An environmentally controlled appliance enclosure includes an enclosed spacer and a heater assembly positioned within the spacer. The method is useful, for example, for assessing particle sizes and size distributions in mixtures containing both particles of the substance and other materials. A receiver filters each transmitted reference signal using that reference signal’s chip code. The system also includes a dosing portion having a dosing plate defining a dosing hole. The plane-wave responses for each feature are combined to generate a modeled pattern response. Also disclosed is a light-emitting optical component comprising such a converter material and a method for producing such components.