Electronics > Projects, Designs, and Technical Stuff

DIY Focus Stacking for Macro Photography

<< < (5/10) > >>

Dave:
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.

mawyatt:

--- Quote from: RoGeorge on June 30, 2020, 12:48:43 am ---
--- Quote from: mawyatt on May 08, 2020, 05:00:34 pm ---Focus stacking in macro photography
...
Piezo Electric Stage Development.
...
Hopefully some folks will find this interesting.

--- End quote ---

Took the time to browse a few of the links, and wow!  Very nice projects.   :-+
And the die photos, after focus stacking, are amazing.   :clap:

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.

--- End quote ---

To 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_wcB

If 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#p252513

Another 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#p252513

Best,

mawyatt:

--- Quote from: Dave on July 01, 2020, 08:14:34 pm ---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.

--- End quote ---

Thanks.

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, 

mawyatt:
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 image :o

Best,

mawyatt:
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,

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod