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Definition of Terms
Range refers to the allowable wavelength range of the optical input signal.
Wavelength
Absolute accuracy indicates the maximum wavelength error over the allowed
environmental conditions. The wavelength accuracy is based on fundamental
physical constants, which are absolute standards not requiring traceability to
artifacts kept at national standards laboratories. Two He-Ne gas lasers are
used. First, there is an internal 632.991 nm-vacuum (473.6127 THz) reference
laser
during manufacturing at 1523.488 nm, or 196.7804 THz
Differential Accuracy indicates the maximum wavelength error in measuring
the wavelength difference between two signals that are simultaneously
present.
Minimum Resolvable Separation indicates the minimum wavelength separa-
tion of two laser lines required to measure each wavelength simultaneously.
Two laser lines closer in wavelength than the minimum resolvable separation
are not resolved and one average wavelength is displayed.
Display Resolution indicates the minimum incremental change in displayed
wavelength.
Calibration Accuracy indicates the maximum power calibration error at the
Amplitude
specified wavelengths over the allowed environmental conditions. The ampli-
tude calibration accuracy is traceable to a National Institute of Standards and
Technology (NIST) calibrated optical power meter. NIST is the national stan-
dards laboratory of the United States.
Flatness refers to the maximum amplitude error in a measurement between
two lines that are separated in wavelength by no more than the specified
amount.
Linearity indicates the maximum power error in measuring the change in power
1. Obarski, G. E. 1990. "Wavelength Measurement System for Optical Fiber Communications" NIST
Technical Note 1336 (February): 18. Take the average of the two frequencies straddling gain center.
2. D. A. Jennings, F. R. Peterson, and K. M. Evenson. 1979. "Frequency measurement of the 260-THz
(1.15 micron) He-Ne laser" Optics Letters Vol. 4, No. 5 (May): 129-130.
1
. To verify absolute wavelength accuracy, an external laser is measured
Specifications and Regulatory Information
Definition of Terms
2
.
6-3
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