I designed and ordered the circuit board for the profilometer today. The core functionality is simple—all we’re doing is driving three stepper motors off the Tinkerboard’s GPIO pins, and taking input from three corresponding endstops. This leaves us with an awful lot of spare pins, however, so I added an additional three stepper drivers and six MOSFETs, leaving four pins to spare. If I want to elaborate on this project in the future, I’ll be all set.

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The software needed to run the optical profilometer has fundamental components: one to run on the Tinkerboard and do most of the work, and a user interface. This could all be rolled into one, but for the sake of ease of use, stability, my curiosity about web apps, and the Tinkerboard’s single graphics output channel, we’ll build this out as two separate applications.

Although there are a number of precidents for machine control software of this nature using a direct USB or ethernet connection to the machine in question, I think the link ought to be accomplished by WiFi and a server. Endless, frustrating 3D printer experience has given me strong feelings about this. The machine is run by a full-blown computer that is more than up to the task, and ought to be able to stand alone. Besides, I want to build a system that more closely resembles one that would be found in a commercial product.

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I’m building an optical profilometer. Made with a microscope, a projector, a camera, and a computer vision algorithm, it will measure the three dimensional topography of a sample by repeatedly imaging the sample at different heights, and measuring when each region of the sample crosses the microscope’s focal plane.

The idea is this:

• Begin with a fluorescence microscope, with a camera and a motorized stage. Remove the light source, and in its place, add a DLP projector, such that it can project an image onto the substrate.
• Use the projector to project a grid of crosshatches onto a tiny region of the substrate. Each one will correspond to a vertical pixel in the ultimate 3D image.
• Step the stage of the microscope up through all its possible Z values, capturing an image each time.
• Dice the image into squares, each corresponding to one of the hashmarks, a single XY pixel. Run each segment of each image through a computer vision algorithm, and assign it a score according to how in focus it is.
• For each pixel choose the Z value corresponding to the layer with the highest in-focus score. You now have X, Y, and Z values for the pixel.
• Do this process on a step-and-repeat basis over the entire area you want to image.
• Create a 3D mesh from all the pixels.

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Space Trader is a text-based roleplaying and strategy game for iOS, in which the user plays the captain of an interstellar merchant spacecraft and travels the galaxy, buying and selling goods, performing quests, and interacting with police and pirates.

Space Trader was once upon a time a Palm Pilot game, which as a twelve year old I wasted many happy hours playing. (Although its lineage, apparently, goes all the way back to an Atari game called “Elite“, by way of a Commedore 64 version.) When I decided two years ago that I needed to learn Swift, Space Trader seemed like a thing that needed to exist in the world again. A little digging revealed that the original source code was available, so I decided I’d recreate the game for the iPhone, keeping the original flavor and feel of the game as faithfully as possible while updating the UI to a modern idiom.

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From 2012 to 2014, I cofounded and led engineering at a startup that produced an FDM 3D printer, one of the first on the prosumer market to achieve reliability and professional print quality, and to feature soluble support. Our original website, preserved for posterity, can be seen here.

Though it has become a poster child for undeserved hype, 3D printing looked in 2012 like a technology with fundamentally transformative potential. We believed (and still do), that additive manufacturing would play a major role in the world economy by making it possible to produce highly complex physical objects very cheaply. To realize this, either the cost of the high-quality commercial machines (e.g. Stratasys) would have to dramatically decrease, or the quality of the hobbyist machines (e.g. MakerBot) would have to dramatically increase. The former seemed unlikely, but we didn’t perceive a reason for the latter not to happen quickly.

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