My giant Fresnel lens has a linear focal point.
It is better than the focal point on the previous lens I salvaged but not, as I had hoped a spot focal point. The frame and stand are finished and at some point I will attempt to remove the linear diffraction grooves and turn it into a spot lens using this method. As it is the lens would be great for solar cooking but that is not sufficient for what I have in mind. I should have taken some photos of the testing but it’s not like it was dramatic.
The sun guide bracket is visible in this image. Basically a bracket perpendicular to the lens’s surface with a whole the shadow and bright spot from which allows alignment to the sun.
Salvaged timber throughout as usual.
Last day with visiting family members, nice barbecue and long talks. Four year immunisations for L, car registration transfer hurdles completed.
Ready to paint.