Print PDF
Favorite
Email
Step 8Lens Mount
Clearly, our death ray is missing something. If you swivel the lens up so it's perpendicular to the sun's rays, you'll just get a spot of bright light on the piece of plywood at the focus. Once you do this (yes, I recommend it - but don't let the thing catch on fire), you'll know just where to put the focusing lens.
Materials Required:
The easiest way to set up the optics here is to mount the main focusing lens on the end of a tube around 2 inches wide. This will do exactly what this instructable does - collimate the light into a smaller beam. In a sense, the entire device is already doing this with the sun's parallel rays, but we want the smallest beam possible.
Up until now, I was troubled and lost as to what I would use for this part. What was needed was essentially two tubes inside each other, the inner one allowed to telescope in and out easily, but be able to stay put. Then, while wandering the aisles of Home Depot I found the perfect part: a PVC expansion joint for 2" conduit pipe. It consists of two pipes, the inner one having two o-rings and a lot of silicon lube , allowing it to slide in and out of the outer pipe beautifully. It also happened to be a perfect fit for my 57mm focusing lens.
Preparing the Tube
This was fairly straight forward - the inner tube had a rim sticking out past the ridge where the lens wanted to sit, so I made quick work of it with a miter saw (a hack saw would work equally well, just take it slow and rotate the tube as you're cutting). After a quick sand, the tube was ready for the lens.
Epoxy
I rifled through the adhesives toolbox, found something appropriate for both glass and plastic (Duco Cement) and glued down the lens. A day later someone knocked the tube over and the lens popped off, so I decided to use epoxy to seal the lens in. This worked better (the specific epoxy isn't that important, just pile it up around the sides of the lens to keep it in).
Note: Since diverging light is entering this lens, we want the least curved side of the lens (assuming your lens isn't symmetrical) facing out so the angle of incidence is lower, minimizing loss of light by reflection. Imagine a stone skipping off a pond versus a stone dropping straight down (which is what we want in this case).
Materials Required:
- 2" PVC expansion joint
- Your favorite epoxy
- Miter saw or hack saw
- Sand paper (60, 150)
The easiest way to set up the optics here is to mount the main focusing lens on the end of a tube around 2 inches wide. This will do exactly what this instructable does - collimate the light into a smaller beam. In a sense, the entire device is already doing this with the sun's parallel rays, but we want the smallest beam possible.
Up until now, I was troubled and lost as to what I would use for this part. What was needed was essentially two tubes inside each other, the inner one allowed to telescope in and out easily, but be able to stay put. Then, while wandering the aisles of Home Depot I found the perfect part: a PVC expansion joint for 2" conduit pipe. It consists of two pipes, the inner one having two o-rings and a lot of silicon lube , allowing it to slide in and out of the outer pipe beautifully. It also happened to be a perfect fit for my 57mm focusing lens.
Preparing the Tube
This was fairly straight forward - the inner tube had a rim sticking out past the ridge where the lens wanted to sit, so I made quick work of it with a miter saw (a hack saw would work equally well, just take it slow and rotate the tube as you're cutting). After a quick sand, the tube was ready for the lens.
Epoxy
I rifled through the adhesives toolbox, found something appropriate for both glass and plastic (Duco Cement) and glued down the lens. A day later someone knocked the tube over and the lens popped off, so I decided to use epoxy to seal the lens in. This worked better (the specific epoxy isn't that important, just pile it up around the sides of the lens to keep it in).
Note: Since diverging light is entering this lens, we want the least curved side of the lens (assuming your lens isn't symmetrical) facing out so the angle of incidence is lower, minimizing loss of light by reflection. Imagine a stone skipping off a pond versus a stone dropping straight down (which is what we want in this case).
| « Previous Step | Download PDFView All Steps | Next Step » |
 |
Add Comment
|
