AstroBlog

While I read a lot about how important is correct cover slip thickness for high quality microphoto I never actually realized how DAMN important it really is. Below you can see results of my small experiment where I set cover slip thickness collar to 0.12-0.2mm on Carl Zeiss Jena 40X 0.95 dry objective. (One on the left http://www.microscopy-uk.org.uk/mag//imgoct06/iw40x1.jpg). Being high NA dry lens it is very susceptible to all deviations from the designed parameters. In my case the distance between the objective and CCD was way above the designed 160mm (Probably close to 210mm). And due to this fact (I believe) I can see more through the eyepiece than when using my Canon 550D.

Anyway here is the video

Better quality downloadable AVI file is here

ObjectiveCollarAnimation (69)

Technical details:

I took 9 frames with Canon 550D in so called silent mode (using liveview) each at different collar settings.

I didn’t move the subject, change the lighting or anything else. So the difference is solely due to different levels of spherical aberration. As you can plainly see in my case 0.2mm cover slip thickness is optimal. Unfortunately I cannot go above that value to test I image quality can be improved further. I’ll do this test one more time when I have Canon adapter of correct length.

Spherical aberration in hi NA dry microscope objective, 10.0 out of 10 based on 2 ratings

Tags:

This entry was posted by admin on Tuesday, May 31st, 2011 at 20:02 and is filed under Microscope. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.