IR Wavelengths Check Putting Greens
Michael D. Wheeler
LINCOLN, Neb. -- Golfers are never short of excuses when it comes to lackluster play, but blaming the greens may soon be a thing of the past. Engineers at the University of Nebraska have designed a device that uses IR wavelengths to determine whether irregularities on a green are likely to throw a golf ball off course.
For 20 years, the US Golf Association has relied on a rudimentary device called a Stimpmeter to test the uniformity of greens. One end of the device is raised to a 20° angle until the ball rolls across the putting surface. If the distance a ball travels varies by less than 15 cm within a set of rolls, the green is considered uniform. The problem with the Stimpmeter, however, is that it offers only a rough measurement to compare one green on a course with another, and it provides no data about the turf characteristics, which can affect how a ball will roll on a given green.
This problem led Roch Gaussoin, an associate professor at the university, and graduate student Anne Rist to design a system that could accurately assess how a ball decelerates. Gaussoin attached a Stimpmeter to a polyvinyl chloride pipe and inserted 10 photoelectric switches spaced at 15-cm intervals inside. Each switch contains an IR-emitting diode and a silicon phototransistor, both manufactured by Honeywell Inc. in Phoenix. After the ball passes the first switch, it breaks the 935-nm beam, causing a computer to record the time it takes the ball to travel to each switch and to give an accurate picture of the ball's deceleration. The results are then uploaded to a laptop computer and analyzed to discover irregularities.
"The whole principle here was -- according to fundamental physics -- a 'bump in the road' will affect a ball's deceleration," Gaussoin said. "We looked at doing this using a radar gun, but that had its disadvantages. You're comparing 40 m/s with a baseball pitch vs. 2 m/s on a putting green. That slow speed isn't detectable with Doppler [radar]."
Gaussoin's system not only gives an accurate indication of imperfections on a green, but also is relatively inexpensive to construct, costing less than $2000. Although he has no immediate plans to commercialize the device, Gaussoin said it could prove an important research tool for determining how quickly greens respond to conventional treatments. Mowing increases the variation within each green, according to early trials of the device, and greens mowed twice in the same direction tend to be the most inconsistent.
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