left to right, distances are positive.  If right
>to left, they are negative.  At each reflection, the sign of the directions
>changes.  (For example; if light is going left to right, the sign of
>distances is positive.  If that light is reflected, the next distance is
>negative.  If it is again reflected, the sign changes back to positive.)
>
>3.  Each surface has a radius of curvature, aperture, thickness, and media
>associated with it.  Surfaces may also have special data such as conic
>constant associated with them.  The thickness and media are understood to
>be where the light is entering upon traversing the surface.
>
>4.  For a curved surface, if the center of curvature is to the right of the
>surface, the ROC is a positive number.  If the COC is to the left of the
>surface, the ROC is a negative number.
>
>5.  Each surface has a thickness associated with it.  The thickness is
>simply the distance to the next sequential surface.  Lenses have a
>thickness to them, of course.  Air spaces are also considered 
>"thicknesses".
>
>    Are these basic rules the same in all programs?  They seem to be
>consistent with all the optics and ray-tracing texts I have read.  What
>other "rules" might be considered common to most if not all programs?
>
>John D. Upton
>Georgetown, TX
><http://www.atm-workshop.com/>     "The ATM's Workshop"
><http://members.aol.com/RonWin20/> "Ronchi For Windows Home Page"
>
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