| From:
Stuart Wilson, Design Manager for Thorlux
Subject:
Mercian Refractor Development
Product
Web Page
Product
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|
Having
had a great deal of success using Photopia (and FiELD)
in the design of reflectors, it was with some confidence
that we tackled a combined Refractor / Reflector system
for a new bulkhead. We compiled an extremely ambitious
specification, looking to achieve market leading SHR
of around 8:1 with good cut-off above horizontal to
reduce upward light pollution.
First
using Photopia to optimise the reflector elements, and
trying many combinations of reflector facets / materials,
it became easier to quantify the likely design constraints
for the prisms.
The
refractor module seemed suspiciously easy to use and
after many iterations of the prism clusters. Photopia
predicted that our brief was a realistic proposition.
By studying each bank of prisms in isolation we gained
a good understanding of their effect on the distribution
curve.
A
stereolithography model was made from clear resin to
validate the results prior to tooling. The results were
a very close match. The final product was tooled as
an injection moulding in clear u.v. stable polycarbonate
and achieved its targets with flying colours.
I
doubt if we would have had the expertise to design the
refractor or the time and confidence to develop the
optics without the help of Photopia (and the support
of Lighting Technologies).
Photopia
continues to give us a competitive edge through a reduction
in time scales and superior performance with each new
product we develop. |
From:
Ed Bilson, ReflectDesign LLC.
Subject:
Photopia 2.0 Review
|
I’m
an optical design consultant and I’d be lost
without a good raytracing program. The first program
I bought
was accurate and fairly fast but lacked a library of
lamps and materials. The second one I bought has a
library
of materials and can use solid models from a CAD program,
but it lacks a lamp library and takes hours to do a
100,000 ray analysis. I tried Photopia 1.5 but was
hindered
by the polygon limit.
Photopia
2.0 however, has everything a raytracing program
should
have plus even more. It has an extensive lamp library
that uses IES files for accurate distributions. A
library
of real world materials, tested with a photometer designed
by Lighting Technologies specifically for the purpose
of optical modeling. Photopia 2.0 is the fastest
ray
tracer I’ve ever used; it traces millions of
rays in minutes.
Photopia
is accurate. I’ve compared Photopia results
against the other ray tracers using the same designs.
The Photopia
results were the closest to the tested fixtures results.
You can review distribution curves, shaded plots,
and
a photometric report during ray tracing. Photopia has
some 2D design tools that let you do simple 2D ray
tracing.
But
the real plus is the Parametric Optical Design Tools.
With a minimum of input, Photopia creates either
extruded
or revolved 3D reflectors. You can change the design
parameters and re-test on the fly. There are a few
minor
things I’d like to see changed but I have been
told they are already in the queue for a maintenance
update. The image is an example of a forward throw
reflector
that I evaluated with Photopia.
Ed
Bilson
REFLECTDESIGN LLC
|
| From:
John Byrne
Subject:
R&D User's Overview of Photopia and Lumen Micro |
I
have been a user of Lighting Technologies' suite of
lighting-software tools for over 7 years, and in that
time this family of luminaire design and analysis software
has become indispensable. Using the range of tools available
form LTI, luminaire design cycles have been reduced
from typically many months to weeks; in some cases even
days. The benefits of reducing the cycle of concept-design
to volume production for a luminaire manufacturer in
today's fast-changing market, has become the main priority
for the design team. Only by utilising a combination
of fast, highly accurate luminaire analysis software
(Photopia), and an intuitive and user-friendly lighting
design package (Lumen-Micro) have manufacturers kept
ahead of their competition using more traditional methods
of design and analysis.
A
typical luminaire design scenario for new project would
involve an initial discussion with the customer to assess
the photometric performance requirements of the new
luminaire with a view to the requirements of his actual
application. From this information, a specification
would be created relating to intensity distribution;
choice of lamp; preliminary reflector dimensions and
possible materials. (Lumen-Micro was utilised extensively
for the initial development of the design, using 'simulated'
photometric data files representing the proposed luminaire's
performance. The customer's own CAD geometry of the
area to be illuminated, would be imported into Lumen-Micro
and the necessary calculations carried out often during
the meeting itself).
Having
arrived at a photometric specification for the proposed
luminaire, a preliminary reflector design would be created
and a suitable lamp and reflector material chosen from
the extensive library of lamp and material models available
within the Photopia database. It is important to note
that this source data is derived from the laboratory
measurement of actual lamps and reflector materials
and not just a 'generic' data file assuming the performance
of the lamps and materials.
Using
Photopia to analyse a luminaire optical design, enables
highly accurate predictions to be made as to the 'real
world' performance of the final production version of
the luminaire. The accuracy of the final production
lamp/reflector combination depends greatly on the initial
design geometry, but when compared with measurements
taken with a scanning photometer, variances of less
than 10% of intensity distribution are the norm, and
in some cases where some design-optimisation is undertaken,
verified accuracies of less than 5% are achievable.
Another
application for the Photopia/Lumen-Micro combination
is as a research tool for new lamp and reflector development.
I have designed many new light sources and modelled
them purely as data files for use with Photopia, effectively
creating a lamp which does not yet exist. This enabled
me to refine the characteristics of the new lamp design
totally within the software environment, so that when
an approach is finally made to the lamp manufacturer
to request a new or special lamp, the knowledge of its
performance may be readily predicted. This also enables
the luminaire manufacturer to have a completed reflector
design ready for market when the new lamp becomes commercially
available. This is where really significant time and
cost savings can be made, in bringing a new product
to the market, way ahead of the competition, as the
only time they can work with this new lamp is when the
manufacturer actually releases the pre-production samples;
(by this time the Photopia user has already moved on
to the next new design).
Using
tolerancing or optimisation of the lamp design, one
may also assess the performance implications of manufacturing
tolerances on the final luminaire design. In most reflector
designs, a 'perfect' lamp is assumed- one which has
geometry and photometry in accordance with the manufacturer's
exact specifications.
In
the real world such lamps are rare indeed. Tolerances
in lamp geometry and photometry vary greatly from the
original specification from lamp-to-lamp and even manufacturer-to-manufacturer.
These variances in performance can be measured in a
photometer using lamps representing commonly available
production lamps, and their effects on the performance
of the final optical system may be calculated within
Photopia. This enables the designer to produce a reflector
design that will perform to the required specification
with any lamp of the specified type. Often the driving
force in reflector design is maximising efficiency (light
output) not quality of light. With a 'perfect lamp'
a reflector design can be tuned to maximise the light
output. But use a lamp with a light-centre length one
or two millimetres out of tolerance (again, by no means
a rare event), and the beam quality of this design will
probably become totally unacceptable. Whereas the design,
which takes into account manufacturing tolerances, may
quite not achieve the light output, but will retain
the quality of beam using available off-the-shelf light
sources.
As
can be seen above, Photopia and Lumen-Micro can be used
in combination to great effect in the design of new
luminaires, helping the manufacturer get their new luminaires
to market ahead of the competition. I would personally
recommend any of these software tools from LTI on their
performance alone; but there are the additional factors
often overlooked by potential purchasers of software
which can be as important as the performance of the
product itself: Issues such as Reliable technical support;
Very competitive pricing; Lighting-specific technical
ability of the software supplier; and Regular upgrades. |
