Coverglass thickness of 0

[microscopeboi]

hey, im looking at some high mag (40-100x) nikon objectives and i noticed that some are very low priced and they all have a coverglass thickness of 0, would the resolution of these objectives be hindered if i used .13-.17mm coverglass? typically, they are the Nikon CF plan infinity corrected. Thanks

[c-krebs]

It would be best to know what objectives you are referring to. But if they are higher magnifications (40-100X) truly designed for use without a coverslip ("0") then you need to be careful. As the numerical aperture of an objective gets higher, a deviation from the designed cover slip thickness can cause image deterioration. You'll often see an NA of about 0.40 as about the largest where this effect can be tolerated, within reason. Naturally it varies greatly with the thickness error. NA's above 0.40 can be very sensitive to these errors.

Look at the discussion (and especially the last two charts... Figure 3 and Table 1) on this page to get some sense of the amount of images degradation based on NA and the thickness error.
https://www.microscopyu.com/microscopy- ... correction

[microscopeboi]

okay, thank you!

[microscopeboi]

also, the objective is:
https://www.ebay.com/itm/Nikon-CF-Plan- ... SwUu5b7Eqw

[microscopeboi]

nevermind, i contacted the seller and it turns out this was a metallurgic objective lol my bad.

[Scarodactyl]

Generally that is what a metallurgical objective is (though they'd also need to tolerate epi illumination).