[OpenSPIM] Cobolt lasers in OpenSPIM?

[Jan Krieger]

Hi!

we are using Cobolt DPSS lasers in a dual-color SPIM setup (not an 
openSPIM, but a comparable design: 
http://www.dkfz.de/Macromol/research/spim.html and a new publication to 
appear in a few days/weeks: Krieger, Singh etal. (2013): "Dual-Color 
Fluorescence Cross-Correlation Spectroscopy on a Single Plane 
Illumination Microscope (SPIM-FCCS)", OPtics Express, accepted). The 
lasers are generally good, but you should care for a few things:

1. As most DPSS lasers they are stable at the specified output power, 
but might get instable if you go below 10% of that power (our 25mW 
lasers typically show a TEM20 or TEM10 mode, when driven at 1mW output 
power instead of 25mW, where they have a nice TEM00) ... but thats 
generally true for all DPSS lasers, so in oder to reduce the laser 
power, you should use neutral-density filters or waveplate+ polarizer cube.

2. The Cobolt 491nm laser is good, but has a little green light coming 
out of the cavity (a few microwatt @ ~530nm), so I would strongly advice 
a cleanup-filter. On the 561nm laser I haven't noticed anything yet.

3. A general thing on two-color illumination on a SPIM: We had some 
problems, when combining the two beams immediately behind the lasers. 
The focal points of the lasers were not overlapping (distance ~10µm), 
but then we have a very thin lightsheet (~1.5µm FWHM, i.e. NA0.3 
overilluminated) and accordingly small depth of focus. Depending on your 
application that may not be that much of a problem. Anyways we're using 
two beam expanders and combine the expanded beams. This also allows us 
to independently move the focal points along the lightsheet axis. I'm 
attatching a sketch of the setup (5x-beam expanders, 100mm/300mm relais 
telescope, 100mm cylindrical lens, 10x/NA0.3 Nikon air objective).

4. As we just replaced a ArKr laser by two DPSS lasers, I talked to a 
lot of different companies ... all the DPSS lasers are more or less 
comparable. Some are maybe spectrally a bit cleaner or slightly more 
stable, but Cobolt offers good value for the price and we are very happy 
with those guys ;-)

5. About the beam-combiner I would also have second thoughts: On the one 
hand see point 3 above and the other problem is that you can realign the 
beamcombiner (it's glued internally, so if it's missaligned at some 
point, you cannot do much), so I would simply buy a dichroic and a 
second mirror. Then you can use these two to fully align the second 
laser beam:

+---------+                \
| LASER 2 |-----------------\ mirror
+---------+                 |\
                             |
                             |
+---------+                \| dichroic
| LASER 1 |-----------------\==============> SPIM
+---------+                  \

Here you can align the SPIM first with laser 1 and then use the mirror 
and dichroic (both on kinematic mirror mounts) to align the second laser.

Hope that helps,
JAN



Am 19.12.2013 11:17, schrieb Veli-Pekka Ronkainen:
> Hi all,
>
> Has anyone used Cobolt DPSS lasers in OpenSPIM? There is a nice
> selection of lasers with different wavelengths and output powers listed
> on their catalogue. Moreover, micro-manager seems to have device support
> for Cobolts (Cobolt Laser Controller by name). We’d be interested
> especially in Cobolt Dual Combiner, which allows a permanently aligned
> combination of any 2 wavelengths to one single output. That would be
> very handy in multi-color imaging. So, can anyone comment on the Cobolts
> and the functionality in OpenSPIM?
>
> Regards,
>
> Veli-Pekka Ronkainen
>
> Biocenter Oulu, Finland
>

-------------- next part --------------
A non-text attachment was scrubbed...
Name: spim_schematic.pdf
Type: application/pdf
Size: 177011 bytes
Desc: not available
URL: <http://openspim.org/pipermail/openspim/attachments/20131219/a88e3506/attachment-0002.pdf>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: j_krieger.vcf
Type: text/x-vcard
Size: 408 bytes
Desc: not available
URL: <http://openspim.org/pipermail/openspim/attachments/20131219/a88e3506/attachment-0002.vcf>