dclaar@hpcupt1.HP.COM (Doug Claar) (12/29/89)
Here's another naive laser question (BTW, is there a good text that might help answer some of these?): Why can't I do the following: 1) Pull a vacuum on the living room 2) Open my (black and white) TV's picture tube 3) Wash out the phospher 4) Replace the electron gun with a laser (If powerful enough, skip 3...) 5) Project 'I Love Lucy' onto my dirty window Or, if intensity modulation is a problem, why can't I pull a vacuum on my den and follow steps 2-4 for my monochrome monitor, and scare the neighbors by projecting Lotus 1-2-3 spreadsheets on the clouds. OR IN SIMPLER TERMS (although I hope you enjoyed the bit of tongue in cheek above): Why can't I deflect my laser electromagnetically, and not electromechanically. (Oh, now you remember me--I was the one that asked how to aim a laser, and most all of the responses where electromechanical, or had various side effects (like diffusing the beam)) Any insight gratefully accepted. Doug Claar HP Computer Systems Division UUCP: mcvax!decvax!hplabs!hpda!dclaar -or- ucbvax!hpda!dclaar ARPA: dclaar%hpda@hplabs.HP.COM
dclaar@hpcupt1.HP.COM (Doug Claar) (12/30/89)
>Here's another naive laser question >Why can't I deflect my laser electromagnetically, and not Blush. Seems like it is naive all around. As someone pointed out, light doesn't consist of charged particles. Guess I don't have to pull a vacuum on the living room after all...my wife will be sooo happy! Doug Claar HP Computer Systems Division UUCP: mcvax!decvax!hplabs!hpda!dclaar -or- ucbvax!hpda!dclaar ARPA: dclaar%hpda@hplabs.HP.COM
dclaar@hpcupt1.HP.COM (Doug Claar) (12/30/89)
>Why did you want to "pull a vaccuum" on your living room or den?
Obviously, I didn' want the picture tube to implode, so I
figured--what the heck--just hook up the vacuum pump and suck
the air out of the whole thing! I discovered that this technique
doesn't work, though, after the cat exploded.
Obviously :-),
personal p.s. to Michael Bergman:
My mailer bounced with bergman@m2c.org.
And bergman@odin.m2c.org.
And bergman@128.188.1.3.
So, here's my reply.henry@utzoo.uucp (Henry Spencer) (12/30/89)
In article <6220004@hpcupt1.HP.COM> dclaar@hpcupt1.HP.COM (Doug Claar) writes: >... Why can't I deflect my laser electromagnetically, and not >electromechanically... Because light is essentially completely unaffected by electromagnetic fields of any normal intensity. CRTs are dealing with electrons, which are a very different story. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1989: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
wb8foz@mthvax.cs.miami.edu (David Lesher) (12/30/89)
In article <6220005@hpcupt1.HP.COM> dclaar@hpcupt1.HP.COM (Doug Claar) writes: >>Here's another naive laser question >>Why can't I deflect my laser electromagnetically, and not It shouldn't be a problem to do this. All you need is a big enough chunk of magnetic monopole. Don't have any here, but maybe you should try Edmund's. If that doesn't work well enough, Stephen Hawkins would likely recommend a piece of black hole. I'd avoid this, however. May tend to stain the carpet. -- A host is a host & from coast to coast...wb8foz@mthvax.cs.miami.edu no one will talk to a host that's close..............(305) 255-RTFM Unless the host (that isn't close)......................pob 570-335 is busy, hung or dead....................................33257-0335
kimf@tybalt.caltech.edu (Kim Flowers) (12/31/89)
Would it be possible to cause a laser beam to scan by deflecting it off or through a piezoelectric (?) mirror or lense? If so, by how much? mAd_QuArK! Kim Flowers kimf@tybalt.caltech.edu
mmm@cup.portal.com (Mark Robert Thorson) (12/31/89)
If the recent news from Japan indicates that gravity itself can be modulated, you could replace the deflection yolk with a couple of spinning gryoscopes. Then you could sweep a laser around. I'd wait until Hitachi makes one before buying it.
henry@utzoo.uucp (Henry Spencer) (01/01/90)
In article <13100@cit-vax.Caltech.Edu> kimf@tybalt.caltech.edu.UUCP (Kim Flowers) writes: >Would it be possible to cause a laser beam to scan by deflecting it >off or through a piezoelectric (?) mirror or lense? If so, by how much? Probably, although the good piezoelectric materials are mostly not transparent. There are a variety of ways of deflecting light using interactions with matter, with the properties of the matter altered by electric or magnetic fields, standing waves of ultrasound, etc. Most are difficult to implement and give quite small deflections, which is why things like laser printers still use spinning mirrors. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1989: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
bph@buengc.BU.EDU (Blair P. Houghton) (01/02/90)
In article <13100@cit-vax.Caltech.Edu> kimf@tybalt.caltech.edu.UUCP (Kim Flowers) writes: >Would it be possible to cause a laser beam to scan by deflecting it >off or through a piezoelectric (?) mirror or lense? If so, by how much? Yes. It's been done a number of times, apparently. I first saw a description of it in Annals of Biomedical Engineering a couple of years ago. The researchers were using the laser to illuminate a lattice of points on the surface of electroactive tissue (e.g. heart muscle) that had been coated with an electroluminescent fluid. As the muscle contracts, the myoelectric dipole wavefront propagates across the surface, activating the fluid, and when the laser hits the fluid its fluorescence indicates the potential at that point. Using a piezoelectric element (I don't remember whether they used it as a refractor or reflector) meant they could scan something like 32 or 64 points on a sizeable piece of tissue in some very short time, milliseconds or microseconds, or something. --Blair "Bibliographies? We don' need no steenking bibliographies..."
whit@milton.acs.washington.edu (John Whitmore) (01/02/90)
There are some light-steering possibilities in propogation of light through a medium (vacuum won't do). The Kerr effect, for one, changes the deflection of a particular polarization of light as it goes through a prism (and with enough reflections through the prism, it might just give some deflection angle that could be useful). The problem can also be solved by vibrating a mirror in front of the laser, but it's not as safe and easy as a cathode ray tube. The Kerr effect is typically employed for Q-switching lasers (i.e. detuning them) and uses a high voltage to get some substantial effect; the inside of a TV has high voltages at the scanning frequency anyway... I am known for my brilliance, John Whitmore by those who do not know me well.
cradens@uceng.UC.EDU (carl radens) (01/03/90)
In article <13100@cit-vax.Caltech.Edu>, kimf@tybalt.caltech.edu (Kim Flowers) writes: > Would it be possible to cause a laser beam to scan by deflecting it > off or through a piezoelectric (?) mirror or lense? If so, by how much? > Kim Flowers > kimf@tybalt.caltech.edu Acousto-optic devices operate by a photo-elastic interaction. Many examples of practical bulk devices and optical guided wave devices have been presented in the technical literature. Bulk devicesy are commercially available in Lithium Niobate and some of the III-V compound semiconductors. See: _Electro-Optical and Acousto-Optic Scanning and Deflection_ by M. Gottlieb et al., Marcel Dekker, 1983. Carl Radens, Cincinnati cradens@uceng.uc.edu
jeffw@midas.WR.TEK.COM (Jeff Winslow) (01/03/90)
In article <25507@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >If the recent news from Japan indicates that gravity itself can be modulated, >you could replace the deflection yolk with a couple of spinning gryoscopes. Not unless you want egg on your face. Sorry.
tom@cs.utah.edu (Tom Blockovich) (01/06/90)
In article <1989Dec31.224613.23057@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >Most are difficult to implement and give quite small deflections, >which is why things like laser printers still use spinning mirrors. >- ^^^^^^^^^^^^^^^^^- A laser printer that I am familiar with is the Xerox 8700 (DEC LN01), and yes it does use a spinning mirror (polygon). But there is a video modulator that deflects the laser beam. The deflection is not alot, only about 1/4" at a distance of less than a foot. That could be considerable farther away though. The video modulator is used to deflect the beam so that it will hit a stop, in effect turning it off and on. Tom Blockovich at the U of U tom@cs.utah.edu (801)581-5805 at Digital Tom Blockovich @ slo (801)565-3043
siegman@sierra.Stanford.EDU (Anthony E. Siegman) (01/07/90)
Take a typical low-cost He-Ne or semiconductor-diode laser -- average power is a few milliwatts (and only red is conveniently available -- blue or green still hard to obtain). Spread that average light power out to fill a reasonable TV screen size. It will be so faint as to be invisible. To put enough light onto a screen to have a good viewable picture requires on the order of _watts_ of each color (obviously the total power needed goes up with screen size). Present-day visible lasers with average power outputs in the few watt range cost kilo-dollars and require kilowatts of electrical power input (not to mention cooling water, short lifetime, etc.) Laser projection TV may come, but not for a few years, until major improvements in visible lasers have occurred.
sorka@ucscb.UCSC.EDU (Alan Waterman) (01/08/90)
Uh excuse me? What does projecting a laser on the screen of a CRT have to do with laser TV? Have you considred the possibility of projecting 3 lasers(RGB) onto a white projection screen? However, I think that super high res LCD screens will be TV technology of the future.