http://confocal-microscopy-list.275.s1.nabble.com/Laser-Safety-and-Alignment-in-the-laboratory-tp5756773p5760781.html
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> Stephan,
>
> The first thing you'll definitely want to do is get some basic laser
> training for you and all members of your laboratory who would be involved
> in any laser beam alignment. Some universities now provide laser safety
> training courses in addition to the usual annual general lab safety
> courses. The notes and materials of one such laser safety course can be
> found here:
>
>
http://www.ehs.utoronto.ca/services/laserpg/laserhome.htm>
> Here is one specific page on good alignment practices:
>
>
http://www.ehs.utoronto.ca/Assets/ehs+Digital+Assets/ehs3/laserpg/beam+alignment.pdf>
> When I was at the University of Toronto, the laser safety program was
> still relatively new, and the person in charge for all university laser
> safety had to actively seek out labs using lasers or wait for labs to seek
> him out because there was no master list of which research labs had these
> kinds of tools and getting the word out about the course was difficult.
> Ask around at your university and find out if such a course exists there.
>
> As for rigging your own lasers into a laser combiner system for a confocal
> microscope, it can be done if you understand the combiner architecture and
> use sturdy mounts that have good stability and provide the right degrees
> of freedom for movement. Sometimes you'll find clear windows held in
> rotating mounts for each laser that act as fine adjustment beam shifters
> inside the combiner. Coupling laser light into the optical fiber that
> eventually connects to the confocal scan head can be quite frustrating and
> requires patience and practice. There is a systematic way to "walk" the
> laser beam into the right alignment, but only the technical
> representatives of your microscope maker or laser combiner will know that
> specific procedure.
>
> The other thing you should recognize is that the dichoric mirrors present
> in the laser combiners are usually designed for a specific laser
> wavelength. If the laser you're replacing is not of the same wavelength,
> you'll need to find out what the characteristics of the dichroics the
> laser beam is interacting with (transmission or reflection) are, otherwise
> you could lose a significant amount of light down the path. (If you can't
> get that specific information, just feed the laser beam through or reflect
> the beam off the mirror and measure the laser power before and after the
> mirror with a laser power meter to find out if the laser wavelength and
> mirror are compatible. You should expect 80-95% transmission or
> reflection).
>
> Finally, many laser scanning confocal microscope laser combiners use a
> polarization maintaining (PM) optical fiber to deliver light to the scan
> head and maximize light throughput, meaning that the fiber expects the
> incoming laser light to have a specific polarization orientation. If the
> polarization angle of your laser is orthogonal to the PM fiber axis, then
> you will have very little light coming out the exit end of the fiber.
> Usually this fiber orientation is vertical or horizontal with respect to
> the combiner base. Cylindrical HeNe lasers on older comber systems can be
> rotated in their mount to satisfy this condition, but this is not the case
> for small cubic diode based lasers. If when mounted to a base the diode
> laser does not have the same polarization orientation as the optical fiber
> mount in the combiner, you could insert some polarization rotating optics
> (half-wave plates) into the beam, but the custom mounts will become more
> complicated. Alternatively, if the polarization angle of the diode laser
> is vertical or horizontal with respect to the base of the laser (this
> information can be found on the laser makers website, or you can test it
> yourself with a polarizer / sheet of polaroid film), you could mount it 90
> degrees on it's side with respect to the combiner.
>
> Unfortunately I don't have much experience with the alignment of beams
> through AOTFs, but I know these devices also expect a certain laser
> polarization and they will have to be "tuned" if the new laser does not
> have the same wavelength as the old one being replaced.
>
> There may be other aspects associated with this whole process that I'm
> still not aware of or familiar with. For example, I can't tell you what
> power laser beam you should buy on your own (20 mW? 50 mW? 100 mW or
> higher?). I also recently learned that if high power lasers are to be
> coupled into such a system, it's possible the optical fiber can be damaged
> in the alignment process.
>
> The bottom line is, before you go out and experiment with this (after
> you've been certified by a laser safety training course), make sure you're
> not violating any service contracts with your microscope maker (if you
> have one). Perhaps you could buy the lasers yourself and ask ahead of time
> if your microscope provider would be willing to help you with the
> installation and save you some down time.
>
> Good luck!
>
>> John Oreopoulos
>> Research Assistant
>> Spectral Applied Research
>> 9078 Leslie Street, Unit 11
>> Richmond Hill
>> Ontario, Canada
>
>
> On 2010-11-19, at 5:07 PM, Stephen Bunnell wrote:
>
>> *****
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>>
>> Dear all,
>>
>> Although I do a good deal of imaging, I'm a biologist by training,
>> and
>> have little familiarity with the installation and alignment of lasers
>> and
>> with the pertinent safety considerations. I'd like to change this,
>> especially since I have a dead Kr/Ar laser on a 3-laser 5-line launch
>> that
>> uses an AOTF and feeds a single fiber. This laser is heavily used to
>> provide
>> both 568 and 643 lines, but is pretty weak, at ~15mW per line.
>>
>> Ideally, I'd like to replace the laser with more powerful diode-based
>> lasers, but the laser platform is a custom job, and I am not comfortable
>> drilling into it to create new mounting positions. I get the feeling
>> that it
>> would be rather expensive to migrate all the viable components to a new
>> platform and replace the Kr/Ar with diode lasers. Alternately, I could
>> get
>> the laser refurbished (a steal, at ~$2000), but then I'd still face the
>> dismounting, remounting, and alignment of the laser. I am not currently
>> comfortable with the alignment and safety aspects of such an
>> installation.
>> I'm looking for guidance on how to learn these skills. Is this the kind
>> of
>> thing one can learn by doing, or do I need expert guidance? If I'm going
>> to
>> start doing my own laser installation and alignment (and I think that I
>> should), what training and safety kit should I be getting? Where might I
>> get
>> the relevant training?
>>
>> Thanks much,
>>
>> Steve
>>
>>
>>
>>
>> ****************************************************************************
>> Stephen C. Bunnell, Ph.D.
>> Assistant Professor
>> Tufts University Medical School
>> Department of Pathology
>> Jaharis Bldg., Room 512
>> 150 Harrison Ave.
>> Boston, MA 02111
>>
>> Phone: (617) 636-2174
>> Fax: (617) 636-2990
>> Email:
[hidden email]
>