An apparatus for determining the depolarization efficiency of a environment includes a transmitter, a receiver, and signal processing circuitry. A reference object is located within the environment at a reference distance. The transmitter includes a radiation source providing incident radiation that has an initial polarization as it enters the environment. The receiver receives returned radiation from the reference, which may be diffuse reflection or photoluminescence. The signal processing circuitry calculates the depolarization efficiency of the environment from the initial polarization, luminescence or final polarization, and the reference distance. A method of determining depolarization efficiency includes directing incident radiation having initial polarization through an environment onto a reference, detecting returned radiation from the reference, and calculating the depolarization efficiency using the initial polarization and the luminescence or final polarization.