Transmissive VPH Grating for Confocal Microscopy Light Loss
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Solution Overview
Problem
Confocal scanning microscopes with spectroscopic detection functions face inefficiencies due to the use of reflective diffraction gratings, which result in high light loss across a wide wavelength region, limiting the brightness and quality of fluorescence images.
Innovation Solution
Incorporating a transmissive Volume Phase Holographic (VPH) grating that achieves higher diffraction efficiency and maintains a fixed diffraction direction for various wavelengths, allowing for improved light-use efficiency and efficient fluorescence detection across a wide wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective diffraction grating is used as spectroscopic means, then the microscope can achieve spectroscopic detection function, but light loss is large and diffraction efficiency is low (at most 70%)
Solution Approach 1:
The patent changes the fundamental parameters of the diffraction grating: transitioning from reflective to transmissive type, and from surface-relief to volume phase holographic structure. This parameter change enables diffraction efficiency to exceed 90% across a wide wavelength region, resolving the contradiction between light loss and diffraction efficiency.
2Reliability
If a surface-relief diffraction grating is used, then the grating can diffract light, but the diffraction efficiency is limited to 70% at most
Solution Approach 1:
The patent inverts the conventional approach by using a transmissive diffraction grating instead of a reflective one. This inversion of the basic working principle allows light to pass through the volume phase holographic grating, achieving diffraction efficiency greater than 90% and significantly reducing light loss.
3Productivity
If the microscope scans the sample at high speed, then productivity is improved, but the light quantity obtained per unit time is small
Solution Approach 1:
By changing the diffraction grating parameters to achieve >90% diffraction efficiency, the system maximizes the utilization of limited fluorescence photons. This allows high-speed scanning to be maintained while obtaining sufficient light quantity for bright fluorescence images.
4Measurement precision
If spectroscopic means is used to disperse light, then wavelength separation is achieved, but a large quantity of light is lost
Solution Approach 1:
The patent changes the spectroscopic means from conventional reflective diffraction gratings to transmissive volume phase holographic gratings. This parameter change achieves both effective wavelength separation and diffraction efficiency exceeding 90%, resolving the contradiction between measurement precision and energy loss.
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 VPH grating enhances light-use efficiency and allows for high-speed, high-efficiency spectral data acquisition by maintaining a fixed diffraction direction, optimizing fluorescence detection without altering the wavelength region, thereby improving image brightness and quality.
Implementation Method 1
a transmissive VPH grating for dispersing light from the sample
Implementation Method 2
a transmissive Volume Phase Holographic (VPH) grating that achieves higher diffraction efficiency
Implementation Method 3
a photodetector for detecting the light diffracted by the VPH grating
Data Source
AI summary
A scanning microscope is provided with a scan unit that scans a sample, the scanning microscope including: a transmissive VPH grating for dispersing light from the sample; and a photodetector for detecting the light diffracted by the VPH grating.