NetNotes
cleaned the anode and cathode hoping the removing any debris would help solve my issue. Te vacuum pumping out the system is working fine and easily pumps below 100 mTorr. SeeVac appears to have gone under or been bought since making the Conductavac IV (~25 years of age) so trying to find a troubleshooting source has been difficult. Any suggestions, whether is specially pertains to the Conductavac IV or any sputter coater, on my amp problem will be greatly appreciated. Joe Heintz
josephheintz@gmail.com Tu Aug 4 Check for breakdown of the high-temperature epoxy around the
electrical feed-through at the top. I had that problem in the past. Phil Oshel
oshel1pe@cmich.edu Tu Aug 4 My start at troubleshooting would be to determine (1) if the
ammeter is at fault or (2) if the current being measured is really fluctuating as the meter seems to indicate. Background: Ammeters are typically voltmeters that measure the voltage drop across a shunt resistor. Ten, using Ohms law, the current measured = I = V/R, where V is the voltage drop measured and R is the value of the shunt resistance. Te shunt resistor may be external to the meter, inside the meter case, or for very low currents the resistance of the meter coil itself will suffice (there would be no shunt resistor—external or internal—in this instance). Suggested troubleshooting: Aſter rechecking and cleaning any connections to a possible external shunt resistor, I would substitute a good digital volt-ohm-meter (a typical Fluke 112, etc.) for the suspect ammeter, set to read amperage, and see if the fluctuations reproduce. With the results of this test, you should then know whether the meter needs replacing or you need to keep looking elsewhere. Rick Ross
richard.ross@
allisontransmission.com Tu Aug 4
Instrumentation: cleaning mirrors I’d like to know if anyone has attempted to successfully clean the
oil off of a dirty mirror without ruining it or drilled out a larger hole through the mirror to get a wider field of view. Please let me know if you have tried these things, even if it didn’t work. Dan Ruscitto ruscid2@
rpi.edu Tu Jul 14 I routinely clean dielectric-coated front surface mirrors in
positioning interferometers by blowing dust off and solvent/blow dry cleaning with airbrush. Tis method may work for metal front-surface mirrors, but I never tried it. Instead of drilling larger hole in existing mirror and risking ruining the instrument, I’d suggest making a replacement with the desired hole and substituting it for existing. Higher cost, but you have a solid fallback plan in case something goes wrong. Valery Ray
vray@partbeamsystech.com Tu Jul 14
Instrumentation: Lytro camera Has anyone else seen this:
http://www.lytro.com/? My immediate
questions: 1. Does it actually work? 2. Can it be applied to microscopy? James M. Ehrman
jehrman@mta.ca Fri Aug 12 Is it just a fancy way of presenting extended focus images? You
click on the picture and it knows which image in the through focus series to show? Rosemary White
rosemary.white@csiro.au Sat Aug 13 Tis type of camera is known as a plenoptic camera.
Wikipedia has a short description of this technology here: http://
en.wikipedia.org/wiki/Plenoptic_camera the references do a good job explaining the technology in depth. In fact, reference 2 is a paper coauthored by the founder, Dr. Ren Ng, of Lytro. Tis video from Adobe shows the technology in action:
http://www.youtube.com/ watch?v=jS7usnHmNZ0. Chris Winkler
microwink@gmail.com Sat Aug 13
58
I saw this new technology, and my first impulse was the same:
Can that be used for microscopy? If you look at the technology, it works essentially by breaking up the image into many smaller images through the use of an array of microlenses. Tese lenses are spatially distributed, and each one sees the object from a slightly different angle. A modern light microscope is “infinity corrected.” Te objective lenses are designed so that the light is focused to infinity. If I understand that correctly, the microlenses in such a camera would all see the same image, and the images could not be focused aſter the fact. Of course, it might be possible to design objective lenses that allow the use of such a camera. Mike Bode
mike.bode@resaltatech. com Sun Aug 14
Instrumentation: inverted microscopes I am a big fan of data, calculations or references if you can supply
any. Tere is some lore in my facility that inverted microscopes are optically inferior to upright microscopes. I realize they have a more complicated light path. Terefore, I’m wondering with a modern microscope how inferior, if at all, are inverted microscopes compared to upright microscopes everything else being equal (objectives, filters, camera and sample preparation). Mary Raven mary.raven@lifesci.
ucsb.edu Wed Aug 17 Te customary difference is that an inverted scope is supplied
with a long working distance and hence lower NA condenser. So for transmitted light modes, the NA of the inverted condenser is too small to fill the objective and hence imaging suffers. Note that this doesn’t matter for fluorescence and other incident light modes, and many inverteds can be equipped with a high NA condenser and thus brought to par (of course the working distance will go down). Tobias Baskin
baskin@bio.umass.edu Wed Aug 17
TEM:
biosample at 200 KV We have one user that prepares his biological tissues in resin
and then cut them for TEM studies. He has been using an 80 kV TEM for that, but that TEM doesn’t have digital camera and he wants to start using ours. We have a JEOL 2100 TEM operating at 200 kV. We can run the sample and do some imaging while playing a bit with the settings of the scope, but still in some cases the sample ends up burning. I’m not experienced with biological samples. Is there a different sample preparation he should look for, or maybe change his resin or do cryo-cut, before coming to our scope, or is there a certain group of settings I should work with for this particular case? Marcela Redigolo
marcela.redigolo@
mail.wvu.edu Wed Jul 27 By burning do you mean bubbling or exploding sections?
Sometimes a thin carbon coating of the section will improve things greatly, even if the sections are on carbon-coated Formvar or lacey film supports. I can use a 10 nm STEM probe in a 2100F for EDS line scans and maps of biological sections—if carbon coated. Without the carbon coating the films can explode under the beam. In TEM mode I tend to use spot sizes 3–5 to minimize beam exposure/ damage. I do not believe a cryo cut would be of any value. A small objective aperture will help prevent/balance charging effects. How thick are the sections? I generally find 150–250 nm quite fine. I grew up in the Materials world and now manage a structural biology TEM facility. HAADF STEM can be a great way to image biological low contrast samples. Roseann Csencsits rcsencsits@lbl. gov Wed Jul 27 Your 200 kV microscope will work very well down at 80 kV and when you return to 200 kV it will regain its absolute stability
www.microscopy-today.com • 2011 November
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