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I don't think Jacob's ladders count.

http://www.repairfaq.org/sam/jacobs.htm

"I don't know what kind of crack you're on but the lasers I used would put out between 2 and 4 watts with over 20 lines across the entire visible spectrum."

http://www.repairfaq.org/sam/w... - Uhhh, what? I'm certainly not counting 20+ lines there.

Also, a measly 4 watts? I've got nearly double that in my pocket laser.

I don't claim to be an imaging expert, but a few odd details about the experimental method jumped out at me. It's been known for some time now that diffusive and other scene-perturbing objects (e.g. grossly distorting 'lenses' such as a Coke bottle) can be nullified using a structured light technique to characterize and effectively 'undo' the perturber. A simple structured light example is to replace the light source with a DLP projector and take multiple images with only one pixel illuminated at a time. More clever implementations can replace the single pixels with speckle patterns, zebra stripes, etc., and replace the 2D imager with a single-pixel photocell. Other neat tricks can then be performed such as reconstructing the image from the POV of the light source rather than the imaging device.

The experimentals shown in this paper all seem to have two things in common: 1) the "object" in each case is a backlit, 2D binary pattern on a transparency film or similar, with a relatively small illuminated area, and 2) an extremely narrowband (laser, actually) light source is used. The paper does mention several times that the light source is non-coherent, but it is a laser under the hood. This explains the numerous references to "speckle" in the images, which may leave most readers scratching their heads since things don't normally speckle when looked at through a slice of onion under ordinary light. Speckling is a laser (de)coherence phenomenon where the rays are put slightly out of coherence so as to interfere constructively and destructively.

These things suggest to me that while the paper is definitely interesting, there is no need to worry about the neighbors snapping passable nudes through your shower door or Feds cataloging your grow farm via pictures of a blank wall through your window. This sounds more like a modest extension to what's already been done stirring coherent and structured-light in a pot with convolution and autocorrellation methods.

Since the coherence length of cheap semiconductor lasers (e.g. laser pointers) can be on the order of 1mm or less, it's possible to call even a straight-up laserbeam "non-coherent narrowband light" with a somewhat straight face. Likewise, the quasi-point-sources created using a sparse geometric 2D aperture in transparency film, backlight by the aforementioned source, is pretty close to structured light for practical purposes. The takeaway message is these are very special lighting and "scene" conditions that are not representative of everyday photographic circumstances. So not to worry just yet :-)

Divide your rent or mortgage by the square footage of your house+garage+basement. Calculate the number of square feet this stuff will occupy to find out how much your "free" stuff costs per month. In much of the US it has been upwards of $1 per square foot per month. So each 19" CRT or "pizza box" Sun or SGI is probably costing a couple of bucks a month depending on how high you can stack them. Is it worth that to you? For most stuff and most people, the answer is sadly no and the value half-life of technology is decreasing every year as manufacturers lock consumers into their planned-obsolescence trap.
If you'll get enough enjoyment out of it, by all means collect it. I hope slashdotters haven't lost their nerdy mojo and are just trying to hoard the good stuff for themselves. But in case people here really lack imagination, here are a few items that might be worth keeping:

• All modern hard drives contain strong rare-earth magnets.
• Laser printers have unusual optical devices. Older ones might have helium neon lasers (watch it, the power supply is far more deadly than the laser beam!) But even more interesting are the acoustical optical crystals which can modulate any light source in a fraction of a second.
• At the current price of copper, a CRT yoke magnets and flyback transformer might bring in a few bucks. But first figure out what you're going to do with the rest of it.
• Tantalum "Super capacitors" might be of value just for the rare-earth content. But you'd need a lot of them. Better to donate to an electronics recycling charity.
• Laser disk players also have Helium neon lasers, beam splitters, high quality servos and optical components.
• Early projection TVs and video projectors and studio cameras and projectors might have a cold mirror (interference infrared filter) as well as an interference filter/mirror optical device for splitting white light into red, green and blue channels.
• VCRs, Printers have strong motors, gears, solonoids and other electromechanical parts.
• Ocilloscopes often contain unusual high-persistance phosphors. Build yourself a scintillation radiation detector or see what happens if you shine a UV LED onto it.

Whatever you do, don't throw it in your ordinary trash. The only thing worse than paying $1000/month rent for a house full of junk is ruining our environment with something that does have value. Check your local area, electronics recycling is a value proposition for some metals (e.g. gold) but also for the rare earth elements in capacitors and hard drive magnets.

My approach would be to find a small business with an electric furnace. Melt down all the crap, separate out the gold and other precious metals, and then sell the scrap metal b y the pound. Metals are worth money. You could probably extract more tnan a few troy ounces of gold.

• All modern hard drives contain strong rare-earth magnets.
• Laser printers have unusual optical devices. Older ones might have helium neon lasers (watch it, the power supply is far more deadly than the laser beam!) But even more interesting are the acoustical optical crystals which can modulate any light source in a fraction of a second.
• At the current price of copper, a CRT yoke magnets and flyback transformer might bring in a few bucks. But first figure out what you're going to do with the rest of it.
• Tantalum "Super capacitors" might be of value just for the rare-earth content. But you'd need a lot of them. Better to donate to an electronics recycling charity.
• Laser disk players also have Helium neon lasers, beam splitters, high quality servos and optical components.
• Early projection TVs and video projectors and studio cameras and projectors might have a cold mirror (interference infrared filter) as well as an interference filter/mirror optical device for splitting white light into red, green and blue channels.
• VCRs, Printers have strong motors, gears, solonoids and other electromechanical parts.
• Ocilloscopes often contain unusual high-persistance phosphors. Build yourself a scintillation radiation detector or see what happens if you shine a UV LED onto it.

Whatever you do, don't throw it in your ordinary trash. The only thing worse than paying $1000/month rent for a house full of junk is ruining our environment with something that does have value. Check your local area, electronics recycling is a value proposition for some metals (e.g. gold) but also for the rare earth elements in capacitors and hard drive magnets.

- rabbit's foot
- magic wand
- crystal ball
- hammer
- hand grenade

(from here)

Don't try to scare people away by bringing up terms which you don't understand. A microwatt is a lot of power at these frequencies.

I definitely understand the terms and agree that -42dBm is a useful amount of power at 60GHz. Thanks for the ad hominem.

My point is that if you've got all that power and all that real estate to run such a large and terribly inefficient signal source, what does using it actually give you?

In any real-world comms application I can think of (outside the laboratory), spatial and temporal coherence are not needed and introduce more problems that they solve. The beamwidth is narrow but is still diffraction-limited; the same limit can easily be achieved with normal high gain antennas (at 30-70GHz, high gain antennas are tiny).

If for some reason you need temporal coherence, your only choices of modulation are by direct modulation of the pump laser; that is, mixing (heterodyning) the output of the maser with a modulating signal by conventional means (semiconductor mixer, for instance) would destroy the coherence. I suppose you could do the mixing in a non-linear waveguide setup, but that would be a lot of microwave plumbing. Similar results can be achieved using regular old polarized antennas without limiting your modulation choices.

In other words, using a maser for comms is a solution looking for a problem.

In your example, a 1 watt optical laser would be at best 45% efficient. So you're looking at about 2.2 Watts input for 63 uW out. A 20 GHz DRO followed by a doubler or tripler would give you significantly more output power per unit of input power, as well as be tunable and tiny. The DRO in the link consumes a maximum of 31.7 dBm of power and emits 13 dBm of RF. an IMPATT diode would be another good choice.

I've been waiting for myself to get enough free time to show *exactly this*. The vast majority of TVs - basically everything except LCDs without any kind of "dynamic contrast" feature - have current consumption that is dependent on screen brightness. A Google or similar statistical hivemind could potentially tease out the shows being displayed on a screen in a 'normal' house (not only contrived lab setup) because most household power consumption either switches on much larger timescales than scene-brightness transitions (most don't flick their light switches every few seconds) or else have a repeatable current profile (dish / clothes washer and other appliances). These repeatable light + appliance patterns could be used similarly to estimate when you are home and how many guests you are housing (via how often the dish/laundry runs).

An old electronic technician's trick got me started on the idea - when repairing blown gadgets, you wire an ordinary lightbulb socket in series with the outlet you plug the gadget into. Start with a low-wattage e.g. 40W fridge bulb, and move up as needed. The bulb acts as a current limiter in case there are any remaining faults, and gives you a visual indication of the gadget's instantaneous current, with various 'normal' and fault conditions producing a distinct visual pattern (e.g. "solid on" at plug-in usually indicates a dead short across the HOT / main switching transistor). When doing this with a CRT set (haven't tried it with others), the bulb brightness does directly and eerily track the average scene brightness.

Uh, no. They actually kept the filaments of all the tubes, including the CRT, hot (or at least warm) all the time. The power switch enabled/disabled the power to all the other circuitry.

Old Ad for an instant-on TV.

repair FAQ re: instant-on.

Influence of the AA5 on TV design. Mentions rectifier inline with filaments to keep them warm.

The author of that article actually mentioned that we have been able to make green lasers, but that they are not efficient enough to be used.

Actually, the author of that summary mentioned that we have been able to make green diode lasers, but they are not efficient enough to be used for applications that need high efficiency. (they're used all the time for applications that don't need high efficiency-- laser pointers, for example-- take a look at google).

The author of the summary failed to point out that green lasers using technologies other than semiconductor diode lasers have been avalable for decades.

Copper vapor lasers are quite efficient, actually, although argon ion lasers efficiencies are indeed pretty low. Doubled YAG lasers are very commonly used for green-- a diode-pumped doubled YAG can get a wallplug efficiency of around 20%, IIRC.

A good Helium-Neon (HeNe) laser tube has a divergence half-angle of 1 mR (milliRadian). At 100 feet, that's a beam diameter of 2.4 inches. (For you metric folk, at 30m the beam is 6 cm in diameter). That's hardly a one-eye beam, and that's from a very well collimated HeNe laser. A diode pointer will have far worse collimation, hence a much larger diameter beam. Laser diodes have intrinsic beam divergences on the order of several tens of degrees. With their crappy lenses to correct it, it might get down to 5 mR, which results in a 12" beam diameter at 100 feet.

[ beam diameter = 2 * x * tan div_angle, where x is the distance from the pointer ].

I recommend Sam's Laser FAQ; it is an incredible source of information on lasers: http://www.repairfaq.org/sam/lasersam.htm

Can't you die from the voltages inside a colour TV?

I remember reading a long time ago that contact with the back of a colour TV tube was "invariably fatal". Mind you from your experience and a bit of Googling maybe they were just being overly cautious -

http://www.repairfaq.org/REPAIR/F_safety.html
"TVs and monitors may have up to 35 KV on the CRT but the current is low - a couple of milliamps. However, the CRT capacitance can hold a painful charge for a long time. "

Elsewhere they mention that if you add a capacitor, it's dangerous, but so long as there's no capacitance connected, there isn't enough current available at 35kV to kill you.

We used to write FEM problems that'd take weeks to solve, so I did some random scribbles, given the rapid climb of n^n and that the 'per-second' part can integrate out 3.5 digits in an hour, or 6 digits per week...

A 40 point problem becomes 10^64 photons (10^19 seconds coming from the sun).
A 35 point problem becomes 10^34 photons (10^-9 seconds from the sun)

An eyeful of sunlight has 10^15 per second, according to: http://www.umich.edu/~urecord/0405/Mar07_05/02.sht ml
Oddly, a 1mW laser generates roughly the same (according to a quick democalc found at http://www.repairfaq.org/sam/laserioi.htm#ioilpm4)

Since we're playing strictly gedanken-games, I say we make a 10-meter parabolic concentrator (pi * 5m^2 * 10kcm^2 /6cm^2-per-eyeful = 10^5, and run the test for a week. That's gonna give 10^11 x as many photons. 10^26 photons per week.

Heh, you're right... still not gonna scale worth beans, even assuming I didn't hose the above googling of physics vals or the math...

Does anyone know where I can go to learn to build my own desktop lasers? I have found Sam's laser FAQ before, but surely there are other sources out there.

I've always just bought whatever high capacity stuff I can find that's on sale and use a nice charger. I've had cells last nearly ten years by babying them this way.

As for the batteries, NiMH have higher capacity but a pretty horrible self-discharge rate. NiCds are a bit better, but to get decent usage out of either you really need to make a habit of topping them up before going off on your little expeditions. And always, always bring some alkalines with you. Their shelf life is phenomenal.

Oh, and don't forget that the NiCd memory effect is a myth. Let it die, already.

I cut it open and found that two resistors had melted at quite a high temperature. This was a Feit 13 watt Conserv-Energy unit.

Until this happened, I was quite happy with the Feit bulbs - they start fast, have a decent color, and fit in all my fixtures! Here's the schematic of the unit that died - the resistors are on the bases of the two transistors.

• a fire extinguisher (a model approved for use over mains-connected equipments)

• a first-aid kit

• a big wall-mounted red button for turning mains voltage off

Tube filaments were designed for a warm up time of 11 seconds. Since the resistance of the filaments varied as they heated, it was important, in a series string where the low voltage filaments operated from the 120 line, to keep the filament heating uniform so the voltage dropped across each tube stayed relatively constant as all the tubes got up to operating temperature.

I agree with the parent that there were sets where the filaments stayed on all the time for an "Instant-On" effect. Actually it was an always-on situation, but the B+ and high voltage wasn't applied until the set was "turned on". See http://www.repairfaq.org/REPAIR/F_tvfaqd.html#TVFA QD_005

This technology has been around for a while.

German Schneider AG attempted to bring down the price to the consumer level ten years ago, and produced some reference design, but then went bankrupt.

http://www.hcinema.de/laser.htm is in German (Babel at your own risk), but the diagram near the top shows the basic idea: three lasers are combined into one beam, which is then scanned across the screen using two rotating mirrors. Obviously, the optical technology is fragile, with many opportunities to screw up the image.

According to http://www.repairfaq.org/sam/laserlia.htm#liaschn, the technology was/is already quite successful in large scale public displays.

Ummm, dude, they do.

Read this: Northern/Southern Hemisphere corrections and adjustments

Careful whom you call a "dumbass" for they could be the one who is correct and you the one who is wrong.

From repairfaq

All other monitors will degrade picture quality when the degaussing is not
able to completely compensate for the earth magnetic field. With a tube built
for the wrong hemisphere it is possible that the effect of the vertical
component of the earth magnetic field will give a residual landing error.
This can not be corrected by turning any of the available adjustments,
digital or not. Re-alignment might become a very costly job.

( But also... )

Note that is it quite possible that you will never encounter any of these
problems. The extent to which your particular monitor or TV is affected
depends on many factors - many of which you have no control over.

The CRT tube is tuned to negate the magnetic influence in the hemisphere its designed for.
If you take a Northern tube and go to Australia with it (or vice versa), the screen may need correction.

See here for more info

Yes. I got attuned to it when I was a kid from old Apple II monitors that were left on after the computer was shut off.

It's indicative of some part in the video circuitry actually vibrating ever so slightly in response to the frequency of the current running through it:

http://www.repairfaq.org/samnew/tvfaq/tvwhine.htm

NiMH leak too fast. I've got a digicam, and it's always flat whenever I want to take any pictures.

The self discharge current is way high - 3 to 10 times NiCd.

http://www.repairfaq.org/ELE/F_NiCd_Battery.html#N ICDBATTERY_024

Mind you, you can always keep a spare set in the fridge, the discharge is slower at low temp.

No, it's not nonsense. The fields generated by the deflection coils, etc., ARE much greater in magnitude than the Earth's field, but they're AC fields. The DC offset of these fields is relatively small, and the Earth's field (also DC) IS sufficient to cause a visible shift in the position of the raster and affect the beam landing, etc.. This is why, for instance, there ARE often problems when trying to use a "Northern hemisphere" monitor in the Southern hemisphere.

Having said that, however, this isn't really something the average user needs to worry about. In the detailed specs for any monitor, there generally ARE a set of specific ambient conditions under which certain performance specs are intended to be checked. These usually include the ambient magnetic fields (which also tells you what magnetic environment was used at the factory for adjustment), and the orientation of the monitor within those fields. For the vast majority of monitors, the specified ambient conditions simulate average magnetic fields in the U.S. or Europe (which are very similar), and the monitor is specified as facing east or west within those fields.

The "time tunnel" effect is always a crowd pleaser. Drill a hole in a penny and press it onto the shaft of a small DC motor. (It needs to be almost, but not perfectly, perpendicular to the shaft.) Glue a small mirror (1" square or less) onto the penny. Turn on the motor and bounce the beam off the spinning mirror. Add some fog to the room and dim the lights, and you've got a very cool effect indeed. (Wrap a rubber band around the barrel of the laser pointer to keep it on, and tape it into position near the spinning mirror.)

Or you can build two spinning mirror assemblies and generate lissajous patterns. (Think: Spirograph)

Or use some hot glue to tack a tiny mirror onto your speaker's woofer. Bounce the laser off the mirror while you play loud music, and you'll get all sorts of wierd patterns.

Or lay a CD-ROM on your turntable (you do still have one, right?) with the reflective surface up, and bounce the laser off the disc. (The narrow tracks act like a diffraction grating, splitting a single beam into multiple beams.) Slowly rotate the turntable platter (especially with the disc slightly offset from center) to get more effects.

Have a look at my site for some idea of the types of effects you can produce.

Here are a few other sites that might give you more ideas:

LaserFx.com

Sam's Laser Faq

I do belive drinking gasoline will still give you stomach cancer

That did surprise me when I read it, because I couldn't think of a good chemical mechanism that would explain (relatively) unreactive alkanes to react with human tissue. So for those of you who went along that same path of inquiry, the short answer is that it is toxic and/or carcinogenic because of the additives like Pb and/or C6H6, not the CH3-C(CH3)2-CH(CH3)-CH2CH3 (or equivalent) itself.

Sorry, accidentally posted AC.

Not microwatts, milliwatts. AFAIK, CD players use lasers in the 1-5mw range. They just happen to put out their power much more efficiently than a 60W light bulb (i.e. brighter than the equivalent area of the sun)

This has some useful information. So does this.

Not microwatts, milliwatts. AFAIK, CD players use lasers in the 1-5mw range. They just happen to put out their power much more efficiently than a 60W light bulb (i.e. brighter than the equivalent area of the sun)

This has some useful information.

> Laser images printed on the retina? what are the safety concerns with this?
> i would think "burn in" would once again be a serious issue.

The problem with a laser of a sufficient power (say, 5mW or higher) would be vaporizing the retina.

However, Class I lasers (under 0.4mW) are safe even for continuous viewing. For example, Sony has been using a laser for AutoFocus assist in its camcorders and digital cameras for quite a while.

• http://www.n1bug.net/tech/laser/alc_wa6ejo.html
• http://www.messaggeri.it/xoptoelettronica.htm
• http://www.hut.fi/Misc/Electronics/circuits/laserl ink.html
• http://www.repairfaq.org/sam/laserdps.htm
• http://www.qsl.net/wb9ajz/laser/data/cheepo.txt
• http://www.clansullivan.com/joseph/projects/laser. htm

Simple googling... shows it is

Mainly it occurs on high end monitors. And they have sophisticated means built in to combat it.

The filter/power supply capacitors contain a lot of juice.

I felt compelled to do some Googling. Here are some results:

"Some of the large filter capacitors commonly found in line operated equipment store a potentially lethal charge."

"If any significant voltage is found after powering off some capacitors (like the high voltage of the CRT in a TV or video monitor), it will retain a dangerous or at least painful charge for days or longer!)"

"Be very careful, since these voltages are dangerous."

I'm not giving credence to the wild claims that the capacitors in a CRT device hold their charge for months, or that you have to let a CRT sit for 72 hours before taking the cover off (you can always discharge the capacitors). But they are dangerous and their is no question that they are lethal, particularly if you hooked them up to a home-made taser.
Also realize that any electrical current-even a small one-can be lethal if it passes through the human heart.

Macrovision works by exploiting a "feature" in VHS that isn't in most TVs. It's all explained here.

Professional VCRs typically have a TBC built in; you can also get a standalone TBC. Either way, they're not particuarly cheap, but if you're going to be backing up a large VHS library, it's probably a good investment.

See the ArsTechnica Guide to Capturing, Cleaning, & Compressing Video and the sci.electronics.repair Macrovision FAQ for more info.

sci.electronics.repair FAQ will teach you both how to fix the most common faults in equipment and give you all the safety info you need. However as for the latter, all I can say is read, read and reread - it's your life after all...

It's my understanding that Macrovision is effective not only because it kicks off a macrovision detecter in newer VCRs, but because it also scrambles the image, degrading quality subtly (but the TV won't really pick that fact up and send it on to you) which the VCR does not compensate for, and destroying the image. It's not had to find documentation that backs this up. So using your beta might or might not help, and it likely only will help if you have one of the ancient top-loaders that aren't even soft touch. Personally, I have a Super Beta, which I assume has an AGC circuit. It has a stereo DAC for digital storage of audio too, but no digital input :(

Thanks for playing though.

To shorten the pulse length you need to quench the main xenon tube earlier. One way to do this might be to put a smaller flash lamp (available at radio shack?) in series with a smallish capacitor and put those in parallel to the main flash lamp. The goal is to trigger the smaller flash lamp as a turn off circuit, it will divert the current into the small capacitor which will drop the voltage across the main flash lamp causing it to stop conducting. The small capacitor will rapidly charge and hence little energy would be used in turning off the circuit.

Strobe Faq

Now that you have a main trigger and a quench trigger, you can have your BASIC stamp control the flash duration. A normal flash lasts a millisecond or so, you could probably put this flash very close to your target (perhaps with some plexiglas to protect it) and trigger the flash for say 50-200 microseconds instead giving a much faster stop-motion (though darker picture).

Crank up the CCD sensitivity and bring the flash close and you'd be all set.

Alternatively you could use a pre-built "auto flash" and replace the light sensor with a output line from the BASIC stamp. This would cost more, but be easier from a construction standpoint since the quench design is debugged already.

You may have to put some tape over the sensor, and open the case and control the quench with a clip lead.

As the othe two posters mentioned, you are a likely candidate for doing something wrong. The issue is with capacitors. Capacitors are used to increase the voltage available to the CRT. The voltage they build up is many magnitudes higher than what comes through the mains. The catch is even when unplugged they maintain their charge, unless they are either properly discharged, or find themselves the nearest human tinkering with them.

Just to give you an idea, from Repair FAQ :

"TVs and monitors may have up to 35 KV on the CRT but the current is low - a couple of milliamps. However, the CRT capacitance can hold a painful charge for a long time. In addition, portions of the circuitry of TVs and monitors - as well as all other devices that plug into the wall socket - are line connected. This is actually more dangerous than the high voltage due to the greater current available - and a few hundred volts can make you just as dead as 35 KV!"

Here's one to chew on...

Pink Floyd "Pulse" on CD costs $28.99

Although phasing out, the same concert used to be available on VHS (in HI-FI audio, not digital but very good quality) for $14.99. It included all the same exact audio, plus the great video footage of the concert. Funny that the DVD release of the concert still has not been released.

There are so many examples of the f**ked up pricing with the RIAA.

Not necessarily. Ever played the Asteroids arcade game? It used a vector monitor. This works by using magnetics to draw a line directly onto specific points on the screen, or something like that. See here.

That said, I don't think it is practical enough to use as a normal monitor.

The itsy-bitsy holes/slots in invar shadow mask and "Trinitron" monitors can be as small as .25mm.

The PC can only output CVBS or S-Video (anyone seen a PC Video card that outputs component video?)

If you've been going to the Sunnyvale Fry's (aka Nerdstroms), you can save time, hassle, and even money. About 4 blocks away, there's a place called Action Computer that has every kind of cable you need, as well as hard drives, laptops, and all the usual PC hardware, frequently cheaper than Fry's. And here's the kicker: the staff know what they're doing. They are helpful, friendly, and also have a good return policy. And no, I don't work for them. I just give them a lot of my money every month.

Now, if you don't live in Silicon Valley, my point remains. In many cities, especially college towns, there's a grungy storefront in a strip mall with an unlikely name like Zero-Gee Electronics, or Servo Systems or something. That's the place to go for your hardware. They may not have an espresso bar, but they'll know what kind of fan you need for an Alienware case.

As a matter of fact, some helpful soul has posted a list of these places here

Sorry for being clueless, but what's Macrovision?

*sigh* Macrovision FAQ It's kinda old, but...

Remember, Google is your friend.

There is no such thing as a NiCd memory effect.

1. Alkaline (yes, there are rechargable alkalines)
2. NiMH (most of the life of alkalines)
3. NiCd (holds least charge)

However, this is more expensive - and therefore no manufacturers use it.

More expensive? How would you get the voltage you needed to run the machine? The chemical makeup of a cell determines its potential voltage.

NiCd = 1.2v
NiMh = 1.2v
Lead Acid = 2v
Li-ion = 3.6v
Alkaline = 1.5v

The only way to increase the voltage is to put them in series or double stack the internal construction but that is not any different then putting two individual batteries in series. A good example of that is a car battery, it is actually equivelent to 6 individual lead acid cells sharing the same electrolyte.

If your laptop could run on 3.6 volts then you could use Li-ion cells to run and charge it in parallel like you suggest. Any required voltage higher then that would require a conversion process with a voltage multiplier (dc-ac-dc) which is not very efficient and probably not very practical or use what you have now which is a bunch of individual cells tied together in series to form a battery with a higher voltage. Charging and discharging circuits made these days are "smarter" then they used to be and will shut off at a level that should not reverse a cell when discharging or overheat when charging. In post earlier in this story a guy claimed putting tape over the voltage sensor leads allowed much more use out of his current battery, well that is because the protection for the battery was removed. Cells do go bad and have different tolerances, even charging as battery of cells in parallel like you suggest would still cause the same cell to fail just as quickly and lower the batteries overall capacity as each cell can not be monitored or charged directly.

This site has a decent battery/cell description as does the somewhat dated sci.electronics.repair nicad battery faq

Offtopic here..
Every type of cell has advantages and disadvanges and good and bad ways to charge and use them. Knowing the type you have and the proper method of caring for them will make them last longer.

1 it would be impossible to get those kinds of intense magnetic fields without using superconductors. Conventional conductors would melt with the kind of electrical current you would need.

2 unfortunately buckyballs don't seem to lubricate. but see that post on FLIR made with nanotechnology for more commercial nanotech products.

3 You want great 3d uses of holograms? Try imaging This technique could generalise for anything else you want to look at under a microscope in 3D. Cells. Fuel rods in a nuke reactor. the hologram captures all that data at the quantum level.

the application is commercial because there are hologram companies that sell equipment to other companies. If you want to get into it yourself for next to nothing look at this link and search for hologram