Surface-Emitting Laser Array Illumination for TOF Depth Cameras
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Solution Overview
Problem
Time-of-flight (TOF) depth cameras face challenges in uniformly illuminating large, non-circular image environments with a desired intensity profile, leading to inefficient light usage and potential waste, as existing methods struggle to control the light distribution and cross-sectional shape of illumination.
Innovation Solution
A TOF depth camera system utilizing a plurality of surface-emitting lasers configured to generate coherent light, paired with an optical assembly that shapes and transmits the light to match the image environment's shape, and optionally a homogenizing light guide to adjust the light source's apparent size and distribution, ensuring uniform illumination across the environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-order optics are used to shape diverging light from side-emitting light sources, then the light distribution can be controlled to fill the image environment, but the design and manufacturing precision requirements become extremely high
Solution Approach 1:
The patent changes the fundamental parameters of the light source by using surface-emitting lasers that emit light in a specific directional pattern (e.g., conical emission) rather than omnidirectional side-emitting sources. This parameter change in emission geometry allows the use of simpler optical elements while achieving the desired illumination distribution across the image environment.
Solution Approach 2:
The patent employs an array of multiple surface-emitting laser elements arranged in specific geometric configurations. By segmenting the light source into multiple controllable elements, the system can shape the overall illumination pattern through the collective behavior of individual lasers, reducing the complexity requirements for each optical element while maintaining precise light distribution control.
2Area of stationary object
If conventional light sources are used to illuminate large volume image environments, then the image environment can be filled with light, but the cross-sectional shape control and intensity profile uniformity become difficult to achieve
Solution Approach 1:
The patent utilizes the asymmetric emission characteristics of surface-emitting lasers (such as conical emission patterns with specific half-angles) to match the geometric requirements of the image environment. By aligning the asymmetric light emission with the asymmetric shape of the detection volume, the system achieves uniform intensity distribution across the entire illuminated area without requiring complex corrective optics.
Solution Approach 2:
The patent transitions from considering only two-dimensional light distribution to utilizing three-dimensional emission patterns from surface-emitting lasers. The conical emission geometry provides control in multiple spatial dimensions simultaneously, enabling uniform illumination of large volume environments with complex cross-sectional shapes by adding the depth dimension to the illumination control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reshapes the illumination light to match the image environment's shape and intensity requirements, enhancing light utilization and reducing waste by providing a consistent illumination profile, which improves the accuracy of depth information capture.
Implementation Method 1
a light source including a plurality of surface-emitting lasers configured to generate coherent light
Implementation Method 2
an optical assembly configured to transmit light from the plurality of surface-emitting lasers to the image environment
Implementation Method 3
an image sensor configured to detect at least a portion of return light reflected from the image environment
Data Source
AI summary
Various embodiments of TOF depth cameras and methods for illuminating image environments with illumination light are provided herein. In one example, a TOF depth camera configured to collect image data from an image environment illuminated by illumination light includes a light source including a plurality of surface-emitting lasers configured to generate coherent light. The example TOF camera also includes an optical assembly configured to transmit light from the plurality of surface-emitting lasers to the image environment and an image sensor configured to detect at least a portion of return light reflected from the image environment.