A self-mixing interferometry sensor module includes at least two light emitters of the same type, a detector unit and an electronic processing unit. Each light emitter is operable to emit coherent electromagnetic radiation out of the sensor module and undergo self-mixing interference (SMI) caused by reflections of the emitted electromagnetic radiation from an external object outside the sensor module. The detector unit is operable to generate output signals indicative of the SMI of the light emitters, respectively. The electronic processing unit is operable to generate a difference signal from the output signals indicative of a movement of the external object.

Disclosed are various systems and methods of using interferometry to measure the tear film for disease prediction and treatment. A point-by-point scan of a corneal surface of an eye is obtained from an interferometry system, including at least an interference signal. Next, a large field-of-view of the corneal surface is obtained from an objective lens with a curved focal plane matched to a curvature of the corneal surface. Subsequently, motion correction is performed on the point-by-point scan. Then, noise is filtered from the interference signal. A tear film lipid layer signal and a precorneal tear film signal are separated from the filtered interference signal. Later, a best fit frequency for the tear film lipid layer signal and the precorneal tear film signal are determined. Then, a thickness of the tear film lipid layer and the precorneal tear film are determined based at least in part on the best fit frequency.