Today the US Patent & Trademark Office published a patent application from Apple that relates to the field of digital image capture, and more particularly to the field of three dimensional (3D) image capturing. In the big picture, the patent is related to the technology used for Apple's TrueDepth camera using a dot projector instead of traditional laser beams to determine 3D imagery which is power hungry and not suitable for devices like the iPhone.

Apple notes that one type of non-contacting technology involves using a structured-light source to capture 3D images. Structured-light sources project a known pattern of light (e.g., a stripe pattern) onto the surfaces of a physical object to detect for deformations in the pattern. One or more cameras capture the pattern deformities as the structured-light is illuminated onto the physical object. Using the captured pattern deformities, an image capturing system is able to calculate the depth and surface information within the field of view of the camera.

Unfortunately, the structured-light sources are often laser-based light sources that typically are expense and power hungry components, and thus, prevent the implementation of 3D image capturing systems as electronic devices that have relatively limited computational and power resources, such as mobile devices.

Apple's solution to the problem presented above is their invention that provides a method to resolve 3D spatial information for a plurality of image capturing systems.

The method includes obtaining communication synchronization between a first image capture system and one or more additional image capture systems prior to image capturing events. After synchronization, the method then enters an image capturing phase that involves generating a first flash pulse that projects a light pattern into an environment at a first time and captures a first image of the environment that includes the light pattern as deformed by the environment.

The first flash pulse may be modulated to encode an identifier of the first image capture system and potentially, other camera information. A second flash from one of the other image capture systems flashes at a second time based on the communication synchronization, where the second flash encodes an identifier of the second image capture system and potentially, other camera information related to the second image capturing system.

During the second flash, the first image capture system captures a second image of the environment. Based on the information captured in the first and second images including the identifier and camera information, the first image capture system determines the orientation of the second image capture system relative to the first image capture system.

Apple's patent FIG. 3A below is a schematic diagram of an embodiment of a multi-camera system; FIG. 3B shows, in block diagram form, the multi-camera system determining relative location and orientation of each of the cameras.

More specifically, we're able to see in patent FIG. 3A, a multi-camera system #300 comprises a plurality of cameras #302 that capture a scene #306. While the patent dramatizes the cameras as being two individual standalone cameras, it's really describing Apple's Dual Lens TrueDepth Camera.

The scene may comprise one or more physical objects that are located within at least a part of the field of view for each of the cameras. Additionally, each of the cameras may include an independent structured-light source #308 adapted to project a pre-determined light pattern (e.g., a 2D array of dots or pattern of lines) into scene #306. This would be describing what Apple now calls the 'dot projector.'

The structured-light source may include one or more optical flash components that discharge light to project the pre-determined light pattern and illuminate the scene. In one embodiment, the structured-light source generates a flash using high-current, low voltage light emitting diodes (LEDs).

Other embodiments may use other types of flash devices, such as xenon-based flash devices or one or more laser elements, such as vertical cavity surface emitting lasers (VCSEL) in single element or array form projected through an optical lens system, to illuminate the scene.

One of Apple's Vertical Cavity Surface Emitting Laser (VCSEL) suppliers is IQE and another being Lumentum.

Apple's patent application 20170324949 was filed back in Q2 2016.

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