Reservoir of soapy water at the top, needle valve to control flow, monofilament line forms the rails. Solution is collected at the bottom and pumped back to the top.
<imgsrc='img/overall.jpg'height=500px>
<imgsrc='img/tank.jpg'height=500px>
<imgsrc='img/lps-warmup.jpg'height=300px>
<imgsrc='img/first-fringes.jpg'height=300px>
I first tried single color power LEDs to see interference fringes. I didn't observe very clear fringes. Then I switched to a low-pressure sodium lamp. I saw very clear fringes.
<imgsrc='img/lps-warmup.jpg'height=250px>
<imgsrc='img/first-fringes.jpg'height=250px>
### First videos
line
<imgsrc='vid/line-small.mp4'>
finger
<imgsrc='vid/finger-small.mp4'>
I need to fix the flicker from the ballast for my low pressure sodium lamp.