Ripples in 488nm channel

[Charu Tanwar]

I must thank you all for all the valuable suggestions. I will take some time to try all of them and then keep you updated.

Thanks

Charu

CHARU TANWAR
Imaging Specialist
Advanced Instrumentation Research Facility
Jawaharlal Nehru University
New Delhi 110067
India.

--- On Mon, 17/5/10, [hidden email] <[hidden email]> wrote:

From: [hidden email] <[hidden email]>
Subject: Re: Ripples in 488nm channel
To: [hidden email]
Date: Monday, 17 May, 2010, 4:15 PM

Hi,
 
here's another hint: Check activity in other labs next to you. I once had an
issue with laser fluctuations that were caused by a machine next door. Okay, no
definite proof for this, but plugging the laser to a different power circuit
solved the issue. Sorry for the double post if this has been suggested
already...
 
-Martin
--
Dr.rer.nat. Martin Vogel
Max-Planck-Institute of Biophysics
Frankfurt, Germany


Johannes Helm <p.j.helm@...> hat am 17. Mai 2010 um 12:22
geschrieben:

> Hi, again, Charu,
>
>
> the weird thing is that you don't have the ripples in the morning, when
> starting, but get them later on.
>
> In order to make the haystack with the hidden needle a little bit smaller,
> is it possible that you do the following things (unless you've already
> done them):
>
> a)
> Switch off the laser for quite some time so that it can coold down but
> keep the rest of the setup switched on. Then scan. Are the ripples there
> at once or not?
>
> b)
> If the ripples are there straight away in a), keep the laser on and switch
> off the rest and keep the rest switched off for quite some time to cool
> down. Switch on again and scan. Ripples there at once?
>
> c)
> Possibly the ripples aren't there straight away in neither a) nor b).
> Then, keep everything on for quite some time but do not scan. Like that,
> any fibers, fibercouplings, apertures a.s.o. in the ray path of the laser
> beam could cool down. Then scan again. Are the ripples there at once?
>
> This might help to nail down the culprit.
>
> Good success and best wishes,
>
> Johannes
>
>
> --
> P. Johannes Helm
>
> Voice:        ([phone] (office)
> Fax:        [phone] (office)

[Michael Weber-4]

That sounds like a challenging riddle. Can I recapitulate that...
- you are using an Olympus FV1000
- the problem appears in channel 1+2
- ... and with every objective
- ... also in transmitted light
- ... but only with 488 nm
- ... and only after a certain runtime
?

Some thoughts:
1) Channels 1+2 in a FV1000 are usually spectral detectors, right? Do you
have ordinary filter-based channels available? This should be channel 3 in
a standard configuration. Check if you get ripples there with 488 nm
excitation. The spectral channels have a lower optical density and
therefore block less back-reflected light.
2) What is the range of laser power you are using? Try to image at 2-5 %
AOTF transmission max. (setting in the Fluoview software). Do you still
get ripples?
3) Since the ripples appear in transmitted light as well, it cannot be
back-reflection (only). Do the ripples appear with other wavelengths of
the Argon laser - i.e. 458 or 514 nm? If yes, I would guess something is
wrong with the laser coupling. Probably not the fiber itself, because then
I would expect it to appear with the remaining visible light wavelengths
emitted by the other lasers (561, 633 nm etc.) as well.

Good luck, and keep us updated!

Michael

> I must thank you all for all the valuable suggestions. I will take some
> time to try all of them and then keep you updated.
> Thanks
> Charu
>
> CHARU TANWAR
> Imaging Specialist
> Advanced Instrumentation Research Facility
> Jawaharlal Nehru University
> New Delhi 110067
> India.
>
> --- On Mon, 17/5/10, [hidden email] <[hidden email]> wrote:
>
>
> From: [hidden email] <[hidden email]>
> Subject: Re: Ripples in 488nm channel
> To: [hidden email]
> Date: Monday, 17 May, 2010, 4:15 PM
>
>
> Hi,
>  
> here's another hint: Check activity in other labs next to you. I once had
> an
> issue with laser fluctuations that were caused by a machine next door.
> Okay, no
> definite proof for this, but plugging the laser to a different power
> circuit
> solved the issue. Sorry for the double post if this has been suggested
> already...
>  
> -Martin
> --
> Dr.rer.nat. Martin Vogel
> Max-Planck-Institute of Biophysics
> Frankfurt, Germany
>
>
> Johannes Helm <[hidden email]> hat am 17. Mai 2010 um 12:22
> geschrieben:
>
>> Hi, again, Charu,
>>
>>
>> the weird thing is that you don't have the ripples in the morning, when
>> starting, but get them later on.
>>
>> In order to make the haystack with the hidden needle a little bit
>> smaller,
>> is it possible that you do the following things (unless you've already
>> done them):
>>
>> a)
>> Switch off the laser for quite some time so that it can coold down but
>> keep the rest of the setup switched on. Then scan. Are the ripples there
>> at once or not?
>>
>> b)
>> If the ripples are there straight away in a), keep the laser on and
>> switch
>> off the rest and keep the rest switched off for quite some time to cool
>> down. Switch on again and scan. Ripples there at once?
>>
>> c)
>> Possibly the ripples aren't there straight away in neither a) nor b).
>> Then, keep everything on for quite some time but do not scan. Like that,
>> any fibers, fibercouplings, apertures a.s.o. in the ray path of the
>> laser
>> beam could cool down. Then scan again. Are the ripples there at once?
>>
>> This might help to nail down the culprit.
>>
>> Good success and best wishes,
>>
>> Johannes
>>
>>
>> --
>> P. Johannes Helm
>>
>> Voice:        ([phone] (office)
>> Fax:        [phone] (office)