ornitz@kodak.UUCP (barry ornitz) (07/29/88)
In article <17588@glacier.STANFORD.EDU> jbn@glacier.UUCP (John B. Nagle) writes: > > Some recent work at Stanford on solar cells has produced experimental >units with around 30% efficiency. (This is not something that I'm involved >with; I just happened to hear about it.) These are considered "concentrator >cells", for they work at higher light intensities than sunlight, and thus would >be used with collecting optics in solar energy applications. > > The solar energy applications aside, devices like this open up the >possibility of performing power distribution within electronic systems >via optical means. While there are efficiency penalties, in situations >where other considerations predominate, such as RFI/EMI, EMP immunity, >electrical safety, and explosion prevention, there will be a role for >optical power distribution. From operating rooms to jet fighters, from >fuel storage tanks to high-end audio equipment, the advantages of optical >power distribution, coupled with fiber-optic signal cabling, offer >advantages over traditional electrical conductors. > > John Nagle Before this posting gets cold, let me point out an extremely _important_ error. Optical power transmission is _not_ necessarily safe for use in an explosive atmosphere. Speaking as someone who designs instrumentation for the chemical industry, I am familiar with the requirements for intrinsic safety and explosion-proof construction. I am currently working with researchers at the University of Tennessee on a laser based chemical process instrument.One of the first concerns in the design is safety, as the instrument may be used in Class I, Division I atmospheres. [Class I locations are those where flammable gases or vapors may be present in the air in quantities sufficient to produce an explosive or ignitable mixture. A Division I location is one in which the probability of the atmosphere being hazardous is high by underwriting standards. A Group designation may also be stated; this is a more specific subclassification of the nature of the hazard. Hydrogen falls into Group B, for example, and gasoline falls in Group D.] Literature searches by the UT researchers were performed upon the request of the industrial sponsors of the research to determine the actual safety of fiber optic/laser systems. I do not have the full set of references yet, but some interesting facts have surfaced. Researchers in England have discovered that power levels in the fraction of a watt range have sufficient power to ignite explosive atmospheres under many conditions. A simple break in the fiber-optic cable is often sufficient. I will try to contact Dr. Mike Roberts at UT next week to get more details as to the exact power levels, etc. Operating rooms, fuel storage areas, etc. fall into the category of hazardous areas. Fiber optic cables carrying more than a few milliwatts should probably be treated the same as electrical wiring and be run in explosion proof conduits or in armored jackets. The potential safety hazards should be studied carefully before an open laser beam should ever be used in a hazardous atmosphere (i.e. laser surgery). This posting is not meant to demean in any way the significant work being done in optical power transmission. It is only to point out an important safety aspect that is often overlooked. When I get more information, I will pass it on to the net. Thanks. Barry L. Ornitz Process Instrumentation Research Lab ----------------- | ___ ________ | | | / / | | Dr. Barry L. Ornitz UUCP:..rutgers!rochester!kodak!ornitz | | / / | | Eastman Kodak Company | |< < K O D A K| | Eastman Chemicals Division Research Laboratories | | \ \ | | P. O. Box 1972 | |__\ \________| | Kingsport, TN 37662 615/229-4904 | | -----------------