Fluorescence Observation Unit with Beam Combining Prism
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Solution Overview
Problem
Multiphoton-excitation-type observation apparatuses face difficulties in efficiently collecting and detecting fluorescence from large scanning areas and scattering materials like biological tissues, as the fluorescence is scattered and hard to guide into optical fibers.
Innovation Solution
A fluorescence observation unit with a scanner, pupil projection lens, image-forming lens, and dichroic mirror is used to focus ultrashort pulsed laser light, split off fluorescence from the optical path, and guide it through a multi-mode optical fiber to a photodetector, employing a first optical system with positive refractive power and a second with negative refractive power to compactly collect and direct fluorescence efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fluorescence is split off immediately behind the objective lens before returning to the scanner, then the fluorescence collection path is simplified, but the position of the fluorescence beam varies with scanner movement making it difficult to guide into an optical fiber for large scanning areas
Solution Approach 1:
A beam combining prism is introduced as an intermediary component between the objective lens and the optical fiber. This prism combines the laser beam path and fluorescence beam path, allowing the fluorescence to be guided into the optical fiber while maintaining the simplified collection path. The beam combining prism acts as a mediator that resolves the conflict between path simplification and guidance difficulty.
2Area of stationary object
If the scanning area scanned by the scanner is increased, then the observation coverage is improved, but the fluorescence beam position varies more making it difficult to enter the optical fiber
Solution Approach 1:
The beam combining prism serves as a fixed intermediary that maintains consistent optical path geometry regardless of scanner position. By introducing this stationary component, the system can scan larger areas while the fluorescence beam continues to be reliably guided into the optical fiber through the fixed prism geometry.
3Illumination intensity
If fluorescence is collected from a wide area of the sample, then the brightness of the fluorescence image is improved, but the fluorescence is scattered by the sample making detection more difficult
Solution Approach 1:
The invention extracts the fluorescence signal from the scattered light field by using the beam combining prism to separate and guide the fluorescence beam into the optical fiber. This extraction process isolates the useful fluorescence signal from the scattered background, enabling detection of fluorescence from wide areas while maintaining image brightness.
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 configuration allows for efficient collection and detection of fluorescence from deep within samples, even when scanning large areas or using scattering materials, resulting in bright and sharp fluorescence images.
Implementation Method 1
fluorescence generated at a light-focusing position due to a multiphoton excitation effect by focusing ultrashort pulsed laser light on a specimen
Implementation Method 2
a dichroic mirror that splits off, from the optical path of the ultrashort pulsed laser light, fluorescence
Implementation Method 3
is guided to an external photodetector by an optical fiber
Data Source
AI summary
A fluorescence observation apparatus includes a fluorescence observation unit, which includes a scanner that scans ultrashort pulsed laser light from a light source, a pupil projection lens that focuses the laser light scanned by the scanner, an image-forming lens that converts the focused laser light to substantially collimated light and causes the laser light to be incident on an objective lens, and a dichroic mirror that splits off fluorescence that is generated by the laser light focused on a sample by the objective lens and is collected by the objective lens. A photodetector detects the fluorescence split off by the dichroic mirror. A multi-mode optical fiber connects the fluorescence observation unit and the photodetector. A swiveling mechanism causes the fluorescence observation unit to swivel about an axis near the focal position of the objective lens. And a light-source optical fiber connects the light source and the fluorescence observation unit.