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4X Objective Lens Test Comparison - Part 1
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harisA



Joined: 03 Jul 2011
Posts: 445
Location: Greece

PostPosted: Sun Dec 10, 2017 10:02 am    Post subject: Reply with quote

Many thanks for sharing the information with us. I have 2 questions.

1)Can you please be more specific about the painters tape? Are you using it after cleaning the wafers in ultrasonic bath?
2)What is the dimensions of your wafer test target?I 'm thinking of buying some 6'' wafer plates through ebay but their size requires a much bigger ultrasonic cleaner than I have.May its possible to cut them someway.
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ChrisR
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Joined: 14 Mar 2009
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Location: Near London, UK

PostPosted: Sun Dec 10, 2017 3:30 pm    Post subject: Reply with quote

A Magnum Opus indeed, even if magnum was only 4x Smile

Well done Robert.
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RobertOToole



Joined: 17 Jan 2013
Posts: 487
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PostPosted: Sun Dec 10, 2017 5:25 pm    Post subject: Reply with quote

harisA wrote:
Many thanks for sharing the information with us. I have 2 questions.

1)Can you please be more specific about the painters tape? Are you using it after cleaning the wafers in ultrasonic bath?
2)What is the dimensions of your wafer test target?I 'm thinking of buying some 6'' wafer plates through ebay but their size requires a much bigger ultrasonic cleaner than I have.May its possible to cut them someway.


Glad to help!

I found best results using two steps.

1. Scratching the wafer was a concern so I used a super soft micro-fiber cloth with one misting of non-streak window cleaner to avoid leaving any streaks. This was to remove any film or anything sticky.

At that point you will still have lots of tiny white dots or particles that stick to the wafer, maybe due to a static charge? Brushing had no effect, it made it worse. Forced air wouldn't dislodge them.

2. This is the most important step. I use the painter's tape to stick and peel it back a few times in the same target area strip.

This results in a perfect clean like-new finish like nothing else I tried.

After trying so many methods I didn't think it was possible to get it as clean as when I received it, but the tape did it.

Hope you will see similar results.

Robert
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Lou Jost



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Location: Ecuador

PostPosted: Sun Dec 10, 2017 6:18 pm    Post subject: Reply with quote

I've found that white specks of dirt are a useful addition to my test surfaces. That's where CA and astigmatism shows up best.
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RobertOToole



Joined: 17 Jan 2013
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PostPosted: Sun Dec 10, 2017 8:44 pm    Post subject: Reply with quote

Lou Jost wrote:
I've found that white specks of dirt are a useful addition to my test surfaces. That's where CA and astigmatism shows up best.


The funny part is, at least in my office, I can get it perfectly clean, but by the time I set everything up and test fire a few, and shoot, there are specks again!

But you are right Lou, CAs really show up well on a white speck.

One seller on Ebay claimed he had factory new wafer so I bought a few, the seller is in France. They were 100% scratched, every square mm.

I complained. He denied it. I filed a claim a Ebay claim not as described. He credited me 100%.

Now those are my favorite wafers, the fine scratches really make is easy to judge sharpness. Confused


Last edited by RobertOToole on Sun Dec 10, 2017 11:48 pm; edited 1 time in total
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RobertOToole



Joined: 17 Jan 2013
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PostPosted: Sun Dec 10, 2017 8:46 pm    Post subject: Reply with quote

ChrisR wrote:
A Magnum Opus indeed, even if magnum was only 4x Smile

Well done Robert.


Thank you for all the help and advice.

You are a true friend Very Happy

Robert
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Smokedaddy



Joined: 07 Oct 2006
Posts: 835
Location: Phoenix, Arizona

PostPosted: Sun Dec 10, 2017 9:15 pm    Post subject: Reply with quote

A beautiful website nicely laid out and clean looking. Thanks for all the hard work.
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mawyatt



Joined: 22 Aug 2013
Posts: 1129
Location: Clearwater

PostPosted: Mon Dec 11, 2017 7:01 am    Post subject: Reply with quote

I haven't tried Robert's painters tape idea yet, I might use a lint remover clothes roller for getting lint off cloths since I don't have any painter's tape. He has very good idea IMO especially if it doesn't damage or leave a residue on the wafer surface.

I've had some success with using a semisoft brush and blowing air while brushing, this still leaves some debris behind though.

Another thing I've found that keeping the wafer/chip covered at all times, and keeping the setup out of any direct air movement (such as AC vent blowing, or ceiling fans). Tiny micron level debris is everywhere, and this is why semiconductors are processed in "clean rooms" and the facilities go to great lengths and expense to remove any possible contaminates. A single sodium atom in the wrong place can cause a chip to fail (upsets the threshold voltage of sub micron FETs), so imagine what a micron size particle would do Sad

Surfaces of the newer chip processes use a different surface passivation than the much older wafters like these 6" versions. These new wafer surfaces may have polyamide or BCB plastics which are soft and easily scratched, more so than the older wafer passivation.

Great work Robert, looks like those $17 AmScope 4X are a real bargain. Razz

Best,

Mike
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RobertOToole



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PostPosted: Mon Dec 11, 2017 9:16 am    Post subject: Reply with quote

mawyatt wrote:
...Another thing I've found that keeping the wafer/chip covered at all times, and keeping the setup out of any direct air movement (such as AC vent blowing, or ceiling fans). .....


Good advice.

I learned the hard way, an exposed wafer will attract dust like super-magnet.

Now I am careful to keep an index card over the top of my diffuser dome and over the wafer when its not in use.


Robert
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Yawns



Joined: 20 Dec 2015
Posts: 102
Location: Portugal

PostPosted: Mon Dec 11, 2017 1:30 pm    Post subject: Reply with quote

Thank you for your effort and for sharing ... I posted a link at the Extreme Macro Facebook group and people there are also quiet excited about your test ...

Just 2 remarks and forgive me in advance if I am wrong ...

1) In the "settings" you forgot to mention what lens you used as "tube" for the infinty corrected lenses .. or at least I read the post several times and couldn't find any mention to the tube lens...

you say:

2) "The Amscope objective is running at nominal aperture of f/4 (NA 0.10), compared to the MP-E at f/2.8" ...
I think it's f/5 isnt't it? ... 1/ 2Na ...?

Thank you
Antonio
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rjlittlefield
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PostPosted: Mon Dec 11, 2017 1:43 pm    Post subject: Reply with quote

Yawns wrote:
you say:

2) "The Amscope objective is running at nominal aperture of f/4 (NA 0.10), compared to the MP-E at f/2.8" ...
I think it's f/5 isnt't it? ... 1/ 2Na ...?

f/4 for the Amscope is a correct value when comparing with the MP-E.

When used at 4X and NA 0.10, the Amscope objective is NA 0.025 = effective f/20 on the camera side.

To achieve effective f/20 at 4X, the MP-E would have to be set on f/4, following the classic rule of nominal Fnumber*(magnification+1), 4*(4+1)=20.

You're correct that on the subject side NA 0.10 = f/5. Again, that's the same as what the MP-E would do at 4X if you set to nominal f/4.

As often happens, the underlying issue is what the numbers mean. When used as intended, the Amscope objective gives effective f/5 on the subject side, but the lens itself would be rated as f/4 based on focal length and aperture diameter.

--Rik
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RobertOToole



Joined: 17 Jan 2013
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PostPosted: Mon Dec 11, 2017 1:51 pm    Post subject: Reply with quote

Yawns wrote:
Thank you for your effort and for sharing ... I posted a link at the Extreme Macro Facebook group and people there are also quiet excited about your test ...


Thanks Antonio.

Yawns wrote:


Just 2 remarks and forgive me in advance if I am wrong ...

1) In the "settings" you forgot to mention what lens you used as "tube" for the infinty corrected lenses .. or at least I read the post several times and couldn't find any mention to the tube lens...


You know you might be right!

For infinity corrected optics, I used the Sigma diopter, instead of the Raynox or prime lens since its M52 so it fits my studio rig nicely. I find the CA correction on the Sigma best out of the Raynox or 200mm primes. I read someplace the Sigma diopter has UD glass but I don't know for sure.

Yawns wrote:


2) "The Amscope objective is running at nominal aperture of f/4 (NA 0.10), compared to the MP-E at f/2.8" ...
I think it's f/5 isnt't it? ... 1/ 2Na ...?


Yup you are right, I read over that so many times! Good catch.

4x .1 = f20 effective - f5 Nominal
4x .13 = f15 - f3
4x .16 = 12.5 - 2.5
4x .20 = f10 - f2

Thanks for taking time to post this!

Robert
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RobertOToole



Joined: 17 Jan 2013
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PostPosted: Mon Dec 11, 2017 2:05 pm    Post subject: Reply with quote

rjlittlefield wrote:
Yawns wrote:
you say:

2) "The Amscope objective is running at nominal aperture of f/4 (NA 0.10), compared to the MP-E at f/2.8" ...
I think it's f/5 isnt't it? ... 1/ 2Na ...?

f/4 for the Amscope is a correct value when comparing with the MP-E.

When used at 4X and NA 0.10, the Amscope objective is NA 0.025 = effective f/20 on the camera side.

To achieve effective f/20 at 4X, the MP-E would have to be set on f/4, following the classic rule of nominal Fnumber*(magnification+1), 4*(4+1)=20.

You're correct that on the subject side NA 0.10 = f/5. Again, that's the same as what the MP-E would do at 4X if you set to nominal f/4.

As often happens, the underlying issue is what the numbers mean. When used as intended, the Amscope objective gives effective f/5 on the subject side, but the lens itself would be rated as f/4 based on focal length and aperture diameter.

--Rik


Thanks for the excellent information, as always!

Robert
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glmory



Joined: 30 Dec 2016
Posts: 23

PostPosted: Tue Dec 19, 2017 8:29 pm    Post subject: LOMO on a Labophot Reply with quote

After reading this and the expensive objective review, it seems like the LOMO 3.7X or Amscope $17 objectives are the logical choice of the finite objectives.

Is there any reason these two objectives would not work properly on an Labophot microscope?
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zzffnn



Joined: 22 May 2014
Posts: 1530
Location: Texas USA

PostPosted: Tue Dec 19, 2017 9:54 pm    Post subject: Re: LOMO on a Labophot Reply with quote

glmory wrote:
Is there any reason these two objectives would not work properly on an Labophot microscope?


The Amscope 4x work on Labophot for sure. And the 3.7x would likely work too.

Most other short LOMO objectives are too short to focus on Labophot (scope stage cannot go up high enough). But the 3.7x has a parfocal height that is a bit longer than the 33mm LOMO standard height.
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