Miniaturized ToF Phase Calibration Cover for Crosstalk-Free Setup
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Solution Overview
Problem
Existing time-of-flight (ToF) camera calibration systems are bulky and require large physical spaces due to stray light interference, making it challenging to calibrate multiple modules in parallel without crosstalk, and they struggle with accurate phase offset calibration across pixels.
Innovation Solution
A miniaturized phase calibration apparatus that encloses the ToF module with a geometry ensuring equal time-of-flight for reflected signals, using elliptical or spherical covers to prevent stray light and allow multiple modules to be calibrated in a tight space without crosstalk, and employs optical attenuators and waveguides to maintain signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional ToF camera calibration system is used, then calibration can be performed, but the system becomes bulky and requires large physical spaces due to stray light interference
Solution Approach 1:
The calibration system is segmented into separate functional components: multiple ToF modules are independently enclosed in separate housings, each with its own light source and pixel array. This segmentation allows compact arrangement while maintaining calibration functionality, as each module can be calibrated independently or in parallel without requiring a single large shared space.
Solution Approach 2:
The harmful stray light is extracted and isolated from the calibration process by enclosing each ToF module in its own housing with internal reflectors. The reflectors are designed to contain and redirect light within each module's housing, preventing stray light from escaping into the shared calibration space. This extraction of the stray light problem allows multiple modules to be positioned closely together without interference.
2Productivity
If multiple ToF modules are calibrated in parallel in a tight space, then calibration efficiency increases, but crosstalk occurs between modules
Solution Approach 1:
The system segments the calibration process into independent channels by providing each ToF module with its own dedicated light source and enclosing housing. This segmentation prevents crosstalk between modules during parallel calibration, as light from one module cannot escape to be detected by another module's pixel array.
Solution Approach 2:
The reflector acts as an intermediary element within each housing that mediates the light path between the light source and pixel array. The reflector is positioned and shaped to ensure that light reflected from the reflector returns to the pixel array with a substantially equal time-of-flight, while also preventing light from escaping the housing. This intermediary structure enables reliable parallel calibration by isolating each module's optical path.
3Measurement precision
If the geometry of the calibration device is optimized for equal time-of-flight, then phase calibration accuracy improves, but the device complexity increases
Solution Approach 1:
The reflector is designed with a curved surface (spherical or elliptical geometry) positioned at a specific distance from the pixel array. This curved geometry naturally ensures that light rays traveling different paths from the light source to the reflector and back to the pixel array have substantially equal time-of-flight. The curvature compensates for path length differences, providing accurate phase calibration without requiring complex active control mechanisms.
Solution Approach 2:
The reflector is positioned at a distance from the pixel array that is less than the distance from the light source to the pixel array. This creates an equipotential condition where the total optical path length (light source to reflector to pixel array) is substantially equal for all reflected light rays. This geometric arrangement ensures uniform time-of-flight across the pixel array, enabling accurate phase offset calibration.
4Reliability
If optical attenuators and waveguides are added to maintain signal integrity, then signal quality improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Optical attenuators are positioned at specific locations within the housing, such as near the light source or in the light path, to provide localized signal control. Waveguides are implemented only where needed to guide light from the light source to the pixel array through the housing. This localized implementation of optical control elements maintains signal integrity without requiring complex systems throughout the entire apparatus, thereby reducing manufacturing complexity.
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
Enables accurate phase offset calibration of multiple ToF modules in a compact setup, reducing errors in phase calibration and preventing stray light interference, allowing simultaneous calibration without module interference.
Implementation Method 1
a reflector configured to reflect at least some of the plurality of light signals
Implementation Method 2
a waveguide configured to guide the at least some of the plurality of light signals from the light source to the pixel array
Data Source
AI summary
Systems and apparatus for phase calibration in time-of-flight cameras. In particular, systems and methods are presented for a miniaturized cover design that at least partially encloses the time-of-flight (ToF) module. The geometry of the miniaturized design causes the signals reflected from the calibration device back to the ToF imager to have essentially the same time-of-flight. The design of the calibration device prevents the modulated emissions from leaking out to the environment.