High NA darkfield comparison

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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Hobbyst46
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Joined: Mon Aug 21, 2017 9:02 pm

High NA darkfield comparison

#1 Post by Hobbyst46 » Tue Sep 17, 2019 5:36 pm

Hello all,

Here is another small test of the Ultracondenser (cardiodid dark field oil condenser), pushing towards the high NA limit. I do not have any objectives of NA>1 with iris or funnel stops. This is a comparison between my three 100X objectives: a 100X1.3 Planapo Ph3 oil (the prestigious one) 160/0.17, and two simple 100X1.25 achromats (not Plan), one with a black collar and 160/-, and one that is all-metallic and unspecified about the coverslip. The front lens openings of the achromats are naturally smaller than that of the Planapo, and the two of them appear to be of the same diameter.
The test subject is a strew diatom slide, mountant - Pleurax, oiled above and below. Illumination was the 10W LED light, filtered through an intereference filter that passes light of wavelength<560nm, so violet+blue+green. I could narrow the range even to 450-500nm, but the intensity fell drastically so I could not see the specimen clearly, and gave it up.

The 100X1.3 is outside the feasible DF range. It yields a nice phase contrast image though, as shown.
The 100X1.25 (black) yields a quasi-DF. Some post processing made it look better.
The 100X1.25 (metal) yields an oblique view.

So - at least for hobby use, and unexpected (for me at least), those non-pretentious, non-plan objectives can be fun.
Attachments
three 100X objectives.jpg
three 100X objectives.jpg (64.71 KiB) Viewed 1662 times
100X1.3 Planapo oil Ph3 (stack of  7).jpg
100X1.3 Planapo oil Ph3 (stack of 7).jpg (30.24 KiB) Viewed 1662 times
100X1.25 oil black collar (stack of 3).jpg
100X1.25 oil black collar (stack of 3).jpg (33.77 KiB) Viewed 1662 times
100X1.25 oil black collar (stack of 3) after PP.jpg
100X1.25 oil black collar (stack of 3) after PP.jpg (28.32 KiB) Viewed 1662 times
100X1.25 oil all metal (stack of 2).jpg
100X1.25 oil all metal (stack of 2).jpg (27.36 KiB) Viewed 1662 times
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

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