Intro to Fourier Optics and the 4F correlator

It seems strange that a single piece of glass can compute the Fourier transform of an image, but it is true (sort of). I explore an optical arrangement known as a 4F correlator, and note the practical considerations that are rarely discussed in existing sources.

http://www.imagemagick.org/Usage/fourier/

Large area detector for X-rays

I built a large area detector that is sensitive to X-rays and will be used in an upcoming project. The detector is constructed from a "Lanex Regular" X-ray intensifying screen, and a Hamamatsu R6094 photomultiplier tube (PMT). The PMT amplifies the light from the intensifying screen which is emitted when an X-ray strikes the screen. The area of the screen allows it to catch many X-ray photons created by backscatter. The PMT is setup with a simple 100K resistor between the anode and ground. A 1V output corresponds to a 1 microamp anode current. I'll probably add a very simple opamp circuit to this, and then pipe it into an A/D converted for digitization.

Reverse-engineering and testing an x-ray filament supply

I bought a set of x-ray equipment on eBay, which included an x-ray head unit, 50KV supply, and filament power supply. The filament supply has a 25-pin connector, and no data or markings on the case or board. I spent some time reverse-engineering the circuit, and determined how it should be connected to make an emission-controlled x-ray system. I tested the whole thing, and it appears to be working as intended at 50KV / 1 mA.  The head unit produces a beam of about 25 degrees total angle.

Turning a laminated wooden vase on the lathe

I've made a series of wooden vases and similar items by laminating contrasting boards, then turning them on the lathe. I like to use walnut, maple and either bloodwood or padauk to create a white/black/red theme. I almost never use stains, instead I just finish the wood with clear wipe-on polyurethane, using two coats for a fairly matte finish.

Measuring the voltage, current, and light output of a strobe flash lamp (Speedotron 4803)

I wired up a high-power photography strobe light to my oscilloscope and made some measurements of the input voltage, current and light output.