Optical Shutter for Modulated Signal Detection
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Solution Overview
Problem
Existing beacon systems that utilize modulated optical signals require broadband or high-speed detector devices for demodulation, making them unsuitable for detection by low-frequency sensors or viewers, and lack the ability to selectively enable content visibility for specific detectors or viewers.
Innovation Solution
The method involves shifting high-speed modulated optical signals to a lower frequency band using a secondary modulator, such as an optical shutter, allowing detection by low-frequency detectors like the human eye or low-frame-rate cameras, creating a favorable aliasing situation that enables detection of seemingly constant light sources by low-frequency detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If broadband high-speed detector devices are used to detect modulated optical signals, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an optical shutter as an intermediary device between the modulated optical source and the detector. The shutter modulates the optical signal at a frequency that creates a favorable aliasing effect, transforming the high-frequency modulated signal into a lower frequency signal that can be detected by simple low-frequency detectors, thereby eliminating the need for complex broadband high-speed detectors
Solution Approach 2:
The patent replaces the electronic demodulation system (mixer and low-pass filter) with an optical modulation approach using an optical shutter. This substitution transfers the demodulation function from the electronic domain to the optical domain, allowing simple detectors to capture the aliased signal directly without requiring complex electronic processing
2Productivity
If high-speed modulated optical signals are transmitted, then communication bandwidth is improved, but compatibility with low-frequency detectors deteriorates
Solution Approach 1:
The patent employs periodic action by using an optical shutter that opens and closes at specific frequencies to create aliasing effects. The shutter's periodic modulation transforms the high-frequency optical signal into a lower frequency signal that appears as a baseband signal to low-frequency detectors, enabling compatibility while maintaining the original high-bandwidth communication capability
Solution Approach 2:
The patent changes the frequency parameter of the optical signal through the aliasing effect created by the optical shutter. By adjusting the shutter frequency to be close to the optical signal frequency, the system transforms the high-frequency signal into a lower frequency aliased signal, allowing the same optical source to be detected by both high-speed and low-frequency detectors
3Productivity
If optical signals are modulated at high frequency, then signal transmission efficiency is improved, but detectability by human eye or low-frame-rate cameras deteriorates
Solution Approach 1:
The optical shutter serves as a mediator that bridges the gap between high-frequency optical signals and low-frequency human vision or camera detection. By introducing the shutter's periodic transmission blocks, it creates an aliased signal that appears at a frequency visible to the human eye or detectable by low-frame-rate cameras, while the underlying high-frequency communication signal remains intact
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 enables the detection of modulated optical signals by low-frequency detectors without the need for high-speed electronics, allowing for selective visibility of supplemental content and enhanced viewing experiences, while maintaining secrecy from other viewers or detectors.
Implementation Method 1
The effect of oscillating the optical shutter between the beacon and the detector is to create a favorable aliasing situation so that the beacon can easily be observed by a low-frequency detector. When the shutter frequency is close to the beacon frequency, the alias frequency of the beacon as observed through the shutter is the difference of the frequency of the beacon and that of the shutter.
Data Source
AI summary
Methods and apparatuses for enabling detection of a modulated optical source involve one or more modulated optical signals shifted, i.e., demodulated optically, to one or more base band signals that are detectable by one or more low-frequency detectors.