DIY Focus Stacking for Macro Photography - Page 1
Forum section: electronics / projects

author: mawyatt
author_rank: Super Contributor
timestamp: May 08, 2020, 05:00:34 pm
content: Focus stacking in macro photography involves techniques to deal with the very shallow Depth of Focus. For example when capturing images around 5X magnification the DoF can be as shallow as 0.028mm (28 microns)! Techniques and software have been developed to capture multiple images at different focus positions, either by changing the lens focus or moving the camera/lens or subject, then "stacking" them together to render an image with much larger in focus areas.At high magnifications moving the camera/lens is usually accomplished by a precision linear rails, either manual or motor driven. Commercial motor driven focus rails from Wemacro, Stackshot and others are very good and automated. When the desire is high resolution (high magnification) and a large Field of View, then focus stacking alone can't cover the intended area, so a type of stacking that involves a macro "Panorama" of multiple stacking images is required, often called Stack and Stitch, or S&S. There isn't any inexpensive available commercial equipment for S&S, so this opportunity begs for the DIY approach. Also if one wants to venture beyond what the standard commercial focus rails offer in performance, a DIY approach become attractive.Photomacrography is a great site for those interesting in macro photography, including DIY type efforts from custom developed lens to complete rig setups.https://www.photomacrography.net/forum/Here's a few examples that I've been involved with.Some videos.https://www.photomacrography.net/forum/viewtopic.php?t=39392&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39396&highlight=Custom developed S&S system based around Raspberry Pi Development.https://www.photomacrography.net/forum/viewtopic.php?t=38511&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=38548&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=38604&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=38512&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39318&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39428&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39755&highlight=Stepper Motor Controller Development.https://www.photomacrography.net/forum/viewtopic.php?t=39473&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39689&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39428&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=39756&highlight=Piezo Electric Stage Development.https://www.photomacrography.net/forum/viewtopic.php?t=40679&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=40681&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=40682&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=40510&highlight=LED Strobe Light Development.https://www.photomacrography.net/forum/viewtopic.php?t=40999&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=41353&highlight=https://www.photomacrography.net/forum/viewtopic.php?t=41464&highlight=Chip image source for some older renderings, latest results are still proprietary. Download images for full resolution, the last image is a sliver (cracked off during attempted wafer split) of a very old abused wafer that was a test image for the Fully Automated S&S System mentioned, its ~29,000 by 22,000 pixels.http://img.gg/taIZ99MFew older examples.Hopefully some folks will find this interesting.Best,Mike

author: RoGeorge
author_rank: Super Contributor
timestamp: June 29, 2020, 08:31:10 pm
content: An older focus stacking related idea of mine, that I will probably never pursue, so just dropping it here:- use an electrically controlled focus lens (based on electrowetting, so the focus adjusting to be faster than for a mechanically controlled focus), either DYI (https://youtu.be/tOEyxavTiGw) or ready made (https://www.corning.com/worldwide/en/innovation/corning-emerging-innovations/corning-varioptic-lenses.html). If the adjustable lens is not fast, maybe using a mechanically vibrated ocular.- high speed camera taking snapshots while the focus plane is changed with the controlled lens- FPGA implementing a live focus stacking algorithmShortly said, an automated focus stacking camera/microscope. The result should be a live image (movie) with increased depth of field.In cases where direct eye observation is required (optically), a fast LCD screen can be put in the optical path of the microscope, to dim out those pixels identified by the stacking algorithm as out of focus. The LCD will have only an on/off level for each pixel (each pixel driven by the focus stacking algorithm), so the eye could integrate over time only the sharp pixels for each focal plane.

author: DrG
author_rank: Super Contributor
timestamp: June 29, 2020, 08:39:41 pm
content: This is news to me and thanks. It sounds like HDR but for focus. Instead of stacking different exposures, which are easy to shoot using bracketing, the same idea is done with focus? That is making my head hurtBookmarked this thread and that site -

author: SilverSolder
author_rank: Super Contributor
timestamp: June 30, 2020, 12:13:19 am
content: You can do focus stacks with your normal SLR (or at least variable focus!) camera by taking several pictures (min 2 of course), loading them into Photoshop, and run the Photomerge function. Easy as!Of course, things get harder and harder the shallower the depth of field. The mechanics of holding the camera becomes the main problem at some point.

author: DrG
author_rank: Super Contributor
timestamp: June 30, 2020, 12:30:16 am
content: Quote from: SilverSolder on June 30, 2020, 12:13:19 amBy bracketing f-stop? or am I just not getting it?

author: RoGeorge
author_rank: Super Contributor
timestamp: June 30, 2020, 12:48:43 am
content: Quote from: mawyatt on May 08, 2020, 05:00:34 pmTook the time to browse a few of the links, and wow! Very nice projects.And the die photos, after focus stacking, are amazing.About the piezo stage project, does that model need pulses to move, similar with a stepper, or is it some sort of voltage to position actuator? From your project logs it seems to me that your piezo stage is rather a piezo actuator than a piezo stepper. If so, did you happened to experiment with a stepper piezostage, too?I'm asking because one of my way too many bucket list projects is to experiment with a DIY nanostage (just a lump of piezo material for each axis, with an inertial weight attached at one side, and the free moving stage attached at the other side of the piezo lump, moving just by friction and inertia and a sawtooth waveform driving the piezo, no Archimedes screws, only free moving axis, similar with the idea from the inertial motor), and I will be very curious to learn how well a DIY piezo stage can perform.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 30, 2020, 01:14:16 am
content: Quote from: DrG on June 30, 2020, 12:30:16 amBy bracketing the focus - imagine a manual focus lens, you turn the focus ring a tiny bit between each shot, so different parts of the 3d subject come in focus in each one.What Photoshop (and other applications) do with those shots is to pick the parts of each image with the sharpest focus, and weld them all together into one image, where everything is sharply focused!

author: todd_fuller
author_rank: Contributor
timestamp: June 30, 2020, 01:26:58 am
content: Seems like the now-defunct Lytro camera would be perfect for this application. It was able to change field of view in software after the fact. Pretty interesting technology. Their real camera was $$$ though.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 30, 2020, 03:00:46 am
content: I resort to stacking quite often. Some of the newer digitals have it built in. My Z6 does, but unfortunately the lenses I like to use are manual focus so I have to do it manually. I've tried focusing with the lens, focusing on a rail and focusing just the body, with the lens in a fixed position. Best results have been focusing the lens. The images can be put together with the free CombineZP, but it crashes with a lot of large images. Picolay is another free one, or there's the standard Helicon Focus and maybe a couple others.

author: Thomas
author_rank: Regular Contributor
timestamp: June 30, 2020, 10:44:18 am
content: I used Helicon Remote and Helicon Focus with my SLR for focus stacking. Interestinghttps://www.heliconsoft.com/heliconsoft-products/helicon-remote/https://www.heliconsoft.com/heliconsoft-products/helicon-focus/Below is a picture of my watch, stacked from 28 images.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 30, 2020, 10:54:19 am
content: Quote from: Conrad Hoffman on June 30, 2020, 03:00:46 amPicolay has the best alignment algo of all the ones I've tried, far superior to Photoshop which tends to give up on low contrast images.

author: DrG
author_rank: Super Contributor
timestamp: June 30, 2020, 12:26:56 pm
content: Quote from: Conrad Hoffman on June 30, 2020, 03:00:46 amJust doing some reading about this. Do you make a distinction between focus stacking and focus bracketing?https://www.mu-43.com/threads/what-is-the-difference-between-focus-stacking-and-focus-bracketing.81617/My current DSLR does not have focus bracketing. Some years ago, I played around with the Canon SDK and I wondered if it could be used to control the focus stepper. Looking around this morning, apparently the answer is yes - e.g., DSLR Bracketerhttp://milosparipovic.com/#/devand now I am looking into DSLR Controller app for androidhttps://dslrcontroller.com/to control my EOS 200D.*drat* there is a couple hundred hours of very cool stuff herecurse you people

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 30, 2020, 05:10:41 pm
content: Quote from: DrG on June 30, 2020, 12:26:56 pmI've never heard things described as in that link. Taking multiple images at different focus points and combining them to achieve "impossible" depth of field is AFAIK, focus stacking. Never heard focus bracketing before, but I don't get out much. ;-)Once you start playing with this, you'll probably find it addictive.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 30, 2020, 05:26:02 pm
content: To attempt to define some terms...Exposure bracketing is basically shooting extra pictures exposed above and/or below the starting setting, to make sure you get at least one correctly exposed image (and/or use it for HDR photos).Focus bracketing sounds like the same idea applied to focusing... to be convenient, it really needs to be built in to the camera.Focus stacking is a deliberate, intentional use of focus for a series of single shots, that you intend to use to create a greater whole.

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 06:00:02 pm
content: Quote from: RoGeorge on June 30, 2020, 12:48:43 amThe piezo stages are operated Continuous Closed Loop and use a strain gauge in a bridge configuration for position sensing. The piezo elements are continuous voltage driven by a low noise high voltage amplifer with the stain gauge as feedback and command position from a 16 bit DAC controlled by a RPi. See details at PM. Note linearity and the 750nm range! Think this was with 4nm DAC increment resolution.https://www.photomacrography.net/forum/viewtopic.php?f=25&t=40510&hilit=Piezo+StageHope this helps,Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 06:24:08 pm
content: A few answers to some questions.1) Generally in-camera focus stacking doesn't work well when the magnification goes beyond ~ 2X, it's better to move the camera/lens and/or subject. Perspective issues become a problem. Check out PM for more details.2) Often special lens are used in stacking other than the standard camera "macro lens". Reversed lenses, stacked lenses, inspection lenses, microscope lenses, reproduction lenses, and bellows lenses for example. See PM for more details.3) Special telecentric lenses, or near telecentric, are often used for serious Stack and Stitch (S&S) work. S&S is like a macro panaorama where multiple focus stacks are stitched together to render a much larger image. We've done 29000 by 23000 pixels chip images, and soon much larger!!4) Lighting becomes more difficult as the magnification increases. Many use flash/strobes to help with vibration issues. Highly diffused light is generally required, many times with multiple layers of diffusion.Anyway, lots of things to deal with, the mentioned PM site is devoted to macro imaging and a great resource.https://www.photomacrography.net/index.htmHere's a very low res (original is ~40MB JPEG) chip image example. It's a Direct Digital to Antenna (DD2A) chip (patent 7903016) from long ago, process was IBM Silicon Germanium 9HP 90nm BiCMOS.Best,

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 01, 2020, 06:35:41 pm
content: I am also subscribing to interesting thread.The images are beyond awesome.

author: DrG
author_rank: Super Contributor
timestamp: July 01, 2020, 06:40:33 pm
content: Quote from: mawyatt on July 01, 2020, 06:24:08 pmYeah, I have been doing some due diligence and reading on the wide range of the subject matter. It is intriguing.I also went to the site and looked around and read the posting policies and so on. Thanks for making me aware of it.I don't have the equipment to do it properly right now but it is on my radar. I may try an attempt with what I have. Believe it or not, one consideration is all the other projects ongoing and on the list.

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 06:46:48 pm
content: Quote from: schmitt trigger on July 01, 2020, 06:35:41 pmThanks.I'll post more low resolution images and details if you and others want (many images I can't show though). Don't want to take up space unless folks are interested.The history behind all this started way back in ~2003, when we wanted to get images of the chips we designed but wanted something other than the usual microscope type chip image.Best,

author: RoGeorge
author_rank: Super Contributor
timestamp: July 01, 2020, 07:27:05 pm
content: Yes, of course, please post more pics!Also, in general there is a lack of information about how a certain transistor, stage or other schematic structure looks like in silicon (e.g. people asking to read a die photo similar with reading a schematic:https://www.eevblog.com/forum/projects/die-shot-features-help/), so any other explanations or annotations will be appreciated.

author: Dave
author_rank: Super Contributor
timestamp: July 01, 2020, 08:14:34 pm
content: Incredibly interesting thread. The pictures look surreal, almost like a fancy 3D render.Speaking of DOF, would it not be possible to make it a bit deeper by reducing the aperture and extending the exposure time? Or are you already at that limit with the 28um example?I understand that it would never achieve the same effect as focus stacking, but it would at least reduce the number of images required, making the precision/mechanical tolerances of the automated jig a bit looser.

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 08:20:04 pm
content: Quote from: RoGeorge on June 30, 2020, 12:48:43 amTo elaborate more on the Piezo Stage Technology. This is the same technology used in the semiconductor fabrication processes and involves a clever arrangement of precise cuts (laser) in a solid chunck of Stainless Steel, these cuts create a special mechanical type bearing called a Flexure. A long piezo element comprised of many smaller piezo sections is mounted into the SS structure by means of compression, under applied voltage the piezo elements expand and "push" against the SS structure to create movement. See more details on the PI site.https://www.pi-usa.us/en/products/piezo-flexure-nanopositioners/?onl_goog_piezo_pos&gclid=Cj0KCQjw6PD3BRDPARIsAN8pHuENs--371LYn7jUgtgRU4uIro2KceY6ev7YfPrrAHESquNtg7WIUHwaArmJEALw_wcBIf you decide to go ahead with your DIY project, we've developed a couple DIY closed loop controllers for the PI stages (P601 and P603) that work with the Raspberry Pi. These PI stages sometimes show up on eBay for a reasonable price.https://www.photomacrography.net/forum/viewtopic.php?f=25&t=40123&p=252513&hilit=VCM#p252513Another interesting concept is using an ordinary speaker as a Voice Coil Motor, you can see some notes here.https://www.photomacrography.net/forum/viewtopic.php?f=25&t=40123&p=252513&hilit=VCM#p252513Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 08:41:35 pm
content: Quote from: Dave on July 01, 2020, 08:14:34 pmThanks.The effective aperture (EA) generally follows as Lens Aperture, or LA, as LM(1+M), where lens aperture is the normal "reading" on most cameras (Nikon shows the EA, not LA). When you get an EA that's beyond about F20 or so, diffraction begins to eat your lunch if your images are viewed at larger sizes. Normal lenses this doesn't matter, since shooting a bird at 100 feet or a portrait at 10 feet, M is very small, so M+1 ~ 1 and EA ~ LA. However when shooting macro this becomes a problem, example shooting at 1X the EA is twice the LA, so one would begin to see diffraction effects around LA of just f11 (in very high quality work this is below f8!!). So "stopping down" the aperture to increase the depth of focus has a limited range.Some of the latest software tools attempt to reverse this situation, by using a de-convolution to partially remove some of the diffraction induced blurring. I haven't used any of the tools yet, so can't comment reliably, but others have shown good results.Some the "benchmark" microscope objectives from Mitutoyo (5X, 10X, 20X) have an EA of ~18, so this is a good indication of where things begin to suffer from diffraction effects.Depth of Focus = Lambda/(NA^2), where lambda is wavelength (550nm for green), NA is numerical aperture or M/(2*EA)Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 08:54:15 pm
content: Here's a few more very low resolution images that I can show. All of these are from long ago, so allowed to show. Note damage on 1st imageBest,

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 09:12:09 pm
content: And a couple more.The colorful chip is a new type (~8 years ago) ADC from USC in TSMC 65nm CMOS, called non-uniform sampling. It basically has a varying output data rate based upon the waveform characteristics, so it quantizes in amplitude and time and creates it's own antialiasing filter.The other chip is an experimental Iridium Receiver in IBM SiGe 8WL 130nm BiCMOS.Best,

author: Hydron
author_rank: Super Contributor
timestamp: July 01, 2020, 10:04:05 pm
content: Ooh, seems the focus stacking rabbit-hole goes deeper than I imagined...I'm wondering if there is any use of 3D printers as a readily available focusing stage - just attach the camera to the Z axis and send some G-code to wind it up a little bit per photo? Probably wouldn't work on the higher magnification end, but maybe with more modest setups? Apologies if this is widely done or doesn't work - didn't see anything about it in my brief look at the equipment section of the forum.Appreciate the images!

author: 2N3055
author_rank: Super Contributor
timestamp: July 01, 2020, 10:23:03 pm
content: Amazing!

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 10:42:25 pm
content: Quote from: Hydron on July 01, 2020, 10:04:05 pmI think the best value for a good setup would be the WeMacro focus rail and the WeMacro Vertical Stand, this works well up to about 10X and some have good results beyond. Pretty much plug-n-play with your camera and lens. A couple simple mods extends the Vertical Stand to handle beyond 20X, this stand also works horizontally if you get the option.For beginning DIY you'll probably end up spending more to get things in good working order than just getting the WeMacro. Once your "hooked" then you'll want to get better focus rails, camera, lenses, setups and it never ends, please don't ask how I knowThis is really where the DIY comes into play.Think we've pretty much pegged the limit performance on focus rails with the THK KR types, with 400 step motors and Trinamic based controllers, that's when the piezo efforts began. This is seriously expensive stuff new, well the THK stuff is also, so eBay becomes a valuable resourceIf you watch sometimes you can find a bargain, but it's always a risk like anything off eBay.Some folks have 3D printed various adapters, holding fixtures and light fixtures, but I haven't seen anything like a focus rail.The camera is probably the least important item in the setup, almost anything will work, and work well. Lenses and lighting become critical for high resolution images, and handling vibration issues becomes a never ended task, especially as you increase magnification. Kinda like the folks doing the high resolution LTZ1000 voltage references, at those levels everything matters!!Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 01, 2020, 10:54:28 pm
content: Quote from: 2N3055 on July 01, 2020, 10:23:03 pmThanks.A colleague got a 55 inch OLED display mainly to show these chip images (well not these, but some later proprietary ones). He also had one printed on a very large metal base. They look incredible, now he's probably going for a larger OLED screen!!If seeing a 1/2 gigpixel chip image printed the size of a wall sounds interesting, especially if it's one of your chips, then you are probably going to get hookedBest,

author: RoGeorge
author_rank: Super Contributor
timestamp: July 01, 2020, 11:27:46 pm
content: Quote from: mawyatt on July 01, 2020, 10:42:25 pmThe speaker as a focus stage idea you mentioned before seems a very good alternative. Much easier to control than a piezo actuator, also, since is a mass produced item, a speaker is very cheap.Another idea that just came when you wrote together the words voice coil actuator and speaker (mass produced), was the actuator from a CD/DVD/BluRay unit. It is mass produced (so it's very cheap), and is capable of very high speed moves on more than one axis. Has all the mechanics in place, very low inertia and high speed photodiodes to implement a very fast PID for stabilisation.Gave it a search and found a nice paper (https://doi.org/10.1021/acssensors.8b00340) about reverse engineering the optical head of a disc unit (3 different models from gaming consoles). In the supplementary material there is a slide show presentation and some control schematics, too:https://pubs.acs.org/doi/abs/10.1021/acssensors.8b00340The up down range is quite limited, just a couple of millimeters, probably enough for a chip die or a very small insect.

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 12:33:10 am
content: Quote from: RoGeorge on July 01, 2020, 11:27:46 pmInteresting, thanks for showing. I wonder how much load these actuators can handle?The P601 and P603 PI Piezo Stages can handle moderately heavy loads in Closed Loop, this was the weak link of the speaker VCM. There was no practical way for feedback, so it operated Open Loop and suffered from position errors.The THK KR rail types are very well designed and use a temp compensating base metal, probably the best available in screw type linear rails. With the Piezo stage operating in closed loop we created a setup at high magnification (800X I recall) and watched the image as a hair dryer on hot setting blew hot air across the piezo stage. It hardly moved, the control voltage was all over the place to keep the loop closed but the stage was rock steady. When this was done to the THK KR20 the image quickly drifted off screen, direct consequence of open loop operation, even with the superb THK KR20!!The setup we use for high magnifications utilize the piezo stage and the THK KR20 rail. The KR20 is used for coarse camera/lens positioning and the Piezo stage for fine moving the subject. Many times I don't bother powering the THK rail up, just use it as a manual positioner by turning the motor shaft. Since we know the motor steps (400) and the KR pitch (1mm/turn) we can make movements by hand just counting motor cogs steps at 2.5um/step. If we need something between steps, the the KR20 must be powered to get fractional steps. The Trinamic controllers have 256 micro-step increments, so theoretically you could get 1mm/400/256, or 9.765nm increments. Of course this is ridiculous, a reasonable estimate would be 10 to 20 times that.Best,

author: c64
author_rank: Frequent Contributor
timestamp: July 02, 2020, 05:46:16 am
content: These pictures look awesome. So sharp, look more like 3d models not photos.Subscribe.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 02, 2020, 07:34:44 am
content: Quote from: 2N3055 on July 01, 2020, 10:23:03 pmQuote from: c64 on July 02, 2020, 05:46:16 amhis collection can be downloaded atnikonimagespace(100MB+) from his threadSome Older Chip Imagesthis will not consist of the techy stuffs discussed here and on the photomacrography forum he linked alone. photo/color doctoring is one discipline in photography also required, used in movies everytime without muggles knowing it. i used to combine photos for HDR effect and then later add punch to the color. you dont get such color in real life... few random example attached... btw i downloaded his collection for my keeping and learning later, the folder name where i've put it tells something about its ranking..Code::\Knowledge\Digital Camera\Masterpiece\mawyatt (eevblog)not have a use for FOV bracketing yet, let alone the lens used by OP to get microscopic pictures of the silicons. but one trick to increase FOV is reduce lens aperture as much as you can (pinhole camera), since amount of ambient lighting will be much reduced, you'll need more powerful artificial lightings to help with colors painting where they need to be (photographer's rule to paint with lights). i can see some imperfection in the focus stitching, either its manually edited, or the stitch SW used is not so perfect yet. maybe manual editing and "space re-warping" in photoshop can give better result esp in exhibition or competition grade purpose. ymmv and fwiw..

author: Hydron
author_rank: Super Contributor
timestamp: July 02, 2020, 08:47:44 am
content: Quote from: mawyatt on July 01, 2020, 10:42:25 pmI didn't mean printing parts to use as a focus rail, but to use the printer itself as one! On my printer a full step on the Z axis is 40 microns, and it does 1/16th microstepping so you'll get a bit more resolution from that, albeit not as linear. The X and Y axes are significantly more coarse and are likely to have issues when throwing significant loads around (e.g. my early Canon non-USM 100mm macro lens plus a camera is fairly heavy), but if you attached a sample to the Z axis and moved it up by full step increments then in theory you can move it relative to a camera sitting on the bed pointing up at it. Control is a simple as sending G code commands with the Z move distance (there may be some jiggery pokery forcing it to move without a homing cycle first, but you could get around that by homing first then setting it up for photography).This is obviously on the less extreme side compared to piezo stages etc, but I might test it in the 1-2x max macro range I can manage with the gear I have at hand.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 02, 2020, 08:51:55 am
content: Quote from: mawyatt on July 02, 2020, 12:33:10 amIndeed, load weight for a CD optical head is not much, probably a gram or so at most.Another type of closed loop actuator, even easier to use and totally free for DIY experiments will be the actuator from an older hard disk. HDD heads already heave the control loop, are trivial to position with nothing but software and an old PC.I've played a few times with opened HDD running. They can work in open air for a very long time, for many days if not weeks, in a normal living room. The drawback is that the absolute position of the actuator is read from one of the spinning disks, so the disk must spin for the original control loop to keep the actuator in place, therefore it will come with some vibrations from the spinning plates. Maybe synchronizing the camera trigger with the angular position of the spinning disks, or maybe keeping the objective open for infinite exposure time and just flashing some LED lights in sync with the disk RPM might help catching the vibrations always in the same position. I don't know.However, once locked on a track, the HDD heads are very stable, it was not easy to unlock their position by hand. I didn't measured the force, but I'll guess the actuator could drive an extra load of tens to hundreds of grams. That should be enough for a small stage with a chip die or an insect.I imagine the HDD to stage adapter like a big loop of fishing wire that is anchored to the arm of the HDD actuator. The fishing wire loop is bigger than the HDD, and leaving the HDD body through small holes in the sides of the HDD frame, so to not keep the HDD plates spinning it open air. Small ball bearings in the corners of the closed loop of the fishing wire might help. Seems too complicated already.Maybe just a small aluminium stage anchored with 2 screws on the actuator's arm would be enough. Far from ideal, but good for insects and free to try, with only a weekend long, or so, of tinkering. Or, it might not work at all because the PID coefficients might not cope with a much heavier load...Speaking of insects and macro shots and focus stacking, a trick that I've discovered by serendipity:To arrange the photo posture of a live insect, and to make it stay still in the given position for a few minutes, put the insect in a refrigerator, 40° F (4° C) for half an hour, or so.This won't hurt the insect. To them, those cold temperatures might easily happen in the wild during a cold night. It will take to an insect a couple of minutes before its temperature will raise enough to start moving, even when put in the direct sunlight for a better photo. That should be enough time for a quick focus stacking shooting session.Back to that gorgeous photo you posted before, "Iridium- DMap-Obj-1a-Edit.jpg", a stupid question, but please keep in mind that I know nothing about laying a circuit in a die, so here it is:Are those spheres the soldering balls? Asking because they seem incredibly close to various die structures. Some of them look like they have no dedicated pad area underneath. Isn't there a danger for the melted soldering ball to cover or get too close to the die structures? Then, there are some circular structures in the most left corner, I assume are some microwave coils. Wouldn't those coils be too close to the PCB traces, or to the PCB copper planes that the PCB designer might put underneath the coils area, and thus ruin the coil's Q factor by the Eddy currents induced into the PCB's copper?

author: Thomas
author_rank: Regular Contributor
timestamp: July 02, 2020, 10:45:54 am
content: Amazing images, mawyatt.Clearly, this topic doesn't stop at an SLR with a macro lens and some software.The rabbit hole is deeper than I thought. Way deeper

author: fcb
author_rank: Super Contributor
timestamp: July 02, 2020, 11:31:07 am
content: Gorgeous images!! - any chance you can post these in high res so I can get one made into a poster for my lab wall.

author: Rerouter
author_rank: Super Contributor
timestamp: July 02, 2020, 12:26:09 pm
content: I feel I have missed it, but are there any free focus stacking programs anyone can recommend to give it a try?

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 12:27:10 pm
content: Quote from: Mechatrommer on July 02, 2020, 07:34:44 amThis works (reducing lens aperture) to increase the in-focus depth, but at the same time degrades the image quality due to diffraction blurring. Diffraction is the limiting factor in achieving good depth of focus and the effective aperture is usually kept below 20.Regarding aperture, the Effective Aperture (EA) that affects the image quality, not the lens aperture your camera reports (unless it's a Nikon which reports Effective Aperture), follows Effective Aperture = Lens Aperture (1 + Magnification). So at 1X magnification the EA is 2 times the Lens Aperture. Most of the high quality microscope lenses, which have a fixed aperture, stay under 20 for this reason.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 12:46:37 pm
content: Quote from: Hydron on July 02, 2020, 08:47:44 amOk I see what you are referencing now.Pointing the exposed camera lens upwards is probably not a good idea, since things can fall onto the lens surface. If you could mount the camera/lens onto the Z axis stage facing downward like a normal setup that should work. Having a minimum 40um step in the Z axis will limit the magnification to less than 4X because of depth of focus. Most use setups which have under 5um minimum step size, many under 1um.The piezo stages are an extreme case, where you are working at very high magnifications. The piezo stages mentioned have a total travel of less than 0.25mm, and step sizes of less than 0.01um!!Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 01:03:54 pm
content: Quote from: RoGeorge on July 02, 2020, 08:51:55 amYes those are tiny (100um diameter) solder balls for flip-chip mounting. Many years of material engineering went into the metal alloy, size, shape and wetting surface design of these solder balls so they make reliable connections without shorting to other structure.Those solder balls are difficult to work with (photograph) since they are like tiny spherical mirrors and reflect everything around including the light sources. So highly diffused uniform lighting is required to keep the specular artifacts in check.Great question, the coils are small inductors utilized for impedance matching networks. All the effects due to Eddy currents, silicon die subsurface and PCB placement are taken into account. The EM fields are mostly confined to much less than the physical distance between the die surface when flip mounted and the PCB surface due to the high dielectric constant of silicon (~11), so the PCB has little effect on the inductor.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 01:25:35 pm
content: Quote from: fcb on July 02, 2020, 11:31:07 amThanks. Sure I can provide some higher resolution images, but they are limited in size for posting here I believe. If you look at DP Review some are available at higher resolution. Do a search for Chip Images and more will show up, the author is mawyatt2002, I've posted a few there.https://www.dpreview.com/forums/post/60270789Another resource is at Nikon Image Space mentioned in one of the above threads, where you can download the images in higher resolution.I also can send some directly but my email is limited to just 10MB.Best

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 01:26:53 pm
content: Quote from: Rerouter on July 02, 2020, 12:26:09 pmI use Zerene, but it's not free. You can download a free trial though.Best,

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 02, 2020, 03:32:20 pm
content: Quote from: Rerouter on July 02, 2020, 12:26:09 pmthere are few in the list... i used Enfuse as one of the tools to do HDR stitching, it seems now to support focus stacking as well...https://en.wikipedia.org/wiki/Focus_stackingps: for keen programmers, you can start with edge detection algorithmhttps://en.wikipedia.org/wiki/Edge_detection. where more edges information in the picture (higher spectral content or less compressible a particular portion of the image), thats where the focus should be, thats where to give more weight (or to put less mask) on the image, i guess this is how classic software based "contrast detection" auto focus in digital cameras work. blur the mask to avoid nasty result and then overlap them all. it should be not that difficult for a simple stitcher.Quote from: fcb on July 02, 2020, 11:31:07 amfew replies up is the link in nikonimages.....

author: Dave
author_rank: Super Contributor
timestamp: July 02, 2020, 03:45:50 pm
content: Quote from: mawyatt on July 01, 2020, 08:41:35 pmThanks for the explanation, knew there had to be some sort of catch behind it.

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 05:39:28 pm
content: Quote from: Dave on July 02, 2020, 03:45:50 pmUnfortunately there's no free lunchAlthough, lately some research work has filtered down and folks are using what's called "blind deconvolution" algorithms to help remove some of the effects of diffraction. We haven't used these algorithms (yet) but others have shown good image improvements.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2020, 05:51:06 pm
content: Quote from: Mechatrommer on July 02, 2020, 03:32:20 pmPS has this capability built-in. It works OK, but has problems with involved macro stitching. Used it for a few simple stitching efforts, but it choked on some more complex stitches, so we ended up getting PTGui which works very well. PTGui has a somewhat long learning curve, but handled massive stitches rendering over 1/2 gigapixel (from 16~19 stacking session, stacked images rendered from ~300 images per stack at 36Mpixel per image, a total of over 200 gigapixels collected).Best,