3D Depth Imaging With Single-Photon Pattern Detection
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Solution Overview
Problem
Existing depth imaging systems face challenges in achieving high-speed scanning and sufficient illumination in strong ambient light conditions, particularly in outdoor environments, with current technologies being limited by sensor framerate and requiring excessive optical power.
Innovation Solution
A method and system utilizing a projector to project a light pattern onto a field of view within a short time window, synchronized with a camera sensor to detect single photons, and employing a binary logic status for pixels to isolate the projected pattern from ambient noise, enabling high-speed depth profiling with minimal optical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-speed imaging system is used to monitor distortions of the projected line, then the depth profile can be determined at high speed, but the sensor framerate becomes the limiting factor for scanning speed
Solution Approach 1:
The patent applies periodic action by using a pulsed laser source that projects light patterns at specific time intervals rather than continuously. The laser is pulsed at a frequency synchronized with the sensor exposure, allowing the system to accumulate photons from multiple pulses during a single exposure window. This periodic illumination enables high-speed scanning without being limited by the sensor's continuous framerate, as the effective scanning speed is determined by the pulse frequency and accumulation window rather than the sensor's frame rate.
2Measurement precision
If the exposure time is extended to accumulate sufficient photons, then the signal-to-noise ratio improves, but the system speed decreases
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the laser pulsing with the sensor exposure timing. The system prepares the sensor to be sensitive during specific time windows that coincide with the expected arrival of reflected photons from the pulsed laser. This timing synchronization allows the sensor to accumulate photons efficiently during the exposure window without requiring extended exposure times, thereby maintaining both high speed and good signal-to-noise ratio through optimized temporal coordination rather than simply extending exposure duration.
3Adaptability or versatility
If conventional sensors are used to image the projected line, then the system can operate in various lighting conditions, but sufficient illumination power is required to overcome ambient light noise
Solution Approach 1:
The patent applies the blessing in disguise principle by using the ambient light not as a harmful factor to be overcome, but as a temporal reference. The system measures the ambient light level during a first time window and then uses this information to subtract the ambient light contribution from the total signal measured during a second time window that includes both ambient light and the reflected laser signal. This approach converts the harmful ambient light noise into a useful reference measurement, enabling the system to operate in bright ambient conditions without requiring excessive illumination power to overcome the noise.
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 high-speed depth imaging with improved depth resolution and reduced optical power consumption, even in ambient light, by using single-photon detectors and coincidence imaging to filter out ambient noise, allowing for efficient depth profiling in complex lighting conditions.
Implementation Method 1
synchronized with the projection of the pattern during at least one observation window within said time window, said camera sensor comprising a matrix of pixels (1), each comprising a photodetector
Data Source
AI summary
Depth imaging system implementing the method of any of the previous claims comprising:a. an imaging device (4) comprising a matrix of pixels (1) each pixel comprising a photodetector (9) capable of detecting single photons impinging thereon and optics able to make an image of the field of view on the matrix of pixel (1), said single photon detector having a binary logic status of true when a photon is detected and a logic status of false when no photon is detected in a timeframe;b. a projector (5) able to project a pattern in a time window of less than 10 μsec, preferably less than 1 μsec;c. a controller synchronizing the projector (5) time window and the imaging device timeframe;d. a logic determining, in use, the presence, during the timeframe, of contiguous pixels (11) in the true state, and calculating the depth profile corresponding to said contiguous pixels (11).