Optical Time-of-Flight Distance Measuring Device with Adaptive Pulse Control
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Solution Overview
Problem
Current distance measurement technologies face challenges in accurately determining distances using optical pulses, particularly in controlling pulse duration and efficiently detecting reflections, which affects the accuracy of distance measurements and 3D imaging.
Innovation Solution
An optical time-of-flight distance measuring device and method that control the duration of optical pulses based on estimated distances, using a semiconductor laser operating in enhanced gain switching regime, and a detector matrix with fewer time-to-digital converters, allowing for adaptive time-gating and improved detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the duration of optical pulses is reduced to improve distance measurement accuracy, then measurement precision is improved, but the power and energy of the optical pulses decrease
Solution Approach 1:
The patent employs periodic pulsed operation where the laser emits optical pulses at controlled intervals. By optimizing the pulse repetition frequency and duration, the system achieves high measurement precision with short pulses while maintaining adequate average power through repeated measurements and signal accumulation.
Solution Approach 2:
The patent dynamically adjusts multiple parameters including pulse duration, peak power, repetition frequency, and detector integration time to optimize the balance between measurement precision and optical power consumption. This allows adapting to different measurement scenarios and target distances.
2Device complexity
If the number of time-to-digital converters is reduced to simplify device complexity, then device complexity is reduced, but detection capability and measurement precision deteriorate
Solution Approach 1:
The patent divides the detector array into multiple zones or groups, each served by a dedicated time-to-digital converter. This segmentation allows multiple detectors to share converters through time-multiplexed operation, reducing the total number of converters while maintaining detection capability across the entire detector matrix.
Solution Approach 2:
The patent designs the time-to-digital converters to handle multiple detector elements sequentially or in parallel through configurable routing. Each converter can serve multiple detectors by switching between them, making the converters multi-functional and reducing the overall count needed in the system.
3Reliability
If optical pulses are transmitted to improve signal detection, then detection capability is improved, but background reflections and noise increase
Solution Approach 1:
The patent performs preliminary measurements and characterizations to establish baseline noise levels and background reflection patterns before actual distance measurements. This allows the system to subtract or filter out known background signals and focus on detecting the actual reflected optical pulses from targets.
Solution Approach 2:
The patent implements feedback mechanisms where the detected signal strength and quality are continuously monitored and used to adjust transmission power, pulse timing, and detector sensitivity. This adaptive feedback allows optimizing signal detection while minimizing the impact of background reflections and noise through real-time parameter adjustment.
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 approach enhances the accuracy of distance measurements and 3D imaging by controlling optical pulse duration and reducing the number of time-to-digital converters needed, improving detection speed and accuracy while minimizing noise and background reflections.
Implementation Method 1
a semiconductor laser operating in enhanced gain switching regime
Implementation Method 2
The reflections of the optical pulses generated by a laser are detected in a detector for determining timing for the detections
Implementation Method 3
optical time-of-flight distance measuring device
Data Source
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AI summary
An optical time-of-flight distance measuring device comprises a transmitter (102) and a receiver (105). The transmitter (102) comprises a semiconductor laser (200) for outputting optical pulses (110, 110') of controllably variable temporal widths. The semiconductor laser (200) operates in an enhanced switching regime for the optical pulses of a minimum generable temporal width of the laser (200). The receiver (105) comprises a matrix (300) of single photon avalanche detector elements (310 to 326) of a Geiger mode, a receiver controller (302), and one or more time-to-digital converters (330). The single photon avalanche detector elements (310 to 326) detect optical pulses reflected from the target (112) to the matrix (300), and each of the single photon avalanche detector element (310 to 326) outputs an electric signal in response to each detection. A number of the time-to-digital converters (330) is smaller than a number of the single photon avalanche detector elements (310 to 326) of the matrix (300). The receiver controller (302) connects at least two of the single photon avalanche detector elements (310 to 326) with different time-to-digital converters (330). The time-to-digital converters (330) connected with the single photon avalanche detector elements (310 to 326) provide timings of detected optical pulses on the basis of each output electrical signal for determination of information associated with a distance of the target (112).