Systems and methods are presented that use light sensors and computing devices to compute the depth of an object using shuttered light pulses. In one embodiment, depth is determined as follows: A light emitter emits a pulse of light that is directed toward an object. The pulse is reflected off the object and travels toward a beam splitter. The beam splitter splits the reflected pulse into multiple pulses, with each pulse directed to a shuttered sensor with a different shutter location. The shuttered sensors measure the integrated intensity of the light, and these values are used to determine the depth of the object. A method is presented which calibrates a system that has an arbitrary number of shutters and enables the system to determine the depth of an object, even in the presence of ambient illumination and scattered light.
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from the following U.S. provisional patent application, which is hereby incorporated by reference: Ser. No. 60/510,198, filed on Oct. 9, 2003, entitled "Enhanced Shape Recovery with Shuttered Pulses of Light."
A rangefinding device and a method for determining the range of an object from a rangefinding device are provided. A train of light pulses each having an emission time and a pulse duration is generated. The pulse duration is set to twice the round-trip time to a maximum range of the device. The light pulses are reflected back toward the device by the object and detected according to three time intervals, respectively determined by a background gate, a ranging gate and a pulse energy gate. The light energy received during each interval is integrated and the integrated light value corresponding to the ranging gate is normalized using the values from the other two intervals. The range of the object is determined from the normalized ranging measurement and calibration data.
