h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Optical Microscopes - A629877
Author: Hell - U171578

This entry is a part of an entry complex on microscopy. It can perfectly stand alone.

I am aware of the University, nevertheless I prefer to submit this to peer review. The links will have to be added after the (potential) inclusion to the guide.

HELL

Hi HELL,

I was going to seggest a mention of oil immersion objectives in this, until I saw that you had a whole separate entry on objectives!!

Most of these are just typos or minor linguistic points. I can add almost nothing technical to your discussion.

1) "innumerous" is not a word as far as I am aware. I think you could use "numerous" to mean many or "innumerable" to mean too many to count.

2) Under "ocular" you mention that double-ocular is possible, but don't mention that this allows you to view the object in stereo. Not an issue if you are looking at v. tiny sturctures in transmission mode, but useful if you are just looking a small things by reflectance.

3) "The first number (followed by the 'x', the 'magnification factor') indicates how big a blop will look like" I think "blop" should be "blob". You don't need the "like" at the end (or at the end of the following sentence).

4) I don't know if there is a Guide entry on plane-polarisation of light, but if there is, you might want to link it under "contrast".

5)By 'try and error' is more commonly "trial & error".

6) "these lenses are very sensible towards differences" is a rather antiquated use of "sensible", more common would be to use "sensitive".

7) "paralell" under confocal should be "parallel".

8) "were made be available" - the "be" is unnecessary.

9) I would replace "common" in "in order to obtain common images" with "traditional" because otherwise, it sound's like something that the images have in common, which I don't think you intend.

As I say, all these are minor points on a generally excellant entry. Goodness knows how you have the time to write all these high quality articles!



Ugi

Again a whole lot, without much to comment on for content.

Ugi saw a number of typo's, but he left some for me
I agree with his innumerous, it doen't seem right.
Is it "appertures" or "apertures"?

"clamp which holds probe immobilized" should have "the" added after "holds".

Although "laterally" is correct, I think "horizontally" will be more clear.

A few times you say "comming", should be "coming" I think.

"at a frist glance" should be "at a first glance".

"infinetly" should be "infinitly".

"Aberrations: The resolution limt" limit.

In Sample Preparation: thechniques.

In modern optical... : (preferably monochromatic and very paralell). should be parallel.
"development and improvement of laser" better "lasers" (and again paralell)


With the magnification factor you only mention the factor, with the confocal microscope only the resolution in nm.
Can you add an indication what sort of resolution a magnification of 100 means? I always thought that you can get much more than 100.

You keep amazing me with the amount of entries, I almost don't dare to say: "Keep on the good work"!

Aw-right Margin (I'll call you Margin OK?) What happened to Marijn?

Anyways: Glad you found the mystery-typos (points for you - you're top on the highscore Marjijijn.)

Oh: It's aperture with one -p- if it's wrong in there I'll correct it ASAP. (Even though I have seen both spellings in the net, even British companies seem to mess it up.) The rest is obviously sloppy typing and laziness. I'll fix it in a moment.

--- Magnification factors versus Resolution ----

You can magnify things 20,000 times if you want. You can even do it with a Xerox-copy-machine (There was an article about that novel method XMM - Xerox magnification microscopy - as a joke in the journal of improbable research... You know? The guys from the IgNobel Prize?) ... Erm... Where were we?... Oh yes. You can magnify stuff as much as you want, if you don't have resolution it's worth nothing. Resolution is ONLY given by the numeric aperture, which can be at best 1.4 (or 1.6 if you are using - hi-toxic - carbondisulfide as immersion medium), so, the best achievable resolution for a confocal microscope can be 150 nm - period (that's the calculated limit, of course in practice you have 300 nm). The best resolution for a common microscope can be around 200 nm - period (see parenthesis before) - Plus, there is the depth resolution, but that's another loong story. The magnification will only tell how much you can enlarge the details. Counterconversely if you have super-detailed info sized as big as a thumbnail you'd probably want to have some magnification. An objective with a factor of 100 is in this case more than enough to 'see' the resolution limit (300 or so nm) as big as 30 microns or even larger if you're using more clever detectors and a computer.

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Erm... Did this confuse you even more? If so ask. I'll be glad to try to explain it again.

HELL