Multispectral Filter Unit Using Polarization Isolation Against Ghosting
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Solution Overview
Problem
Existing imaging systems face issues with ghosting due to reflections from band-pass filters, particularly in multispectral camera systems that capture images in multiple wavelengths.
Innovation Solution
Incorporating a filter unit with band-pass filters and optical elements such as quarter-wave plates and polarized light filters, arranged to convert linearly polarized light into circularly or elliptically polarized light, to form optical isolators that prevent re-reflection at the band-pass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If band-pass filters are used to capture images in multiple wavelengths, then spectral imaging capability is improved, but ghosting occurs due to light reflections from the filters
Solution Approach 1:
A quarter-wave plate is introduced as an intermediary optical element between the band-pass filter and the imaging sensor. This wave plate converts linearly polarized light (from the filter) into circularly polarized light, thereby preventing direct reflection back to the sensor that causes ghosting, while still allowing the desired spectral information to pass through
Solution Approach 2:
The polarization state of light is changed by using a quarter-wave plate to convert linearly polarized light into circularly polarized light. This parameter change in the light's polarization state prevents the harmful reflection effect that causes ghosting, while maintaining the spectral imaging function
2Object-affected harmful factors
If optical elements are added to suppress ghosting, then ghosting is reduced, but device complexity increases
Solution Approach 1:
The quarter-wave plate is integrated into the existing optical path of the band-pass filter system, merging the ghosting suppression function with the spectral filtering function in a unified optical assembly, thereby minimizing additional complexity
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
Effectively suppresses ghosting, enabling high-quality capture of images dispersed in multiple wavelengths by preventing light reflections and allowing for precise spectral imaging.
Implementation Method 1
a wave plate which converts linearly polarized light into circularly polarized light or elliptically polarized light
Implementation Method 2
an optical element on at least one of an object side or an image side of the band-pass filter, the optical element is composed of a polarized light filter
Implementation Method 3
each include a band-pass filter, and each include an optical element
Implementation Method 4
arranged to convert linearly polarized light into circularly or elliptically polarized light, to form optical isolators that prevent re-reflection at the band-pass filters
Data Source
AI summary
Provided are a lens device, a filter unit, and an imaging apparatus capable of suppressing occurrence of ghosts. The lens device includes a filter unit in an optical path. The filter unit has a plurality of opening portions including a first opening portion and a second opening portion. At least the first opening portion and the second opening portion each include a band-pass filter, and each include an optical element on at least one of an object side or an image side of the band-pass filter. The optical element is composed of a polarized light filter and a wave plate which converts linearly polarized light into circularly polarized light or elliptically polarized light. The first opening portion and the second opening portion pass light in different wavelength regions and different polarization directions.