Re: Just how much can we magnigy?

From: Kevin Cunningham (smskjd_at_mindspring.com)
Date: 02/13/05 

Date: Sun, 13 Feb 2005 15:08:42 GMT

"justbeats" <steve_beats@hotmail.com> wrote in message
news:1108244940.152935.195080@z14g2000cwz.googlegroups.com...
> Ignoring self illumination (e.g. fluorescence), and assuming high
> contast, any idea of the limits on detection?
>
> For instance, a 0.05 micron black dot would be perceptable against a
> white background (but not resolved if there were two of them within
> 0.01 micron of each other).
>
> How small does the dot have to be before it can no longer be perceived?
> Does this become an issue of contrast (ratio of area of dot to area of
> background within airy disk)?
>
> Cheers
> Beats
>
There's a huge difference between detection and resolution. A detectable
thing can't be measured, thats the big difference between a resovable image
and a detectable. Dark field can detect all kinds of stuff but since you
can't resolve them it is useless.

Think of a brick building at a distance. At first you see a red brick
colored building, the building itself is resolved but the bricks aren't. At
some point as you approach the building you can see the mortar lines and the
bricks are resolved. When you are right beside the building you can see
details in the mortar and bricks. Now since we people have only one NA you
can see that magnification had nothing to do with resolving the image, it
was distance that changed.

Kevin Cunningham

Relevant Pages

  • Re: Just how much can we magnigy?
    ... >There's a huge difference between detection and resolution. ... thats the big difference between a resovable image ... >can't resolve them it is useless. ... the building itself is resolved but the bricks aren't. ...
    (sci.techniques.microscopy)
  • Re: Just how much can we magnigy?
    ... > 0.01 micron of each other). ... > How small does the dot have to be before it can no longer be perceived? ... These are small aerosol-type particles, ... Detection has to do with received power, signal to noise considerations, ...
    (sci.techniques.microscopy)
  • Re: Just how much can we magnigy?
    ... any idea of the limits on detection? ... a 0.05 micron black dot would be perceptable against a ... white background (but not resolved if there were two of them within ... How small does the dot have to be before it can no longer be perceived? ...
    (sci.techniques.microscopy)