South African Research Team Creates World's First Digital Laser

smi.james.th writes in with news about new laser technology developed in South Africa. "The Council for Scientific and Industrial Research (CSIR) announced in Pretoria on Tuesday that it had developed the world's first digital laser. 'I am always very cautious about using the term "breakthrough",' noted Science and Technology Minister Derek Hanekom. 'We scrutinized this very carefully before we said that this is really new! South African scientists are once again making noteworthy contributions to the world.'... A normal laser contains two mirrors, opposed to each other and at opposite ends of the instrument. One is highly reflective and the other is a curved, partially reflective mirror. In the digital laser, the curved mirror is replaced by a liquid crystal display (LCD) system. The LCD is connected to a computer and monitor."

Comments

Important part the summary neglected

[mcgrew]

Researchers use the computer to specify the laser beam shape they require and to programme it into the LCD. By this means, one laser can swiftly produce many different beam shapes. Previously, changing the shape of a laser beam required physically replacing the curved mirror in the laser. As the mirror has to be carefully aligned, this is a time consuming process.

Re:Important part the summary neglected

[mcgrew]

Oops, I forgot the blockquotes. That was from TFA (not a good FA IMO)

Re:Important part the summary neglected

[hedwards]

I fail to see how that's digital, but it's a cool advancement none the less. The beam itself is still just a laser beam.

Re:Important part the summary neglected

[girlintraining]

As the mirror has to be carefully aligned, this is a time consuming process.

This has already been partially solved using nano mirrors -- basically the rear reflector is a pile of mirrors that each have independent servos. It's nano tech. Like I said... early stages.

Re:Important part the summary neglected

[ackthpt]

Researchers use the computer to specify the laser beam shape they require and to programme it into the LCD. By this means, one laser can swiftly produce many different beam shapes. Previously, changing the shape of a laser beam required physically replacing the curved mirror in the laser. As the mirror has to be carefully aligned, this is a time consuming process.

This will be of immense benefit to mankind.

Once I fit one of these in the back of my car it will spell out messages for drivers following me to read; e.g. Your Turn Signal Has Been On For The Past 3 Miles.

Re:Important part the summary neglected

[TechyImmigrant]

Maybe it has fingers.

Re:Important part the summary neglected

[Lumpy]

Exactly, I believe the TI DLP system has been in use for this for quite a while. Last time I went looking they had DLP chip in the lab that was able to handle almost 15 watts of laser power without a problem. http://focus.ti.com/pdfs/dlpdmd/Using_Lasers_with_DLP(r)_Technology.pdf for one of their earlier papers on this.

Re:Important part the summary neglected

[PopeRatzo]

Once I fit one of these in the back of my car it will spell out messages for drivers following me to read; e.g. Your Turn Signal Has Been On For The Past 3 Miles.

"Spell out messages"? Hell, I want one that will vaporize the guy that's been tailgating me since the St Louis turnoff.

Re:Important part the summary neglected

[mcgrew]

I fail to see how that's digital

An English major wrote it. It uses a computer-controlled LCD instead of a curved mirror. There are benefits, TFA isn't very good at explaining them because the guy who wrote the article either didn't understand the concepts or really sucks at communicating them. You really have to look hard through the overabundance of redundant marketspeak verbiage to grok it.

Re:Important part the summary neglected

[Em Adespoton]

I fail to see how that's digital

An English major wrote it. It uses a computer-controlled LCD instead of a curved mirror. There are benefits, TFA isn't very good at explaining them because the guy who wrote the article either didn't understand the concepts or really sucks at communicating them. You really have to look hard through the overabundance of redundant marketspeak verbiage to grok it.

I doubt an English major wrote it -- it looks an awful lot like a Communications major wrote it; an English major wouldn't use an overabundance of redundant marketspeak, but would instead make all sorts of obscure references in fairly terse but accurate English.

Re:Important part the summary neglected

[LoRdTAW]

I would assume YMMV but the rear mirrors in industrial lasers are quite easy to tune. I work at a laser welding shop where we use lamp pumped pulsed Nd:YAG lasers. Rear mirror alignment is done manually using two screws and takes about 20-30 minutes thanks to the built in tuning meter. You set a pulse rate and width (eg 20Hz, each pulse 2ms long) and watch the power meter. You start with a number that gives you 10 watts and then tune until you can't get the power any higher(you now might have 15W. Then you do 50W, 100W ,150W etc. until you hit the lasers power limit (500W for our machines) and your done. I did this twice when we configure a workstation and added a new laser. This is for our three Lumonics JK lasers. The ancient Raytheon is a bit different and is tuned by a service tech and the Trumpf we have is rock solid and never touched though has the worlds most shitty configuration software.

Half as effective

[Anonymous Coward]

Unfortunately it's half as effective.

See, the 1s have sharp edges and really abrade the material, but the 0s just roll right off.

All we need now

[Anonymous Coward]

Is digital sharks

Summary seems to be somewhat misleading.

[Ungrounded Lightning]

My impression is that, because the mirror is "replaced" with the LCD, the LCD is inside the cavity, with each pixel modulating either the Q or the polarization of a particular chunk of the cross-section of the cavity. This amounts to adjusting the gain of the various modes of the cavity and thus switching which one(s) oscillate and consume the energy from the amplifier in the cavity.

Though the modes that are selected would not be mapped one-to-one onto the pixels, , you can control a lot of modes with the ciquid crystal display - probably all of them available, or up to the number of pixels in the liquid crystal device.

You can also switch them as fast as the liquid crystal switches. With modern drivers (which remember the previous state of the liquid crystal in each pixel and temporarily overdrive those that must change more in order to switch them rapidly, rather than just letting them settle passively into the new state) you can switch it at 60 Hz or better.

You might use holographic techniques to change the angle of the beam, or emit a number of beams of various intensities in various directions. Result: Scanning and image formation without moving parts (other than the molecules in the display).

I think the computation to turn it into a (one-color) projector would be pretty much a straight 2-D FFT times a nonliinear tweak to deal with energy-stealing among modes.

I'd like to see versions of this with array-of-Kerr-cells in place of the liquid crystal device (for more rapid modulation, at the cost of high voltage drivers), or digital light processors for the mirrors (though the latter are more on/off than continuously adjustable so they might be more limited on what beams they can form).

Re: Summary seems to be somewhat misleading.

[Lumpy]

About 6, but only if you dont have quantum entanglement.

Too bad this idea was patented in 2000

[goombah99]

here's the patent from 2000
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US6031852.pdf

instead of an LCD, which are slow, the inventors used an accoustoptic modulator as the pattern former. Those are fast. In fact they are so fast they could also use the pattern former to sweep the wavelength in real time or q switch the laser.