shared reference silicon wafer for comparisons

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chris_ma
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shared reference silicon wafer for comparisons

Post by chris_ma »

I thought I'll pick up on Lou's post but create a new topic so it's easier for people to find. here the original post:
Lou Jost wrote:
would actually nice to have identical wafers spread out over forum members so that tests could be done to compare lenses across continents
This really would be an excellent idea. Why don't we act on it? Find one with really fine detail (preferably with those nice resolution test patterns on it) and either buy dupes and sell to others on the forum to recover costs, or cut one into pieces with a glass cutter and send the pieces to others.

Robert, I'd love to split or buy a duplicate wafer with you. Do you have duplicates of one with a fine test pattern? Or could you choose a source for a given known-good type which has multiple copies, so we could all buy one?


I'm in if we find some at reasonable prices (the larger ones seem to have gotten quite expensive).

So far I could only find sources which send random copies and those I got are not really fine enough to judge things like moire.

maybe we could use some small ones, not so good to judge flat field, but easier to find in large quantities, cheaper and also better for shipping.

I got a set of these:
https://www.ebay.de/itm/100pcs-Toshiba- ... 3743175642
they are quite small (2.5x2.5mm) but seem to have a good structure. will make a test tomorrow to see if they would qualify.
chris

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Adalbert
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Post by Adalbert »

Hello Chris,
Good idea!
I have already asked for that in the following thread:
https://www.photomacrography.net/forum/ ... ip&start=0
This chip: https://www.bw-optik.de/restposten/test ... tpraeparat
BR, ADi

Macro_Cosmos
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Post by Macro_Cosmos »

This can be done, yeah. I have a box of cut wafer chips, one of which I used in my recent tests, its fine structures makes a decent target for CA and sharpness testing. I have 2 trays, a total of 100 of them. The person I bought it from has even more.

I'm planning to photograph them all and let the forum decide on the best target to use.

As for specific CA and distortion tests, I can get a bunch of those misroscopy calibration targets from Taobao, they are cheap, decent quality. There are gridded ones that work well for distortion testing.

From that, we simply need to standardise our lighting to make results completely consistent. There's not a lot of us doing these tests anyway, so one tray of good silicon chips fitting the criteria will do. These chips can be put in an envelope and posted for very cheap prices.

chris_ma
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Post by chris_ma »

Adalbert wrote:I have already asked for that in the following thread:
https://www.photomacrography.net/forum/ ... ip&start=0
This chip: https://www.bw-optik.de/restposten/test ... tpraeparat
these look nice for measurements, but do they also have some irregular pattens for aliasing/moire tests?

I find that straight lines can be "cheated" by the debayer algorithm, so I'm interested in targets that have a irregular pattern as well.

Marco_Cosmos, would be great to see your collection and get a matching sample if possible.

the seller I got mine from has quite a nice selection, maybe Robert can look through them and suggest one which seems suitable.

https://www.ebay.de/sch/m.html?item=113 ... co&_sop=15

these seem quite suitable to me:
https://www.ebay.de/itm/70pcs-Generalpl ... 3938914158
https://www.ebay.de/itm/36pcs-Samsung-S ... 2901840130
https://www.ebay.de/itm/250pcs-ELAN-Mic ... 3769485715
https://www.ebay.de/itm/100pcs-Toshiba- ... 3743175642
https://www.ebay.de/itm/250pcs-Mosel-Vi ... 3758907652
chris

Macro_Cosmos
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Post by Macro_Cosmos »

Aberco is a nice guy too, he's also a photographer and owns a small business in silicon manufacturing, although I don't think he has an account here.

Image
This is what the tray looks like. They are uncapsulated chips, really good the mesh pattern is good for sharpness and the structures are good for CA/LoCA

That said, this seems like a far better idea, as we have information on it:
https://www.bw-optik.de/restposten/test ... tpraeparat

Expensive for what is it though, it's just a naked chip. My tray isn't even $2.
The chip itself has a length of 3.6mm in diameter, which means using a 10x lens, one gets the entire piece in the frame.
Image

This fact is useful in calibrating the tube lens to the correct magnification. That's how I discovered that my ITL-200 was producing higher magnifications.

Macro_Cosmos
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Post by Macro_Cosmos »

[Edit AdminCR for image size. Click picture for larger view]
Image

Here's a panorama of it. 9 shots, 2 is enough but I wanted to use the sharpest portion of the lens.

Edmund Optics 10x was used, Alphatube, D810.
I'm going to tweak and optimise the shots for stitching. Some parts aren't as sharp, which means the software is using lesser sharp portions for some frames when stitching.

Lou Jost
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Post by Lou Jost »

I'd like to hear from Robert about this, since he has the most experience using wafers as test patterns.

I prefer non-colorful chips, preferably black and silver, because these show all CA.

I think they need to be much bigger than 2.5mm, to ensure flatness across the whole field of view of the objective or lens.

The ones that have actual resolution test bars would be ideal.

Some of them don't have very fine detail; ideally we could find one with multiple levels of detail.
Last edited by Lou Jost on Fri Feb 14, 2020 1:29 pm, edited 1 time in total.

JohnDownie
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Post by JohnDownie »

This is very interesting.

You could have friendly postal matches at particular magnifications, perhaps an "Unlimited" division.

RobertOToole
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Post by RobertOToole »

Lou Jost wrote:I'd like to hear from Robert about this, since he has the most experience using wafers as test patterns.

I prefer non-colorful chips, preferably black and silver, because these show all CA.

I think they need to be much bigger than 2.5mm, to ensure flatness across the whole field of view of the objective or lens.

The ones that have actual resolution test bars would be ideal.

Some of them don't have very fne detail; ideally we could find one with multiple levels of detail.
Hi Lou,

I agree, having resolution bars or super micro-printing patterns would be best, it really makes judging differences in sharpness easy.

Also true about contrast areas, some lenses look great with colorful disks but CA like crazy with contrastly disks so a wafer with colors and some contrasty sections would be great.

No we have to find a seller with the right disk with a bunch of copies, hopefully for a low price.

I dont have any multiples of any of my wafers.

Best,

Robert

Lou Jost
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Post by Lou Jost »

Robert, do you have any tips about which wafers have those test patterns?

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Post by Smokedaddy »


Smokedaddy
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Post by Smokedaddy »

On a more serious note, if the quality of these is acceptable (doubtful) they are inexpensive. <g.

https://www.ebay.com/itm/A3-Resolving-T ... -0oFRju7NQ

-JW:

Lou Jost
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Post by Lou Jost »

A calibrated test pattern like those would be very useful, but they don't look like they get fine enough.

The transparent ones have a huge advantage over wafers: lighting from below is much easier to standardize than lighting from above, and short working distances don't cause problems with that kind of lighting, so the results would not be confounded with effects of working distance on lighting angles.

Smokedaddy
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Post by Smokedaddy »

... I wonder if they make a reticle target that would work? I don't know much about them.

https://bolioptics.com/multiple-scale-r ... t20122171/

Image

Image


-JW:

Lou Jost
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Post by Lou Jost »

But those are nowhere near fine enough to be informative at the magnifiaction you are using there. What is the magnification?

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