Hi all,
I have a question about airy patterns and how these determine resolution in images. So to increase resolution the airy pattern should be made smaller. In microscopy this is achieved by using higher numerical aperture lenses and shorter wavelengths. I have also read that the more diffraction orders the lens can capture the higher the resolution or perhaps its that the image is a more accurate representation of the object. One thing i find confusing is that the zeroth order or central maximum is said to be the light that is undeviated or not diffracted so how is this actually useful information? Secondly, in confocal microscopy it is conventional to set the detection pinhole to one airy unit which i understand to mean that the zeroth order and the 1st order (minimum) is also captured everything outside this is excluded. And in fact making the pinhole smaller than 1 airy unit actually improves resolution. So to me i find these two points contradictory, i.e. you want to capture as many diffraction orders as possible yet with confocal you gain resolution by not doing this.. Can anyone explain if i've misinterpreted something here? I understand that a compromise has to be met when setting the pinhole as allowing too much light through increases the optical section and reduces resolution. I guess i've been thinking about the airy pattern influencing lateral resolution, hence capture more orders yet for axial resolution you'd want to minimise the amount of the airy pattern that you capture..
I'd really appreciate any feedback on this.
Thanks,
Matt
I have a question about airy patterns and how these determine resolution in images. So to increase resolution the airy pattern should be made smaller. In microscopy this is achieved by using higher numerical aperture lenses and shorter wavelengths. I have also read that the more diffraction orders the lens can capture the higher the resolution or perhaps its that the image is a more accurate representation of the object. One thing i find confusing is that the zeroth order or central maximum is said to be the light that is undeviated or not diffracted so how is this actually useful information? Secondly, in confocal microscopy it is conventional to set the detection pinhole to one airy unit which i understand to mean that the zeroth order and the 1st order (minimum) is also captured everything outside this is excluded. And in fact making the pinhole smaller than 1 airy unit actually improves resolution. So to me i find these two points contradictory, i.e. you want to capture as many diffraction orders as possible yet with confocal you gain resolution by not doing this.. Can anyone explain if i've misinterpreted something here? I understand that a compromise has to be met when setting the pinhole as allowing too much light through increases the optical section and reduces resolution. I guess i've been thinking about the airy pattern influencing lateral resolution, hence capture more orders yet for axial resolution you'd want to minimise the amount of the airy pattern that you capture..
I'd really appreciate any feedback on this.
Thanks,
Matt