https://www.youtube.com/watch?v=6mGEGs7 ... 3F0_2igL_x
I have watched this series (4 part) several times and it still helps me set some of the concepts in my head.
Neal
Abbe refraction
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ImperatorRex
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Re: Abbe refraction
Can also highly recomment:
Understanding the Light Microscope by Peter Evennett
1. Conjugate Planes in the microscope (0 – 21:00 min)
The optical system of a microscope embodies two series of planes which are conjugate – optically linked, as images one of another. These are the ‘Field’ set of planes consisting of the object and its images, and the ‘Aperture’ set of planes which includes the light source (lamp filament) and it subsequent images. These planes are demonstrated here using a specially assembled microscope and video camera system.
2. Diffraction and the microscope image (21:00 – 50:51 min)
The most important function of a microscope is resolution – the ability to handle information about fine detail – and this is limited by the phenomenon of diffraction. Two factors are involved – the wavelength of the light, and the Numerical Aperture of the objective lens. The importance of these two factors was demonstrated in 1873 by Ernst Abbe in his ‘Theory of the Microscope’, and illustrated by a series of experiments. These experiments are demonstrated here, again using the specially-adapted microscope. Understanding this section will benefit from having followed section 1.
3. Dark-field Microscopy (51:41 – 59:40 min)
The second important function of a microscope is to provide contrast in the images of transparent and otherwise invisible objects. Dark-field (or Dark-ground) microscopy offers a simple and inexpensive method of enhancing contrast. It is explained here as a sequel to the Diffraction Experiments, using the same demonstration equipment, and should therefore be viewed following sections 1 & 2.
4. Phase-contrast Microscopy (59:40 min)
This section demonstrates the principle of a second system of enhancing visibility of transparent objects, Phase Contrast. Again this is demonstrated using the equipment as in earlier sections, and it should therefore be viewed following these.
The video was enabled by German Research Foundation (DFG) core facility funding of the Biopolis Dresden Imaging Platform (BioDIP). The video has been recorded by Christian Spataro.
Understanding the Light Microscope by Peter Evennett
1. Conjugate Planes in the microscope (0 – 21:00 min)
The optical system of a microscope embodies two series of planes which are conjugate – optically linked, as images one of another. These are the ‘Field’ set of planes consisting of the object and its images, and the ‘Aperture’ set of planes which includes the light source (lamp filament) and it subsequent images. These planes are demonstrated here using a specially assembled microscope and video camera system.
2. Diffraction and the microscope image (21:00 – 50:51 min)
The most important function of a microscope is resolution – the ability to handle information about fine detail – and this is limited by the phenomenon of diffraction. Two factors are involved – the wavelength of the light, and the Numerical Aperture of the objective lens. The importance of these two factors was demonstrated in 1873 by Ernst Abbe in his ‘Theory of the Microscope’, and illustrated by a series of experiments. These experiments are demonstrated here, again using the specially-adapted microscope. Understanding this section will benefit from having followed section 1.
3. Dark-field Microscopy (51:41 – 59:40 min)
The second important function of a microscope is to provide contrast in the images of transparent and otherwise invisible objects. Dark-field (or Dark-ground) microscopy offers a simple and inexpensive method of enhancing contrast. It is explained here as a sequel to the Diffraction Experiments, using the same demonstration equipment, and should therefore be viewed following sections 1 & 2.
4. Phase-contrast Microscopy (59:40 min)
This section demonstrates the principle of a second system of enhancing visibility of transparent objects, Phase Contrast. Again this is demonstrated using the equipment as in earlier sections, and it should therefore be viewed following these.
The video was enabled by German Research Foundation (DFG) core facility funding of the Biopolis Dresden Imaging Platform (BioDIP). The video has been recorded by Christian Spataro.