Characterizing a light dependent resistor (LDR) response to a laser diode using Malus' Law

Abstract

We propose a new technique to measure the non-linear response of a light dependent resistor (LDR) to a laser diode. We model the LDR resistance R versus the laser's intensity I as a power law model: R = aI^β. To determine β and $\alpha$, a parameter related to a, we configure the LDR and another variable resistor into a voltage divider circuit and obtain voltage measurements as we vary the light intensity via cross-polarizers. We obtain the best estimates for α = 13.271 and β = −0.924, confirming the non-linear response of the LDR. We compare these values to the calibration constants from the direct resistance measurement of the LDR, and discuss the advantages of our proposed technique.