Multispectral Lens-Compound for Pixel-Accurate Alignment

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Solution Overview

Problem

Conventional multispectral cameras face challenges in aligning color matrices and focusing different bands of light, particularly in fast-moving applications like UAVs and skin analysis, due to high costs, weight, and inferior image quality, which limits their effectiveness in capturing multiple spectral bands efficiently.

Innovation Solution

A multispectral imaging lens-compound with multiple lenses of identical field of view and focal length, equipped with bandpass filters, allows for the capture of multiple spectral bands on a single digital camera, enabling post-acquisition digital alignment of color matrices and correcting chromatic aberration, thus enhancing image quality and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional multispectral cameras use multiple cameras or multi-lens designs to capture multiple spectral bands, then spectral coverage is improved, but device complexity and alignment difficulty increase

Engineering Contradiction:
Improvespectral coverageVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The lens is segmented into multiple independent optical elements (first lens for visible light, second lens for infrared light) that can be separately optimized for their respective spectral ranges. This segmentation allows each lens to be designed with specific optical characteristics suited to its wavelength range, improving spectral coverage while managing complexity through modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The imaging device achieves multi-functionality by using a single camera sensor that can detect multiple spectral bands (visible and infrared) through the coordinated action of multiple lenses with different spectral transmission characteristics. This universal sensor design eliminates the need for separate cameras for each spectral band, reducing overall device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If conventional multispectral cameras use rotating filters or prism-based designs, then spectral band separation is achieved, but image quality and resolution deteriorate

Engineering Contradiction:
Improvespectral band separationVSAvoidimage quality
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

Instead of using a single lens with rotating filters or prisms that compromise image quality, the system segments the spectral separation function across multiple fixed lenses, each optimized for specific wavelength ranges. This eliminates the need for complex moving parts or refractive elements that degrade image quality, while maintaining high resolution through dedicated optical paths

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses multiple lenses that are substantially identical in design and characteristics, creating parallel optical paths that can be independently optimized. This copying approach allows each lens to be manufactured with high precision using the same proven design, ensuring consistent image quality across all spectral bands while simplifying manufacturing

Inventive Principle:
Principle #26Copying

3Adaptability or versatility

If conventional multispectral cameras capture images at different times from different angles during UAV flight, then spectral data is collected, but spatial alignment accuracy deteriorates due to time lapse

Engineering Contradiction:
Improvespectral data collectionVSAvoidspatial alignment accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system enables simultaneous capture of multiple spectral bands through multiple lenses that operate continuously and synchronously on the same instantaneous image plane. This eliminates time-lapse between captures, ensuring all spectral data corresponds to the exact same spatial position, thereby maintaining high spatial alignment accuracy even during UAV flight

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The multiple lenses are pre-positioned and optically aligned on the camera body before image capture, establishing fixed, precise spatial relationships between different spectral channels. This preliminary optical alignment ensures that all lenses capture images from the exact same angle and position simultaneously, eliminating alignment errors that would occur with sequential capture

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If single lens designs are used to maintain simplicity, then device complexity is reduced, but the ability to focus different bands of light deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidfocus precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The focusing function is segmented across multiple lenses, each optimized for specific spectral bands. By distributing the optical elements across separate lenses rather than trying to focus all wavelengths through a single lens, the system achieves precise focus for each band while keeping each individual lens simple and easy to manufacture

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each lens is designed with specific optical characteristics tailored to its designated spectral range (e.g., infrared transmission properties for the second lens). This local optimization ensures that each lens provides optimal focus and transmission for its target wavelength range while maintaining overall system simplicity through standardized lens designs

Inventive Principle:
Principle #3Local quality

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

This solution enables high-quality, synchronized, and aligned multispectral imaging across multiple bands, overcoming the limitations of conventional cameras by allowing pixel-accurate alignment and improved exposure balance, making it suitable for agricultural and medical applications.

Implementation Method 1

Each lens is associated with a different single or multi bandpass filter, allowing the passage of at least one visible band, and one non-visible band selected from the group consisting of near infra-red bands and ultra violet bands of light, through the filters to the sensor

Methodology Applied
Scientific EffectBandpass filtering: Filter (optical)

Implementation Method 2

The lenses are of substantially identical field of view and substantially identical image circle at the sensor plane. The lenses are also of substantially identical focal length

Methodology Applied
Scientific EffectLight focusing: Lens

Implementation Method 3

one or more of the lenses includes an optical element to correct the chromatic aberration, which is created due to the different wavelengths of the light passing through the different lenses

Methodology Applied
Scientific EffectChromatic aberration correction: Lens

Data Source

PatentEP3308209B1Multispectral imaging apparatus
Publication Date: 2020.05.27 AGROWING LTD
  • EP3308209B1 patent drawingFigure 1
  • EP3308209B1 patent drawingFigure 2a~2b
  • EP3308209B1 patent drawingFigure 2c

AI summary

A lens compound for connecting to an interchangeable lens mount of a digital camera having a single image sensor, the lens compound including a body; a single mount connecting ring mounted on the body for connecting to the lens mount of the digital camera; at least two lenses of substantially identical focal length mounted in the body; and a different single or multi bandpass filter associated with each of the lenses, allowing the passage of at least one visible band and one non-visible band, selected from the group consisting of near infra-red bands and ultra violet bands of light, through the filters to the sensor; wherein the lenses are of substantially identical field of view and substantially identical image circle at a sensor plane of the image sensor.