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Hi Zhang,

I agree with Pawel that this is the most probable explanation. It is known to happen with LSM700s, which indeed have no AOTF to keep their price low. A Zeiss technician can check/fix this very easily by changing laser-modulation parameters.

Best,

Laurent.
 

-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Z.J. Zhang
Sent: 12 August 2013 19:11
To: [log in to unmask]
Subject: Zeiss LSM 700 Confocal- laser problem

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Hi everyone:

I am having a weird problem with my Zeiss LSM 700 confocal microscope and hope you could shed light on it -

When I tried to scan with the lasers off (turning the lasers off via the ZEN software), I can literally see a relatively bright light coming from the objective! The light looks white, which I assume is the combination of the blue, green and red lasers. Although the detected fluorescence signal is 'minimal', it still worries that 1). It might photobleach my sample; and 2). When I scan with one laser, the other lasers might be on as well, so I wouldn't know what exactly I am scanning with!

I was told by Zeiss that this is "normal" because there are no mechanical shutters in the scan head. I have a hard time to believe it and here are my questions:

1). Does anyone experience the same/similar problem?
2). What could be the possible cause?
3). How am I supposed to fix it?

Thank you,

Zhaojie

Zhaojie Zhang, Ph. D.
Director, Jenkins Microscopy Facility
University of Wyoming
Laramie, WY 82071
PHONE: 307-766-3038
FAX: 307-766-5625