Proven Condition Monitoring Solutions

Optical Pick-up Information

The Optical Pick-Up unit is designed to be temporarily fitted for aircraft testing purposes.  It is used to produce a speed reference signal from a rotating component for timing and indexing purposes. OPU’s have an operating range of up to 2 meters and can be used to simplify installation when the use of an MPU is not practical or safe. Helitune OPU’s have been specifically designed for aircraft installations and are ideally suited for use on helicopter tail rotors and high speed transmission shafts.

The Optical Pick-Up unit works by transmitting a beam of infra red light, which is reflected back to the unit by the passing of a target of reflective tape or paint attached to the rotating component. An electrical pulse is produced each time the target comes into view and the red LED indicator illuminates on the OPU body. This signal is used to generate a speed output and a timing reference for balance data, vibration signatures and tracking information.

Technical Specification
Sensing Speed Range
Sensing Distance
Timing resolution
Operating Temperature Range

3 to 50,000 rpm (subject to min.
target passing period of 50μs)
20 to 1000 mm for reflective tape with
25x25 mm target 75 to 200 mm for
reflective paint  with 25x25 mm target
0.25º (<6000 rpm), 7µs (<6000 rpm),
@ 120 mm with reflective paint
38,000 hours
-40º C to +70º C
Red lamp in presence of target

Electrical Specification

Electrical Interface
Power Supply

MIL-DTL-26482 (Example mating connector: 62GB-51T08-04S)
One TTL compatible output. (Max sink/source current 10mA)
+10 to +30V DC, at 100mA max.
Reverse polarity protection
10M ohm @ 100V (case to electronics)

Physical Specification
Helitune Part Number

56mm (Including stud) x 48 mm
(excluding mating connector) x 25 mm
83 grams, including 2 locking nuts
16 mm long stud concentric with
the sensing elements with 5/8 UNF thread
DIN 40 050 IP65

  • OPU Data Sheet

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    Download OPU Data Sheet

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