Biprism Laser Countermeasure for Missile Tracking
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Solution Overview
Problem
Current counter-measure devices for infrared homing-head missiles are cumbersome, pose a fire risk, compromise stealth, and have limited effectiveness due to the use of pyrotechnic decoys and discharge lamp-based jammers, which are bulky and inefficient.
Innovation Solution
A compact counter-measure and tracking device using a biprism orientation head with prisms made of different materials to render coherent laser beams non-coherent, eliminating interference and allowing for precise tracking and jamming with a single, high-intensity laser source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnic decoy devices are used for counter-measures, then the aircraft is protected from infrared homing-head missiles, but the device becomes cumbersome, creates fire risk, compromises stealth, and requires regular replacement
Solution Approach 1:
The patent replaces mechanical pyrotechnic decoy devices with an optical-based DIRCM system using infrared laser sources and optical components (beam splitter, steering mirrors, focus lenses) to deliver counter-measures electronically, eliminating the need for physical decoy cartridges and their associated handling, storage, and replacement complexities
Solution Approach 2:
The DIRCM system integrates multiple functions into a single device: missile detection through infrared sensors, tracking through optical tracking mechanisms, and counter-measure delivery through the infrared laser source, replacing multiple separate systems (detection, tracking, and counter-measure devices) with one unified platform
2Reliability
If discharge lamp-based infrared illumination jammers are used, then counter-measure capability is provided, but the optical devices become bulky and heavy
Solution Approach 1:
The patent transitions from discharge lamp-based illumination sources to infrared laser sources, fundamentally changing the optical parameter of light generation. Laser sources produce highly directional, coherent beams with much lower divergence, enabling compact optical paths and eliminating the need for large, heavy optical components required by discharge lamps
Solution Approach 2:
The optical path is segmented and redirected using a beam splitter and steering mirrors, allowing the infrared laser beam to be delivered through a compact, folded optical path rather than requiring a straight-line path that would demand large optical components and increase overall device size
3Device complexity
If a single laser source is used for both tracking and jamming, then device compactness is improved, but beam coherence causes interference
Solution Approach 1:
The patent extracts the coherent portion of the laser beam for tracking purposes while directing the remaining incoherent or less coherent portion for jamming. The beam splitter divides the laser beam into two separate paths: one for tracking (utilizing coherence for precision) and one for jamming (where coherence is less critical or deliberately degraded to avoid interference)
Solution Approach 2:
Different portions of the laser beam are assigned different quality characteristics: the tracking beam maintains high coherence for precise target acquisition, while the jamming beam is intentionally made less coherent or incoherent to prevent interference patterns, with each beam path optimized for its specific function
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 device is highly compact, resistant to vibrations, and provides effective tracking and jamming without the need for bulky optics, maintaining aircraft stealth and extending protection beyond initial decoy depletion.
Implementation Method 1
the refractive index difference between the prisms being suitable for introducing an optical path difference between the two sub-beams which is greater than the coherent length of the incident beam, so as to render the two sub-beams mutually non-coherent and thus prevent any interference between these two sub-beams
Implementation Method 2
the orientation head comprises a biprism including two prisms made of different materials and suited to dividing the transmitted beam into two sub-beams
Implementation Method 3
an infrared laser source (5), characterised in that the orientation head comprises a biprism including two prisms made of different materials and suited to dividing the transmitted beam into two sub-beams
Implementation Method 4
the refractive index difference between the prisms being suitable for introducing an optical path difference between the two sub-beams which is greater than the coherent length of the incident beam
Data Source
AI summary
The invention concerns a device for countering and tracking a threat in the form of a homing-head missile, comprising a homing head adapted to receive an incident coherent light beam and to deflect same to produce a transmitted beam. The invention is characterized in that the homing head comprises a biprism including two prisms made of different materials and adapted to divide the transmitted beam into two sub-beams, the refractive index difference between the prisms being adapted to introduce an optical path difference between the two sub-beams which is greater than the coherence length of the incident beam.