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According to the Epilepsy Foundation:

Even in predisposed individuals, many factors must combine to trigger the
photosensitive reaction such as the frequency of the flash (that is, how
quickly the light is flashing), its brightness, the contrast with background
lighting, the distance between the viewer and the light source, the
wavelength of the light, and whether a person's eyes are open or closed. The
frequency or speed of flashing light that is most likely to cause seizures
varies from person to person. Generally, flashing lights most likely to
trigger seizures are between the frequency of 5 to 30 flashes per second
(Hertz).

http://www.epilepsyfoundation.org/answerplace/Medical/seizures/precipitants/photosensitivity/photosensitivity.cfm

I interpret their information to mean that the risk is low, but is also very
hard to completely eliminate since individual sensitivities are quite
variable.  I wonder if it would be possible to use timed sampling with a
digital video cam to replace the strobe, but I suppose the video might
flicker, leading to the same issues.

Dave Smith

On Tue, Mar 18, 2008 at 4:23 PM, Glen Moore <[log in to unmask]> wrote:

> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related
> institutions.
>
> *****************************************************************************
>
> Don
>
> We have had no reported problems - No complaints in 10 years of operation.
>
> The strobing is fast - the pump is tied to the mains frequency - drip
> frequency is 100Hz.
>
> Love the exhibit! It creates lost of discussion between visitors.
>
> Glen Moore
> Science Centre and Planetarium
> Wollongong, Australia
>
>
> ----- Original Message -----
> From: "Don Marvel" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, March 19, 2008 6:40 AM
> Subject: Strobe Drip
>
>
> > ISEN-ASTC-L is a service of the Association of Science-Technology
> Centers
> > Incorporated, a worldwide network of science museums and related
> institutions.
> >
>
> ****************************************************************************
> *
> >
> > Greetings,
> >
> > We're considering building a Strobe Drip exhibit, in which a steady drip
> is
> > optically captured by a strobe light so visitors can study the dynamics
> of
> > individual drops and experiment with strobe rate and phase
> relationships.
> > Aware of the potential hazard that strobes pose for people prone to
> > seizures, we wonder what sort of experiences other museums have had with
> > this sort of thing.  We know we'll need to position the exhibit
> carefully
> > and provide a sign so that visitors are informed about the strobe before
> > they encounter it.  Have any of you had issues with this, and what is
> the
> > general feeling regarding risk (liability) vs. reward (visitor
> experience)?
> >
> > Many thanks for your time and thoughts,
> >
> > Don Marvel
> > Exhibits Director, WonderLab Museum of Science, Health and Technology
> > 308 West 4th Street
> > Bloomington, Indiana  47404
> > # 812.337.1337 x22
> > www.wonderlab.org
> >
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> For information about the Association of Science-Technology Centers and
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-- 
David L. Smith
Da Vinci Science Center
Allentown, PA
http://www.davinci-center.org

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