Retro-reflective optical element for remote sensing
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Solution Overview
Problem
Conventional free-space optical remote sensing techniques, such as Brillouin and Raman lidar, face limitations due to low molecular backscatter levels and the need for stable light sources, which are challenging to maintain, especially in marine environments, restricting their effectiveness in environments like water where Raman techniques are hindered by restricted transmission windows.
Innovation Solution
The use of retro-reflective optical elements with a focuser part and a separate reflector part, optionally coated with photo-luminescent materials, enhances retro-reflection efficiency and allows for the detection of environmental properties like temperature, pressure, and salinity by varying the photo-luminescent response based on environmental changes, enabling efficient monitoring without the need for high-index materials or stable light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional free-space optical remote sensing techniques (Brillouin and Raman lidar) are used, then molecular backscatter can be detected, but the backscatter levels are very low and the techniques are limited by low signal strength
Solution Approach 1:
The retro-reflective optical element is divided into two separate parts: a focuser part and a reflector part connected across an open spacing. This segmentation allows the focuser to concentrate incident light onto a small area of the reflector, significantly enhancing the retro-reflected signal strength without requiring the light to pass through the entire element multiple times.
Solution Approach 2:
The patent introduces retro-reflective optical elements as intermediary objects deployed in the monitored environment. These elements act as mediators between the remote light source and detector, converting weak molecular backscatter into enhanced retro-reflected signals that carry environmental information while maintaining much stronger signal levels.
2Measurement precision
If Raman scattering techniques are used, then frequency shifts can be detected, but the technique is limited in environments with restricted transmission windows such as underwater
Solution Approach 1:
The retro-reflective optical element is designed to work with various types of light sources and detection schemes, making it universally applicable across different environments. The element can be used with Brillouin scattering, Raman scattering, or other optical interaction techniques, and can function in air, water, or other media with different transmission windows by simply changing the optical properties of the focuser and reflector materials.
3Measurement precision
If remote light sources are placed at desired locations for atmospheric research, then spectral absorption estimates can be made, but this is not possible or desirable in marine environments
Solution Approach 1:
The system eliminates the need for remote light sources by deploying retro-reflective optical elements that passively return light to a co-located detector. The optical elements serve themselves by automatically focusing and retro-reflecting light without requiring external power or control systems, making the technique easily deployable in marine environments where placing remote light sources is impractical.
4Productivity
If high-index materials are used in retro-reflective elements, then focusing efficiency may be improved, but such materials are expensive and of limited availability
Solution Approach 1:
The patent applies different optical properties to different parts of the retro-reflective element. The focuser part uses materials with appropriate refractive indices for the specific application environment (air or water), while the reflector part uses highly reflective materials. This local differentiation of material properties optimizes performance without requiring expensive high-index materials throughout the entire structure.
Solution Approach 2:
The patent adjusts the refractive index parameter of the focuser material based on the operating environment. For underwater applications, materials with refractive indices matched to water are used, while for aerial applications, materials optimized for air are used. This parameter adaptation allows the use of readily available materials while maintaining high retro-reflection efficiency in each specific environment.
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 improves the efficiency of remote sensing by enhancing retro-reflection and allowing for the accurate monitoring of environmental properties, even in challenging conditions like underwater environments, through the use of lower refractive index materials and photo-luminescent responses, thereby overcoming the limitations of existing techniques.
Implementation Method 1
The optical element includes a body comprising a focuser part of positive optical power partly surrounded by a reflector part separated therefrom and connected thereto across an open spacing. The optical coating is arranged over an outer surface of the reflector part thereat to receive light which has been at least partially converged by the focuser part for subsequent retro-reflection.
Implementation Method 2
The optical coating is arranged over an outer surface of the reflector part thereat to receive light which has been at least partially converged by the focuser part for subsequent retro-reflection.
Implementation Method 3
The optical element(s) bears a photo-luminescent material, and provide a source of excitation light for irradiating the photo-luminescent material remotely when the optical element is placed within a monitored environment. The photo-luminescent response may be variable according to changes in a physical property of the monitored environment.
Data Source
AI summary
A system for remotely sensing light emanating from within a monitored environment. The system comprises one or more retro-reflective optical elements bearing an optically reflective optical coating upon a surface thereof and positionable within the environment to be monitored, and a light source arranged to direct a beam of light at the optical element(s). A detector is arranged to receive from the optical element(s) light returned by the optical coating in response to the beam of light and to detect a property of the monitored environment according to said returned light. The optical element includes a body comprising a focuser part of positive optical power partly surrounded by a reflector part separated therefrom and connected thereto across an open spacing. The optical coating is arranged over an outer surface of the reflector part thereat to receive light which has been at least partially converged by the focuser part for subsequent retro-reflection.