Acousto-Optical Beam Splitter for Scanning Microscopes
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Solution Overview
Problem
Scanning microscopes using conventional dichroic main beam splitters often experience disruptive stripes of unknown origin, which cannot be observed and interfere with image quality.
Innovation Solution
An acousto-optical main beam splitter is designed with a mechanical wave of a specific sound frequency for the illumination light wavelength, featuring a dispersive optical component and distinct entry surfaces for different linear polarization directions to remove illumination light components from the detected light beam, preventing disruptive stripes by compensating for spatial color splitting and directing light efficiently onto illumination and detection paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an acousto-optic component is used as main beam splitter, then the disruptive stripes observed with dichroic beam splitters are eliminated, but thermal output and diffraction efficiency issues arise
Solution Approach 1:
The patent replaces the conventional dichroic beam splitter with an acousto-optic component that uses sound waves (mechanical vibrations) to diffract light. The transducer generates acoustic waves in the crystal, creating a diffraction grating that redirects illumination light while allowing detection light to pass through, thereby eliminating disruptive stripes without the energy losses associated with dichroic filters.
Solution Approach 2:
The patent utilizes the wavelength-dependent diffraction angle property of acousto-optic components. By adjusting the frequency of the acoustic wave and exploiting the different wavelengths of illumination light versus detection light, the system achieves selective diffraction: illumination light is diffracted at angles that direct it to the sample, while detection light passes through undiffracted to the detector, resolving the efficiency issue through precise parameter control.
2Adaptability or versatility
If multiple mechanical waves with different frequencies are generated to illuminate with several wavelengths, then multi-wavelength illumination is achieved, but the complexity of the system increases
Solution Approach 1:
The patent employs a single acousto-optic component that can handle multiple wavelengths by varying the acoustic wave frequency. The transducer can generate different frequency acoustic waves to diffract different illumination wavelengths, allowing one component to perform multiple wavelength selection functions that would otherwise require multiple separate components, thereby reducing system complexity while maintaining versatility.
Solution Approach 2:
The patent utilizes the dynamic control capability of the acousto-optic component, where the diffraction characteristics can be changed in real-time by adjusting the acoustic wave frequency. This dynamic adjustment allows the system to switch between different illumination wavelengths on demand, providing multi-wavelength capability without the need for multiple static optical paths or components.
3Loss of energy
If a single sound frequency is used for the mechanical wave, then thermal output is reduced, but control over different polarization directions becomes challenging
Solution Approach 1:
The patent introduces asymmetric optical elements (such as wave plates or polarizing beam splitters) in combination with the acousto-optic component. These asymmetric elements manipulate the polarization states of light differently for different orientations, enabling the system to control both s-polarized and p-polarized illumination light using a single acoustic frequency, thereby resolving the polarization control challenge without increasing thermal output.
Solution Approach 2:
The patent uses polarization control elements as intermediaries between the single-frequency acousto-optic component and the illumination/detection paths. These intermediary components convert or separate polarization states, allowing the single acoustic frequency to effectively control both polarization directions by preparing the light in appropriate polarization states before it interacts with the acousto-optic crystal.
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 significantly reduces thermal output and diffraction efficiency issues, eliminating disruptive stripes and allowing for precise control of light paths, enhancing image quality by directing illumination light and removing unwanted wavelengths effectively.
Implementation Method 1
Light passing through the crystal undergoes diffraction at the optical grating. Accordingly, the light is deflected in different diffraction orders and directions.
Implementation Method 2
The functionality of such an acousto-optic component is essentially based on the interaction of the illumination light with a mechanical wave. In some acousto-optic components, such as an AOTF, the mechanical wave must have a very specific frequency so that the Bragg condition is fulfilled precisely for light of the desired illumination wavelength.
Implementation Method 3
at least one dispersive optical component that compensates for a (at least partially) spatial color splitting of a primary light and/or the illumination light caused by the crystal of the acousto-optic main beam splitter
Implementation Method 4
The transducer usually comprises a piezoelectric material and an electrode positioned above and below it. By electrically applying radio frequencies, typically in the range of 30 MHz to 800 MHz, to the electrodes, the piezoelectric material is set into vibration, generating an acoustic wave
Implementation Method 5
the mechanical wave must have a very specific frequency so that the Bragg condition is fulfilled precisely for light of the desired illumination wavelength
Data Source
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AI summary
The invention relates to an acousto-optical main beam splitter for a scanning microscope, embodied and determined to guide illumination light with a preselected or preselectable illumination light wavelength onto an illumination beam path for illuminating a sample and to guide detection light coming from a sample onto a detection beam path. The acousto-optical main beam splitter is characterized in that, in the acousto-optical main beam splitter, a mechanical wave with a sound frequency assigned to the illumination light wavelength propagates or a plurality of mechanical waves, which have the same sound frequency, which is assigned to the illumination light wavelength, propagate, wherein both a portion of the detection light beam including the illumination light wavelength and a first linear polarization direction and a portion of the detection light including the illumination light wavelength and a second linear polarization direction perpendicular to the first linear polarization direction are deflected from the detection light beam coming from a sample by an interaction with the one mechanical wave or by interaction with the mechanical waves and, as result, removed from the detection light beam and/or wherein the acousto-optical main beam splitter is embodied to deflect both the portion of illumination light, which includes the preselected illumination light wavelength and a first linear polarization direction, and the portion of illumination light, which includes the preselected illumination light wavelength and a second linear polarization direction different from, in particular perpendicular to, the first linear polarization direction, onto an illumination beam path for illuminating a sample as a result of interaction with the one mechanical wave or as a result of interaction with the mechanical waves.