Re: Safe to run multiphoton laser at 100% power for overnight continuous imaging?

Posted by Moulding, Dale on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Safe-to-run-multiphoton-laser-at-100-power-for-overnight-continuous-imaging-tp7588726p7588742.html

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Hi Craig,

that is the exact model of power meter I destroyed trying to measure 2P laser power. I was new to the job and had no idea the power meter had limits. I measured visible lasers and got expected results. Measured 2P laser and each time I repeated the measure the value decreased, a lot!
Asked thorlabs, and they explained I’d somewhat exceeded the power capacity as peak power was 100s of kW and average power >2W. Considerably more than the 150 mW limit. I asked if the 175C thermal meter (2W max) would be ok but Thorlabs didn’t recommend it.
I no longer measure the 2P laser power directly, but do periodic comparisons of chroma slide brightness to check powers are as expected.

Any recommendations for an economical 2P suitable meter?

Cheers

Dale

Dale Moulding PhD FRMS
ICH Light Microscopy Facility
UCL Great Ormond Street lnstitute of Child Health
30 Guilford Street
London WC1N 1EH
Mob: [phone]
Tel: [phone]
Please acknowledge use of the BRC funded facility in all publications:
http://www.ucl.ac.uk/ich/core-scientific-facilities-centres/confocal-microscopy

________________________________
From: Confocal Microscopy List <[hidden email]> on behalf of Craig Brideau <[hidden email]>
Sent: 26 September 2018 18:18:04
To: [hidden email]
Subject: Re: Safe to run multiphoton laser at 100% power for overnight continuous imaging?

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If you will allow me a shameless plug, I assisted Thorlabs with the design
for a power meter for this specific purpose. I worked with the prototype
and provided feedback alongside Dr. Pina Colarusso. There is an index
matching gel under the surface which deals with the high NA rays, and you
can use water or immersion oil safely on the sensor face:

https://www.thorlabs.com/thorproduct.cfm?partnumber=S170C

It is actually manufactured at one of their facilities in Germany. :)

Craig



On Wed, Sep 26, 2018 at 5:17 AM Steffen Dietzel <[hidden email]> wrote:

> But (as far as I know) the usual power meters only give an accurate
> reading with light that falls orthogonally on their surface. So with a
> high NA objective, at the sample plane the measured value would be
> substantially less than the actual power and you only get a 'minimal
> estimate'.
> Apparently it is virtually impossible to do this measurement at the
> sample plane accurately with the usual tools.
>
> Steffen
>
> --
> ------------------------------------------------------------
> Steffen Dietzel, PD Dr. rer. nat
> Ludwig-Maximilians-Universität München
> Biomedical Center (BMC)
> Head of the Core Facility Bioimaging
>
> Großhaderner Straße 9
> D-82152 Planegg-Martinsried
> Germany
>
> http://www.bioimaging.bmc.med.uni-muenchen.de
>