Suggestions for Particle Counting Microscope?

[wbuhler]

I need to determine the particle count captured on a filter paper but I'm new to the game. So I need help from the more experienced! I'm looking to pick up an microscope for counting those particles manually.

Any brand y'all recommend? Any features to pay attention to?

Some background info: We are setting up a net filters in a line to capture particles. The expected particles would be ~80 micron (0.003 in) so I figured a microscope with a magnification of 60x and eyepieces with reticles would do the trick.
My company has a limited budget so I'm ruling out the $8k metallurgical microscopes.

Thanks.

 

[CoryPad]

The German microscope manufacturers are my preference - Leica or Zeiss. However, they are expensive also.

 

[HDS]

Field of view is important. You want to look at the largest area possible. It can be hard to move the slide around to count different areas.

Also you will want an easy way to attach a digital camera. This will make the counting easier and provide some documentation. It could also increase the magnification. This can often be done by removing the eye piece and inserting an inexpensive adapter.

A more through technique is to resuspend the particles out of the filter into a liquid. This sample can then be analyzed with a particle counting & sizing instrument. Some of them use the electrical sensing zone technique or camera based systems. This can get a much larger percentage of the particles from the filter. If you can not afford one of those there are particle analysis labs that will run the samples for you.

 

[IRstuff]

One caveat on field of view is that a too large FOV will make it more difficult to count particles. You need to establish what your limits are, i.e., how big or small is a "particle?" What will you do with clumps; are the clumps?

If your particles are small enough to force the FOV to be less than the area searched, you'll need a mechanized and measurable motion stage, and you'll need to have some means of keeping track of whether you've counted a particle or not. A delineated background of squares or whatever would be needed.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[floattuber]

In addition to the microscope, they make software that does this automatically, however it's not cheap. The olympus microscopes that my previous company used were about $45,000 each plus the price of the basic software. Particle counting was extra.

Have you thought about outsourcing this work to a materials or semiconductor lab?

 

[Ron]

Meiji is a good, relatively inexpensive microscope line. Spend some bucks for a good precision counting grid in the the particle size range you expect. Meiji has counting grids as small as 0.01mm

 

[Ron]

ps...I'm not selling Meiji...I have one and like it.

 

[IRstuff]

There are software packages that are cheap and/or free:

http://ddsdx.uthscsa.edu/Imagetool.asp

will do object counting, but it's pushing 9 yrs since it was developed, and it is likely to crash on newer machines.

Nonetheless, there may be other packages with similar features.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[wbuhler]

HDS & IRstuff - Thanks for the good input on FOV.
We have the capability of attaching a camera to the microscope but the magnification # goes out the window and we can't tell what it is unless we use a precisely delineated background. I will check out the ImageTool soft.

floattuber - We currently send fluid samples to labs for evaluation. We now have a project that requires monitoring of the particle size for each production unit, making it impractical to outsource.

Ron - Thanks, I'm going to look into the Meiji line.

 

[tomwalz]

Not sure just what kinds of counts you want to do but I get a lot of use out of my Proscope. I beleive they have lens in your desired diopter.

I also find the 30x with standard and polarized lighting amazingly useful upon occasion.

Tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[unclesyd]

One caveat about your approach to particle counting is make sure your filter paper doesn't contribute to the problem. Particles from filter paper cost use a ton of money.

What is the precision required?

If your requirements will allow, you might want to look at an inspection microscope. We used this approach for particle counts in turbine oils.

http://www.2spi.com/catalog/magnifiers/graticules-inspection-microscopes.shtml

This link is to a company we bought a lot of reticules from.

http://www.reticles.com/countingreticles.htm