Refractive index compensation for measurements in air is easily achieved with the Environmental Module.

The Environmental Module (PS-EM) is an accessory product for the PICOSCALE. It monitors the environmental parameters such as temperature, relative humidity, and air pressure. With these data the PICOSCALE controller is able to correct the recorded displacement data for changes in the refractive index of air and thus virtual drifts of the target mirror.

Temperature Sensor

Accuracy - 0.1 °C
Resolution - 0.01 °C

Relative Humidity Sensor

Accuracy - 1.8 % RH
Resolution - 0.04 % RH

Pressure Sensor

Accuracy - 1.5 mbar
Resolution - 0.03 mbar

Overall

Δn/n - 4 x 10-7

Parameter Name	Parameter Value
Type	temperature humidity pressure
Applications	air environmental