Light Scanning Microscope Beam Splitter Extrafocal Signal Separation
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Solution Overview
Problem
Conventional light scanning microscopes face challenges with confocal detection being optimal only for specific pupil diameters, leading to poorer results or signal loss, and suffer from strong background signals and crosstalk when multiple spots are moved over thicker samples due to extrafocal light passing through pinholes.
Innovation Solution
A second detector is placed outside the imaging beam path, with a beam splitter deflecting sample radiation from the diaphragm onto it, creating an additional detection channel for extrafocal light, and a second beam splitter allows detection perpendicular to the optical axis, enhancing image quality by separating confocal and extrafocal signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If confocal detection is performed with a predefined pupil diameter, then optimal detection is achieved, but larger or smaller pupil diameters lead to poorer results or signal loss
Solution Approach 1:
The detection system is segmented into two independent detection channels: a first detector for confocal detection through pinholes and a second detector for extrafocal light detection. This segmentation allows each detector to be optimized for its specific detection mode, enabling the system to handle different pupil diameters effectively without compromise.
Solution Approach 2:
A beam splitter is introduced as an intermediary element that divides the sample radiation into two paths: one directed to the first detector through the diaphragm for confocal detection, and another directed to the second detector for extrafocal light detection. This intermediary enables simultaneous operation of both detection modes.
2Productivity
If several spots are moved simultaneously in the predefined region of the sample, then imaging speed is improved, but strong background signal occurs due to extrafocal light passing through pinholes
Solution Approach 1:
The harmful extrafocal light is extracted from the main detection path by directing it to a separate second detector through the beam splitter. This allows the first detector to receive primarily confocal signal while the second detector specifically captures and measures the extrafocal background light for subsequent subtraction.
Solution Approach 2:
The system uses feedback by measuring the extrafocal light intensity with the second detector and using this information to correct the confocal images. The background signal detected by the second detector is subtracted from the total signal to recover the pure confocal signal, thereby eliminating the harmful background effect.
3Productivity
If several spots are moved simultaneously in the predefined region of the sample, then imaging speed is improved, but undesired crosstalk occurs
Solution Approach 1:
The second detector provides feedback information about the extrafocal light that causes crosstalk between adjacent spots. By measuring and subtracting this crosstalk component, the system recovers the true confocal signal for each spot, eliminating the information loss due to crosstalk while maintaining high imaging speed.
4Adaptability or versatility
If a beam splitter is added to deflect sample radiation onto a second detector, then an additional detection channel is provided, but device complexity increases
Solution Approach 1:
The beam splitter serves multiple functions: it divides the sample radiation for simultaneous confocal and extrafocal detection, enables operation with multiple pupil diameters, and supports both single-spot and multi-spot imaging modes. This multi-functionality justifies the added complexity by providing comprehensive detection capabilities in a single optical element.
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 setup reduces background noise and crosstalk, improving confocal imaging by providing an additional detection channel for extrafocal radiation, allowing for better signal separation and enhanced image quality, especially in thicker samples.
Implementation Method 1
a beam splitter is arranged in the imaging beam path between the sample and the diaphragm, wherein the beam splitter deflects sample radiation, coming from the diaphragm, onto the second detector
Implementation Method 2
an imaging lens system, having an optical axis, for imaging the predefined region along an imaging beam path running from the sample as far as the first detector
Implementation Method 3
several illumination beams are generated, each illumination beam is moved, as a spot, in a predefined region of a sample, for the purpose of exciting sample radiation
Data Source
AI summary
A light scanning microscope with an illumination module generates several illumination beams and moves them, in each case as a spot, in a predefined region of a sample to excite sample radiation. A detector module for confocal detection of the sample radiation excited by each spot includes a first detector, an imaging lens system, having an optical axis, for imaging the predefined region along an imaging beam path running from the sample as far as the first detector, and a rotatable diaphragm with several pinholes located in a pinhole plane. The diaphragm, upon rotation, may be located at least partially in the imaging beam path for confocal detection. A second detector may be arranged outside of the imaging beam path. A first beam splitter may be arranged in the imaging beam path between the sample and the diaphragm. The beam splitter deflects sample radiation onto the second detector.