Factory and user optical channel calibrations (also known as O/E calibration) compensate for the photo detector's responsivity. Photodetectors are calibrated for fiber optic apps. For a N109X-series DCA-M modules and N1000A plug-in modules, you can use this dialog tab to perform optical calibrations at both factory and user wavelengths. This procedure involves routing a known internal reference voltage to all channels of the board. The reference voltage is then read at a. Calibration is the process of configuring a sensor to provide accurate measurements by comparing its output to a known reference standard. the process that converst raw data (e.