Hughey & Phillips (H&P) designs and manufactures flashing and steady state anti-collision lighting used on above-ground obstructions like communication towers, antennas, buildings, wind turbines, grain elevators, smoke stacks, bridges and other man-made structures that are potential collision hazards for aircraft. Used as either standalone fixtures or as part of integrated systems, these low, medium, and high intensity lighting devices illuminate obstructions to aerial navigation as specified by the FAA, FCC, ICAO, DGAC of Mexico and Transport Canada. The required light output intensity of H&P’s products increases with altitude - the higher the elevation, the greater the required output intensity.
In order to be visible during the day and at night from up to 10 miles away, these flashing warning beacons must repeatedly and reliably produce high intensity light output of up to 300,000 effective candelas. Because strobe rates for obstruction lights are extremely fast, the required light intensity measured on a peak basis for certain lights exceeds 10 million candelas. The light output is so intense that it can be difficult to get an accurate reading using traditional photometric measuring equipment.
During the design phase, Hughey & Phillips’ engineers use a goniophotometer to conduct 6 to 7 hour-long small increment tests that empirically verify the performance of the lighting devices and provide finite detail on the individual strobe flashes. The goniophotometer is also used to individually test every obstruction lighting device that the company produces to make sure it meets or exceeds the mandated national or international photometric standards for its intended application. The results of these tests are provided to the end user on delivery of their obstruction light.
Lighting engineers realized that the company needed to update the antiquated, manually-operated photometric equipment currently in use, and contacted several manufacturers of goniophotometers to review their products and capabilities. To meet H&P applications, the goniophotometer system needed to be rugged enough to withstand constant use over a 16 hour day. The equipment also had to be user friendly for both the highly technical engineering staff and the less technical production staff.
According to Stephen Schneider, president of Hughey & Phillips, Hoffman Engineering offered both rugged equipment and intuitive, easy to use programming and software that required minimal staff training. “We needed a device that could endure constant daily use through two straight shifts. Many goniophotometer designs feature moving parts - arms that rotate around the light and benches or tables that rotate on multiple axes. The problem is, the more moving parts there are, the more likely something on the device will break down. Hoffman’s product is built like a tank. Only the turntable moves, so nothing can wear out.”
Measuring 30 inches in height and 21 inches in diameter, the biggest H&P obstruction lights are much larger than the aircraft and automotive lights that are typically tested on goniophotometers. H&P could select from Hoffman’s 30-inch open top, 40-inch, 60-inch, and 80-inch frames sizes and could also select standard or heavy duty systems for large or heavy lights. After evaluating all of Hoffman’s product offerings, H&P acquired the 30-inch open top configuration goniophotometer.
Choosing the goniophotometer was just the start of the process. Both the device itself and the software that automated the testing processes needed to be customized for the specific tests that Hughey & Phillips planned to conduct. To meet the unique measurement requirements of H&P obstruction lights, Hoffman modified their core software to accommodate the algorithms that prove compliance with industry specifications.
To customize software and meet H&P requirements, optical engineers from Hoffman’s lighting lab visited the Hughey & Phillips facility in Urbana, Ohio. They noted that, at just 75 feet long, the photometric tunnel where the goniophotometer was positioned was substantially shorter than the traditional 100 foot tunnel, a factor that would negatively affect the dynamic range of the measuring detectors. The extremely high intensity levels of Hughey & Philips’ obstruction lights, combined with the abbreviated tunnel length, resulted in light levels that exceeded the measurement capability of Hoffman’s standard measurement detector.
“Since extending their tunnel length or reducing the output of their lights were not viable options for H&P, we had to find an alternative solution that maintained the high level of accuracy and the performance of the goniophotometer,” explained Ken Wagner, Hoffman’s vice president of technology. “Our solution was to install a customized attenuation filter onto the measurement detector to allow the goniophotometer system to accurately measure the extraordinarily high peak intensities of the H&P lights. By designing a removable attenuation filter, the device could be installed only when needed to test H&P’s most powerful products, and removed to test their standard obstruction lights. It was then a simple matter for Hoffman software engineers to implement the required software changes to accommodate swapping the filter in or out when needed.”
With these changes, the fully automated goniophotometer system effectively and accurately measures the entire range of Hughey & Phillips’ product line. Even at a shortened test distance of just 75 feet, the system is capable of accurately measuring extremely high intensity lights of greater than 10 million candelas or the lowest intensity lights of less than one candela.
Hoffman’s goniophotometer system has been fully operational at H&P for about three years. Both the optical engineers and production technicians at H&P operate the system without a problem and with very little training. The system delivers accurate, consistent data for both empirical testing and performance testing.
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