Wavelength-Compensating Optical Coupler for VIS-NIR Imaging
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Solution Overview
Problem
Conventional optical instruments are not optimized for both visible and NIR light imaging, leading to poor quality NIR images due to uncorrected aberrations and focal plane shifts, making them incompatible with high-resolution VIS-NIR imaging systems that use a single color image sensor.
Innovation Solution
A novel optical coupler that splits the optical path into visible and NIR paths, using an afocal prism assembly with dichroic coatings and materials of different refractive indices to compensate for path length differences and aberrations, ensuring corrected image projection without degrading visible spectrum performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical instruments are used for NIR imaging, then visible light imaging performance is maintained, but NIR image quality deteriorates due to uncorrected aberrations and focal plane shifts
Solution Approach 1:
The optical coupler is divided into separate visible and NIR optical paths, allowing independent optimization for each wavelength range. The visible light path maintains conventional optical design while the NIR path incorporates specialized correction elements to address aberrations and focal plane shifts specific to near-infrared wavelengths.
Solution Approach 2:
An intermediary optical path is introduced between the conventional optical instrument and the image sensor. This intermediate coupler system includes dichroic mirrors and wavelength-specific lens elements that selectively process visible and NIR light separately, enabling correction of NIR aberrations without affecting visible light performance.
2Device complexity
If a single color image sensor is used for both visible and NIR imaging, then system complexity is reduced, but image quality deteriorates due to focal plane shifts between visible and NIR wavelengths
Solution Approach 1:
The optical coupler performs preliminary correction of focal plane shifts before the light reaches the image sensor. By incorporating NIR-specific lens elements and adjusting optical path lengths in advance, the system pre-compensates for focal plane differences, ensuring that both visible and NIR wavelengths focus at the same plane on the sensor.
Solution Approach 2:
The optical system utilizes parameter changes in refractive indices of optical materials at different wavelengths. By selecting materials with appropriate dispersion characteristics and designing lens elements with specific focal lengths for NIR wavelengths, the system adjusts optical parameters to achieve focal plane coincidence for both visible and NIR imaging.
3Ease of operation
If conventional optical instruments are used without modification, then ease of operation is maintained, but NIR imaging capability deteriorates due to optical path length differences
Solution Approach 1:
The optical coupler is designed as a universal interface that can be attached to conventional optical instruments to enable both visible and NIR imaging capabilities. The multi-functional coupler handles wavelength separation, path length compensation, and aberration correction in a single integrated unit, allowing conventional instruments to perform dual-wavelength imaging without complex modifications.
Solution Approach 2:
The optical coupler serves as an intermediary device that bridges conventional optical instruments and modern VIS-NIR imaging systems. It includes adapter mechanisms and mounting interfaces that facilitate easy attachment to conventional instruments while providing the necessary optical corrections for high-quality NIR imaging.
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 the use of conventional optical instruments with VIS-NIR imaging systems by correcting optical aberrations and focal plane shifts, resulting in improved NIR image quality without compromising visible spectrum performance.
Implementation Method 1
a dichroic beam splitter that reflects visible light and transmits NIR light
Implementation Method 2
materials of different refractive indices to compensate for path length differences
Data Source
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AI summary
An optical system, in particular for endoscopic applications, is disclosed which uses wavelength-compensating optical components, in particular prisms, made of materials with different inter-element coatings and refractive indices to image significantly different wavelength-ranges (VIS and NIR) onto the same image plane of an image acquisition device, such as a CCD sensor.