Can't see those pesky laser etched part numbers on chips? Dave demonstrates what's happening with the microscope polarising filter lenses on Twitter that's blowing people's minds. Does it actually work?
And other tricks of the trade.
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#ElectronicsCreators #Microscope #Polarizing
The reason why circular polarizers are preferred by photographers is subtle and not really adequately explained by "works much better than linear polarizers". The photos you would take with a linear polarizer would look *identical* to a so-called "circular polarizer", but the linear polarizer would send linearly polarized light into the camera, which can confuse and upset the auto-focus/auto-exposure features of the camera. So the circular polarizer adds some wizardy *after* the linear polarizer (namely a quarter waveplate) to take the light which has already been filtered by the linear polarizer part, and scrambles/circularizes the polarization. The filtering-according-to-polarization has already happened, but the polarization is rescrambled so that it doesn't screw with the auto-focus etc. It just so happens that if you somehow attach the filter *backwards*, what you end up with is a filter that would be selective to circularly polarized light, but that's not the way we attach these filters to our cameras. So TL;DR, it's really a terrible choice of name. A "circular polarizer" is a linear polarizer with a little hack added to prevent it from breaking auto-focus; and it has practically nothing to do (as far as the end user is concerned) with circular polarization.
100% correct.
Thanks, dude! Explains everything. So basically we can treat it as 2 separate films, not one. Will attenuation get bigger on those? Is there a usecase for linear polarizer in photography (low light conditions or something)?
@@__-nd4hf I'd wager that the attenuation caused by the quarter wave plate is pretty negligible; I can't imagine a reason for actually preferring a pure linear polarizer.
Yes, that what I said in the video, it upsets the autofocus and other systems.
He literally said the same thing in the video.
Fantastic, I'm 3min 30 sec in and I'm off to go buy that filter from the local photography shop. So exited. I'll watch the rest of the video when I come back. Can't wait!!!
Oh dearrrr! When he gets back, he's gonna be soooo pissed! ROFL
🤣🤣@@BlondieSL
oh my. you should finished watching the video first. hahaha
Saved me $20 today, thanks Dave! Saw the tweet today, nearly bought the magic disc on impulse. Glad I didn't!
As I saw the first half The video I was like welp I’m sold and about closed the video and went to Amazon - I just kept listening because my hands were full. Glad I did
Same
On the other end Dave almost make me waste money on the first part of the video :P
Cross polarisation is what's used in geology with thin sections to identify minerals.
Also in biology and crystallology. I made my own setup to look at stress patterns in plastics and glass. Stressing glass in the setup is really trippy
What he has done in fact is to reproduce the cross polarizing system of a petrographic microscope, while also adding a quarter-wave retarder. The problem is that he didn't have a control on the incoming light polarization.
that sounds similar to spectroscopy, thanks for telling.
"Goose arm" because a goose's arm is way more flexible than a goose's neck 😂😂. As usual, a great informative video.
Polarising sunglasses are a must when driving IMHO. Road paint becomes more neon-like, road signs alike, you can see through the windscreens of other cars and see where the drivers are looking etc.
When I got my first pair seeing the other drivers through the back window glare was the best party trick
I had some for a few weeks, but the tinting on the rear windows of multiple cars I drove at the time would appear all checker board like... Which made it harder to see what was behind. I should probably get some again since we own zero of those cars now, and I use the centre mirror much less now after several years of euro truck sim.
There was a time when polarising sunglasses were a serious hazzard when driving as the laminations and curves of a car windscreen would show up rainbow patterns all over the place which made it very hard to see the road properly. Even now they can cause problems as all those LCD screens in cars these days also polarise the light so it can be hard to read your binnacle displays (let alone the sat nav). Basically they reduce road glare but CAN create unwanted patterns so must be chosen with great care.
I use my TV on a white screen as a light source, Then using a circuler polariser on my camera. I put a bit of moulded plastic in between them and you get some really wierd and out of this world photos from just plastic. It highlights the stress inside the moulded plastic.
Any example photos?
For those without ready access to a dumpster where they might find an LCD screen, polarizing film is quite cheaply available on Amazon in sheets of various sizes....
Yeah, I've found that side lighting is more effective than polarizers. If you have a small, high intensity flashlight you can shine it on the part from the side temporarily to read the markings while leaving the microscope and lighting set-up alone. Most of my microscope viewing is to asses solder connections, which turn to dark grey or black viewed through polarizers.
I saw that clip and thought about it for a minute and I was pretty sure it needed polarized light as well. Thanks for the demo.
Thanks for shedding some light on this
I've been using a simple technique: a small amount of silicone grease applied with a cotton swab over the chip. When I clean the grease, the inscriptions become very sharp without needing a microscope.
Yep, swap of IPA and the numbers appear instantly!
I use the "andonstar polarizer film disc" bought on eBay and is very effective. Essentially you use two discs for side Led illuminators and one for the objective. Once adjusted works like magic
Nice Video Dave! The effect that the image gets darker by using the polarisation foil with unpolarized light is not due to losses. Because randomly unpolarized light means that 50% of the light matches the direction of the polarisation foil, leads to a blocking of these 50%. So because 50% of the electric fields gets blocked, the light intensity should drop by 1/sqrt(2) if I remember correctly
And when you add a third polariser to the mix, things get really weird.
Wow this is pretty interesting thanks for sharing Dave
Polarising filters are a ton of fun to play with You can get circular polarised film from those disposable 3D glasses
I've found many of your videos to be "illuminating," but this one takes the cake! Excellent lighting overview. Thank you.
Different kind of polarization and also lighting conditions is very important when setting up machine vision cameras... (could be for reading these chippies on an assembly line too)
Cheaper to use both the lenses of a single polarized movie glasses ... a child's polarized movie glasses will set you back around £1 As shown in this video, but use one movie glasses lens over a light source, and other for viewing as shown in the video ... 1st find the lenses correct orientation, place one lens over the another held up to a light, look through, and flip and 360 rotate a lens until you can't see through them both ... when you find the darkest reaction, this is when you know you have the correct orientation ... remembering the lenses correct way around, use one over light source, one for viewing through as shown in the video ... using polarized movie glasses to convert a standard compound microscope into polarized light is common in microscopy
Or, if you have the glasses still in tact, you want to set it up so the light goes through one lens as if it was going towards your eye, and then reflect off the surface and come out through the other lens. That is so both are acting as linear polarisers, and rotating one lens around will change the brightness. If you go the other way, so light goes out from your eye, reflect off the surface and then back into the other eye, then rotating the lens will do pretty much nothing.
Just found your channel today. Very useful and practical information. Subbed. Thanks m8. 🖖 👌
I've always just got in the habit of slightly tilting what I'm working on if I need to read a part number. Would love to eventually get a good adjustable polarizing light setup at some point, but what I have works well enough for pretty much everything.
It's a fun trick though, I had a run in with it just out of college. I had to inspect circuit boards overmoulded with a transparent material. This caused some issues near the injection port because the material was so hot that it washed away the nearby solder and caused little balls of solder to dissipate throughout the plastic. I was tasked with inspecting the outcome, but to improve release upon cooling they had sand-blasted the surface of the mould, the result was a quite effective diffusor which created a hazy surface. While x-ray worked somewhat, it wasn't ideal to find little balls of solder, so in the end out of sheer misery I tried a metallurgy microscope with different filters, the polarizer worked every single time because it neatly removed all the scattered light from the rough surface. What also worked surprisingly well was an immersion objective, but that tended to be quite messy.
High again Dave. I tried the marker trick you mentioned during this video. It worked really well. I used a red Staedtler marker, dabbed some ink all over the IC's surface, and was immediately able to see what I could barely make out with a magnifying glass. Thanks for this trick. It helped me a lot.
you should have done this episode with a 1458 op-amp
Im a photographer. And every time I show people the effect a polarizing filter has on anything reflective like, windows, water, glass, random surfaces.. basically anything. Their minds usually become... "BLOWN"
I have a DIY light for my microscope, it has four LEDs spread out and angled towards the middle and I have a little joystick which controls the relative brightness of them all. It means that you can control the direction of the lighting from the joystick.
Dave doesn't really make the point that when light is reflected from a surface at an angle, it is possible to get an angle where the reflected light is completely polarised. This called "Brewster's angle" (see en.wikipedia.org/wiki/Brewster%27s_angle ). A single polarising filter can then remove that light, so that the black surface of the chip is seen as black again, thus allowing the etching to stand out clearly. You don't need to polarise the incident light for that effect to work, so you don't need two filters. You just need to have the illumination coming from an angle, and the viewpoint at a similar angle on the other side. That's exactly how Polaroid sunglasses work.
Polaroid makes sunglasses?
@@newtonfigley6948 From en.wikipedia.org/wiki/Polaroid_Corporation "The original Polaroid Corporation was founded in Cambridge, Massachusetts, by Edwin Land and George W. Wheelwright III in 1937. ... Polaroid’s initial market was in polarized sunglasses - spawned from Land’s self-guided research in light polarization. Land, having completed his freshman year at Harvard University, left to pursue this market, resulting in Polaroid's birth." So, yes.
Polarized light and and a filter are useful for inspecting faint and hard to see numbers. It's also good for eliminating solder glare in some of your videos Dave, so keep it on the camera for future use.
You had me at the beginning, thought I might need to go get one of them filters. Even trying to angle my light source sometimes I just have a hard time reading some chips. On occasion I've put some drops of isopropyl alcohol on the chips and that sometimes helps.
Thank you Dave
Sticking a linear polarizer film to a ring light and looking through the middle should do the trick, too. Also smartphones with non-OLED screens could be used as a makeshift polarized light source.
But wait, does that work or not? I'd have guessed that the polarizer on the lens needs to be at 90 degrees with respect to the polarizer on the light, so what you're describing here would be the worst possible case we saw while spinning the polarizer around?
@@TheHuesSciTech In my understanding you want only the light to enter your eyes that came from the same angle as you are watching. When you stick a polarizer sheet under the ring light it would first filter the light's light and on the way back only let this light return to your eyes. As result you are removing the light from surrounding light sources.
@@MetalheadAndNerd No, it would enhance reflection where polarisation is kept. But the light from elsewhere will just be filtered as it comes through. Ideally you want the only light source used to be polarised, or at least the only significant light source. And then you want the return path to be polarised, but in a manner where you can rotate the 2 with respect to each other to allow different polarisation through.
@@jeffreyblack666 Are you hoping that the edged surface changes the light's polarization in a different way than the non-edged surface?
@@MetalheadAndNerd Yes, as the video shows. Based upon what happens it appears that the main chip surface preserves the polarisation, while the engraved surface does not. If that is the case, it means without a polariser or with them in the same orientation, the chip surface appears bright and you can't easily see the markings. But when oriented at 90 degrees, the majority of the light reflecting off the chip is blocked as it is the wrong polarisation.
i was standing between two piers on a sunny day. my pixel could only pick up the reflections on the surface of the water so i held my polarized sunglasses in front of the camera and the shots of everything going on underwater were pretty amazing.
Love that 6809 reveal. Working on my homemade Color Computer project and that's the CPU for it. But of course I'm using the 63C09 instead because it supports faster speeds and has a few more features while being 100% backwards compatible.
Awesome, I peeled some polarizing film from a broken LCD TV and have a camera polarizer.
I remember seeing polarizer on microscopes to see smaller things in biology (number of years ago). Never quite understood how it worked but you could see smaller cell with it.
A simple double trick experiment. LOL Love it!
you got me good at the start with this one
If rotating the polariser changed it, it either isn't a filter for only allowing circular polarised light through, or you are using it backwards. A great advantage of circular polarisers is that the orientation doesn't matter. But that is for use in things like 3D movies. A circular polariser typically works by combining a linear polariser with a quarter wave plate. To produce circular polarised light, it is first made into linear polarised light and then the quarter wave plate makes it into circular polarised light. To then filter it, it goes in reverse, first passing it through a quarter wave plate to make it linear, and then filtering that linear polarised light. Also, a lot of screens these days are starting to have circular polarisers on them as well, as it helps cut down glare.
I work on a lot of boards coated with laquer or conformal coating type of gel and I find a uv light helps make the numbers glow....
Try looking at some random rocks (minerals) through that scope. ;) These things have been common in geology forever.
Wow. Thank you!
Super fantastic! I use my smartphone (have no microscope) with torch on. Usually I take a picture and then enlarge it. But couldn't read the part numbers on a few mosfets. All I had to do was to take the picture from a sharp angle - thanks!
Totally worth getting two polarising filters (one on the light source and one just before the lens) if you are interested in mineralogy, geology, gemmology, cell biology, optical physics, materials sciences, seeing stresses in transparent or translucent materials, etc, etc. especially if you already have a good microscope to play with. In my experience the polarising filters from old lcds are pretty good especially if you can get a few with the same orientation (some screens actually have more than one per side) and you get them to stay flat. You don’t have to use a transmitted light microscope (where the light goes through the sample) to see the effects most samples of anything which isn’t clear the whole way through will reflect enough light to give you a good look. If the samples are totally clear you can use a mirror under the sample angled very slightly so it doesn’t shine light straight into the lens. (Transmitted light microscopes have a condenser under the stage which focuses the light making it so only one light path goes through the same bit of sample into your eye which makes divisions like cell walls and stuff so they will not be nice thin lines without one) Circular and linear polarising filters will actually produce different effects when looking at some materials.
This is usually called cross-polarized reflected light and is actually often used in macro photography. I've been using if for quite a while to discover otherwise hidden details in meteorites. The difference is indeed striking. The required investment is also insignificant.
Having a vision impairment when I work on PC PCB's and I am trying to read a particular chip or even read silk screening on a motherboard or soldering I use a very vright adjustable LET torch and I try different brightness's or angles with a magnifying glass to see what I have to see. A microscope is the next thing on my to buy list. Thank you for the advice from this video this will help me alot.
My trick for reading chips is an angled point source light, like an led torch or my phone. Works great!
Brilliant! I’m stealing this and using my sunglasses
What a roller coaster, this.
if you want to test things with polarizers you can find them in a defective monitor .. just check the backplate reflective setup. made up of all kind of polarizing (at least two filters with 90° offset), reflecting and diffusing light filters to get a more even and straight back lighting for the pixels.. (and be careful in old monitors so you dont break the HV cfl tubes)
Nice video, i need this!
this is great. i use an old smartphone as a microscope and it must have a polarized lens on it because iv no problems at all reading etchings on chips. but if i ever up grade to the real thing i'l know what to do. thank you Dave, & thank you to the guy who found this to work in the 1st place... VERY COOL/HANDY : )
Seems like a good technique to quickly visually inspect lots of solder joints without having to change the lighting setup multiple times.
Note that with a polarizing filter half the reflections on your solder joints and reflections on the edges of the raised tracks also disappear, and make the image better to judge. Downside is that you need double the light, so you could miss out on depth of field.
This is soooo cool. Thanks! 😍
Side note: A thing which may be useful are alternate light sources, e.g. infrared and ultraviolet. I remember a clip a coupla years back where they had discovered that exploding caps left a residue easily detectable under UV light. N.B. Protect your eyes and use appropriate filters to protect your scope or camera.
Thanks dave! From canary islands👏👌😎
And this is generally why Pick N Place machines will have LED illumination at a few different angles to the part. That lets them better differentiate between the main outline of the part and reflective "pits" etc. Some fancy PnP machines will even read the part number, and compare it to the BOM. It is quite magical using a polarizing filter on a camera, which you see the reflections disappear from water, windows etc. You can try it on your own eyeballs, too. lol
Good old youtube recs just pointed this one out to me, im a bit behind the times. I typically just put my phone torch as close to the plane of the surface of the chip as possible - i think it makes a shadow in the engraving... I'm curious as to whether there are other applications for this though 🤔
yeah its a multi way dance between the benefit of the polarization filter, vs the amount of light reduction vs extra lighting needed to maintain the same level of effective illumination... vs the amount of zoom you need to get a sufficient resolution fidelity vs the auto exposure on the camera and the other noise performance sensitivity etc capability of the ccd sensor etc. so its finding the optimal set of tradeoffs to make the most out of your own specific combination of pieces of equipment. however the thing i didnt know before was that circular polarization is better than linear. because i tried linear. also the cheapesst plastic films introduce abberations and optical distortions reducing quality and fidelity which is avoided by a rigid glass or hard plastic polarization filter. which is more expensive of course maybe a cheaper filter on the light source perhaps would not matter? if you then can spend more on the lens filter to get a better one i suppose overall polarization filters makes more sense on higher end equipment or only after you have already over maxe the illumination such that your sensor is already saturating over exposed. since adding the polarization then cuts the amount of light getting thru, thus bringing down the amount of light reaching the sensor. but that is also must be considering the maximum 'usable' zoom level too (which isnt too zoomed to still capture the full set of chip markings without cropping out), which then also changes the effective exposure (or aperture whatever you call it). as zoom by just itself can be dimming the image more stops than the polarization filter is capable of. depending on how small the chip is you need to be reading from... i guess some people go even smaller with biological microscopes and die shots. but we arent so interested in those types of hobbies. at least not until the industry moves forwards again into 'ultra smd' whatever. those will be dark times indeed. because will be requiring an even higher zoom. hehe
I do the same, play with the light. Also my Eakins microscope has some nice software feature like WDR that is reducing light reflection.
I use brake cleaner fluid. Sometimes if there is some grease in or on the laser engraved texts it realy helps to make it visible again. If there is grease on it, sometimes just changing ligthing direction doesn't help. And you just can't wipe that off from the surface, and it is changing light reflection from the engraved areas.
I had to giggle. Photographers have known this trick for years. Cool Vid.
Reflected light is always polarized, therefore use a big mirror to reflect a light source once to create polarized light!
For me the most value part of this video is 8:12 : look how good the trace at the bottom(?) track is to see, on the right picture.
Nice magic trick dave
A few years ago I found that using a blue LED torch helped to see the markings on IC's if you got the angle right - I guess it improves the contrast, or maybe the markings fluoresce somewhat. Sadly my little blue torch got dropped down a drain and didn't survive the process!
A bit too late, but I absolutely love polarizing magic. Last year I bought some polarized sunglasses from a gas station, about $20, nothing fancy, and I'm not ever buying regular sunglasses again. They are so good that I rarely go out without them, mostly on very cloudy days or at night. And I totally forgot I can get one for my camera too, since I am into photography a bit too...
I just put a drop of Isopropyl alcohol from my wash bottle. Works better than a sharpie.
My microscope has a polarizer pair as a basic option... It's a medical/scientific microscope, though... It's great to see various transparent crystals inside cells... I also had Polaroid sunglasses in the past... They made all the puddles on the road and windshields of cars almost invisible...
Very interesting ... and your answer is even better. Really, this is all about glare. I bought a ring light with my microscope and was rather disappointed for 2 reasons: 1) It was WAY too dim. The dimmer knob was useless, since it always needed to be at Maximum. Perhaps I could have bought a more powerful one? 2) The ring produced a HUGE amount of glare, making it difficult to see and giving me headaches. This is because of the small diameter of the ring. Basically, the light goes almost straight down, and bounces straight back up. Horrible. This becomes worse as you raise the microscope. A larger ring would help ... but there's a practical limit to the size, and a higher cost. My solution: I made a simple bracket, attached to the lens with a ring adapter, on which I placed 2 ordinary (100W equivalent) LED bulbs, which are offset 100mm on either side of the lens. The arrangement is similar to lights on a copying stand. Also, I added opaque reflectors, so the bright lights are not 'in my face.' I haven't bothered with dimming. I could, but it seems unnecessary. There is LOTS of light to see with, and the glare is completely gone. As you correctly suggest, reducing the glare is all about placing a light off to the side. I've never used my ring light again ... my solution works much better. Any difficulty reading text, I just rotate the chip/board until it becomes visible.
Hey, was that this simple all the time, or is now april first in Australia ? :)
what helped me in the past is using a pencil and drawing some lines on the chip, the itched part rub the pencil more than the other part of the chip and its more visible..
“Quality Inspection lab requests that all chips be oriented in the same direction so they don’t need to adjust the polarising filters so much.”
Bought a Leica S9d with polariser last week !
I use a cheap bottle of $1 water based acrylic white paint. Just barely wet your finger with the paint, touch the top of the chip then immediately wipe it off. The paint fills in the etched part numbers and you can then read them with a naked eye from any angle. If you want to remove the paint you can use a cotton swab with alcohol, though it doesn't harm anything and there is barely any paint on the part if you just wipe it back off. Never found a chip where it didn't work and takes seconds to do.
Actually amazing
Maybe the trick is to have a ring-light where the polarization changes with the angle (along the ring). Then a polarizing filter basically filters the incident-angle and you dont need to fiddle around with an additional light.
Wondering if this is similar to the hp technology for enhanced reflectance imaging that they developed in the early 2000s and used with great success in the Antikythera investigations.
I gotta get myself one of those goose arms! 😂 Crazy Aussie's 👍
Also great on a dashcam. Cuts a lot of reflections and glare.
If the object lay flat on the table, I usually turn my ring light off, put a light source (soft light is better) from six o'clock direction from the object, rise it up so the light falls about 45° to the object. It works quite well for me to read those laser markings.
On the other hand, it's well known that the best way to read those pesky barely-readable markings found on EPROM chips is taking a close-up photo of them with a digital camera that has a xenon-based flash. Accept no substitutes, a smartphone's LED flash won't work...
Now I got it. I used for years the trick with taking a shot with the cellphone with flash activated and from an angle. I take a burst while moving so some of them will show right:)
Is there any type of OCR to help read? What would you guys say is the best cheap Microscope?
He needs it because of the ring light. So you need cross polarization to block the reflections. You are using an off axis light so you can simply position your lights ource such that it is not producing an incident angle reflection on the chips. For real full put a piece of "transparent" plastic between the polarized film on the light and your polarizing filter. Rotate the polarizing filter until the light looks black and enjoy all the pretty colors of the light being bent by the birefringence of the plastic! With the two polarizers 90 deg opposed they block all the light (this was an old school way cinematographers would do a fade to black without any post processing... Two polarizing filters and you turn one during the shot.) The plastic alters the polarization of the light (differently at different frequencies) and makes pretty prismatic colors in the plastic.
Inking the chip with a marker reminds me of the way I mark torx bits. The sizes are stamped but hard to read, so I rub a white wax crayon on them. The wax stays in the groove and makes the numbers stand out.
I think that the difference is going to be much bigger on a cheap microscope and/or a black/white pcb. Those pcbs are very hard to inspect due to reflection with the cheap microscopes
Does the polarized setup let you see the part number when lighting from any angle? If so, it can be a real quality of life thing to have
The main idea behind these setups is that both the objective and the light ring has to have a polarizing filter. In these Leica ringlights (I have an S9i with a LED3000 RL polarized ring light) the objective has a fixed polarizing filter, and the outer filter in front of the ringlight is rotatating. It does NOT matter much at what angle you are holding your board/part/ic, since the ringlight polarization and your objective polarization are adjusted to avoin reflections, the visibility of direct-markings remains unaffected. For anyone wanting a cheap alternative, you just need to cut a circle and a larger ring from a polarizing filter salvaged from an old LCD and mount/glue one in front of a cheap ringlight and mount another one in front of the microscope objective (after adjusting it). It's a-nice-to-have if you could 3D print a ring for the ringlight filter so that you can adjust the reflectivity as you go.
Whoa! Dual Daves!
Never had a chance to check it out, but would IR or UV light disclose those pesky markings any better? Seems to me that I once read about using a cheap webcam with the IR filter removed to see markings better.
I used to use different colours of electrical tape over the lens of small LED torches to see different details of objects.
Anybody who spends a lot of time inspecting boards with these magnifiers, rarely puts the board down. Always tilting and moving it around
And this would work equally well in those conditions. Tilt of the board is completely irrelevant.
Hello sir can you tell me the name of your microscope light ?
- 12:45 You don't need a sharpie, licking your finger and rubbing it will often suffice. Sometimes I resort to smearing a bit of white thermal-grease into the etchings. - 14:23 In my experience, polarizing film does _not_ "peel off nicely" (at least from TVs), they're pretty horrible and messy to get off. 😕
I used to use the click wheel filter on the Olympus microscope
Damn, I could sleep without that pun today.
Does it have the same effect if you use florescent lights?
Woah tried it and its fucking AMAZING! If only I knew this sooner... Edit: Caveat is that its really only effective on matte finishes. The more specular packages with the narrow engraving (e.g. SMT transistors) don't work any better. Still the pair of junk polarized sunglass lenses are now in the drawer. I like! And for me it helps as the "microscope" is my eyes. Real time saver on a large board to just buzz through it with a flashlight and not have to re-orient it.
Dave, What was that board with the 68B09 on it?
cool! I wonder if it helps to see a rubbed-off part number?