Characteristic Slope Values; Determination Of Unknown Slope Values; Attenuation - optris CTratio Operator's Manual

Characteristic Slope Values

The slope is the quotient of the emissivities of both of the overlapping wavelength bands. The factory default
value for the slope is 1,000. The following slopes are typical reference values. The real slope can vary
depending on the metal alloy and surface finish.
Cobalt, Iron, Nickel, Stainless steel, Steel
Cobalt, Iron (solid, molten), Molybdenum,
Nickel, Platinum, Rhodium, Stainless steel,
Steel, Tantalum, Tungsten, Wolfram

Determination of unknown Slope values

Basically you can use the same methods to determine an unknown slope as described under
► Determination of unknown Emissivities. As the CTratio is dedicated for high temperature applications,
only the first method may be practically applicable (use of a t/c or other contact probe).

Attenuation

The CTratio is able to measure the temperature of targets smaller than the field of view (FOV). If the target
size is smaller than the FOV (and thus attenuating the signal) this may cause a small inaccuracy of the
reading. The inaccuracy is dependent on the object temperature and value of attenuation. The higher the
object temperature and attenuation the higher the inaccuracy of the sensor.
40
► oxidized surfaces
► unoxidized surfaces
optris CTratio – E2013-04-A
Slope: 1,000
Slope: 1,060