Macro Images of a Chip

A friend from the Omaha Maker Group gave me an interesting chip a while back. Apparently it is some kind of optically sensitive chip, it has a clear case.
I thought it would be interesting to take some macro photos of it and see if I could capture some of the details of the die. I started out with just some simple shots with the kit lens and extension tubes.
Easy enough to see, but lighting was difficult with the chip as close to the lens as it was. You can see the wires and a little detail of the chip, and the lighting in this one gives a nice shadow on the wires.
I then switched to my long telephoto lens, extension tubes. This let me move the chip back from the lens a few inches, which made getting light in much easier. It didn't produce an image that was any more magnified though.
The chip is about 2.5mm on the short dimension.
From here I added a 10X macro expander lens and also a 10 triplet hand-lens to see if I could get any closer. This was difficult because it's a separate lens and can't easily be mounted on-axis with the camera lens. With a little fiddling around it came out ok. I can see a lot of details, though it's starting to get fuzzy around the outside, only the middle is relatively free of aberration.
Here's a crop from that image.
In the original photo the 2.5mm chip is a bit over 1100 pixels across, giving about 2170 nanometers per pixel. The narrowest traces are about 4 pixels wide, about 0.0003 inches. I'm not sure what the aperture was set to, but this is probably not bad performance for a first attempt. I'll have to do some reading and set up my equipment a little more carefully and see if I can sharpen this up a little more.
Edit: with a little more fiddling I got it down to 580 nanometers per pixel. Pretty sure I can take it farther, but I need to set up something to handle adjusting the sample position for fine focus. It's pretty fiddly. Also need to get some bright light onto it so I can see it in the live view. My dim desk lamp doesn't really cast enough light for this.

2014 Robotics Expo Wrapup

Thanks again to everyone who helped make today’s booth at the Robotics Expo a huge success again this year.  Booth volunteers included Ben, Don, Mike, Michael, Brandon, Nick and Jared, with material support from Patrick, Sarah, Eric, Dave and Katlynn.  [Apologies in advance if I missed anyone].

If you weren’t able to make it out today, but would like to volunteer at some point in the future, just keep your eyes on the mailing list, as we’ll have several more opportunities throughout the year.

Photographic Depth of Field

I was curious why a large aperture on a lens reduces depth of field. To investigate this I set my camera up with a macro extension tube and a subject with lots of depth.

The subject is a potassium sodium tartrate (Rochelle salt) crystal mounted in a brass holder, with a copper contact wire for detecting the crystal's piezoelectric properties. From the perspective of the camera, this setup looks like this:

This image shows a very short field, as is typical with macro photos that are taken from very close to the lens. The focal plane is about 10 degrees off of perpendicular from the surface of the coins, and intersects the subject about where the copper wire wraps around the crystal.

To understand why some parts of the image created when the aperture is large are blurry, it's helpful to visualize the paths the light takes through the lens. I used this simulator to make a simple diagram:

From any given point on the subject on the left, light passes through every point on the lens and is focused onto the camera's sensor. If you imagine a tiny bug with an equally tiny camera walking around on the big lens and taking his own pictures of the subject, you would noticed that depending on where he was standing, his photos would each be slightly different, sometimes from a little higher or lower, or one side or the other. We can simulate the bug camera photos by taking a picture through a pinhole placed in front of the lens.

Because the tiny bug camera has a really tiny aperture, all his photos will have very large depth of field, they'll be sharp all over. My bug-simulator has a fairly large pinhole, you can see it near the top of the image, it's about 2mm wide, so I won't get as much depth of field, but you can definitely see that much more of the depth of the image is in focus, compare to the image above and note how in these both the rubber band near the back of the image and the reeds on the edge of the coin are sharp. Here the bug is walking from one side of the lens to the other:

It's hard to tell in the still images, but the perspective is different in each shot, the angles all change a bit as the bug walks across the lens. It's easier to see this if you user a bigger hole so that you get a full-frame image instead of the circular shot, but it's harder to see the increase in the depth of field. Here is another example with a slot to let in more light. Left side from the top of the lens, right side from the bottom. 

Since the tiny bug camera can only collect a tiny bit of light with each photo, all those slightly-different photos will be quite dark. If we stack them all up to increase the brightness, we get the image we would get from the regular-sized camera. It's a bright, but only the parts that were all the same in the individual images will still look sharp in the combined image. The parts that were all slightly different will be all mixed together, making them appear blurry. 

That's exactly what the big lens is doing, stacking together thousands of different perspectives of the view all taken at the same time. We could get deeper depth of field in the image by using a smaller aperture, but that makes the image darker. To compensate we can increase the light on the subject, leave the shutter open longer, or use a more sensitive sensor.

To really see this effect, it's best to see it in a video, so check this out:

2014 FirLumber Rally Photos

OMG’s innaugeral FirLumber Rally was a great success, with 17 cars competing.  Official results will be posted shortly, but in summary, Dave’s electric cheater was the fastest, Eric’s elephant was the most creative, and Nate’s car was the least effort to build.  Additionally, Dan’s kids’ cars were the fastest among the Squares.

We’re just a group of Racer tech wizards who drive a Barbie, but rely on a cowboy.

Members of OMG recently attended Maker Faire Kansas City. While hopeful that we’d be able to race our latest project “Barbie”–a souped-up power wheel–in the Power Racing Series, several set-backs caused us to withdraw from the event. Team OMGFTW (Omaha Maker Group for the win) may have been knocked out this time around, but we’ve already begun working out Barbie’s kinks, which means one thing–we’re already ahead of the game! Though we didn’t get to race, the Omaha World Herald wrote an article about the trials and tribulations of taking Barbie from a mere girly power wheel toy to a lean mean winning machine. We’re just a group of Racer tech wizards who drive a Barbie, but rely on a cowboy.

Another Successful Presentation – Balloon Animals!

Tonight’s meeting was a great success, thanks in large part to Tom’s Balloon Animals presentation/workshop.  Members and visitors were shown, and then guided through making a variety of plants, animals, and inanimate objects.

Additionally, we had a number of visitors, and worked on projects including a Peltier-cooler proof of concept and a grinder stand. We also dusted off an old Teletype, in preparation for it’s impending Twitterification.

Omaha Creative Week Spark Event – Tuesday September 4th, 7pm.

Just a reminder, the Omaha Maker Group’s regular meeting on Tuesday, September 4th is an Omaha Creative Week Spark Event. We have several presentations on the docket, including a summary of the Omaha Maker Group (and Making as a whole), as well as a hands-on presentation on manipulating your car’s onboard computer for diagnostics and customization.

Hope to see everyone there!  If you have questions, don’t hesitate to email

Learn about Lockpicking from a Toool.. member

Would you like to learn about lock picking? Come to our meeting Tuesday July 10th @ 7pm.

The meeting will feature a talk from a member of (The Open Organization of Lockpickers), Steve Beck.

Steve will cover three topics, two of which are a little more hands on-ish, the first will be a basic lockpicking talk, the second will be a re-keying talk with a demo and the third will be about making your own picks with a demo.

Stick around after the talk for socializing and Makery Shenanigans.

Directions to the Makery