Asymmetric Optical Element for TOF Camera Distance Precision
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Solution Overview
Problem
Conventional TOF cameras face challenges in achieving a precise determination of distance to objects due to the need for complex alignment and potential poor signal-to-noise ratios, especially when objects are not centrally positioned relative to the camera.
Innovation Solution
A TOF camera configuration with a radiation source, sensor elements, and an optical element that allows different sensor elements to detect electromagnetic radiation from varying solid angles, with some far-side solid angles having smaller magnitudes than others, enabling precise distance measurement even when objects are not centrally positioned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the TOF camera uses a symmetrical radiation distribution (Gaussian or Lambertian), then the radiation intensity is highest along the axis of symmetry, but the camera must be precisely aligned with the object on the axis of symmetry to achieve a good signal-to-noise ratio, increasing device complexity and alignment difficulty
Solution Approach 1:
The patent applies asymmetry by configuring the optical element with asymmetric optical surfaces that create asymmetric light distribution. This asymmetric optical design redirects light from off-axis objects onto the sensor elements, eliminating the need for precise axial alignment while maintaining measurement precision. The asymmetric surfaces are specifically designed to compensate for the symmetric radiation distribution of the light source.
Solution Approach 2:
The patent implements local quality by creating different optical paths for different regions of the field of view. The optical element is designed with region-specific optical surfaces that redirect light from specific angular ranges to corresponding sensor elements. This allows each sensor element to receive optimized light from its corresponding angular region, improving signal-to-noise ratio without requiring global alignment.
2Measurement precision
If the TOF camera aligns the object centrally in the field of view to achieve good signal-to-noise ratio, then distance measurement precision improves, but the alignment process becomes laborious and time-consuming
Solution Approach 1:
The patent implements self-service through the asymmetric optical element that automatically redirects off-axis light to the appropriate sensor elements without requiring manual alignment. The optical system self-adjusts the light paths based on the object's position, eliminating the need for laborious manual alignment procedures and reducing alignment time to nearly zero.
Solution Approach 2:
The patent applies dynamics by creating an optical system that dynamically adapts to objects at different positions. The asymmetric optical surfaces are designed to redirect light from various angular positions to the corresponding sensor elements, allowing the system to maintain optimal signal-to-noise ratio for objects anywhere in the field of view without requiring static alignment.
3Ease of manufacture
If the TOF camera uses identical solid angles for all sensor elements, then the optical design is simpler, but objects positioned away from the axis of symmetry receive insufficient radiation intensity, reducing measurement precision
Solution Approach 1:
The patent implements local quality by assigning different optical characteristics to different regions of the optical element. Each region of the optical surface is designed with specific curvature and orientation to redirect light from corresponding angular ranges to the appropriate sensor elements. This allows the system to maintain simple manufacturing processes while achieving region-optimized light distribution for improved measurement precision.
4Ease of manufacture
If the radiation source emits symmetrical radiation distribution, then the manufacturing is simpler, but objects not positioned on the axis of symmetry experience poor signal-to-noise ratio
Solution Approach 1:
The patent applies asymmetry by introducing asymmetric optical surfaces that compensate for the symmetric radiation distribution. The asymmetric optical element redirects light from off-axis objects onto the sensor elements, maintaining simple radiation source manufacturing while improving measurement precision for objects at any position. The asymmetric optical design transforms the symmetric light distribution into an asymmetric pattern that covers the entire field of view effectively.
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
This configuration improves the signal-to-noise ratio and allows for precise distance determination regardless of the object's position, enhancing the camera's ability to measure distances accurately and efficiently.
Implementation Method 1
A TOF camera is a 3D camera system that measures distances from the TOF camera to an object by the time of flight (TOF, also ToF) method
Implementation Method 2
detect the electromagnetic radiation reflected and/or scattered by the object
Implementation Method 3
detect the electromagnetic radiation reflected and/or scattered by the object
Implementation Method 4
an optical element, which is arranged for the purpose of influencing the reflected and/or scattered electromagnetic radiation in the radiation path
Data Source
AI summary
A TOF camera for determining a distance to an object comprising: a radiation source configured to emit electromagnetic radiation toward the object, radiation-sensitive sensor elements configured and arranged to detect the electromagnetic radiation reflected/scattered by the object, an optical element arranged to influence the emitted electromagnetic radiation in the radiation path of the reflected/scattered electromagnetic radiation between the object and the sensor elements, a computing unit electrically connected to the radiation source and sensor elements configured to determine a time duration required by the electromagnetic radiation from the radiation source to the object; from the object to the sensor elements; and to determine the distance between the TOF camera and the object depending on the time duration determined. The sensor elements and/or the optical element are configured such that different sensor elements detect the reflected/scattered electromagnetic radiation from different solid angles on the far side of the optical element.