This paper describes both the optical development of an LED-based sports lighting system and the results of the
application of the system to an actual sport field. A traditional sport lighting fixture is generally composed of a single
1500 watt High Intensity Discharge (HID) light source with reflectors used to control the light distribution. The efficacy
of the HID light source is equivalent or nearly equivalent to most LED light sources, putting LEDs at a large cost
disadvantage in a high light output application such as sports lighting due to the number of LEDs and supporting
components required to run an LED system. To assess the feasibility and applicability of LEDs in a sports lighting
application, an LED-based sport light has been developed and installed on a small soccer field specified to have an
average maintained illuminance level of 30 footcandles. An existing HID sport lighting system was also installed on the
same size soccer field adjacent to the LED field with the same average footcandle level for comparison. Results indicate
that LEDs can provide equivalent average illumination; however the LED source and system component cost is
substantially higher. Despite the high cost, it was found that improved optical control afforded by the optical design
used in the system provides a significant improvement in offsite wasted spill light, glare control, and on field uniformity.
This could provide an advantage for LED systems.
The use of reference mirror rotation during the production of a double-exposure hologram is discussed. The rotation of the mirror introduces a phase shift across the hologram that can be observed by scanning one''s head from one end of the hologram to the other. The sign ambiguity of the fringe order can be resolved by noting the apparent motion of the fringes as one scans one''s head across the hologram. This method is easily adapted to existing setups does not distort the original fringe pattern and the amount of phase shift across the hologram can be controlled easily. Sample experiments showing quantitative and qualitative results on a circular membrane are presented. 1.
A study using holographic interferometry (HI) to examine human body surface motion has been done. Skin surface motion resulting from the pumping action of the heart is detectable with holographic methods. We have examined the skin motion in the neck area in detail. The interferograms obtained using a double pulsed ruby laser system provide an image of the human subjects with a fringe pattern superimposed upon that image. The fringe patterns correspond to the motion of the skin during the time between the two laser pulses. These fringe patterns were analyzed and correlated with several known cardiac phenomena. The patterns show a high degree of intra- and inter-subject consistency for healthy male subjects. To determine direction (sign) of skin displacement from standard interferograms a method of introducing reference fringes was incorporated into the system. To confirm that the fringe patterns yield accurate displacement data a point sensor was utilized to directly measure skin movement. Holographic interferometry''s future value as a clinical tool warrants further detailed investigation. 1.