Dominic,
Our lab went for a super-duper custom design job for stimulus presentation.
We have a NEC VT-540 LCD projector that we use to project down the magnet
bore from outside the scanning room. We have a Varian/Siemens 4T magnet so
the projector had to be quite a distance from the magnet (~5m) so the
elctronics would not be affected by the field. We also purchased a Sigma
170-500 mm zoom lens. The large zoom lens incorporated all of the potential
focal lengths we would need (placement of the viewing screen and viewing
mirror, etc.). We then hired Radiant Imaging Inc. to design and construct
a custom realy lens that would match the output of the projector and the
input of the zoom lens to reduce image artifacts like vignetting. They
also constructed a cart with an optical bench rail on it so the projector,
relay lens, and zoom lens could be adjusted independently but kept in linear
alignment. The cart has guides that can be set so if it needs to be moved
it can then be repositioned back to the old location. The system is
amazing. The downside is the cost (projector <$8000 Can.; zoom ~$1000
Can.,; custom relay, optical bench rail, and cart ~$50,000).
Hope that helps.
Sincerely,
Chris
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Christopher G. Thomas, Ph.D.
Software Developer & fMRI Biophysicist
Dept. of Psychology,
University of Western Ontario
(519)661-2111 x.84625
[log in to unmask]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We then contracted out to a company called
----- Original Message -----
From: "Mort, Dominic J" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 09, 2001 11:45 AM
Subject: Hardware of choice for stimulus presentation?
> Dear SPMers, I hope you'll forgive my general non-SPM enquiry.
> I am trying to get a feel for what hardware people are using to get visual
> stimulation to their subjects in the scanner.
> Our subjects currently view a large, conventional (ie. not
ferromagnetically
> modified) LCD panel partly covered with copper shielding. This has
resulted
> in no deleterious interference if about 5 metres from the subject's eyes
but
> obviously at that distance the field of view is rather small.
> I notice that some companies (eg. Barcomedical.com) make the full-monty
LCD
> arrangement deplete of ferromagnetic components for MR compatibility, but
> the cost of these is staggering - more Aston Martin that Austin mini.
> May I ask if anyone knows of any 'half-way house', more affordable
> arrangements? Goggles are definitely out for us because we need our
> ASL-504LRO eye tracker to be able to peek at the pupil.
> Having said that dedicated LCD panels are exorbitant, my enquiries into
LCD
> projectors capable of projecting down the bore to a back-projection screen
> have come up with similarly steep costings - this seems to be because the
> companies (eg. NEC) only make expensive long-throw lenses for their most
> expensive projectors. Is this right? May I ask which models/optics others
> have purchased and the ballpark figure for cost? Such information would
> greatly help me orient to the issues.
> In anticipation, thank you for sharing your ideas.
> Best Wishes
> Dominic J. Mort
> Clinical Research Fellow,
> The Neuro-ophthalmology Group
> Imperial College
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