Uniform illuminator for halogen filament lamps

[Jacek Zagaja]

Gentleman,

I would like to use halogen lamps from Ushio known as WhiteStar: 50W,
5300K, 36° flood beam and attach them to the integral sphere:

http://ucz.tme.szczecin.pl/~jacek/temp/Illuminator.gif

Above figure shows my first idea how it can be done. Uniform luminance
on detector FOV (field of view) is a goal. Waiting for a comments.

Whitestar paper:

http://www.ushio.com/Files/Whitestar-0904.pdf

Regards --Jack Zagaja
Szczecin University of Technology

 

[Victor Roberts]

Gentleman,

I would like to use halogen lamps from Ushio known as WhiteStar: 50W,
5300K, 36° flood beam and attach them to the integral sphere:

http://ucz.tme.szczecin.pl/~jacek/temp/Illuminator.gif

Above figure shows my first idea how it can be done. Uniform luminance
on detector FOV (field of view) is a goal. Waiting for a comments.

Whitestar paper:

http://www.ushio.com/Files/Whitestar-0904.pdf

Regards --Jack Zagaja
Szczecin University of Technology

Your sphere looks OK but you want to make sure that the baffles are a
bit larger than the field of view of the lamp. Also, you don't state
where the baffles are located. There is an optimum position but I
don't have the reference handy. Also, why are you using a directional
source? That will only increase any errors due to a non-ideal coating.
A bare tungsten halogen incandescent filament tube would be a better
choice. Finally, what are you going to coat the sphere and baffles
with?

--
Vic Roberts
http://www.RobertsResearchInc.com
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[Jacek Zagaja]

An aim is to observe visually such a transparent specimen using
uniform diffused light. This must be a daylight with high CRI. There
are some fluorescent like TLD950 but they are very long (50 cm) and
hard to get in depots.

You're right about the naked tube to be better but now one as I know
produce coated naked halogens as a daylight simulators. And of course
the costs - WhiteStars are the cheapest on the market.

Baffle distance need to be calculated - I think that Radiance could be
used for such simulation. I don't have any books about spheres (some
labsphere docs) but mine wouldn't be used for measurements.

Coating of the baffles - lamp side an electro polished stainless
steel? Reverse side and sphere itself would be a DIN painting (stable
undercoat and washable topcoat) or a usual painting from depot but
they are stronger in blue region - not as flat as they should. Look
for the WhiteStar spectra - it's far from d50 which is more flat.

Vic - maybe you know the better idea of using halogens as a uniform
illuminator?

Thanks in advance - Jack,

 

[Victor Roberts]

An aim is to observe visually such a transparent specimen using
uniform diffused light. This must be a daylight with high CRI. There
are some fluorescent like TLD950 but they are very long (50 cm) and
hard to get in depots.

You're right about the naked tube to be better but now one as I know
produce coated naked halogens as a daylight simulators. And of course
the costs - WhiteStars are the cheapest on the market.

Baffle distance need to be calculated - I think that Radiance could be
used for such simulation. I don't have any books about spheres (some
labsphere docs) but mine wouldn't be used for measurements.

Coating of the baffles - lamp side an electro polished stainless
steel? Reverse side and sphere itself would be a DIN painting (stable
undercoat and washable topcoat) or a usual painting from depot but
they are stronger in blue region - not as flat as they should. Look
for the WhiteStar spectra - it's far from d50 which is more flat.

Vic - maybe you know the better idea of using halogens as a uniform
illuminator?

Thanks in advance - Jack,

I would suggest a flat white paint on all interior surfaces,
including the baffles. If the baffles are specular then the light
distribution will not be as uniform.

I don't have a good recommendation for a daylight light source. The
Philips TL-D 90 Graphia Pro has a CCT of 5300 and a CRI of 98 and the
18 watt version is only about 600 mm long, but the spectrum is still
significantly different than sunlight. You should get a better
spectrum from a short arc xenon lamp and the lamp would also be the
size you want, but I don't have enough time today to do any more
research. I will look again tomorrow. Perhaps others in this group may
have better ideas.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

 

[Simon Waldman]

Your sphere looks OK but you want to make sure that the baffles are a
bit larger than the field of view of the lamp. Also, you don't state
where the baffles are located. There is an optimum position but I
don't have the reference handy. Also, why are you using a directional
source?

From what I remember, the Whitestars barely count as directional
sources... they have to let so much warm-coloured light out through the
reflector to get the cool-coloured beam that they're about as bright
from either direction, albeit with a different colour...