LCOS Reflective Modulator for Night Vision Overexposure
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Solution Overview
Problem
Imaging systems, such as those used in vehicles, often suffer from overexposure issues at night due to the limited dynamic range of CCD or CMOS sensors, leading to unclear images, particularly in high-contrast environments like dark tunnels with headlights, which makes it difficult to identify license plate numbers.
Innovation Solution
An exposure-suppressing imaging system that incorporates a first optical assembly, a beam splitter, an LCOS reflective light modulator, a second optical assembly, and a light sensor, where the LCOS modulator selectively alters reflectivity to reduce overexposure by controlling light intensity based on signals from the sensor, ensuring that the image is not overly bright and maintaining detail clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional imaging system uses a CCD or CMOS sensor to capture images at night, then the sensor can detect light, but the limited dynamic range causes overexposure in bright areas (like headlights) and loss of detail
Solution Approach 1:
The patent applies dynamics by making the reflective light modulator dynamically adjustable based on real-time light intensity detection. The controller continuously monitors the light sensor output and adjusts the modulator's reflectivity accordingly, transforming a static imaging system into a dynamic one that adapts to varying light conditions to prevent overexposure while preserving image details
Solution Approach 2:
The reflective light modulator serves as an intermediary element between the incoming light and the CCD/CMOS sensor. By positioning the modulator in the optical path and controlling its reflectivity, it mediates the light intensity reaching the sensor, effectively expanding the usable dynamic range beyond the sensor's native capabilities
2Illumination intensity
If the imaging system increases light sensitivity to capture dark areas, then dark regions become visible, but bright areas become overexposed and lose detail
Solution Approach 1:
The patent applies local quality by enabling different regions of the optical path to have different light transmission characteristics. The reflective light modulator can be controlled to have spatially varying reflectivity across its surface, allowing certain areas to reflect more light while others reflect less, thereby balancing the exposure across different regions of the image
3Illumination intensity
If the system uses high-contrast settings to capture bright lights, then bright areas are captured, but dark areas become extremely dark and unclear
Solution Approach 1:
The patent implements feedback by creating a closed-loop control system where the light sensor continuously monitors the light intensity and feeds this information back to the controller, which then adjusts the reflective light modulator accordingly. This feedback mechanism allows the system to automatically balance the exposure between bright and dark areas, preventing both overexposure and underexposure
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 effectively suppresses overexposure, allowing for clearer image capture at night by automatically adjusting light intensity, enhancing the ability to read license plate numbers and other details in high-contrast scenes.
Implementation Method 1
The LCOS (Liquid Crystal on Silicon) reflective light modulator is positioned at the focal plane, and selectively and partially alters the reflectivity thereof to reflect the first image back to the beam splitter
Implementation Method 2
The beam splitter is positioned between the first optical assembly and the focal plane of the first optical assembly
Implementation Method 3
The light sensor positioned on the focal plane of the second optical assembly and converts the second image into a signal
Data Source
AI summary
An exposure-suppressing imaging system has a first optical assembly forming a first image of an object on a focal plane thereof, a beam splitter positioned between the first optical assembly and the focal plane of the first optical assembly; an LCOS reflective light modulator positioned on the focal plane, and selectively and partially altering the reflectivity thereof to reflect the first image back to the beam splitter; a second optical assembly positioned on a side of the beam splitter and receiving the reflected first image to form a second image on a focal plane of the second optical assembly; a light sensor converting the second image into a signal; and a controller receiving the signal computed as a third image, and selectively controlling the reflectivity of the LCOS reflective light modulator according to whether the signal contains information of overexposure on the third image.