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Hi Steffen, 

In my experience, a turnkey confocal with its interlocks intact will have
all or at least the great majority of the appropriate controls built in.
The important exception is multiphoton scopes, which often had an open
beam path and a powerful beam that could do real damage.

Also, you cannot really align a TIRF system without sending a coherent
beam straight out of the objective.  When doing that you really need to 1)
wear glasses, 2) have unnecessary people out of the room, 3) and keep the
plane of TIRF angle alignment in mind before powering up.  If you turn the
laser on without pointing it straight up first you can easily scan it
across someone¹s face.

Finally, users of this listserv are more likely than most to hotrod their
systems and bypass at least some of the laser safety controls built into
an out of the box scope.  It therefore seems like a pretty good idea to
talk about it here.

All the best, 


TF

Timothy Feinstein, Ph.D. | Confocal Manager
333 Bostwick Ave., N.E., Grand Rapids, Michigan 49503
Phone: 616-234-5819 | Email: [log in to unmask]







On 10/29/13, 6:27 AM, "Steffen Dietzel" <[log in to unmask]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>Since we are on the confocal list, let me ask the following: How much
>danger is there really from lasers in commercial instruments, provided
>the housing is intact. Let's put aside for a moment those devices with
>an open laser beam on the bench - that's obviously a different pair of
>shoes.
>
>In a typical commercial confocal, the laser comes out only after running
>through lenses, so whatever comes out of the objective (or out of the
>revolver, should the objective be screwed out) is not a parallel beam
>but a cone of light which increases in diameter rather fast. So I would
>think that unless someone manages to put his eye directly in front of a
>long distance, low NA objective, the whole thing would be probably less
>dangerous than a laser pointer held by the stereotypical distraught
>professor in front of his audience. Even if the confocal laser has >100
>mW to start with, as in some FRAP-Designs.
>
>Did I miss something?
>
>Not that I would recommend messing around with the laser light, but so
>far I always thought this danger to be negligible.
>
>Steffen
>
>-- 
>------------------------------------------------------------
>Steffen Dietzel, PD Dr. rer. nat
>Ludwig-Maximilians-Universität München
>Walter-Brendel-Zentrum für experimentelle Medizin (WBex)
>Head of light microscopy
>
>Mail room:
>Marchioninistr. 15, D-81377 München
>
>Building location:
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