4-Mirror Laser Radar Scanner for Hostile Environments
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Solution Overview
Problem
Optical scanning systems for hostile environments, such as nuclear reactors, face issues with unwanted reflections due to anti-reflection coatings degrading over time under gamma irradiation and neutron flux, leading to systematic errors in laser radar measurements.
Innovation Solution
A compact optical scanning system using a 4-mirror configuration that allows for full solid-angle scanning without moving the entire system, minimizing unwanted reflections and ensuring high compaction and strength, with a monostatic configuration and separate placement of electro-optical devices outside the hostile environment to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If anti-reflection coatings are applied on prism catheti to reduce unwanted reflections, then measurement precision is improved, but reliability deteriorates due to coating degradation under gamma irradiation and neutron flux
Solution Approach 1:
The patent extracts the vulnerable electro-optical devices (lasers, detectors, and anti-reflection coatings) from the hostile environment. The scanning system is designed to operate with these components positioned outside the reactor core area, eliminating their exposure to gamma irradiation and neutron flux that cause coating degradation and measurement errors
Solution Approach 2:
The patent uses a virtual origin point created by the 4-mirror scanning system to replace the physical prism-based scanning system. This virtual scanning approach eliminates the need for physical anti-reflection coatings on prism surfaces that would degrade under radiation, while maintaining the same scanning functionality through computational geometry
2Device complexity
If a prism-based scanning system is used to achieve compactness, then device complexity is reduced, but object-generated harmful factors increase due to unwanted reflections from catheti
Solution Approach 1:
The patent converts the potential harm of multiple reflection surfaces into a benefit by using 4 mirrors arranged in a specific configuration. While each mirror surface could potentially generate unwanted reflections, the geometric arrangement ensures that reflection paths are precisely controlled and directed only toward the intended target, transforming potential stray light into useful scanned beams
Solution Approach 2:
The patent transitions from a 2D prism surface reflection system to a 3D spatial mirror arrangement system. The 4 mirrors are positioned in three-dimensional space with specific orientations, allowing the system to achieve full solid-angle scanning while controlling reflection paths through spatial geometry rather than relying on coated prism surfaces
3Adaptability or versatility
If the entire optical system is moved for scanning, then adaptability is improved, but weight of moving object increases
Solution Approach 1:
The patent segments the optical system into a stationary heavy component section (electro-optical devices, lasers, detectors) and a light moving section (4-mirror scanning assembly). The mirrors are positioned on a lightweight rotating carrier that can be easily moved to scan different targets, while the heavy components remain fixed in position, dramatically reducing the weight of the moving parts
Solution Approach 2:
The patent introduces a virtual origin point as an intermediary between the stationary electro-optical devices and the moving mirror system. This virtual scanning origin allows the heavy components to remain fixed while the lightweight mirror assembly moves to scan different directions, achieving adaptability without moving the entire system
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 system achieves high accuracy and reliability in laser radar measurements by minimizing unwanted reflections and maintaining optical surface inclination constancy, allowing for precise scanning and imaging in hostile environments with reduced system weight and dimensions.
Implementation Method 1
The system comprises a first rotating element (18) of a first plane, moved by a pan motor, having a central hole (30) for an input of a laser beam (11) aligned with said central hole, a first reflective element (13) inclined with respect to said first plane and positioned so as to collect said laser beam (11) at the same point during the rotation of said first rotating element (18), a second reflective element (14), inclined with respect to said first plane and axially offset with respect to an axis of said central hole, positioned in such a way to collect said laser beam (11) after reflection on said first reflective element (13), a third reflective element (15), inclined with respect to said first plane and positioned above said second reflective element (14), so as to collect said laser beam (11) after reflection on said second reflective element (14) and to reflect it in a direction perpendicular to a second plane (17), a second rotating element (17) of a second plane, moved by a tilt motor, a quarter reflective element (16) fixed to said second rotating element (17), positioned so as to rotate around said perpendicular direction and to collect said laser beam (11) once reflected by said third reflective element (15), configured to send the laser beam (11) toward the target parallel to said second plane (17)
Implementation Method 2
The faces corresponding to the cathetus of the prism (for example isosceles rectangle) may be due to unwanted reflections (stray light). For this reason, the faces corresponding to said cathetus are normally equipped with an anti-reflection coating
Implementation Method 3
The face corresponding to the hypotenuse of the prism is equipped with a total reflection coating so that said face totally reflects the light beam impinging on it
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to an optical apparatus consisting of mirrors and rotating motorized bases that allows to perform scans of the laser beams in (amplitude modulation (AM), and pulsed frequency modulation) incoherent laser radar devices or even in coherent laser radar devices. The invention also relates to an optical scanning apparatus of a laser beam onto a target (T), comprising an active module (MA) and a passive module (MP), wherein said passive module (MP) comprises a launch and reception section and the optical scanning system according to the invention, placed in series with one another.