My uncle is a physicist, and did some pioneering work in the field of thermal camera photo-receptors. He even wrote a book about the field in the 90’s, Fundamentals of Infrared and Visible Detector Operation and Testing (1990, James David Vincent).


The publisher wanted an updated manuscript for a second edition of the book. He’s been working on that for the past couple of years, but ran into a problem. He needed a diagram of a microbolometer.

A microbolometer is a small sensor that is sensitive to infrared radiation. The radiation hits a sensitive material that then heats up, and its resistive value changes. By measuring the resistive change, a temperature can be determined. Thermal cameras, such as FLIR cameras, use an array of microbolometers to generate a thermal image.

Although diagrams exist, the most well known (and oft plagiarized) is in fact under copyright, and not available to be republished without authorization.

He asked me to create a new diagram that would convey the same information but be visually distinguishable from the other well-known image.

After some back and forth, this is the image we came up with. It had to be black and white for printing, and easily readable. He also wanted extraneous information removed, so that there were fewer parts of the image to focus on.


For example, the thicknesses and dimensions, though accurate, are not labeled. To facilitate not having a labeled dimension between the ROIC and the temperature sensitive resistive element, there is a visible shadow. The image was created in Illustrator, and sent to the publisher as an EPS file.

The book, Fundamentals of Infrared and Visible Detector Operation and Testing second Edition (2015, John David Vincent, Steve Hodges, John Vampola, Mark Stegall, Greg Pierce), has been published, and you can see my diagram on page 94, Figure 3.3.




Apple Pi


I recently (2 years ago) purchased a Raspberry Pi (The original model). I bought it off a friend who never ended up using it for anything useful. My intent was to run a small web server with it, and enjoy some savings over the old computer I use for a server that was eating up more than 100 watts of energy.

I also didn’t care for the case it came with. I also happened to have a first generation Airport Extreme that I also got second hand. It served it’s purpose, but had since died. I thought these two might be a match-made in heaven.

I gutted the poor airport extreme and inspected it.

It didn’t know what hit him.

I was going to throw out the PCB entirely, until I noticed that the Raspberry Pi had two holes that matched up perfectly with two holes on the Airport’s main board. I decided to keep the circuit board for mounting purposes, and reuse it’s input jacks since they line up so nicely with the enclosure.

I desoldered all the parts I could near the connectors, and then marked off the part of the PCB I could remove. The intent was to remove all the circuitry that would be difficult to desolder. The result was a completely bare, partial PCB to work with.

I then soldered power, USB and ethernet cables to the circuit board that would then connect to the Pi (so it’s not hardwired in, and can be swapped).


Now I have a low power web server in a cute, unassuming box.

I also wanted to have the filesystem accessible over AFP so I could access it on my desktop. this was easily achieved by installing netatalk using the command:

sudo apt-get install netatalk

Now that I have the server’s disk mounted on my Mac’s desktop, naturally I need a representative icon.


Using a reference picture, I was able to throw this icon together in Illustrator in about a half-hour’s time.

Minimal Heroes

My friend is about to have his first son (after multiple daughters), and as such, is beginning to prep the nursery with decor appropriate for a little boy. He requested that I make some minimal designs that he will print on canvas with familiar super hero logos or identities.

The two he wanted most were Iron Man and Captain America. I did a quick design for each based on the most iconic symbol for each.

I’m not a huge fan of “minimalist” design. When I say minimal, I’m speaking mainly of “flat” design. I can see the appeal of flat design; It’s easy to make, easy to print, easy to display. It feels lazy to me though. My friend however wanted them flatter.

I obliged his request. He was ecstatic. The flatness doesn’t speak to me. It feels sterile, and boring. But he’s happy, so I’m happy.

© 2007-2015 Michael Caldwell