Real-time laser intensity measurement
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Antonio Borgonovo |
Real-time laser intensity measurement
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Dear friends,
Does anyone know if there is any - commercial or homemade - device to measure the laser intensity during a confocal experiment in real time? or else, does any commercial confocal microscope have this possibility as a built-in feature? Thanks Simona e antonio --- Simona Rodighiero, Ph.D. Cellular and Molecular Imaging Platform Fondazione Filarete Viale Ortles 22/4 20139 Milano Tel. +39 02 56660168 |
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Ralf Zenke |
Re: Real-time laser intensity measurement
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Dear Simona,
Our Leica service technician told me that it would be possible for our SP2 (probably also for the SP5) to activate a built-in photo diode for intensity measurements. He just would need to copy or change some files. Nice regards, Ralf Ralf Zenke Max Planck Institute of Biochemistry Core Facility Am Klopferspitz 18 DE-82152 Martinsried near Munich GERMANY Phone: (+49) (89) 8578 3798 Fax: (+49) (89) 8578 2847 www.biochem.mpg.de Dear friends, Does anyone know if there is any - commercial or homemade - device to measure the laser intensity during a confocal experiment in real time? or else, does any commercial confocal microscope have this possibility as a built-in feature? Thanks Simona e antonio --- Simona Rodighiero, Ph.D. Cellular and Molecular Imaging Platform Fondazione Filarete Viale Ortles 22/4 20139 Milano Tel. +39 02 56660168
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Antonio Borgonovo |
Re: Real-time laser intensity measurement
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Thank you Ralf,
we asked our Leica technician several times about this issue, but he never told us about this possibility, at least concerning SP5. Did anyone try to activate this built-in photo diode on Leica Confocal Systems? 2009/10/28 Ralf Zenke <[hidden email]>
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G. Esteban Fernandez |
Re: Real-time laser intensity measurement
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In reply to this post by Antonio Borgonovo
Zeiss 510 confocals (don't know about thew 710) have a detector in the
laser light path to measure relative intensity during acquisition and to monitor stability over time. It is the "ChM" channel. -Esteban On Wed, Oct 28, 2009 at 5:33 AM, Antonio Borgonovo <[hidden email]> wrote: > Dear friends, > > Does anyone know if there is any - commercial or homemade - device to measure the laser > intensity during a confocal experiment in real time? or else, does any commercial confocal > microscope have this possibility as a built-in feature? > > Thank’s > Simona e antonio > > > > --- > Simona Rodighiero, Ph.D. > Cellular and Molecular Imaging Platform > Fondazione Filarete > Viale Ortles 22/4 > 20139 Milano > > Tel. +39 02 56660168 > -- G. Esteban Fernandez, Ph.D. Associate Director Molecular Cytology Core Facility University of Missouri 120 Bond Life Sciences Center Columbia, MO 65211 http://www.biotech.missouri.edu/mcc (573)882-4895 (573)884-9676 fax |
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John Oreopoulos |
Re: Real-time laser intensity measurement
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Simona,
I can think of a homemade solution for this, but it involves building some rigs around the microscope and maybe getting inside the laser combiner for your confocal microscope if you willing and able to do this (ie: protect your eyes and use safety precautions when working with open laser beams and don't break any vendor laws or patents - see earlier threads on this latter topic in the list archive). One way would be to set up a "beam pick-off" optic somewhere between your laser head and the microscope frame. This is basically an optic oriented at some angle which diverts a small percentage of the laser beam in another direction and the rest of the light passes through normally on the same path towards the objective and sample. An example of this kind of optic can be found on the New Focus website (no commercial interest): Actually, if that's too fancy or expensive, you could probably do the same thing with an angled glass coverslip, but it will divert a larger percentage of the laser beam depending on the angle you set it to be. Then you need to position a light detector - a power meter, a diode detector, or something similar - that displays the laser power. Usually these devices can be connected to a computer for data logging via Labview or some other communication language. I wrote a small Labview program to do just that for a Thorlabs power meter (no commercial interest) a few years ago and I could send this to you if you like. Any relative changes in intensity that you detect with this setup reflect changes in the fluctuation of the main laser beam going to the microscope. If you don't have easy access to the laser beam on the input side, you could try monitoring the laser beam power just after the sample if there's space in the transmission pathway of the microscope (ie: towards the condenser lens). Fluorescence is collected backwards in the epifluorescence configuration by the objective, and the excitation laser beam usually passes on right through the sample. If you place a light detector there, you can do the same thing as before. Actually, come to think of it, if your confocal microscope is outfitted with a transmission pathway PMT, you might be able to just use that PMT to monitor relative fluctuations in the laser power without inserting any optics or light detectors into the microscope light path. Our Olympus Fluoview 300 has something like that, but I haven't tried this before. Like Esteban and Ralf have said, if your microscope already has an internal light detector that can be activated, this would probably be the easier and better option to go with. John Oreopoulos, BSc, PhD Candidate University of Toronto Institute For Biomaterials and Biomedical Engineering Centre For Studies in Molecular Imaging On 28-Oct-09, at 10:57 AM, G. Esteban Fernandez wrote:
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R. Eric King |
Re: Real-time laser intensity measurement
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In reply to this post by Antonio Borgonovo
Hello Simona,
We have several different types of external &
internal beam splitters in stock with photodiode & thermopile sensors
built into them.
What type & model laser are you using ? Some
OEM laser systems already have this feature built into the laser head, but
sometimes these are simply not configured
within the power supply, or the user interface.
What is the expected power &/or wavelength
range(s) ?
Best Regards,
R. Eric
King
LASER
INNOVATIONS
----- Original Message -----
From: "Antonio Borgonovo" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, October 28, 2009 3:33
AM
Subject: Real-time laser intensity
measurement Does anyone know if there is any - commercial or homemade - device to measure the laser intensity during a confocal experiment in real time? or else, does any commercial confocal microscope have this possibility as a built-in feature? Thank's Simona e antonio --- Simona Rodighiero, Ph.D. Cellular and Molecular Imaging Platform Fondazione Filarete Viale Ortles 22/4 20139 Milano Tel. +39 02 56660168 |
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Craig Brideau |
Re: Real-time laser intensity measurement
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In reply to this post by John Oreopoulos
Expect about 2-4% reflection from an uncoated piece of glass,
depending on the polarization of the laser and angle of the coverslip. You will also want your beam narrow at the point you insert the coverslip. This will minimize any distortions in the laser beam caused by surface imperfections (and lack of flatness) in the coverslip, since you will be using less of its surface area. If you use an optical beam pickoff this will be less of a worry as they are usually polished to extremely flat tolerances. Craig On Wed, Oct 28, 2009 at 9:33 AM, John Oreopoulos <[hidden email]> wrote: > Actually, if that's too fancy or expensive, you could probably do the same > thing with an angled glass coverslip, but it will divert a larger percentage > of the laser beam depending on the angle you set it to be. Then you need to > position a light detector - a power meter, a diode detector, or something > similar - that displays the laser power. Usually these devices can be > connected to a computer for data logging via Labview or some other > communication language. I wrote a small Labview program to do just that for > a Thorlabs power meter (no commercial interest) a few years ago and I could > send this to you if you like. Any relative changes in intensity that you > detect with this setup reflect changes in the fluctuation of the main laser > beam going to the microscope. |
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Barbara Foster |
Re: Real-time laser intensity measurement
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In reply to this post by Antonio Borgonovo
Dear Simona
XCite [manufactured by Exfo] is just announcing a new stage radiometer that should be helpful. We've been waiting a long time for a commercial radiometer. While it won't measure during the experiment, it will measure at the sample plane, so you should be able to get a very close estimate if the protocol is the same. They were due to release this new product last week at Neuroscience. Their website is www.Exfo-Xcite.com. Caveat: No commercial interest Best regards, Barbara Foster, President and Sr. Consultant Microscopy/Microscopy Education 7101 Royal Glen Trail, Suite A McKinney TX 75070 P: (972)924-5310 Skype: fostermme W: www.MicroscopyEducation.com NEWS! Visit the NEW and IMPROVED www.MicroscopyEducation.com! And don't forget: MME is now scheduling customized, on-site courses for the balance of the year. Call me for a free assessment and quote. At 08:07 AM 10/28/2009, Antonio Borgonovo wrote: Dear friends, |
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simona rodighiero |
Re: Real-time laser intensity measurement
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Thank’s to all for the helpful suggestions! About the use of PMTtrans to monitor the laser intensity variations, this is useful in many application, but not if you are working with samples that change transmission properties during the experiment (i.e. The level of extracellular solution in continuously perfused cells in open chamber configuration..). The reflection signal recorded in an available PMT can be better, but only in xz, because it is too much sensitive in focal plane variations in xy acquisitions. I’ll try to do out of the SP5 secrets.. Best regards simona Il 28/10/09 17:40, "Barbara Foster" <bfoster@...> ha scritto: Dear Simona -- Simona Rodighiero, Ph.D. Piattaforma di Imaging Cellulare e Molecolare Fondazione Filarete Viale Ortles 22/4 20139 Milano Tel. +39 02 56660168 |
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George McNamara |
Re: Real-time laser intensity measurement
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In reply to this post by Antonio Borgonovo
Hi Simona,
As Craig Brideau mentioned, you can use the reflection off the coverglass-mounting medium interface. As a bonus, you get interference reflection contrast images of your specimen for free. If you don't have a LSM510 ChM or equivalent, you can use the transmitted light detector (ChD on the LSM510) to get pixel by pixel intensity measurements. When a laser (or AOTF, etc) flakes out, lines or oscillations show up most obviously when frame averaging is off. I discovered a problem with a new (3 month old) 561 nm laser this way recently. George At 06:33 AM 10/28/2009, you wrote: >Dear friends, > >Does anyone know if there is any - commercial or homemade - device >to measure the laser >intensity during a confocal experiment in real time? or else, does >any commercial confocal >microscope have this possibility as a built-in feature? > >Thank's >Simona e antonio > > > >--- >Simona Rodighiero, Ph.D. >Cellular and Molecular Imaging Platform >Fondazione Filarete >Viale Ortles 22/4 >20139 Milano > >Tel. +39 02 56660168 George McNamara, Ph.D. Image Core Manager Analytical Imaging Core Facility University of Miami, Miller School of Medicine Miami, FL 33136 [hidden email] [hidden email] 305-243-8436 office http://www.sylvester.org/AICF (Analytical Imaging Core Facility) http://www.sylvester.org/AICF/pubspectra.zip (the entire 2000+ spectra .xlsx file is in the zip file) http://home.earthlink.net/~geomcnamara |
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Craig Brideau |
Re: Real-time laser intensity measurement
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Note if you don't want the interference contrast images George
mentions, you can get a glass wedge instead. @:-) The non-parallel surfaces in a wedge prevent 'ghosting' (also can be called beam shear) that causes the phenomena. They are basically polished glass windows with a slight angle between the back and front face. Craig On Sat, Oct 31, 2009 at 10:04 AM, George McNamara <[hidden email]> wrote: > As Craig Brideau mentioned, you can use the reflection off the > coverglass-mounting medium interface. As a bonus, you get interference > reflection contrast images of your specimen for free. > > If you don't have a LSM510 ChM or equivalent, you can use the transmitted > light detector (ChD on the LSM510) to get pixel by pixel intensity > measurements. When a laser (or AOTF, etc) flakes out, lines or oscillations > show up most obviously when frame averaging is off. I discovered a problem > with a new (3 month old) 561 nm laser this way recently. > > George > > > At 06:33 AM 10/28/2009, you wrote: >> >> Dear friends, >> >> Does anyone know if there is any - commercial or homemade - device to >> measure the laser >> intensity during a confocal experiment in real time? or else, does any >> commercial confocal >> microscope have this possibility as a built-in feature? >> >> Thank's >> Simona e antonio >> >> >> >> --- >> Simona Rodighiero, Ph.D. >> Cellular and Molecular Imaging Platform >> Fondazione Filarete >> Viale Ortles 22/4 >> 20139 Milano >> >> Tel. +39 02 56660168 > > > > > > > > George McNamara, Ph.D. > Image Core Manager > Analytical Imaging Core Facility > University of Miami, Miller School of Medicine > Miami, FL 33136 > [hidden email] > [hidden email] > 305-243-8436 office > http://www.sylvester.org/AICF (Analytical Imaging Core Facility) > http://www.sylvester.org/AICF/pubspectra.zip (the entire 2000+ spectra .xlsx > file is in the zip file) > http://home.earthlink.net/~geomcnamara > |
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