Re: Kohler illumination question...


"GTO" <gregor_o@xxxxxxxxxxxxxxx> wrote in message
news:uFWde.909$X21.151@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Did we reach the limit of what we can accomplish with optical microscopy?
> I do not think so. An interesting step into the right direction was
> recently commercialized by Olympus (followed by others, of course) that is
> known as TIRF [1]. But more exciting ways to improve optics is the theory
> of surface plasmon polaritons, a rather new field in optics [2]. Surface
> plasmon polaritons offer a resolution beyond the diffraction limit and may
> open new gateways to future developments in optical microscopy while still
> be considered non near-field applications. Unfortunately, theoretical work
> on SPP's just started. More about SPP's is in [3].
>
> Again, to push optical microscopy into the future, much Physics will have
> to be learned and perfected. But to create a commercial product that
> outperforms the competition, many experiments must be conducted that
> cannot completely be described with Physical models. Either because we
> just don't know exactly the Physics involved or it is just computationally
> not feasible to quantitatively cover the qualitative output of a complex
> experiment.
>
> Most likely, the chair you are sitting in cannot exactly be described with
> any Physical model and all the computational power available. But for your
> chair, what we can calculate might be good enough. Or not? - Wait until
> your chair breaks.
>
> If now the good old Köhler illumination has reached its limit regarding
> today's implementation is a question I cannot objectively answer. But it
> is always good to look at the details, although some of them may not fit
> into the equation. But again, since the perfect microscope does not exist
> (e.g. Apochromats are not corrected for all wavelengths but just for a
> few!), we may already screw up our implementation so much that "perfect
> Köhler" will not come to the rescue.
>
> Gregor
>
> [1] http://www.microscopyu.com/articles/fluorescence/tirf/tirfintro.html
> [2] Smolyaninov I.I. et al, Phys. Rev. Lett., 94, 057401 (2005).
> [3] http://www.unice.fr/lpmc/bdd/agg/download/S-Maxime1.pdf
>
> "justbeats" <steve_beats@xxxxxxxxxxx> wrote in message
> news:1115112720.709666.221980@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> I would not be surprised if we see further improvements even
>> in the design of our old Köhler illumination.
>
> But for all intents and purposes, a modern scope is already running
> "diffraction limited", so what practical benefit could improvements
> offer? Making it cheaper and/or easier to set up would seem the only
> (commercially) viable improvements worth pursuing.
>
Way back in the '20's (I think) TIRF was called "evanescent wave". Some
work was done with it but not a lot since it was difficult to do some things
with it. Evanescent wave travel a very short distance. Decades go by and
better microscopes are built and TIRF comes into favor. The technique
answers some questions we are looking at now. One of my customers was
looking at it. It's really neat to find old types of microscopy coming back
into favor.

Kevin Cunningham
SMS


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