Month: June 2008

Supercontinuum

Saw some supercontinuum (a better explanation here) generation in the lab today. At the top there's a diode laser at 808 nm (the bright white light in the pic, try photographing your TV-remote with a digicam!) that pumps a YAG laser which outputs a 1064 nm pulse. This is then converted to a 532 nm pulse through second harmonic generation and directed into a very fancy holey-fiber in which the supercontinuum is created. In the middle of the pic there are two reflections from a diffraction grating. To the right the zero order diffraction which looks like mostly 532nm to the camera/eye, and to the left the 1st order diffraction where you see a fair bit of blue to the right of the 532nm peak and a bit of yellow/red(ish) to the left of the peak.

Microfluidics test

I got some new microfluidic chips to play with today (courtesy of the Microfabrication Group at TKK). This must be cutting-edge research, since there's an article about using laminar flow cells for single molecule experiments in the latest issue of Nature Methods. I'm testing our custom-built pressure controller which controls the inlet and outlet pressures between 0 and 7 kPa with about 2 Pa resolution. There are three inlet channels (~40 um wide) with blue fluid in the top channel, clear fluid in the middle, and red fluid in the bottom channel. They all meet in the middle of the chip and there's a wider (120 um) outlet channel.

The pressure controller is similar to Fluigent's (described by Fütterer et al. in Lab on Chip), and I'm gluing the 0.6 mm PTFE tubing to the PDMS chip as described by Hartmann et al. in Lab on Chip.

The video shows a sinusoidally modulated pressure applied to each of the input channels as well as varying the pressures manually between zero and maximum.

Rigid Tapping

We've mounted a 500 cpr encoder on the spindle-motor which means it's possible to do rigid tapping. Above some spot-drilling, then a 2.5 mm drill, and then an M3 tap at 500 RPM and 0.5 mm Z-feed per revolution. Below the same thing but with a 5 mm drill and an M6 tap (1 mm Z-feed per rev).

Cool stuff!