Time-of-Flight Distance Sensing With Sequential Photon Windows
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Solution Overview
Problem
Existing distance-measuring devices using single-photon photosensitive microcells, such as SPADs or SNSPDs, suffer from non-linear response due to dead time and saturation issues, especially in high-intensity light conditions, leading to inaccurate distance measurements and increased energy consumption.
Innovation Solution
A measuring device with a processing group that controls photosensitive microcells to perform sequential observation time windows, separating detection times for background noise and pulsed light, allowing for a linear response without the need for data storage or complex histogram processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-photon photosensitive microcells are used for distance measurement, then measurement precision is improved, but non-linear response and saturation occur in high-intensity light conditions
Solution Approach 1:
The patent applies periodic action by implementing sequential observation time windows where photosensitive microcells are activated in alternating sequences. During first time windows, only background noise is detected; during second time windows, both background noise and pulsed light are detected. This periodic activation pattern prevents saturation by ensuring cells are not continuously exposed to high-intensity light, thereby maintaining response linearity while preserving measurement precision.
2Reliability
If sequential observation time windows are implemented, then response linearity is improved, but device complexity increases
Solution Approach 1:
The patent merges the control of multiple photosensitive microcells into a unified sequential control mechanism managed by a single processing group. The control unit coordinates the activation sequences of all microcells, alternately enabling them during first and second observation time windows. This merging approach maintains response linearity through sequential operation while reducing device complexity by using a centralized control structure rather than independent control circuits for each cell.
3Reliability
If multiple photosensitive microcells are used, then measurement reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by activating multiple photosensitive microcells in alternating sequential time windows rather than continuously. During first observation time windows, only a subset of cells detects background noise; during second time windows, the same or different cells detect both background noise and pulsed light. This periodic activation pattern maintains measurement reliability through multiple cells while significantly reducing energy consumption compared to continuous operation of all cells.
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
Achieves precise distance measurements with reduced calculation and storage requirements, overcoming saturation limits and enabling accurate measurements in intense background noise conditions.
Implementation Method 1
each of which is configured to generate an electrical signal following the impact of at least a single photon on its sensitive surface
Implementation Method 2
emission means for emitting a light radiation towards a reference object
Data Source
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AI summary
A device for measuring (1) the distance (d) of a reference object (O) comprising emission means (2) for emitting a light radiation (R), receiving means (3) comprising an area (31) sensitive to said light radiation (R), said sensitive area (31) being provided with one or more photosensitive microcells (4), and a processing group (5) configured to perform said measurement by implementing a first acquisition step comprising starting a plurality (n) of consecutive observation time windows (i) while keeping said emission means (2) deactivated, a second acquisition step comprising starting a plurality (m) of consecutive observation time windows (y) by activating the emission means (2), and a step of defining the time of flight (ToF) value of the measurement based on processing the detection times acquired in the second acquisition step and the detection times (tbgi) acquired in the first acquisition step.