Connect with us

Uniform illuminator for halogen filament lamps

Discussion in 'Lighting' started by Jacek Zagaja, Jul 3, 2005.

Scroll to continue with content
  1. Jacek Zagaja

    Jacek Zagaja Guest

  2. 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
    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.
     
  3. Jacek Zagaja

    Jacek Zagaja Guest

    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,
     
  4. 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.
     
  5. 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...
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-