Coverslips

[ChrisR]

Having discovered that my box of coverslips is the "wrong" thickness (number 1, 0.13mm - 0.17mm) which measure 0.12 - 0.13mm
I'm looking for a supplier (in the UK, probably) of something close to 0.17mm coverslips.
I have to wonder if the cheapest available are out-of-specification thickness!
From the calculation Rik provided, I get that with a humble 'scope's 100x NA 1.2 objective, if the coverslip thickness is out by 4 microns, it gives a half wavefront error. I may be out, but it's sensitive.

Even the correct designation slips, number 1½, is 0.15-0.19mm
DO they usually fall near the middle of the range?
I don't need many but I'd like them to be right. 0.168 - 0.172, please!
Any suggested suppliers?

[Charles Krebs]

https://www.micro-shop.zeiss.com/?l=en& ... 0-9000-000 (about halfway down page)
These have the tightest spec I have seen... D=0.17 mm +/- 0.005
$42/1000

The same are also sold at various places under the Mariienfeld name:
http://www.marienfeld-superior.com/inde ... copes.html

And Schott name as well:
http://www.us.schott.com/nexterion/engl ... ps.html#04


#1.5 covers usually vary between 0.15 to 0.19 in a package, with most in the .016-.018 range. .

From the calculation Rik provided, I get that with a humble 'scope's 100x NA 1.2 objective, if the coverslip thickness is out by 4 microns, it gives a half wavefront error.

No. This is an oil immersion objective. It must be used with immersion oil (the same RI as glass) so the objective "sees" the distance from the objective tip to the subject (which should ideally be in contact with the cover) as a single continuous space with an RI of 1.52. That's why you will rarely find correction collars on oil immersion objectives... not normally needed. It is the "high/dry" (high NA, no oil immersion) objectives that you really need to be careful with as far as cover slip thickness goes. (And if they have a correction collar you have that leeway built in ).

[ChrisR]

tip to the subject (which should ideally be in contact with the cover) as a single continuous space with an RI of 1.52

Ah, got it, thanks, and for the links.
If you have something like a stoma on a leaf (or an insect wing), under a coverslip to hold the leaf flat, would you use something on the underside of the coverslip covering the specimen?

I gather this is where glycerine objectives can come in, but I doubt I'll be using those.