fiber optics?


do IES data files exist for fiber optics lighting?


Hi Judy,


do IES data files exist for fiber optics lighting?

The problem with fiber is that there are so many combinations of
illuminator, lamp, fiber run length, lens, (and quality of
contractor/installation), that ies files would necessarily vary from job
to job and even fixture to fixture. That said, some manufacturers do
provide ies files that describe the performance of one system, and then
give you some multipliers to help you accurately tailor the output of a
given installation.

The Fiberstars site listed above is one example, but you will note that
there is no "bend factor", and no "lousy end finishing because the
contractor was a hack factor", both of which need to be accounted for in
the simulation, yet often difficult to quantify.

So to answer your question: "yes, BUT..." =8-)


On Wed, May 4, 2005 6:13 am, judy lai said:

Rob Guglielmetti


One option might be to use a program such as TracePro to model the fiber
optics. Assuming you know the lamp type used and its lumen output, the
material the fibers and end piece will be made of, the length you'll need
(which shouldn't be too hard to estimate if you know where the box is
located and where the fibers terminate), and an approximate shape for the
end piece, you should be able to put together a fairly accurate distribution
that takes into account losses in the fibers, box, and end piece. TracePro
will allow you to export the distribution to an IES file which you can then
use in radiance. Depending on how accurate you want to get this can take you
anywhere from 20 minutes to a few hours to put together.

I'm not familiar with other ray-tracing/luminaire design programs like
TracePro, but I'm sure there are more out there that allow you to do the
same thing.

Hope this helps!

Dave Maino

My friend Ian Ashdown, an expert in both LEDs and IES files, had this to say on the topic:

From: "Ian Ashdown" <[email protected]>
Date: May 4, 2005 5:52:31 PM PDT
To: "'Greg Ward'" <[email protected]>, <[email protected]>
Subject: RE: desktop radiance led and fiber optic

LED-based luminaires are considered to be the same as any other luminaire
when it comes to photometric data files. TIR Systems (, for
example, offer industry-standard IESNA LM-63-02 data files for their Destiny

There are two classes of fiber optic lighting: 1) the fiber optic emits
light along its length, similar to cold-cathode ("neon") lighting; and 2)
the fiber optic emits light at its end, typically in a housing designed to
look like a small point-source luminaire.

In the first case, the fiber optic is probably best modeled as a Lambertian
emitter. In the second case, industry-standard IESNA LM-63-02 (or EULUMDAT)
data files are applicable.

IESNA Publication LM-76-02, "Photometric Testing of Fiber Optics Lighting
Systems," describes recommended practices for fiber optic photometry.

Ian Ashdown, P. Eng., LC, FIES
byHeart Consultants Limited