Laser Detector Defocused Imaging for Reliable Wavelength Detection
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Solution Overview
Problem
Existing laser detection systems struggle to accurately identify both low and high power lasers, often leading to false alarms or sensor damage, particularly when faced with civilian laser pointers and aircraft navigation lights.
Innovation Solution
A laser detector comprising a forward-facing sensor array with a specific lens arrangement that creates an out-of-focus image for distant light sources, using a bayer type sensor to measure wavelength directly from this image, and a computer processor to distinguish and disregard non-laser sources based on image size and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor array and image processor are used to detect laser events, then civilian laser pointers can be detected with evidence collection capability, but low power lasers may not be detected and high power lasers are likely to damage the sensor
Solution Approach 1:
The patent inverts the conventional focusing approach by deliberately defocusing the lens arrangement. Instead of focusing laser light onto the sensor array to maximize detection sensitivity, the lens is positioned to create out-of-focus images that span multiple pixels. This inversion prevents high power laser damage while maintaining detection capability through the characteristic spatial distribution pattern of the defocused light.
Solution Approach 2:
The patent segments the laser detection function into two parts: the lens arrangement creates a characteristic out-of-focus spatial pattern that spans multiple pixels, and the computer processor analyzes this segmented pattern to identify lasers. This segmentation allows the system to detect laser presence through the unique spatial distribution without concentrating harmful energy on any single sensor element.
2Measurement precision
If the lens arrangement focuses light from distant sources, then detection sensitivity is improved, but the wavelength measurement becomes less accurate and the sensor is more vulnerable to damage
Solution Approach 1:
The patent applies the inversion principle by deliberately defocusing the lens arrangement to create out-of-focus images. This defocused state prevents high power laser damage by spreading energy across multiple pixels, while the computer processor compensates for the lack of spatial concentration by analyzing the characteristic spatial distribution pattern of the defocused light to accurately determine wavelength.
3Reliability
If the laser light is concentrated on a small sensor area, then detection sensitivity is improved, but false alarms increase due to nearby light sources and wavelength measurement accuracy decreases
Solution Approach 1:
The patent inverts the conventional approach by defocusing the lens arrangement. This creates a characteristic out-of-focus spatial pattern that spans multiple pixels, which is unlikely to occur with nearby non-laser light sources. The computer processor identifies this unique pattern to distinguish distant lasers from local light sources, thereby reducing false alarms while maintaining detection sensitivity.
4Adaptability or versatility
If the lens arrangement is focused for proximal light sources, then nearby light sources can be detected, but distant laser sources produce undetectable or ambiguous images
Solution Approach 1:
The patent applies universality by configuring the lens arrangement to create a characteristic out-of-focus pattern for distant light sources that can be universally recognized by the computer processor. This single configuration serves multiple functions: it detects distant lasers, distinguishes them from nearby light sources through the unique spatial pattern, and enables wavelength measurement without requiring separate focusing mechanisms for different distances.
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
Enables reliable detection of both low and high power lasers from a distance, reducing false alarms and protecting the sensor from damage by spreading laser energy over a larger area, allowing accurate wavelength measurement and rapid identification.
Implementation Method 1
The lens arrangement is positioned relative to the array of sensor elements such that any substantially point-like distal light sources where incoming light rays are substantially parallel give rise to a characteristic out of focus image that spans at least eight pixels
Implementation Method 2
The forward facing array of sensor elements is provided as a bayer type sensor having different regions devoted to different wavebands, and the laser detector is arranged to measure the wavelength of the substantially point-like distal light source solely from inside the characteristic out of focus image
Data Source
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AI summary
A laser detector apparatus (1) is provided, where a pixel array (3) is arranged behind a lens arrangement (4) such that distant objects (9) (in general, those at infinity) are out of focus at the pixel array. The image from the pixel array is evaluated by a computer processor (6) to detect such out of focus images which will be of a known size and shape (generally circular spots of known width). This can enable distant laser threats to be readily distinguished from nearby bright objects (10), whilst also protecting the pixel array from powerful laser sources (because the laser energy is not focussed to a point, on the pixel array it is less likely to damage the pixel array). It can also enable the wavelength of the laser to be accurately determined from the ratio of colours in the image of the laser spot, because it will typically not be a saturated image. The apparatus and method are particularly suitable for identifying and distinguishing laser sources across a wide range of brightnesses, and is also suitable for detecting and distinguishing multiple laser sources.