VCSEL Distance Measurement with Photosensor Array
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current distance measurement technologies, such as time-of-flight (TOF) systems, face limitations in achieving high accuracy and intensity of light emission within a compact size due to the imbalance between phototransmitters and photosensors, leading to reduced measurement precision and coverage.
Innovation Solution
The proposed solution involves a distance measurement apparatus and system with multiple photosensors outnumbering phototransmitters, utilizing VCSEL projector units and CMOS/TOF photosensor units to emit and receive light, allowing for higher intensity light emission and longer focal lengths, thereby enhancing distance measurement accuracy and coverage within a limited size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of phototransmitters is increased to improve light emission coverage, then the measurement coverage is improved, but the apparatus size increases
Solution Approach 1:
The patent divides the photodetector array into multiple independent photodetectors, each capable of receiving light from different spatial directions. This segmentation allows the system to achieve wide measurement coverage without proportionally increasing the apparatus size, as each photodetector can be optimized for its specific reception angle and position.
Solution Approach 2:
The patent arranges photodetectors in a two-dimensional array configuration rather than a linear arrangement. This dimensional change enables the system to cover a wider field of view and measurement range without linearly increasing the apparatus footprint, as the 2D arrangement allows parallel light reception from multiple directions simultaneously.
2Illumination intensity
If the number of phototransmitters is increased to improve light emission intensity, then the light emission intensity is improved, but the apparatus size and complexity increase
Solution Approach 1:
The patent employs VCSELs (Vertical-Cavity Surface-Emitting Lasers) that emit light in a highly directional and concentrated manner. This local quality optimization allows each phototransmitter to achieve high emission intensity in its specific direction without requiring multiple lower-intensity sources, thereby maintaining compact apparatus size while achieving sufficient light intensity for distance measurement.
3Measurement precision
If the focal length of photosensors is increased to improve measurement accuracy, then the measurement accuracy is improved, but the apparatus size increases
Solution Approach 1:
The patent uses lens arrays with varying focal lengths arranged in a specific pattern, allowing dynamic optimization of the optical path for different measurement distances. This dynamic optical design enables the system to achieve high measurement accuracy across a wide range of distances without requiring all photosensors to have uniformly long focal lengths, thus controlling the overall apparatus size.
4Measurement precision
If more photosensors are added to improve measurement coverage and accuracy, then the measurement precision and coverage are improved, but the device complexity increases
Solution Approach 1:
The patent designs a unified photodetector array where each photodetector serves multiple functions: it acts as both a light receiver for TOF measurement and a spatial reference for depth mapping. This multi-functionality allows the system to achieve both measurement coverage and accuracy without requiring separate dedicated components, thereby controlling device complexity despite the large number of photodetectors.
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 achieves higher intensity light emission and longer focal lengths, resulting in improved distance measurement accuracy and coverage, even for distant or low-reflective objects, while maintaining a compact apparatus size.
Implementation Method 1
multiple phototransmitters configured to emit light beams to a range to be measured
Implementation Method 2
multiple photosensors each configured to receive a light beam reflected from an object within the range to be measured
Data Source
AI summary
A distance measurement apparatus includes multiple phototransmitters configured to emit light beams to a range to be measured; multiple photosensors each configured to receive a light beam reflected from an object within the range to be measured; and circuitry configured to calculate a distance to the object based on times of light emission of each of the phototransmitters and time of light reception of each of the photosensors. The photosensors outnumber the phototransmitters.