Accu-Scope 3035 Inverted Microscope and lighting

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cpushack
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Accu-Scope 3035 Inverted Microscope and lighting

#1 Post by cpushack » Sat Oct 21, 2017 12:54 am

I recently bought a Accu-Scope 3035 Inverted Metallurgical Microscope, I run a computer museum and want to use it to inspect wafer/silicon dies.

Its this scope here: https://microscopecentral.com/products/ ... gIvWPD_BwE

It comes with 10 25 40 and 60x objectives, though I really only need the 10 and 25.
My problem is this, when using the included halogen light I see mostly reflection/glare from the light, and very little of the sample I am trying to view.

I took off the halogen light and litterally stuck a cheap LED flashlight in its place (same diameter strangely) I could see the sample very well with that, not near as much glare

Am I doing something wrong? I am a bit new to microscopes (as you probably can tell)

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zzffnn
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Re: Accu-Scope 3035 Inverted Microscope and lighting

#2 Post by zzffnn » Sat Oct 21, 2017 1:43 am

It seems that your scope does not come with polarizer inserts or metallurgical darkfield. Those would reduce glare. What you did with LED flashlight at an angle is a good idea too (no, you did nothing wrong).

Welcome to the forum.
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cpushack
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Re: Accu-Scope 3035 Inverted Microscope and lighting

#3 Post by cpushack » Sat Oct 21, 2017 1:59 am

zzffnn wrote:It seems that your scope does not come with polarizer inserts or metallurgical darkfield. Those would reduce glare. What you did with LED flashlight at an angle is a good idea too (no, you did nothing wrong).

Welcome to the forum.
Thank you for the welcome, I wondered if it had to do with polarization. There is a filter slot in the light path, it came with a single blue filter.

I wouldn't mind replacing the halogen with an LED that's made for microscopes, but if I have to I can just get a bit better flashlight I suppose,

Attached is a pic of the setup as well as the one filter
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Re: Accu-Scope 3035 Inverted Microscope and lighting

#4 Post by zzffnn » Sat Oct 21, 2017 2:52 am

Sorry, I misunderstood you. I thought you used LED flashlight at an angle (shining up from objective lens' side), but you actually stuck it straight onto original light path. I don't know why LED looks better that way. Maybe because the LED light cone is much wider, so in effect, it is providing circular oblique (angular) illumination.

Are you sure there is no polarizers provided? You need two polarizers ideally, one before the objective lens, one after.
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Re: Accu-Scope 3035 Inverted Microscope and lighting

#5 Post by c-krebs » Sat Oct 21, 2017 3:02 am

With reflected brightfield epi illumination of highly reflective flat surfaces (like wafers) it is going to nearly impossible to avoid serious glare issues. Polarization would help a great deal. You need 2 polarizers, one between the light and the subject. Another between the subject and eyepieces/camera (referred to as the "analyzer"). You need to be able to rotate one of these to get best effect. Darkfield objectives and lighting is also very helpful but I don't see any provision for that in the link you gave.

The objectives appear to have pretty good working distances. If so, you might be able to illuminate the wafer surface with an external light (like a smaller flashlight or perhaps something like a an Ikea JANSJÖ or two). That should give you much less flare/glare.

http://www.ikea.com/us/en/catalog/products/20169658/#

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Re: Accu-Scope 3035 Inverted Microscope and lighting

#6 Post by cpushack » Sat Oct 21, 2017 7:20 am

c-krebs wrote:With reflected brightfield epi illumination of highly reflective flat surfaces (like wafers) it is going to nearly impossible to avoid serious glare issues. Polarization would help a great deal. You need 2 polarizers, one between the light and the subject. Another between the subject and eyepieces/camera (referred to as the "analyzer"). You need to be able to rotate one of these to get best effect. Darkfield objectives and lighting is also very helpful but I don't see any provision for that in the link you gave.

The objectives appear to have pretty good working distances. If so, you might be able to illuminate the wafer surface with an external light (like a smaller flashlight or perhaps something like a an Ikea JANSJÖ or two). That should give you much less flare/glare.

http://www.ikea.com/us/en/catalog/products/20169658/#
The 10x has pretty good working distance, the 25x is a bit tricky. I plan on getting a 4x and a 20x which should be all I need.

Where can I get polarizers? The blue filter in the picture can slide in and rotate so a polarizer there would work.

I bought this used so none were provided

One btw the subject and analyzer could be more tricky unless it could go under the 10x eyepieces

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Re: Accu-Scope 3035 Inverted Microscope and lighting

#7 Post by cpushack » Sat Oct 21, 2017 7:21 am

zzffnn wrote:Sorry, I misunderstood you. I thought you used LED flashlight at an angle (shining up from objective lens' side), but you actually stuck it straight onto original light path. I don't know why LED looks better that way. Maybe because the LED light cone is much wider, so in effect, it is providing circular oblique (angular) illumination.

Are you sure there is no polarizers provided? You need two polarizers ideally, one before the objective lens, one after.
THe light cone being bigger makes sense, the halogen has a lens it goes through (thats attached to it)

Is there somewhere I can buy different lights for it to replace the halogen?

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Re: Accu-Scope 3035 Inverted Microscope and lighting

#8 Post by zzffnn » Sat Oct 21, 2017 1:13 pm

At the magnification you specified, you probably don't need polarizers. Just use well-diffused exrernal lights from sides. Diffusion around subjects is better than around light source is better for high magnification.

C-krebs pioneered "ping pong ball diffusion" for microscopy. I cannot find a photo from him now, but here is a similar one to give you an idea: viewtopic.php?t=4821

Sorry, I don't know where to get parts for your specific scope. In general, 3rd party parts (say from eBay) will work, as long as:

1) physical dimensions fit and there are spaces for them;
and
2) the ray path is not changed at all (at least not for much worse)
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Re: Accu-Scope 3035 Inverted Microscope and lighting

#9 Post by Hobbyst46 » Sat Oct 21, 2017 2:32 pm

I am not familiar with Accuscope but, in my humble opinion, the "problem" is not with the original light source. Halogen lamps are still standard light sources on premium research metallurgical microscopes. I WOULD NOT replace it with a LED just because of the present issue.

I agree with zzffnn about the oblique illumination due to this particular flashlight and specific optical path, and about the probable benefit of darkfield.

For darkfield, your objectives need to provide a hollow cone of light, i.e. the objective should have a "collar" to project light around the specimen rather than directly at it.
Such objectives are often much thicker than ordinary objectives for brightfield. The collar can be seen when you unscrew the objective from the nosepiece and look through it.

Hope that helps.
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Re: Accu-Scope 3035 Inverted Microscope and lighting

#10 Post by cpushack » Sat Oct 21, 2017 4:58 pm

Hobbyst46 wrote:I am not familiar with Accuscope but, in my humble opinion, the "problem" is not with the original light source. Halogen lamps are still standard light sources on premium research metallurgical microscopes. I WOULD NOT replace it with a LED just because of the present issue.

I agree with zzffnn about the oblique illumination due to this particular flashlight and specific optical path, and about the probable benefit of darkfield.

For darkfield, your objectives need to provide a hollow cone of light, i.e. the objective should have a "collar" to project light around the specimen rather than directly at it.
Such objectives are often much thicker than ordinary objectives for brightfield. The collar can be seen when you unscrew the objective from the nosepiece and look through it.

Hope that helps.
All help is welcome, no worries there

I agree the halogen probably doesnt have a problem per se, I just have to figure out how to use it, or something else for my intended use.

I'll see if the objectives are set up that way, probably not marked as such

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