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Optical System
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A set of three digital video cameras (one JVC model GR-DVM 80 and two JVC model GR-DVM 90) will be used to record the motion of our system of particles. It is necessary to incorporate mirrors and additional lenses to lengthen the light path and increase the depth of field so that it is possible for the video camera to view the entire depth of our sapphire boxes and still resolve individual balls. A zoom magnification is set for each camera taking into account the automatic tele macro function, which has been activated. Each camera is then manually focused to image individual balls with the aid of an additional 400-millimeter focal length plano-convex achromatic lens. These settings will create a recorded image that will clearly distinguish each of our system particles in each of the visible boxes.
To extend the length of the optical path a 3" x 3" first surface mirror will be mounted opposite each video camera. The mirrors are oriented such that a ray of light from the center of the box will reflect off the center of the mirror and into the center of the camera lens. The mirrors are coated with a protected aluminum (AlSiO2) finish to maintain a high reflectivity on the surface of the mirror. Mirrors are mounted onto a delrin backing with glass to plastic epoxy. Delrin backing is then attached by an aluminum mounting plate and three aluminum posts to the experimental frame.
Each camera is enclosed in a box constructed from 3/16" aluminum plate. Closed-cell neoprene foam is packed around the camera to minimize any forces that the camera endures. The foam also confines the camera to prevent it from being jostled out of alignment as a result of vibrations and forces experienced during flight. Epoxied into the lens plate of each camera box is a T-mount containing the additional achromatic lens discussed earlier. A 20-gauge stainless steel (304) plate is placed inside the box and positioned via setscrews in the side of the box to obtain proper collimation of the optical path.
Lighting for the experiment will be provided by high brightness blue LEDs. Blue lights were chosen due to the increased sensitivity of the CCD in each camera to the blue end of the visible spectrum. Lights will be embedded in ¼ inch thick delrin block and mounted to produce uniform lighting of the box set.
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