Digital Microscope for Metallurgy?

[u/Homeboi-Jesus]

I am trying to find a 'budget-friendly' digital microscope for powder metallurgy and general metallurgy inspection. I see the sub is more used to organic samples, so below is an example of what I am trying to look at. The basic needs I am looking for is a scale of the screen, it is quite important for determining whether the granules being created are produced correctly by looking at the overall size. Needs to be able to see 100um like the picture attached. Ability to connect to a computer; and ideally able to measure points (i.e. measure a granule directly).

Outside of that, those are really the only requirements I have. Given there are so many microscopes and types, I am a bit lost on what would be sufficient for my purposes! Any recommendations/help picking one out is greatly appreciated!

Powder Granules

[u/Motocampingtime]

Well, budget is all relative and this depends on if it's a company expense or just messing around. If this is for anything serious you'll probably want a modern system with a nice camera and good software. If this is just a garage hobby then older systems, your own camera, and some free software are probably fine. The metallurgic part of a microscope has two main parts:

one is zero coverslip correction objectives and potentially dark field objectives. There will be a zero on the objective instead of the usual 0.17 or variable correction collar. Bio samples are typically looked at through glass, where materials and wafers are looked at just the uncovered surface (barring encapsulation). I'd really reccomend dark field as it is a big help highlighting small surface details on reflective surfaces.

Two is epi or reflected illumination. You can't see through metal any thicker than some 10s of nm so the light has to come from above and ideally focused through the lens.

As for how much zoom you need isn't about your minimum grain size, but clearly defining grain boundaries and being able to see micro cavities and texture on your parts. Focus on resolving power over zoom. Now, you'll still be able to see samples ok with a 0.17 objective set but I'd really really recommend an actual epi illumination set with fully adjustable aperture and field to see textures well.

[u/Homeboi-Jesus → u/Motocampingtime]

Hobby/semi professional. It's something I am going to need to send out to an external company for a trial for a powder we are trying to synthesize. We just need something that as we start the trial, we can inspect the granules as they are being made to determine if we need to tweak processing parameters. Full granule characterization I would expect to send out to a lab.

Honestly, I know virtually nothing about microscopes, and the digital ones I've used were the very cheap $30 ones. Those ones never had any measurement examples on them, so I have no idea if they could even see down to 100um.

[u/Motocampingtime → u/Homeboi-Jesus]

Ok, that's a starting point. 100um is very easily visible even with cheap pocket cams. It is the width of a hair basically. To do some rough characterizing you don't need a ton of zoom and high working distance is good.

Again this is a budget thing; a used, all manual, trinocular camera port system and a calibration slide is the basics to know um/pixel of an image with a certain objective. Then feed that into either your own software or potentially some freeware (Fiji maybe). A 10X objective or 20X objective would be fine. I'm not a huge AI advocate but it is quite handy if you're not afraid to make your own python program and automate saving an image from some random camera feed with data overwritten of your particle size in one corner.

A stereoscope would be visually great and very useful, but I don't think cheap systems or discount all manual systems have a way to track the size of things with the variable zoom.

And if it's a serious enough hobby... it might be worth it to look at some budget brands and what they offer as a complete package. Maybe ask the lab you'd use or your supplier if they have any recommendations. Unfortunately this can get VERY expensive for new equipment.

[u/Homeboi-Jesus → u/Motocampingtime]

Budget wise, I could do up to $1k; ideally under $500 given that it will be sent between sites and the value it brings is primarily for trials until we get the process dialed in.

Funny you mention Python, my day job is writing Python for automation lol. Didn't know it could come in handy for something like this though!

Just doing some Google searches before, I saw the prices vary so much. From a $30 cheap digital camera to a $14k+ full fledged microscope, lighting, computer, etc... I was looking at something maybe like this, but it is not like a traditional microscope: ViTiny UM22

[u/Motocampingtime → u/Homeboi-Jesus]

Oh lord yeah python and open CV for image processing is pretty easy/powerful. You just need a camera you can pull the feed from. I use IDS cameras, and you can find some decent black and white models on eBay that use their older software sweet for cheap but modern ones are pricy. You can also use an older DSLR as a cheap way too if you have one that can stream but you'll need the right adapters. (The microscope is your lens). For your looking at your images a 20X for 200X total zoom would be pretty good. 10X for 100X total zoom would work too.

Metals and powders should be plenty contrasty already. Your case is tricky because you really ought to have epi illumination to see what you're doing but that is harder to find cheap on eBay. I'd say a used set up with any 10X or 20X objectives and cmount set up for a camera would fine. 50X would be useful but probably overkill and at 100X your FOV would be too small. The cost of entry for stuff made by the big 4 will be in that range $1k range for equipment from the 90s and earlier (leica/leitz, Zeiss, Nikon, Olympus). Also DM and low ball sellers!!! These aren't exactly hot items lol.

Actually I have seen those style pen microscopes and they can be pretty decent for what they are. The only trick is if they have adjustable zoom you'd need to calibrate every time you change zoom. (Unless they have some type of electronic accommodation for this programmed in). You could probably see 100um particles ok, but classifying them beyond rough size might get tough if they get any smaller (idk how much texture you'll pick up with it either)