Of course there are other problems to address such as atmosphere effects on the light, arrival times of the photons to the mirrors and detectors, on and on and on. I believe the project lead claimed a laser sent from Mars to Earth would hit the earth over an area of 12mi. First consider all the things that are moving and how: Earth movement and rotation, Space ship movement, and groudns stations with movement and rotations. Looking at all the problems to address when sending laser between space ship orbiting Mars based to Earth was just mind numbing the extent of the problems. The guys at MIT have concluded and working on solving this problem through the use of lasers. NASA requires on a man mission to MARS nearly 2meg bandwidth of data to meet all their mission parameters. The speaker was one of the project leads. MIT has been awarded a contract from NASA to work on communications problems introduced when sending a man to Mars. Last year at the Amateur Telescope Makers of Boston we had a guest speaker from MIT. The same way one does not put ones finger across the SO-239 connector on any HF TX over 5W applies. 100mw will cause eye damage, if one is fool hardy enough to look into lasers with high power densities.
Possible eye damage is minimal with type I-II devices. Any questions or experience from fellow Hams will be treated with respect. Thank you for taking the time to read this. A good book to get a more comprehensive source is Fiber Optic Communications systems. What I have written here is a very simplistic treatise. If multi-channels are employed, demultplexing is the next stage. They not only detect, they also multiply the optical signal by a factor of 40db! Photomultipliers are very expensive.Īfter detection, filtering is a must. The detectors can be simple L.E.D diodes, Photo transistors with Darlington amplifiers integrated in the same package (my personal favorite for low modulation rates.) The best detectors are photomultiplier tubes. Simple telescopes, frensel lenses, and even Cassagrain dishes can be used. Of course the simplest modulation is CW (no offense!) Receivers consist of many antenna types.
HAM RADIO EME ANTENNA MOON REFLECTION FULL
One can see over 500 full duplex channels Laser modules sport an M.T.B.F (mean time between faileir of 5000 hours) Laser modules are complete with digital modulators with a switch rate of 50 kHz. There are major differences than a laser pen and an O.E.M laser module. A 100mw green laser is visible up to 75 Kilometers (125,000 feet, or 50 miles.) Needless to say this is absolute line of sight. Higher frequencies or wavelength are far more energetic.Ī cheap 5mw laser has a range of 5000meters or 7500 feet. To avoid physics, this equation states that Energy is a function of wavelength. QRP? Not really.Remember high school physics. The Green DPSS laser is a very complicated photonic/optical device. The new green (532nm) laser pointers are nothing like IR and visible red lasers (640nm-700nm) Such elements include Neodium, Vanadium in its Oxide form. Y.A.G is short for Yitterium Aluminum Garnet, which is a cheap synthetic diamond-like synthetic gem. These diodes are used to excite doped Y.A.G rods. I have purchased 35W medical laser diodes for under $300 (on eBay.) The most popular wavelengths are in the 785-810nm. However advances in simple double heterostructure laser diodes, as well as DPSS (diode pumped solid state) are affordable.
Such a chemical Laser is the province of the Advanced Energy Directorate HF in glacial aqueous form will etch glass. However 3um is produced by Deuterium/HF (Hydrogen Fluoride, highly caustic, and the strongest acid available. Such RF is the domain of military and D.A.R.P.A projects.įar infrareds limitation is 3um (micrometer). The RF spectrum state of the art is about 300 teracycles. An ultra simple guide to LASER Ham radio:
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