OTD News
Wire Contrast Measurement Standards
Wire contrast, the contrast of marked characters on wires, has been a critical issue for the military and aircraft
industry since the UV-laser marking technology was introduced a decade ago. Accurate measurement of wire contrast is
critical for accepting wires used in military and commercial jets. Wires having contrast values of 60% or higher are
recommended by the industrial standard (SAE ARP 5607). While many of the laser-marked wires are near this borderline,
it is noted that the 10% to 20% variations of measurement results (in different laboratories or with different
instruments) are too large. The Navy and a committee on Wire and Cables in the Society Automotive Engineers (SAE AE-8D)
raised this issue. Until recently, neither national standards nor independent calibration facilities have been available
to investigate the measurement problems for wire contrast. PL's Optical Technology Division has developed a reference
instrument for measuring wire contrast. From characterizations of the instrument and corrections applied, the uncertainty
of measurement is determined to be within 2% (expanded uncertainty with k=2) for wires in typical range of color and
size. A new NIST calibration service is being established for reference standard wires and for contrast measuring
instruments.
Reference instrument for measuring wire contrast
|
|
Typical wires with Laser Markings
|
|
