TIR critical angle re-adjustent

Posted by Rietdorf, Jens on
URL: http://confocal-microscopy-list.275.s1.nabble.com/reducing-size-of-illumination-in-epi-fluorescence-tp593586p593593.html

Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal

Dear Vitaly,

Both Leica and Zeiss (no commercial interest) provide solutions for
automatic adjustment of the incident beam angle (provided you measure
the tilt of the reflecting interface for each sample). We used simple
stepper motors to automate the turning of the micrometer screw of an
Olympus 3 line setup (again n.c.i) Be aware, the field is decaying
exponentially and you can influence for example the half evanescence
field depth by the angle, [so the distance at which the incident power
has decreased to 50%], but not the depth of the field of view, which in
turn also depends on the incident power and on the concentration and
brightness of the fluorophores.

Cheers, jens

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On
Behalf Of Vitaly Boyko
Sent: Thursday, July 24, 2008 4:48 PM
To: [hidden email]
Subject: TIR critical angle re-adjustent

Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal

Dear All,

Yesterday I have tested our new 585 nm laser in conjuction with 514 nm
argon
and 437 nm diode under TIR conditions.

Even though I have not noticed the need for the critical angle
re-adjustment
between 437 nm and 514 nm lines (77 nm difference), however, when the
critical angle was set for the yellow laser (585 nm), switching from 585
nm
to 514 nm line  (71 nm difference) required the (manual) resetting of
the
critical angle.
I used the 89006 triple beamsplitter (A/R coated), which seemed to
reflect
the 514 argon line (up to 70%).

I am looking for help with the device that would allow quick, low msec
range, critical angle re-adjustment or any other suggestions will be
appreciated.

Thanks a lot in advance,

Vitaly

Vitaly P. Boyko,
NCI-Frederick,
301-846-6575