4-26
IM AQ6376-01EN
Explanation
Conditions under Which “UNCAL” Is Displayed
“UNCAL” is displayed when a single or repeat sweep is started based on the following
relationship between span, setting resolution, and set number of samples:
Setting resolution
Span
x 5 < Set number of samples - 1
Waveforms with Resolutions of 0.1 nm
When the resolution is set to 0.1 nm for measurements of a light source such as a DFB
laser in which with the spectral width is narrower than the instrument’s resolution, very
small spikes may occur at the skirts of the waveform. This type of spike occurs due to
characteristics of the optical block and is not an indication of any problem. Even if such
spikes occur, satisfactory performance in terms of resolution, dynamic range, and the like
can be ensured. These spikes will disappear if the resolution is set to a coarser value.
Ripples in the 1800–1950, 2450–2950 nm Area
Water (OH-) ions present in the monochromator absorb light in the 1800–1950, 2450–
2950 nm area, resulting in ripples in the measurement waveform. Either set a coarser
resolution, use the monochromator in a lower-humidity environment, or execute the
purge described on section 2.3 to reduce the amount of ripples.
4.7 Wavelength (Frequency / Wavenumber) Resolution Settings