Activity for KallePâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Answer | — |
A: Are there any natural materials that can be used as a magnifying lens (or to craft one)? A clear mineral crystal can be worked to a lens shape with enough time and effort. Quartz, sapphire and ruby are likely candidates. Ruby lenses were common on wand style barcode reader pens. Even some salt crystals are routinely used as lenses and optical windows in certain applications (lasers, IR... (more) |
— | about 6 years ago |