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View Full Version : Use of IR lights during gait measurement. Need Info.



Angshuman P Bagchee
02-15-1994, 10:58 PM
Dear BIOMCH-L netters:

This is a query for all who use any kind of video-based motion
analysis. We recently acquired the 3-D motion analysis system from Peak
Performance Lab (Colorado). Our problems stem from using Infrared (IR) lights
that came with the system. I would appreciate if someone with similar
experience can suggest "possible remedies" to the problems described below.

I would like to add that these IR lights are being used for gait
at very low levels of environmental lighting conditions. We discovered that
the Pulnix cameras used are very effective in "seeing" the markers in IR
light (even to the surprise of the technician from Peak). There is, however,
a huge problem with these IR light sources - HEAT.

Since two IR lights are fitted no farther than 10 inches from the camerait is heating the camera up a bit. We would like to know:

(1) Is there a better "brand" of IR light suitable for such operations?

(2) How long, in someone's experience, can each of these camera setup (with
the IR lights) be operated without damaging the setup (including any
changes in the calibration, etc.)?

Note: We tried 20 min. It heats up the camera body to about 10 higher
than the room temp)

(3) Is there a recommended procedure under these circumstances?

(4) The IR lights seem to "crackle", "emit odor", and the glass in the
front of the light (red tinged) is slowly developing cracks that are spreading; any suggestions?

It should be pointed out that the required wattage of each of the
two lights with each camera is 600W, which is what they are right now.

Since, this is a first ever for Peak Performance, they could not
provide much technical support in this matter. Any suggestions from the
best minds in the field, logged on to this system, would be of great help
to us who are new to this exciting field!

Thanking you in advance.

| A. Bagchee |
| Biomechanics-Ergonomics Research Lab |
| Dept of Environmental Health |
| University of Cincinnati Medical Center |
| Cincinnati, OH 45267-0056. |

EMAIL: bagcheap@ucunix.san.uc.edu
PHONE: 513-558-0510