Laser Designation Using Spatial Filtering for Daylight Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current laser designation and pointing systems face challenges in detecting laser signals in daylight conditions due to high background illumination, requiring high peak power pulsed lasers that are costly, complex, and limited in reliability, making them less widely usable.
Innovation Solution
The use of modulated CW laser diodes with high pixel count image sensor arrays, such as CCD or CMOS, which filter the laser signal spatially by collecting light over a longer period from a few pixels, allowing for detection of reflected laser light without the need for high peak power pulsed lasers, and incorporating temporal coding to differentiate between laser signals and background reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If high peak power pulsed lasers are used to detect laser signals in daylight conditions, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies periodic action by using pulsed laser illumination at specific frequencies (e.g., 1 kHz to 100 kHz) to modulate the laser signal. This periodic modulation allows the detection system to distinguish the laser signal from background daylight through frequency-based filtering, enabling detection capability improvement without requiring continuously high peak power that would increase device complexity
Solution Approach 2:
The patent changes the temporal parameters of laser illumination by using variable pulse widths (from nanoseconds to milliseconds) and repetition rates. This parameter adjustment allows optimization of signal-to-noise ratio for daylight detection while maintaining manageable laser peak power levels, thus improving detection capability without proportionally increasing device complexity
2Difficulty of detecting and measuring
If high peak power pulsed lasers are used to detect laser signals in daylight conditions, then detection capability is improved, but cost increases
Solution Approach 1:
The patent employs inexpensive laser diodes that can be pulsed at high frequencies rather than expensive high peak power pulsed lasers. The laser diodes are cost-effective components with sufficient lifetime for the application, enabling daylight detection capability at a fraction of the cost of traditional high peak power laser systems
Solution Approach 2:
By changing the operational parameters to use moderate peak power with high repetition rates and variable pulse widths, the system achieves effective daylight detection without requiring the extremely high peak power levels that would necessitate expensive laser hardware, thus improving detection capability while controlling cost
3Difficulty of detecting and measuring
If temporal filtering over short time spans is used in pulsed systems, then signal detection is improved, but spatial coverage is reduced
Solution Approach 1:
The patent uses periodic laser pulsing with repetition rates from 1 kHz to 100 kHz, allowing the detection system to integrate signals over multiple pulses while maintaining temporal discrimination. This periodic approach enables both short-time temporal filtering for signal detection and extended spatial coverage by scanning across the field of view over successive pulse cycles
Solution Approach 2:
The patent transforms the detection approach by adding the time dimension through periodic pulsing and integration. Instead of attempting to detect signals simultaneously across the entire field of view (spatial dimension only), the system uses temporal integration of periodic pulses to achieve both signal detection and comprehensive spatial coverage through sequential scanning
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 enables effective detection of laser signals in daylight conditions with lower cost and higher reliability, allowing for wider use of laser designation and pointing systems, and provides clear visibility of the laser spot within the field of view, enhancing operational flexibility and safety.
Implementation Method 1
a CW laser source, modulated with a scheme to provide an output stream of laser pulses
Implementation Method 2
a multi-pixel, 2-dimensional image sensor array... for receiving laser pulses reflected from the remote object
Data Source
Figure 1~2
Figure 3~4B
Figure 5A~6
AI summary
A laser designator system using modulated CW laser diodes and a conventional high pixel count image sensor array, such as CCD or CMOS array. These two technologies, diode lasers and imaging sensor arrays are reliable, widely used and inexpensive technologies, as compared with prior art pulsed laser systems. These systems are distinguished from the prior art systems in that they filter the laser signal spatially, by collecting light over a comparatively long period of time from a very few pixels out of the entire field of view of the image sensor array. This is in contrast to the prior art systems where the laser signal is filtered temporarily, over a very short time span, but over a large fraction of the field of view. By spatially filtering the signal outputs of the individual pixels, it becomes possible to subtract the background illumination from the illuminated laser spot.