*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****
I certainly wasn't advocating going to 50C as a routine practice - my
point was that gradients were likely to be more damaging than absolute
temperature. As to pol lenses - I think it's just selection. They
simply pick out the ones which don't show any strain. I know all the
manufacturers read this but I'll bet not one answers!
Guy
Sponsor my next half-marathon on May 15th
There's a special reason - find it out at
http://www.everydayhero.com.au/Guy_Cox_4846
______________________________________________
Associate Professor Guy Cox, MA, DPhil(Oxon)
Australian Centre for Microscopy & Microanalysis,
Madsen Building F09, University of Sydney, NSW 2006
Phone +61 2 9351 3176 Fax +61 2 9351 7682
Mobile 0413 281 861
______________________________________________
http://www.guycox.net
-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]]
On Behalf Of James Pawley
Sent: Wednesday, 30 March 2011 2:27 PM
To: [log in to unmask]
Subject: Re: Objective Heaters
*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****
>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>Maybe I should point out to Dan that it was Steve Cody, not Wamer, who
>mentioned their product. Both Steve and I are interested in the whole
>range of these products simply because we cater for a wide range of
>users, we teach courses for all comers, and (in my case at least) write
>books for the whole gamut of life-science researchers.
>
>
>
>So I would still be interested to get a response from Dan to my query -
>why is it that his controller cannot detect that the heater is detached
>from the lens? It should be simple.
>
>
>
>As to the temperature a lens can handle, I am sure 50C is not a problem
>but it is vital to heat it slowly - there is a lot of glass there and
it
>is a very poor conductor of heat. (Brass isn't that good but it's a
lot
>better than glass). I suspect a body at 50C with optics at 20C would
be
>disastrous.
>
>
>
>
>Guy
Hi Guy and Dan,
I don't have any experience myself but thought that it might be worth
noting that in Chapter 11 (on PSF), Rimas Juskaitis mentions that
when he cycled one lens from RT to 37 deg and back the process
changed the PSF of the lens by a small but detectable amount. Of
course, this wasn't the purpose of the experiment and it is possible
that the lens (or the oil) had not yet regained temperature
equilibrium etc.
However, the change impressed him enough that he mentioned it.
So I am not sure I would want to go to 50 deg. Maybe it might work in
a Pol lens where the lens elements are supposed to be held in such a
way that they are not strained by forces from the mount. I don't know
how they do this but I assume that it means a somewhat more gentle
connection between the brass and glass components. If this is so,
then differences in expansion coefficient between the glass and the
brass may be less likely to distort the shape of the optical surfaces.
Best,
Jim P.
************************************************************************
***
Prof. James B. Pawley, Ph.
608-238-3953
21. N. Prospect Ave. Madison, WI 53726 USA
[log in to unmask]
3D Microscopy of Living Cells Course, June 11-23, 2011, UBC, Vancouver
Canada
Info: http://www.3dcourse.ubc.ca/ Applications due by March
15, 2011
"If it ain't diffraction, it must be statistics." Anon.
>
>
>Sponsor my next half-marathon on May 15th
>
>There's a special reason - find it out at
>
>http://www.everydayhero.com.au/Guy_Cox_4846
><http://www.everydayhero.com.au/Guy_Cox_4846>
>
>______________________________________________
>
>Associate Professor Guy Cox, MA, DPhil(Oxon)
>
>Australian Centre for Microscopy & Microanalysis,
>
>Madsen Building F09, University of Sydney, NSW 2006
>
>
>
>Phone +61 2 9351 3176 Fax +61 2 9351 7682
>
> Mobile 0413 281 861
>
>______________________________________________
>
> http://www.guycox.net <http://www.guycox.net/>
>
>
>
>From: Confocal Microscopy List
[mailto:[log in to unmask]]
>On Behalf Of Dan Focht
>Sent: Tuesday, 29 March 2011 7:25 AM
>To: [log in to unmask]
>Subject: Re: Objective Heaters
>
>
>
>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>Stephan
>
>
>I agree that boxing the whole microscope or stage and objective area is
>a solution.
>However, for those who don't want to box the scope for a variety of
>reasons. The following applies.
>
>From the Warner web page:
>"Heat generated by the isolated collar is not directly communicated to
>the objective but is instead distributed around the objective via a
>conducting sleeve."
>
>When I read this my first impression is, "What?, they intentionally
>isolate the heat source from the objective!"
>That means they rely on radiation, which goes in all directions (not
>just toward the objective) and a little conductivity from air, another
>inefficient heat transfer means.
>Thermal conductivity of air 0.024 W/(m.oC). Thermal conductivity of
>brass 109 W/(m.oC). In terms of thermal transfer efficiency, there is
no
>comparison, not even in the ball park!
>
>Again from the Warner site:
>"The conducting sleeve warms the surrounding air, which in turn gently
>warms the objective. This approach allows the apparatus to take full
>advantage of the thermal characteristics of the surrounding air. The
>warmer achieves its task without directly contacting or exposing the
>objective to significant stresses associated with temperature
>gradients."
>
>I look at it this way.
>I know the thermal characteristics of air, and it is poor.
>You have an objective screwed into a nosepiece that you want to warm to
>37 degrees C.
>The objective is about 150 to 225 grams of brass, glass and airspace
not
>to mention the mass of the nosepiece.
>I mention the mass of the nosepiece because it acts as a heat sink
>requiring constant compensation thus more energy to maintain constant
>temperature.
>
>1. Do you think you can accurately transfer enough heat to warm the
>objective with the additional thermal drain of the nosepiece from an
>air-spaced heat source without excessive heat being produced in the
>vicinity of the objective where it radiates outward and upward?
>
>2. Do you think you can maintain a constant accurate temperature when
>you have to wait for the heat to be transferred through air to get to
>the objective without inducing excessive temperature cycling?
> It is the inefficiency of heat transfer that causes cycling. We
>thermally profile objectives to be certain that the surface that heat
is
>transferred from or to is as efficient as possible to minimize
>
>3. If your thermal transfer efficiency is as good as it should be, the
>heat source only has to be only a couple of percent higher than the
>temperature of the objective.
>Given the thermal inefficiency of air, I never even entertained using
>air to conduct heat to an objective.
>However, if someone out there has one of these and would lend it to me
>for a couple of days, I would be glad to do a thermal propagation
>time-lapse of it with our military grade quantitative IR camera.
>It would be in movie form and I would make it available to anyone that
>wants it. This is a costly thing to do but the data would be worth it.
>
>Note, All four major microscope manufacturers have issued a letter to
me
>that the objectives can withstand up to 50 degrees C. I thought that
>was generous but understandable.
>The temperature of the objective can get a lot higher than 37 degrees
>while it is sitting in the delivery truck waiting to be delivered.
>
>Note, I refrained from naming other companies in my first reply. Now
>that the door is open, I guess ,SWAG, I can walk in.
>
>
>Dan
>
>
>
>> From: Stephen Cody <[log in to unmask]>
>> Date: March 27, 2011 10:30:22 PM EDT
>> To: [log in to unmask]
>> Subject: Re: Objective Heaters
>> Reply-To: Confocal Microscopy List
<[log in to unmask]>
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Dear List,
>>
>> For the sake of completeness I think the Warner objective heater
>should be
>> mentioned. This differs slightly from those discussed so far, in
that
>the
>> heating collar is not directly coupled to the lens. There is instead
a
>> deliberate air space between the heating collar and lens. Presumably
>this
>> adds a little capacitance to the heat transfer process. It may
reduce
>some
>> of the tendency for temperature cycling. It also is their way of
>simplifying
>> the build to suit different shapes and sizes of lens, although they
>sell
>> small, medium and large versions. It should avoid problems with
badly
>> attached heat sensors. Presumably the heat sensor is on the collar
>itself or
>> in the airspace, this would result in a slow, but conservative
heating
>> mechanism.
>>
>> I myself use heated chambers that enclose the stage and objectives,
>with a
>> sub-incubator to control CO2 / Oxygen / Nitrogen and humidity.
>>
>> See link:
>http://www.warneronline.com/product_info.cfm?id=1365&name=Objective
> > Warmers
>>
>>
>> Caveats: I haven't used any commercial objective heaters,
>> No commercial affiliation with any objective heater companies.
>>
>> --
>> Stephen H. Cody
>
>Dan Focht
>[log in to unmask]
>Bioptechs, Inc.
>3560 Beck Rd.
>Butler, PA 16002
>www.bioptechs.com
>Direct 724-282-7145
>Fax 724-282-0745
>Toll Free 877 LIVE-CELL - (548-3235)
>
>________________________________
>
>No virus found in this message.
>Checked by AVG - www.avg.com
>Version: 10.0.1204 / Virus Database: 1498/3534 - Release Date: 03/27/11
--
************************************************************************
***
Prof. James B. Pawley, Ph.
608-238-3953
21. N. Prospect Ave. Madison, WI 53726 USA
[log in to unmask]
3D Microscopy of Living Cells Course, June 11-23, 2011, UBC, Vancouver
Canada
Info: http://www.3dcourse.ubc.ca/ Applications due by March
15, 2011
"If it ain't diffraction, it must be statistics." Anon.
|
