Displacement Measurement - Non Contact - Fibreoptic

Model D171

(Philtec)

Applications:

Displacement Measurement - Non Contact - Fibreoptic

• Ø 4.35 mm Target Spot Size (0.171 inch)

• 50 mm Total Operating Range (2 inch)

• 0.3 mv/µm Far Side Sensitivity (7 mv/mil)

• 0.9 mv/µm Near Side Sensitivity (22 mv/mil)

These are reflective type transducers based upon detecting the intensity of reflected light. With D Model sensors, the output signal is proportional to: a) the gap distance from the sensor tip-to-target; and, b) the reflectivity of the target surface. D models are commonly used in applications where the target reflectivity stays constant, i.e., the target has a reciprocating or vibratory motion parallel to the axis of the sensor. Calibration charts are provided with each sensor tip giving the near and far side voltage output responses to distance. There are three ways to derive accurate distance measurements:

a) within the bounds of the linear range, multiply sensitivity by the change in voltage output

b) create a lookup table using the XY calibration data points

c) use a polynomial curve fit to accurately map the sensor’s output function

The effect of changing target reflectance is to shift the voltage output higher or lower. A gain control is provided for calibration of the sensor output to various target surfaces. Insitu calibration is performed simply, by adjusting the sensor’s tip-to-target gap until the peak output is attained, and then by using the gain control to set the peak voltage reading to full scale. This allows the sensor to be used to perform precision linear motion measurements on most materials.