Patent ID: 8704152

Claim:
An apparatus comprising: a housing having a front surface, a rear surface, and at least one sidewall therebetween; a plurality of optical windows formed in the housing, each of the plurality of optical windows allowing light to pass through from multiple directions, at least some of the plurality of optical windows configured to provide a view angle of at least ninety-degrees; a plurality of photo detectors to generate electrical signals based on received light, each of the plurality of photo detectors disposed within a respective one of the plurality of optical windows; a plurality of light-emitting diodes; a second plurality of optical windows, each of the second plurality of optical windows corresponding to at least one of the plurality of light-emitting diodes; and a control circuit coupled to the plurality of photo detectors to receive the electrical signals, determine light variations from the electrical signals, and determine a change in position of an object based on variation ratios of the light variations received by at least one pair of photo detectors within the plurality of photo detectors in response to determining the light variations.