Macroscopic Interferometry with Swept-Frequency, Shuttered CMOS Sensors

Applications

The method of frequency depth sensing has a range of applications in industrial environments where 3D cameras are employed, such as automobile development and manufacturing. The technology has further applications in consumer grade technologies such as mobile devices, as well as a range of potential military and defense applications. In general, any context involving machine vision or human-computer interaction would be a potential area of application for this technology.

Problem Addressed

Current time-of-flight camera technologies used to calculate distance and object depth by way of shuttered CMOS sensors make use of a technique called delayed phase sampling. This method makes use of a modulated light source to illuminate the desired scene and extracts the shifts in phase from the returning optical signals to calculate distance. While this method has been used successfully in the past, it suffers from three technologically based issues that impede its usefulness, phase-wrapping, multi-path interference, and inaccuracies when signal-to-noise ratio is low.

Technology

The technology employs an alternate electronic technique for estimating distance and object depth using shuttered CMOS sensors, intended to overcome some practical and technological limitations which affect current technologies and methodologies. Existing systems make use of a method called phase sampling, involving the analysis of phase shifts exhibited by optical signals from a light source. While this is a generally viable method it is prone to three major issues that can affect estimation, phase wrapping, multi-path interference, and accuracy issues in situations with low signal-to-noise ratios. The invention avoids these problems by employing tone and frequency sampling from the dual frequency of a signal, facilitated by an amplitude-modulated light source and measures of incident light recorded on individual pixels.

Advantages

  • Avoids technological issues experienced by prior methods
  • Makes use of similar hardware to existing methods