FROM: Slick Dick Jones SUBJECT: battery free night vision??? DATE: Wed, 11 Oct 2000 00:35:12 GMT ORGANIZATION: Deja.com - Before you buy. NEWSGROUPS: sci.optics I found this on www.centuryarms.com "battery free night vision"... Does this really work or is it a bunch of hog wash? Big deal...everyone and their brother has night vision stuff! Not like these they don’t! The new Stargate 15 night vision monocular doesn’t use batteries, doesn’t plug in, isn’t solar powered, no dynamo to wind up, just hold down the lever... that’s it. This radical night vision works on pressure and piezoelectric crystal technology, which, quite frankly is way the hell over our heads, but it’s fun, and it really works! SC041 Condition: New Sent via Deja.com http://www.deja.com/ Before you buy. FROM: Anonymous Prime SUBJECT: Re: battery free night vision??? DATE: Wed, 11 Oct 2000 05:25:40 GMT ORGANIZATION: Road Runner NEWSGROUPS: sci.optics in article 8s0ck1$3vc$1@nnrp1.deja.com, Slick Dick Jones at joe_mama6969@my-deja.com wrote on 10/10/00 5:35 PM: > I found this on www.centuryarms.com "battery free night vision"... > Does this really work or is it a bunch of hog wash? > > Big deal...everyone and their brother has night vision stuff! Not like > these they don’t! The new Stargate 15 night vision monocular doesn’t > use batteries, doesn’t plug in, isn’t solar powered, no dynamo to wind > up, just hold down the lever... that’s it. This radical night vision > works on pressure and piezoelectric crystal technology, which, quite > frankly is way the hell over our heads, but it’s fun, and it really > works! > SC041 Condition: New How do you get around the conservation of energy, the first law of thermodynamics? While it is true that you can get high voltages out of piezoelectric devices sufficient to create secondary electrons, you still have to have enough light to see. This light requires power to generate. I suppose it may be possible to use piezoelectric devices to charge up liquid crystal displays or the like that use ambient light and not require an illuminator the uses power. Bill FROM: "bob" SUBJECT: Re: battery free night vision??? DATE: Wed, 11 Oct 2000 06:07:00 GMT NEWSGROUPS: sci.optics >How do you get around the conservation of energy, the first law of >thermodynamics? While it is true that you can get high voltages out of >piezoelectric devices sufficient to create secondary electrons, you still >have to have enough light to see. This light requires power to generate. > >I suppose it may be possible to use piezoelectric devices to charge up >liquid crystal displays or the like that use ambient light and not require >an illuminator the uses power. night vision tubes take only a slaight bit of power, and the image on the phosphor screen has a decent bit of persistance to it... i have no idea how efficent piezos are in turning mechanical enrgy into electrical energy, but i dont se how this wouldnt be possible, you just wouldnt get a continuous image without a good hand work out :) FROM: Anonymous Prime SUBJECT: Re: battery free night vision??? DATE: Wed, 11 Oct 2000 20:27:08 GMT ORGANIZATION: Road Runner NEWSGROUPS: sci.optics in article 8sTE5.5491$tC5.423978@paloalto-snr1.gtei.net, bob at nomail@nospam.com wrote on 10/10/00 11:07 PM: > >> How do you get around the conservation of energy, the first law of >> thermodynamics? While it is true that you can get high voltages out of >> piezoelectric devices sufficient to create secondary electrons, you still >> have to have enough light to see. This light requires power to generate. >> >> I suppose it may be possible to use piezoelectric devices to charge up >> liquid crystal displays or the like that use ambient light and not require >> an illuminator [that] uses power. My correction in line above. > night vision tubes take only a slaight bit of power, and the image on the > phosphor screen has a decent bit of persistance to it... i have no idea how > efficent piezos are in turning mechanical enrgy into electrical energy, but > i dont se how this wouldnt be possible, you just wouldnt get a continuous > image without a good hand work out :) Whether the phosphor has persistence or not, power has to be supplied to generate the light. It does not make any difference how efficient the piezoelectric conversion is. Batteries would last much longer if they are used in a device that generates light efficiently. That certainly would be possible with yellow green LEDs, for example. Light means power and you cannot get around that fundamental fact! Bill FROM: "bob" SUBJECT: Re: battery free night vision??? DATE: Wed, 11 Oct 2000 20:54:06 GMT NEWSGROUPS: sci.optics >Whether the phosphor has persistence or not, power has to be supplied to >generate the light. It does not make any difference how efficient the >piezoelectric conversion is. Batteries would last much longer if they are >used in a device that generates light efficiently. That certainly would be >possible with yellow green LEDs, for example. Light means power and you >cannot get around that fundamental fact! did you not learn in high school physics class that piezoelectric devices produce POWER when manually compressed? In this case the source of power ends up being your hand, derived form the food you eat. Aparently you push a lever of some sort, this compresses the piezo, this energy is supplied to the tube as a breif pulse, and the phospor retains the image for long enough to see. LED's have no application to image intensifiers curently on the market, so I cant see why you are mentioning them. Batterys would last much longer, huh??? please explain to me how a battery with a finite lifetime, due to a finite energy capacity, could possibly last longer than a source of power that is built into eash and every user of the device? (with the obvious possible exception of someone who is handicapped) FROM: Prof Harvey Rutt SUBJECT: Re: battery free night vision??? DATE: Wed, 11 Oct 2000 13:37:14 +0100 ORGANIZATION: University of Southampton NEWSGROUPS: sci.optics Slick Dick Jones wrote: > I found this on www.centuryarms.com "battery free night vision"... > Does this really work or is it a bunch of hog wash? > > Big deal...everyone and their brother has night vision stuff! Not like > these they don’t! The new Stargate 15 night vision monocular doesn’t > use batteries, doesn’t plug in, isn’t solar powered, no dynamo to wind > up, just hold down the lever... that’s it. This radical night vision > works on pressure and piezoelectric crystal technology, which, quite > frankly is way the hell over our heads, but it’s fun, and it really > works! > SC041 Condition: New > > Sent via Deja.com http://www.deja.com/ > Before you buy. No, not hogwash, it works. This type of 'night vision' device uses a near infrared image convertor tube requiring high voltages at very low currents. (ie, NOT a thermal imager; needs near IR illumination.) The piezo can provide that. There is no 'thermodynamic' problem as another respondent suggested; the energy comes from the user squeezing the piezo; mechanical_>HV->energy in accelerated electron->visible photon. I played with one a while back; on a dim scene an occasonal squeeze & it was fine; if it got bright then squeezing the trigger got a bit irritating, & it was a bit hard to keep it really steady whist squeezing. It was also audible, not good for the 'clandestine' guys......... But they may have improved. Harvey Rutt FROM: Anonymous Prime SUBJECT: Re: battery free night vision??? DATE: Wed, 11 Oct 2000 23:59:32 GMT ORGANIZATION: Road Runner NEWSGROUPS: sci.optics in article Or4F5.2998$8k7.172621@paloalto-snr1.gtei.net, bob at nomail@nospam.com wrote on 10/11/00 1:54 PM: > >> Whether the phosphor has persistence or not, power has to be supplied to >> generate the light. It does not make any difference how efficient the >> piezoelectric conversion is. Batteries would last much longer if they are >> used in a device that generates light efficiently. That certainly would be >> possible with yellow green LEDs, for example. Light means power and you >> cannot get around that fundamental fact! > > > did you not learn in high school physics class that piezoelectric devices > produce POWER when manually compressed? In this case the source of power > ends up being your hand, derived form the food you eat. Aparently you push a > lever of some sort, this compresses the piezo, this energy is supplied to > the tube as a breif pulse, and the phospor retains the image for long enough > to see. Instead of using the term "produce POWER" use the term "transform power." I thought that the argument presented pushed the idea that the piezoelectric converter eliminited the need to provide as much power as if if you cranked a hand generator. The phosphor cannot "retain" the image and emit more light power than was in the initial pulse of energy. > > LED's have no application to image intensifiers curently on the market, so I > cant see why you are mentioning them. My dredging up LEDs was to idicate that something like a liquid crystal display operated from an image intensifier could possibly use ambient light for seeing even though the image intensifier is running at low power. If there is no ambient light, the light power for seeing has to be supplied from somewhere. > > Batterys would last much longer, huh??? please explain to me how a battery > with a finite lifetime, due to a finite energy capacity, could possibly last > longer than a source of power that is built into eash and every user of the > device? (with the obvious possible exception of someone who is handicapped) > > The implication of the original post was that almost no power was required. If that were the case, batteries could last a long time. Look at LCD watches and their batteries. Bill FROM: "bob" SUBJECT: Re: battery free night vision??? DATE: Thu, 12 Oct 2000 01:55:31 GMT NEWSGROUPS: sci.optics >Instead of using the term "produce POWER" use the term "transform power." I >thought that the argument presented pushed the idea that the piezoelectric >converter eliminited the need to provide as much power as if if you cranked >a hand generator. The phosphor cannot "retain" the image and emit more light >power than was in the initial pulse of energy. why would the guy question wether or not the device uses more or less energy if it is powered with aa batterys instead of c cells???? come on now... thats about along the lines of what you were argueing, and if the device ran off of c cells, the iuse of aa's wouldnt violate the laws of thermodynamics, just change the amount of time the image apears for. I belive i mentioned that the image might not be ocnstant with the piezo device, but you seemed to think that was tottaly irrelevant >My dredging up LEDs was to idicate that something like a liquid crystal >display operated from an image intensifier could possibly use ambient light >for seeing even though the image intensifier is running at low power. If >there is no ambient light, the light power for seeing has to be supplied >from somewhere. but that aint the way image intensifiers work.. are you saying it would be more efficent to have an intensifier, go to a ccd, got to an image processor, to display an image on an lcd... instead of jusr having an image intensifier???? >> Batterys would last much longer, huh??? please explain to me how a battery >> with a finite lifetime, due to a finite energy capacity, could possibly last >> longer than a source of power that is built into eash and every user of the >> device? (with the obvious possible exception of someone who is handicapped) >> >> >The implication of the original post was that almost no power was required. >If that were the case, batteries could last a long time. Look at LCD watches >and their batteries. I guess your the only one who caught this implication.... And regardless if it was or was not the case, you would still be wrong.... the device would last longer running off the power of the human body, than it would a battery. The only instance where this would not be the case is if the test subject were to die, and in that case, i dont think he is going to have much need for night vision gear... now is he? FROM: Prof Harvey Rutt SUBJECT: Re: battery free night vision??? DATE: Thu, 12 Oct 2000 11:57:50 +0100 ORGANIZATION: University of Southampton NEWSGROUPS: sci.optics > >The implication of the original post was that almost no power was required. > >If that were the case, batteries could last a long time. Look at LCD > watches > >and their batteries. > > I guess your the only one who caught this implication.... > And regardless if it was or was not the case, you would still be wrong.... > the device would last longer running off the power of the human body, than > it would a battery. The only instance where this would not be the case is if > the test subject were to die, and in that case, i dont think he is going to > have much need for night vision gear... now is he? 'Wrong' in some absolute philosophical sense perhaps (& I'm not even sure of that with modern batteries; the power consumption is so low the battery might outlast me!) but certainly right in practise. The 'implication' was perfectly correct; the power consumption is *miniscule*; the required storage between squeezes of the piezo is *NOT* provided by phosphor persistence, which would cause image lag & be a complete pain, but by a capacitor holding up the HV. The *fact* is that the device we frequently use in the lab for aligning IR systems has not had its battery changed in several years. I've also used it some times to watch animals. Yes, if it had a piezo it wd get its energy from the doughnut I had with my coffee & will work as long as I'm around to squeeze it (more likely, till something breaks!) but who cares? Changing a battery every few years does not really bother me; compare that to your mobile phone, radio, torch, GPS.............. Squeezing a trigger makes the device move & makes a noise/movement; personally I'll change the battery every few years. Harvey Rutt FROM: "bob" SUBJECT: Re: battery free night vision??? DATE: Thu, 12 Oct 2000 14:56:30 GMT NEWSGROUPS: sci.optics Prof Harvey Rutt wrote in message <39E5992D.3E2B89D@ecs.soton.ac.uk>... >'Wrong' in some absolute philosophical sense perhaps (& I'm not even sure of >that with modern batteries; the power consumption is so low the battery might >outlast me!) but certainly right in practise. > >The 'implication' was perfectly correct; the power consumption is *miniscule*; >the required storage between squeezes of the piezo is *NOT* provided by phosphor >persistence, which would cause image lag & be a complete pain, but by a >capacitor holding up the HV. > >The *fact* is that the device we frequently use in the lab for aligning IR >systems has not had its battery changed in several years. I've also used it some >times to watch animals. >Yes, if it had a piezo it wd get its energy from the doughnut I had with my >coffee & will work as long as I'm around to squeeze it (more likely, till >something breaks!) but who cares? Changing a battery every few years does not >really bother me; compare that to your mobile phone, radio, torch, >GPS.............. >Squeezing a trigger makes the device move & makes a noise/movement; personally >I'll change the battery every few years. > >Harvey Rutt > > i never implied it wouldnt be a pain in the rear... I just cant see why this guy is argueing that a battery might still last longer, and it's impossible to power a night viswion device as claimed..... However, to nit pick your fine point to an even finer one, I contend the vision of the image is provided by the persistance of the phosphor. Even after the hv is no longer applied, the phosphor will still alow for the user to see an image. Unless someone cracks open and looks to see if this device uses a hold up capacitor there is no reason not to alow for the possibility that all designers did was connect the piezeo directly to the tube. The tube operates for a brief fraction of a second, and the phosphor alows the eye to see the image for a few secondes. I'm sure these tubes have SOME internal capacitance, but once that is drained it stands to reason the tube will turn on and off extreemly rapidly. if the phospor did not have persistance the image would pulse on and off with every squeeze of the piezo with extreem speed. Possibly with as short a duration as the pulse width from the piezo. Not very useable at all. But not nearly as bad as an iage with a second or two worth of lag, that stays visable for a few seconds... FROM: Prof Harvey Rutt SUBJECT: Re: battery free night vision??? DATE: Fri, 13 Oct 2000 15:29:01 +0100 ORGANIZATION: University of Southampton NEWSGROUPS: sci.optics bob wrote: > i never implied it wouldnt be a pain in the rear... I just cant see why this > guy is argueing that a battery might still last longer, and it's impossible > to power a night viswion device as claimed..... > > However, to nit pick your fine point to an even finer one, I contend the > vision of the image is provided by the persistance of the phosphor. Even > after the hv is no longer applied, the phosphor will still alow for the user > to see an image. Sorry, but this is quite simply wrong. I have used the devices, & am familiar with their 'insides'. Once the HV dies the scenne could not change. There *is* a storage capacitor, it is not just the (tiny) tube stray. If it was phosphor persistence, there wd be severe image smearing. On a dim scene you only have to squeeze the trigger every few tens of seconds, even a minute, and you can move between squeezes; I can turn right round & look at something else! If it was phosphor persistence, I wd still (uselssly) see the old scene! It is, quite definitely, a capacitor holding up the HV after being charged by the piezo. Further clear evidence is that the image 'dies' faster on bright scenes, which take more current, which discharges the cap. faster; there is no mechanism for that with phosphor persistence. Harvey Rutt FROM: "bob" SUBJECT: Re: battery free night vision??? DATE: Fri, 13 Oct 2000 15:41:39 GMT NEWSGROUPS: sci.optics Prof Harvey Rutt wrote in message <39E71C2D.98A96C51@ecs.soton.ac.uk>... > >bob wrote: > >> i never implied it wouldnt be a pain in the rear... I just cant see why this >> guy is argueing that a battery might still last longer, and it's impossible >> to power a night viswion device as claimed..... >> >> However, to nit pick your fine point to an even finer one, I contend the >> vision of the image is provided by the persistance of the phosphor. Even >> after the hv is no longer applied, the phosphor will still alow for the user >> to see an image. > >Sorry, but this is quite simply wrong. I have used the devices, & am familiar >with their 'insides'. >Once the HV dies the scenne could not change. >There *is* a storage capacitor, it is not just the (tiny) tube stray. >If it was phosphor persistence, there wd be severe image smearing. On a dim >scene you only have to squeeze the trigger every few tens of seconds, even a >minute, and you can move between squeezes; I can turn right round & look at >something else! If it was phosphor persistence, I wd still (uselssly) see the >old scene! >It is, quite definitely, a capacitor holding up the HV after being charged by >the piezo. >Further clear evidence is that the image 'dies' faster on bright scenes, which >take more current, which discharges the cap. faster; there is no mechanism for >that with phosphor persistence. > >Harvey Rutt > well then you should have said you know about the innards of these gadgets in the first place then, and there would have been no question as to it's workings then..... BTW, there is some smearing int he image of my find-r-scope, so i would think that such an arraingment as i proposed would be possible. I'm not implying the image would last for seconds.. .but it also wouldnt last for microseconds, either