Spectral Filter for Night Vision Radiant Intensity Management
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Solution Overview
Problem
Night vision devices (NVDs) face challenges in maintaining image resolution and sensitivity due to excessive Night Vision Radiant Intensity (NRi) from artificial lighting sources, which can activate automatic gain control, cause blooming, and reduce performance, especially in enclosed environments where multiple light sources interact, compromising visibility and safety.
Innovation Solution
A method involving the fabrication of filters that absorb a predetermined portion of the optical spectrum, particularly in the 600 nanometers to 900 nanometers range, using polymers with colorants and infrared absorbing dyes, to manage spectral energy and reduce NRi, allowing for night vision compatibility while preserving color recognition and illumination levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If artificial lighting is used to illuminate areas for NVD operation, then visibility is improved, but excessive radiant energy in the 600-900nm range activates automatic gain control and causes blooming, degrading image quality
Solution Approach 1:
The optical spectrum is segmented into different wavelength ranges, with selective filtering applied to the 600-900nm range that is sensitive to NVD automatic gain control, while allowing other wavelengths to pass through for illumination
Solution Approach 2:
The filter exhibits different transmittance properties at different wavelengths - it selectively absorbs in the 600-900nm range while transmitting other wavelengths, creating localized spectral quality control
2Reliability
If spectral filtering is applied to reduce NRi in the 600-900nm range, then NVD performance is improved, but overall illumination intensity may be reduced
Solution Approach 1:
The filter's transmittance parameter is optimized to allow sufficient light transmission in non-sensitive wavelength ranges while blocking the critical 600-900nm range, balancing illumination needs with NVD performance protection
3Illumination intensity
If multiple light sources are used in enclosed environments, then adequate illumination is achieved, but cumulative radiant energy exceeds NVD tolerance levels
Solution Approach 1:
Each light source is equipped with spectral filters that segment the emitted spectrum, ensuring that cumulative radiant energy in the sensitive 600-900nm range from multiple sources remains below NVD automatic gain control activation thresholds
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 solution effectively suppresses excessive light energy within the NVD-sensitive spectrum, maintaining image quality and safety by ensuring adequate illumination without activating automatic gain control, allowing for recognition of reflective colors and self-illuminating signals, even under varying brightness conditions, and reducing the risk of detection by enemy NVDs.
Implementation Method 1
The filter absorbs the predetermined portion of the optical spectrum
Implementation Method 2
The sheet is fabricated from a polymer incorporating a series of colorants and infrared absorbing dyes
Data Source
AI summary
A method is provided for suppressing a predetermined portion of an optical spectrum emanating from a light emitter. The optical spectrum illuminates an illumination area. The method includes the steps of fabricating a filter having a spectrophotometric transmittance and varying the spectrophotometric transmittance of the filter. The filter is positioned between the light emitter and the illumination area, such that the filter absorbs the predetermined portion of the optical spectrum.