Spatial Light Communication Ghost Image Security
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Solution Overview
Problem
Existing spatial light communication systems using phase modulation-type spatial light modulation elements suffer from ghost image leakage, which compromises security even when visibility of the ghost image is reduced.
Innovation Solution
A light transmitting device that adds a dummy signal with the same brightness as the ghost image to the spatial light signal, ensuring the dummy signal is displayed at the position of the ghost image, thereby preventing information leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a phase modulation-type spatial light modulation element is used to transmit spatial light signals, then communication efficiency is improved, but ghost images appear at rotationally symmetric positions causing information leakage
Solution Approach 1:
The invention converts the harmful ghost image into a beneficial security feature by deliberately placing dummy signals at ghost image positions. The ghost image, which originally caused information leakage, is now used as a camouflage location for dummy signals that protect the actual communication signal. The system calculates ghost image positions based on the phase modulation pattern and places dummy signals there, transforming the security vulnerability into a security mechanism.
Solution Approach 2:
The invention changes the 'brightness' or intensity distribution of the spatial light signal by adding dummy signals with specific intensities at ghost image positions. This creates a modified intensity pattern where the dummy signals match the brightness characteristics of expected ghost images, making it difficult for eavesdroppers to distinguish between real and fake signal locations.
2Object-affected harmful factors
If ghost compensation images are used to reduce ghost visibility, then ghost image visibility is reduced, but information leakage still occurs during pulse pattern detection
Solution Approach 1:
The invention performs preliminary action by pre-calculating and pre-positioning dummy signals at all possible ghost image locations before the actual communication signal is transmitted. The system determines the phase modulation pattern, calculates where ghost images will appear, and places dummy signals at those positions in advance. This preliminary placement ensures that even if eavesdroppers detect pulse patterns, they cannot determine which signals are real and which are dummy.
3Reliability
If dummy signals are added to prevent information leakage, then security is improved, but signal complexity increases
Solution Approach 1:
The invention implements self-service by using the phase modulation pattern itself to determine the placement of dummy signals. The system automatically calculates ghost image positions based on the phase modulation parameters and places dummy signals accordingly, without requiring external intervention or complex manual configuration. The phase modulation pattern serves its dual function of both encoding the communication signal and determining the security overlay pattern.
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 security in spatial light communication by making the communication signal undecodable at the ghost image position, without significantly affecting the communication signal's brightness.
Implementation Method 1
a phase modulation-type spatial light modulation element
Implementation Method 2
a light transmitter that transmits a spatial light signal including a communication signal
Data Source
AI summary
A light transmitting device that includes a light transmitter that transmits a spatial light signal including a communication signal, and a light transmission control unit that adds a dummy signal having a same brightness as a ghost image of the communication signal to the spatial light signal and controls the light transmitter in such a way that the dummy signal is displayed at a position of the ghost image.