Active Optical Target Detector Polarization Analysis
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Solution Overview
Problem
Current active optical target detectors (AOTDs) suffer from low signal noise ratio (SNR) due to noise caused by solar energy, affecting range, sensitivity, and size, particularly in missile applications.
Innovation Solution
The system polarizes the transmitted laser beam and uses an analyzer and detector to select the polarized component of the return beam, with optional Faraday rotators or electro-optic modulators to compensate for polarization rotation or ellipticity, allowing for maximum transmittance and adaptability to any input polarization state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current active optical target detectors are used, then target detection function is provided, but signal noise ratio is low due to solar energy interference
Solution Approach 1:
The patent changes the polarization parameter of the transmitted laser beam and configures the analyzer to detect specific polarization states of the return beam. This parameter change allows the system to distinguish the polarized return signal from unpolarized solar interference, significantly improving the signal noise ratio in sunny environments.
Solution Approach 2:
The patent introduces polarization analysis as an intermediary mechanism between the return beam and the detector. The analyzer acts as a mediator that selectively transmits the polarized return signal while blocking unpolarized solar noise, thereby improving reliability without directly modifying the detector itself.
2Reliability
If polarization analysis is added to improve SNR, then detection reliability improves, but device complexity increases
Solution Approach 1:
The patent designs the analyzer to work with standard laser transmitters and detectors, making the polarization enhancement approach universally applicable to existing AOTD systems. The analyzer component itself is a relatively simple optical element that can be integrated without requiring complete system redesign, thus improving reliability with minimal complexity increase.
3Adaptability or versatility
If Faraday rotator or electro-optic modulator is added to compensate polarization changes, then adaptability to different polarization states improves, but device complexity and cost increase
Solution Approach 1:
The patent employs dynamic polarization compensation using Faraday rotators or electro-optic modulators that can adjust their polarization rotation in real-time. This dynamic capability allows the system to adapt to various return beam polarization states caused by different target surfaces, significantly improving versatility. The compensators are positioned in the optical path between transmitter and receiver to actively track and correct polarization changes.
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 SNR, improving detection accuracy and reliability by filtering out unpolarized and orthogonal light sources, effectively addressing the limitations of existing AOTDs in noisy environments.
Implementation Method 1
the transmitted beam is polarized and the inventive receiver includes an analyzer and a detector coupled to the output of the analyzer. The analyzer selects a polarized component of a return beam for input to the detector
Implementation Method 2
the arrangement for compensating for the rotation of the orientation of linear polarization in the returned beam includes a Faraday rotator positioned between the transmitter and the receiver
Implementation Method 3
the arrangement for compensating for ellipticity in the polarization state of the returned beam includes an electro-optic modulator positioned between the transmitter and the receiver
Data Source
AI summary
A receiver including an analyzer and a detector coupled to the output of the analyzer. The analyzer selects a polarized component of a return beam for input to the detector. The analyzer may be linear, circular or elliptical. Coupled with a laser adapted to output a polarized beam, the receiver provides an active optical target detector. An arrangement may be included for compensating for rotation and ellipticity in the returned beam. In one embodiment, the arrangement for compensating for rotation of the orientation of linear polarization in the returned beam includes a Faraday rotator positioned between the transmitter and the analyzer. An arrangement is disclosed for varying the rotation in the returned beam using a Faraday rotator until a maximum transmittance is achieved. In an alternative embodiment, the arrangement for compensating for ellipticity in the returned beam includes an electro-optical modulator positioned between the transmitter and the analyzer. In another alternative embodiment, two electro-optical modulators are included to compensate for any change in the polarization state in the returned beam.