| Instrument | Working principle | Applications |
| Microscope | Convex lens (converging lens) system consisting of very short focal length eyepiece and longer focal length objective | Magnifying tiny objects: molecular studies |
| Telescope | Convex lens system that provides regular magnification | Magnifying distant objects: astronomy |
| Binocular | Pair of telescopes mounted side-by-side | General use |
| Interferometer | Superposition of waves | To study interference properties of light |
| Photometer | Uses a light sensitive element (like photomultiplier) to measure light intensity | Used to measure reflection, scattering, fluorescence etc |
| Polarimeter | Light from a source passing through a polarizer and then measured | Measures dispersion or rotation of polarized light |
| Spectrometer | Works by measuring light intensity | Used to measure light properties: astronomy |
| Autocollimator | Projects and image onto a target mirror and measures deflection of returned image | Component alignment, measure deflection in optomechanical systems |
Optics in the atmosphere
| Observed effect | Underlying cause | Description |
| Blue colour of sky | Rayleigh scattering | Higher frequencies (blue light) get more scattered than lower frequencies |
| Red colour of sunrise and sunset | Mei scattering | Scattering due to suspended particles (like dust) when sun’s rays have to travel longer distance |
| Halos/afterglows | Scattering | Scattering off ice particles |
| Sundog | Scattering | Scattering off ice crystals causing bright spots on the sky |
| Mirage | Refraction | |
| Novaya Zemlya effect | Refraction | Sun appears to rise earlier than predicted |
| Fata Morgana | Refraction due to temperature inversion | Objects beyond the horizon can be seen elevated |
| Rainbow | Total internal reflection |
Optics for photography
| Desired effect | Approach |
| Close up | Use macro lens |
| Long shot | Telephoto lens |
| Panoramic pictures | Wide angle lens |
| Handle low light conditions | Increase exposure time (decrease shutter speed) |
| Fast moving objects | Decrease exposure speed (increase shutter speed) |
| Increase depth of field (foreground and background both in focus) | Increase aperture i.e. f-n |
No comments:
Post a Comment