Loop Powered Distance Transmitter With Single Photon Detection
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Solution Overview
Problem
Conventional loop powered distance transmitters face challenges due to power constraints and flange opening limitations, which restrict their performance in industrial process control systems.
Innovation Solution
A loop powered distance transmitter that operates on a two-wire 4-20 mA circuit, utilizing a laser emitter and single photon detector to determine target distance by measuring the travel time of laser pulses, with power management and lens configurations to optimize performance within power and size constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electronic devices are used in loop powered circuits, then the device can be powered by the circuit, but the device cannot achieve high performance due to power constraints
Solution Approach 1:
The patent transforms the electrical power constraint into an optical energy solution by using a laser emitter that consumes minimal electrical power (less than 100 microwatts) while delivering sufficient optical energy for distance measurement. The system changes from electrical signal processing to optical time-of-flight measurement, fundamentally altering the energy parameter from electrical to optical domain.
Solution Approach 2:
The patent replaces conventional electrical sensing mechanisms with optical-based time-of-flight measurement. Instead of using electrical signals that are constrained by loop power availability, the system uses laser light pulses and single-photon detectors to measure distance, substituting electrical field interactions with optical field interactions that are not limited by the same power constraints.
2Area of stationary object
If the flange opening size is reduced, then the device size is minimized for compact installation, but light detection performance deteriorates
Solution Approach 1:
The patent employs highly sensitive single-photon detector technology that can detect individual photons, effectively creating a 'thin film' of detection capability that requires minimal aperture area. This detector technology allows the system to maintain high measurement precision even with a reduced 2-inch flange opening, as the single-photon sensitivity compensates for the limited light-gathering area.
Solution Approach 2:
The system combines a laser emitter with a single-photon detector in a integrated sensor head, creating a composite measurement system that achieves high precision with minimal aperture. The combination of coherent light source and ultra-sensitive detector creates a synergistic effect that overcomes the geometric limitations of a small flange opening.
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
The solution enables high-performance distance measurement with reduced power consumption and improved light detection, overcoming traditional limitations to provide accurate and efficient distance sensing in industrial settings.
Implementation Method 1
The sensor includes a laser emitter and a light detector. The laser emitter outputs pulses of laser light that contact a target and are reflected back to the sensor.
Implementation Method 2
The light detector receives at least some of the reflected light. The sensor determines the time that the laser pulses take to travel between the laser emitter/light detector and the target
Implementation Method 3
The sensor may also be provided with a lens body with a lens for the light detector and a lens for the laser emitter
Data Source
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AI summary
A distance transmitter for industrial process control systems is provided. The distance transmitter has a laser emitter that outputs laser pulses that strike a target. The laser pulses are reflected back by the target and are received by a light detector. The distance of the target from the sensor is determined by the time it takes for the laser pulses to return to the light detector. The distance transmitter may be mounted to an industrial structure with a flange. The laser emitter and light detector may output and receive laser light through an opening in the flange.