Large Fresnel Magnifying Lens Plastic Magnifier 260 X 177mm Solar Firelighter
£3.90
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This is one item of a 260 X 177mm (approximately 7 X 10.25 inch) rectangular plastic fresnel lens. It is slightly smaller than A4 paper. The focal length is approximately 30cm. The magnification is a theoretical 3X based on the focal length. The material is optical PVC. You can use these as a traditional magnifier but they have a variety of fun uses such as concentrating sunlight onto small photovoltaic solar cell batteries and setting fire to things like scout camp-fires in sunshine. The thickness measures 0.53mm. The material can be cut with strong scissors or a knife.
It's worth mentioning that these are not suitable for use as reversing or side-vision lenses on cars or trucks. You need a diverging lens for that, and they are usually specially made so that they also change the angle of vision off-centre.
It is best to keep them out of the sun when not in use. I have the credit card sized items on another listing in my etsy shop.
I've used these mounted in a frame to project tight beams from infra-red or visible LEDs for light based experimental free space voice or RF link transmission systems, using another similar lens and a photodiode at the receiver end. With a keyswitch on the LED you could use it for morse-code signalling over a substantial distance like an Aldis lamp.
Large Fresnel Magnifying Lens Plastic Magnifier 260 X 177mm Solar Firelighter
£3.90
It's worth mentioning that these are not suitable for use as reversing or side-vision lenses on cars or trucks. You need a diverging lens for that, and they are usually specially made so that they also change the angle of vision off-centre.
It is best to keep them out of the sun when not in use. I have the credit card sized items on another listing in my etsy shop.
I've used these mounted in a frame to project tight beams from infra-red or visible LEDs for light based experimental free space voice or RF link transmission systems, using another similar lens and a photodiode at the receiver end. With a keyswitch on the LED you could use it for morse-code signalling over a substantial distance like an Aldis lamp.