An optical detector is provided with multiple light sources having distinct spectral characteristics, which are controlled on/off across a range of lighting intensity combinations. A measurement sensor receives radiated light that is reflected from a target surface via confined optical channels, and generates representative output signals. A local controller or a remote computing device receives the output signals or corresponding messages from the optical detector, and generates a low resolution spectral data set based on the signals for each of the lighting intensity combinations. The low resolution spectral data set is interpolated based on machine learning algorithms trained with high resolution data from a reference device to generate a high resolution spectral data set associated with the target surface. In an embodiment, an auxiliary sensor measures light reflected from one or more light sources, wherein output signals from the measurement sensor are normalized to output values from the auxiliary sensor.