Image Capturing Apparatus with Correction Filter for Fluorescence Imaging
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Solution Overview
Problem
Existing image capturing apparatuses face challenges in preventing excitation light from leaking into RGB components and correcting focal point differences between visible light and IR, leading to complex structures and reduced sensitivity, especially when using fluorescent materials like indocyanine green (ICG).
Innovation Solution
An image capturing apparatus with a four-color separation unit, a bandpass filter, and a correction filter that includes visible and IR cutting regions with a dummy glass, which prevents excitation light leakage and corrects focal points and light levels without increasing the apparatus complexity, by focusing visible light and adjusting IR focal positions using a circularly shaped dummy glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a four-color separation prism is used to separate light into R/G/B and IR components, then light separation capability is improved, but excitation light leaks into RGB components causing image quality degradation
Solution Approach 1:
A bandpass filter is introduced as an intermediary component between the light source and the four-color separation prism. This filter selectively transmits only the wavelength range needed for fluorescence excitation while blocking excitation light from reaching the image sensor, thereby preventing excitation light leakage into RGB components while maintaining effective light separation capability
Solution Approach 2:
Different regions of the optical path are assigned different filtering properties. The bandpass filter is positioned specifically in the excitation light path to block harmful wavelengths, while the four-color separation prism maintains its light separation function in the emission light path. This localized application of filtering properties solves the contradiction by addressing excitation light leakage without compromising overall light separation performance
2Measurement precision
If the fluorescence image capturing device and visible light image capturing device are arranged to correspond to light path differences, then focal point difference between RGB and IR is corrected, but device structure becomes complicated
Solution Approach 1:
The correction filter with dummy glass is extracted from the complex device arrangement and placed in the optical path between the lens and four-color separation prism. This single component performs the focal point correction function that would otherwise require complex mechanical adjustment of device positions, thereby simplifying the overall device structure while maintaining focal point alignment between RGB and IR images
Solution Approach 2:
The correction filter serves multiple functions simultaneously: it corrects focal point differences between visible light and IR, maintains proper image positioning, and works seamlessly with the four-color separation prism. This multi-functionality eliminates the need for separate adjustment mechanisms, reducing device complexity while achieving precise focal point alignment
3Measurement precision
If peripheral pixels are added to improve IR sensitivity, then IR detection capability is improved, but device structure becomes more complex and sensitivity is reduced
Solution Approach 1:
Instead of adding physical peripheral pixels to the image sensor, a virtual copy of the IR signal is created through the correction filter and optical path design. The dummy glass in the correction filter compensates for focal point differences, allowing the central pixels to capture both visible light and IR information effectively, thereby achieving improved IR sensitivity without increasing device complexity or adding peripheral pixels
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 prevents excitation light leakage, corrects focal points and light levels between visible and IR, and reduces the overall complexity of the apparatus, enabling high-quality fluorescence imaging with improved contrast and sensitivity.
Implementation Method 1
a bandpass filter that is interposed between the mounted lens and the four-color separation unit and does not transmit light near a wavelength band of the excitation light
Implementation Method 2
a correction filter interposed between the bandpass filter and the mounted lens, wherein the correction filter includes a visible light cutting region having a circular shape, an IR cutting region having a circular shape and disposed at a central position of the visible light cutting region, and a dummy glass disposed on a surface of the IR cutting region facing the bandpass filter
Implementation Method 3
an image capturing apparatus that takes a picture of an object including a fluorescent material
Data Source
AI summary
Provided is an image capturing apparatus that not only prevents excitation light from leaking into RGB but also corrects a difference of focal points between visible light and IR and corrects levels of visible light and IR without having a complicated structure. An image capturing apparatus 10 includes a light irradiation unit 12 that irradiates an object including a fluorescent material with excitation light and illuminating light, a four-color separation unit 16 that separates light incident upon a lens 14 into R, G, B, and IR, an image sensor 18 that performs photoelectric conversion on each separated light, a picture signal output unit 20 that generates a picture signal from an electrical signal obtained by the photoelectric conversion, a picture display 22 that displays a picture based on the picture signal, a bandpass filter 24 that does not transmit light near a wavelength band of the excitation light, and a correction filter 26. The correction filter 26 includes a circular visible light cutting region 30 that cuts visible light out of the incident light, a circular IR cutting region 28 that cuts IR out of the incident light, and a dummy glass 32 having a predetermined thickness.