Laser Questions

I'll handle the easy one.

A 1,000 Watt laser has a power of, well, 1,000 Watts (joules/second)

An industrial (commercial) 1,000 Watt CO2 laser generally has the ability to cut through steel up to 5/16" thick.

http://www.youtube.com/watch?v=f1J1QcfeiRg

The coinciding laser beams will not change in wavelength, but the energy they deliver will add up accordingly. In a laser cutting rig (as in the video) the laser melts the metal; the gas blows the molten metal down out of the kerf.

Because the cut is quite fast, the adjacent metal does not heat up very much. This reduces warping in the material.

"#1 I have read that when you hit a hydrogen pellet with a laser beam it will release energy. My question is why and how. Also, can this be done with other substances and which state of matter is the most effective?"

You're speaking of fusion experiments (Nova and Shiva come to mind) performed at Lawrence Livermore Laboratory where a frozen deuterium* pellet is dropped into a spherical chamber and then compressed and heated by multiple, ultra-high-energy laser pulses striking it from different directions.

Other substances - elements - can be fused to release energy, but the yield (the amount of energy released per unit mass) becomes smaller and smaller as the nuclear mass increases. Iron and the heavier elements absorb energy when fused, and therefore have a negative energy yield. Fusion occurs naturally in stars, and is what powers them. Stellar fusion ultimately produces iron as the nuclear "ash" and, consequently, elements heavier than iron can be produced in stars only by means of supernova explosions. About two-thirds of the iron in your body was produced by stellar processes and the heavier elements were produced by supernovae.

_{* Deuterium is a stable, fairly abundant isotope of hydrogen. The nucleus of an ordinary hydrogen atom (aka, protium) consists of a single proton. A deuterium nucleus contains a proton and a neutron, whilst tritium (which is radioactive) contains a proton and two neutrons.}

.Europium,

If, as you state, two thirds of the iron in our bodies comes from stellar processes, from where does the other third come?

Benbenben

Radioactive decay.

Also, in the computer chip (wafer) manufacturing industry, I have seen a firm use a laser to "clean" hydrogen off the silicon wafers.

I use a laser to clean my dishes. Did you know that dried poached egg stuck to the bottom of a Silverstone pan comes off best using wavelengths less than 390 nm?

I thanK you all for your answers. Maybe you can show me the best way to continue my hunt for knowledge on lasers. What is the most informative and advanced book on lasers? I'll attempt to read it and research anything that confuses me. If it is to much for me to handle then the research part will be my learning. What is the best and most effective way to perform tests on lasers?

Advanced books on lasers assume their audiences are already quite expert in the field and, consequently, these books are highly discouraged as a starting point for someone new to the art. The most advanced books on lasers and laser physics assume a mastery of foundational topics such as classical and quantum optics, non-linear optics, linear algebra and matrices, advanced chemistry, quantum mechanics, quantum electronics, differential equations, advanced calculus and other, related subject matter.

The best place to begin is at the beginning. Some good books about lasers and the people who invented them:

How the Laser Happened: Adventures of a Scientist*, by Charles H. Townes

Beam, by Jeff Hecht

Understanding Lasers: An Entry-Level Guide, also by Jeff Hecht

_{* The observatory dome seen on the book's cover is located atop Mount Locke, in west Texas. The dome is one of several belonging to the McDonald Observatory, where I once worked. The laser beam seen leaving the dome was emitted by a laser range-finder which made use of a retro-reflector left behind on the Moon by Apollo astronauts. The reflector returns a very small portion of the beam (which, by the time it reaches the Moon, is several miles in diameter) back to Earth. By multiplying the speed of light by the time it takes for the beam to travel to the Moon and back, one can very accurately estimate the Moon's distance (which is half the value of the result computed above).}

Wow thank you. I will look into those books. Right now I am a freshman in college so I have my whole life ahead of me. I am currently just taking electives but I would love to eventually get into the field of lasers. So I am curious, what is the demand for them and does it pay well?

Laser pointers; laser transits, levels, and plumb bobs; laser cutting of precision parts; laser weapons; laser light show choreography; laser surgical instruments; laser-initiated fusion (?); holography.... Yeah, you have a whole world out there, and likely to expand.

Many of these applications rely on geometry, computer control, etc. Study these, and learn one or more CAD drawing disciplines.

Europium has admirably summarized the theoreticals. On the practical end, some kind of internship or apprenticeship with a laser metal fab shop would be good, and from that you would probably also pick up on other methods such as plasma cutting. Measurement and instrumentation is another important area.

Go west, young man! (Horace Greeley)

Wear eye protection.

A piece of advice: as long as you depend on other people for your information, what you learn will never exceed what they know. Ever.

Now is the perfect time to hone your research skills and start digging. The subject of lasers is vast, deep and wide. The Internet is your friend - especially search engines like Google - that make researching a topic these days a Utopian dream compared with the methods we had no choice but to use in my college days: hard copy only, inter-library loans, physically going to a library, in person, to research a topic [all the while pleading with Bog & His Holy Angels + Saints the info was 1) present, 2) current, and 3) somebody else hadn't checked out the materials and failed to return them prior to graduating].

Assignment: toss a bunch of laser-related words into Google, turn the crank, and see what other laser-related words pop up. Mix these in, in various combinations, and repeat. Add the word "salary" or "salaries" and see what happens. Experiment. You'll learn more in one night than I learned in three weeks the old way.

A demand for laser engineers does exist and can be expected to grow.

The salaries are not brilliant. It all deepends how you sell yourselve though.

The two most massive industries that require lasers are communications (laser through fibres) and optical disk storage. The next consumer item that everyone will have three of in his home is laser projectors instead of televisions. Its tiny, its cheap and it will be in everything, from mobile phones to microwave ovens.

Laser printers might be found right after these two.

Military and medical funds is the biggest driving force in research of lasers up to now. If you like your powerful stuff, military is definately a good place to play with some nice big toys, where 1000 W is probably nothing.

A huge boom was formed from the flat panel display market, where lasers are used to cut and form the panels, pixels etc. Today we also have a new industry on laser diode flat panel displays where each pixel is a laser diode, offering the best colour definition ever. These will use a lot of lasers per device, hehe!!!

The flat panel cutting industry is now enhanced by the solar panel needs for laser scribbing and cutting of the panels and it seems that the global needs for these are rising rapidly.

Marking, drilling, cutting and scribing is a standard market for laser systems. Maybe 30% of food packaging today has been marked by a laser. Its very easy to show people a sample of my work these days as we are having a drink or coffee.

Lasers are here to stay. Their greatest advantage is precission which derives from their incredibly precise wavelength.

A good book to read is nost certainly the Bible of lasers: "Lasers, Antony E. Siegman"

You will need good mathematical skills (any book in the subject of engineering mathematics with plenty of problems and examples should be able to prepare you for that)

In terms of chemistry and science knowledge I would suggest "Chemistry and Chemical Reactivity by Kotz".

If you still think you are missing something, probably in terms of optics, try "Optics by Hecht".

An interesting and comprehensible web based source of information is Sam's lasers

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

and a more scientific source might be the "Encyclopedia of laser Physics and Technology:

http://www.rp-photonics.com/encyclopedia.html

Good luck!

Good luck in your decission.

My suggestion: Move into electronics engineering, but not to ignore your laser interests. They can meld. They did for me. I did laser systems design from the ground up. CO2, YAG, Diode-pumped for industry. Sure, I did well for a decade, but where the hierarchy to go to outsourced and with the immediate affiliates that would not readily share that interface (a struggle). As an obvious 'scapegoat, I was laid off.

I would not say this to scare you off; but would say that the meld of the two technologies are rather narrowed presently. Likely, they will widen in the future greatly.

There is nothing sacred about what is to surely occur in the future. Do you have a sense of psychic or insight? Circa 1953 or thereabouts, I was toying with with an RCA transistor (CK722?. It occurred to me that this may just graduate to "a bunch of these guys aligned together in a little teeny block". Yes, and we know as those as integrated circuits. I've been about half-smart on this and that; maybe something of a "seer". No, I am not; didn't even envision cell phones until just before introduced in the market.

ps: I don't mind one to probe my head. The recipient may learn something that I have. Don't mind sharing.

It's interesting to me that so many others have given those "GA" (good answers) after my interface and reply. What occurs, as I see it, is (e.g.) the responders tend to go off on tangents and off-topic repeatedly. I think they did, in part, on your posting. Maybe they'll continue to beat me up, but it does not matter. When I post, I have a positive answer.

Remarkably, and after some several years, I have a mere 1 "Good Answer".

I think that the CR4 "regulars" are largely nothing more than a clique.

Enough said.

For savioslegacy: I would be glad to further provide you with whatever you so desire info/references as I can. I had mentors when I was 'growing up' with ongoing knowledge back when. I would be pleased to be one of your mentors.

Warning: I can be supportive. I can get on your case, so to say. All should be of a positive orientation. Your choice.

Understand: I do not have any purpose in doing any such thing, but only to further certain knowledge that you may achieve from me. Not to be of any obligation of your part nor mine.

The bottom line: While others here at CR4, or example, cite error in their this and that about at least what they could offer. At that, I think they should not reply if askew.

CR4 replies tend to go off on tangents. This one probably is one of the best at that.

There are those here at CR4 that are very talented and with expertise in many areas. It's difficult to discern which are knowledgeable and those that guess (why would they bother?).

Stick with electronics engineering, whilst peeking into the 'pulse' of technologies going onward (suggested). Talk to your dean, (as long his surname is not "Murphy" (mine was a hoot, but I survived).

FYI, in a nutshell: I did electronics and also Radiological Health (never used that) in college. Worked for Sperry mrf'ing microwave tubes and similar for a couple of years. Draft deferment running out, join the Navy. Made E-6 in like 2-years or so (a record?). Got out after 8 yrs (regret) and ended up hired in the communications industry back in the hometown, like two days later. Long story at that, but after not too long a time was a Veep and area mgr. The significant one. Brought the co. out of the red and into the black within a very short time. Why? Looking back, this co. didn't have any retirement plan. Nada.

Left, and pooped around with a couple of other advisories for a few years and moved on to the 'big city'. Found in Orlando is what I so wanted! Manufacturing! Something that you can design, be the originator, be really fulfilled in seeing it being shipped to the customer! Ahh, the reward of it all!

Hi,

look what is open to the public about NIF, the National Ignition Facility,

this is on Laser fusion.

Building cost was estimated a liittle below 4 G $ in 1994!

RHABE

And they still haven't paid me back, those sods!!!

Well seasoned cast iron beats that hydrochlorofluorobromocarbon/Calphalon/ScanPan shit any time of day, but it is a bit heavier. Cuz it never peels off, for one thing.

I should GA you for the cast iron comment! Every non-stick surface in the world tries to mimick cast iron.

You should find more good info in reading those that have been cited here.

In re #2: There are basically two types of lasers. CW (continuous wave) and pulsed. With pulsed, peak power is significantly greater than CW; determined by duty cycle. The amount of energy required for any power lever depends on the technology used. Nd:YAG lamp pumped lasers have been around for a long time and require a lot of power. Much better efficiency can be obtained today with diode pumping.

#3: Yes, there are methods to combine two laser beams to increase power X2. I haven't seen any method to increase the wavelength, but there are for decreasing by the use of one or more crystal elements; however, significant power is lost.

Original Poster.....

I am a laser engineer....if you want to contact me....email me at chi.square@hotmail.com I've been in this business 20+ years.

Lasers can certainly do unique things and will always be in demand. However, R&D in lasers is a tougher environment than it used to be in the 1980's-1990's. Funding has been tighter especially in the last 5 years although there still is funding out there for R&D....but it is a tougher feild than it used to be.

As I understand it from my physics laser course (long time ago) when the pellet is hit ,with multiple laser beams directed from all angles around it, the electrons on the aluminium atoms are suddenly given enough energy to be liberated from the atoms and form a plasma cloud around the pellet. Incidentally this plasma cloud will block the laser penetration depending on the frequency or wavelength of the laser used. This limits the overall energy output and is called the plasma frequency. This plasma (electron gas) will collapse back onto the atoms as the energy of the electrons in the cloud is released and because the electrons drop back to certain preferred energy states on the atoms this energy released in the form of light is all at a fixed new frequency. The coherent laser light emitted (all in phase and same frequency) is in the x-ray region and forms the basis of star wars type technology. Hope this helps understand parts of your question. Lasers are basically light sources where the light is single frequency (one colour) and each ray vibrates in phase with all of the other rays of light in the source. When this happens the intensity of the overall beam multiplies up tremendously by adding the waves together. In ordinary sources like LEDs the colour is the same but the vibrations of the rays are all over the place so the intensity is less. Merging beams does not change the wavelength but changes the intensity or power of the beam. The aluminium pellet acts to change the wavelength say from infra red to x ray. Other substances can also do this and one laser can be used to excite another thus giving a new wavelength. This is called a pumped laser. I am not an expert but lasers are very interesting pieces of equipment.

Possibly you are thinking of Sandia Lab's Z-Machine, which does generate powerful X-rays?

The Z-Machine uses two small, nested tungsten-wire "cages" which are vaporized and compressed by an extremely powerful electromagnetic "shock wave" (in a manner of speaking) to the extent that the resulting plasma is hot enough to emit intense, "hard" X-rays. Sandia's media folks explain it this way:

"20 million amps of electricity pass through a small core of vertical tungsten wires finer than human hairs. The core is about the size of a spool of thread. The wires dissolve instantly into a cloud of charged particles called a plasma.

The plasma, caught in the grip of the very strong magnetic field accompanying the electrical current, is compressed to the thickness of a pencil lead. This happens very rapidly, at a velocity that would fly a plane from New York to San Francisco in several seconds.

At that point, the ions and electrons have nowhere further to go. Like a speeding car hitting a brick wall, they stop suddenly, releasing energy in the form of X-rays that reach temperatures of several million degrees — the temperature of solar flares."

The Z-Machine does not make use of lasers, however. The plasma is created by an electromagnetic pulse from Z's impressive Marx generators.

Hi, I will try and answer your questions. Some I can answer straight away and some I can give you directions for further reading.

#1. I am unsure of what a hydrogen pellet is, not necessarily related to lasers, but I have a good feeling that the answer to this lies somewhere in the field of what is termed as "laser cooling". Normally we expect photons that impinge on an atom or a material to heat up the item. Scientists have managed to reduce the momentum of moving gas atoms by the use of narrow bandwidth light (i.e. from a laser source), detuned slightly from the characteristic absorption band of the atoms in question. Reduction of momentum is only possible when the atoms hit by the photons are moving against each other, tuned in together due to Doppler effect. Here is a link for further reading:

https://www.answers.com/topic/laser-cooling

Can it be done with other types of matter? Probably yes, however gasses have simple and discreet absorption bands, and also a low enough density that would allow photons to penetrate through its volume, rather than affecting just the surface of a solid body for example.

#2 Its all about efficiency here. Different types of lasers have different efficiencies. For example, an RF-CO2 laser can come up to about 10 to 12 % efficiency, so for 1000 W of light you would need 10 KW of RF power going in. YAGs (solid state crystal lasers often need much more power than that. A laser diode will give you the best efficiency possible, even up to 50% (efficiencies up to 80% can be expected from scientific experiments, but I am not sure how close the industry is to that standard). Diode lasers will have a rather large emitted bandwidth though, as they do not have a Fabry-Perrot resonator cavity. But generally speaking, for a KW of laser power, you would need a few tens of kW of electrical power to feed your beast, and you would also need to stay well out of the beam path.

#3. You can merge laser beams to increase power. If you are planning on increasing the wavelength of a laser beam, then you are probably looking at an "optical parametric oscillator" solution, using non-linear optics. Combining beams to achieve this effect would probably utilise the same theoretical background as these devices. See the following:

https://www.chemie.de/lexikon/e/Optical_parametric_oscillator/

Hope this is helpful.

Good luck with your research!

Hi saviorslegacy,

I thought you might be interested in some pics I took several years ago of a ruby laser rod fluorescing under green light.

The first laser, built by T. H. Maiman in 1960, used a ruby rod as the amplifying medium. Rubies strongly absorb green and violet light and re-emit some of that energy as red light. Green and violet are the two main colors emitted by xenon flash lamps and are the reason these lamps were used to optically "pump" ruby lasers.

In the pix below I'm directing a one milliwatt, 532 nm wavelength (green) laser at a 1/4"-dia x 3"-long rod from an early ruby laser. The ruby fluoresces very nicely!

Cheers!

-e

Nice post! This should tickle the originator our original wanting to learn about lasers! 'Tis a vast opportunity and challenge to grasp In all, there have been a number of responders that have done quite well. It is difficult to be of any assistance in pin-pointing vague inquiries, is as this is. Perhaps inspiration is the key as this may be. As I've seen it, laser technology has largely been dormant for a long period, but has perked up over the past 10 years or so.

Too, and for our inspired one, applications are to be likely a great opportunity: medical for one. Only to achieve 90+% efficency with that collimated energy and focus is a certain key. Sure, with military applications. That's the other side.

The last time I looked, we were getting close to lasing certain attributes of materials almost down to the atomic level, but not quite. For me, I wish that I could starting over with my working life destiny, this is where I would be going. Seriously, and probably DNA/RNA research. Yes, lasers will likely play an important role and be an instrument. Not for an aim to become wealthy, but more of a better sense of fullfillment in life.

A 1000 watt laser will consume more than 1000 watts of power. For example an Argon gas laser is only about 1% wall plug efficient (power consumed to power produced) so it depends on the type of laser used. Solid state lasers are very efficient compared to gas lasers. I first started being interested in lasers when I saw a laser show in Toronto. The entertainment value is hypnotic to say the least. If you want to learn more try visiting

1. http://www.sniffinfo.com for free DIY laser effects devices

As an aside, argon ion lasers are typically less than 0.1% efficient, and the majority are less than 0.01% efficient. One-percent efficiency is extraordinarily high for this type of laser.

way out of my level of understanding but the coolest laser/ hydrogen video I ever saw was at the website of "National Ignition Facility". sounds expensive.