Microscopy: Microscope Imaging and Koehler Illumination (Ron Vale)

Learn more: www.ibiology.org/talks/koehle...
This lecture covers the lenses of the microscope and how they are used to focus light onto a specimen and how light from the specimen is focused onto a camera or the retina of an eye. Koehler illumination, which provides even illumination of a sample, is described.

[@scientia_potentia_est]

Absolutely fantastic videos! Not only do they get the theory and basic principles right and simplified enough for the beginner, but they also have real life examples and usage scenarios. As a beginner histology/microscopy technician I'm super greatful for all of these amazing videos on basic concepts in optical microscopy. Keep it up!

[@dc74835]

Thanks for taking the time to make this video.

[@CharithSenthil]

This video was so helpful. Thank you!

[@lokeshranjanjha1796]

Amazing lecture Series..!!. Thanks a lot :)

[@user-cd6xr2gr7y]

This was really helpful. Thank you so much

[@namirak1]

Great lecture! very appreciated

[@bramdashsachan868]

very well explained 👍

[@Bloomio95]

Something is off here. When you described the köhler illumination (9:49) the focus was in the condensor diaphragm, so that the image of it would be superimposed on the specimen image, but when you explained the image forming planes (16:10), the focus is on the field diaphragm. Which focus is correct? Very well made lecture by the way!

[@troglokev]

Bloomio95 both. There are two sets of conjugate planes. 1. Filament, back focal plane of condenser, front focal plane of objective. 2. Field diaphragm, specimen, back focal plane of eyepiece, retina. For Köhler illumination, both have to be focused as described. When that is correct, light from a point in the filament forms a parallel beam through the specimen. If you are using darkfield or phase contrast, it’s important to set up for Köhler illumination, because these rely on the first set of conjugate planes (the phase annulus in the front focal plane of the objective has to match the phase annulus in the back focal plane of the condenser).

[@jinmingtang1545]

I want to DIY a lightweight microscope in an automatice system, so I want to use LED illumination. Should I still need the collector and condensor? In industrial machine vision, LED light source and colliminator can also provide parallel light, can they replace this system? Thanks!

[@jinmingtang1545]

How about LED illumination? LED light source has no filament, so should it still use Koehler Illumination?

[@muftahadam2928]

Many thanks from Dr M. Adam Libya

[@nikolaradakovic5050]

Dear Dr. Ron, I would like to microscope live cultures of nitrifying and de-nitrifying bacteria. Do I need phase contrast microscope for that purpose?

[@poodook]

When does one describe a focal plane as being the "front" focal plane as opposed to being the "back" focal plane?

[@AlsXZ]

19:14 I think there is a mistake. You told "the back plane of the condenser" but should be "the back plane of the objective lens". Right?

[@jameskellinger8314]

What is the purpose of waving your hands?

[@forevergrateful7858]

Very helpful !1

[@sanzharaitbay7267]

13:17 condenser lens*

[@greenbeecolony1911]

Nice