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Last time I looked (it's over 25 years since I graduated and used such terms so things may have changed recently) mW was milliwatt (one thousandth of a watt) and not microwatt (one millionth of a watt)! The symbol for micro is the greek letter Mu which looks like a 'u' with a leading tail extending below the line.
Mr. Gordon beat me to it, and is correct, of course. The abbreviation mW is for milliwatt and (mu)W is microwatt. I personally think a mu looks more like an inverted h.
I've fixed this glaringly unforgivable foible on the article. It's been one of those weeks. Thanks for getting to it quickly.
All of these specs and attempts at standardization of measurements is moot, because
not one work of VACUUM is mentioned. As we all
know, lasers don't work very well in an atmosphere. There are just too many molecules
of AIR(oxygen, nitrogen, and numerous trace
elements) in the space between beam generator
and target to be meaningful. Pulse length,
and peak power ratings are nice but seldom
reflect the energy actually delivered to the
target. The military is working on aiborne
lasers for missle defense, but testing has
proved that interceptions mustbe done at high altitudes, well above most of the atmoshere
not one work of VACUUM is mentioned. As we all
know, lasers don't work very well in an atmosphere. There are just too many molecules
of AIR(oxygen, nitrogen, and numerous trace
elements) in the space between beam generator
and target to be meaningful. Pulse length,
and peak power ratings are nice but seldom
reflect the energy actually delivered to the
target. The military is working on aiborne
lasers for missle defense, but testing has
proved that interceptions mustbe done at high altitudes, well above most of the atmoshere
"In data storage circles, a Library of Congress is roughly 20 terabytes of uncompressed textual data. That's the digital equivalent (very roughly) of all the text characters in all the books on the shelves of the U.S. Library of Congress, excluding pictures and ancillary nontextual media."
Now, wait a min. that can't be right... I have more than that right here in my main room with that criterion.
Now, wait a min. that can't be right... I have more than that right here in my main room with that criterion.
Also from the nuclear physics world comes the shake (as in three shakes of a lamb's tail) a unit of time equal to 10 nanoseconds.
Alternatively, one can describe the capability of a laser, as the "joule." Joule is the measure of laser "energy" (and electrical energy). The unit, "watt," is a measure of energy per time. Therefore, for the same joule rating, a shorter pulse has more wattage. The joule disguises the actual destructive (or burn) capability of a laser.
As for your "Gillette/Watt" challenge, you are correct. "Even if we had a watt/Gillette conversion, it probably wouldn't be that useful." Without defining the laser spot size, the measure would be useless. A smaller spot size is more destructive than a large spot size for a given "wattage."
As for your "Gillette/Watt" challenge, you are correct. "Even if we had a watt/Gillette conversion, it probably wouldn't be that useful." Without defining the laser spot size, the measure would be useless. A smaller spot size is more destructive than a large spot size for a given "wattage."
http://www.lasing.com/paginas/archivos/his_first.htm
Maiman's first laser was 1 centimeter in diameter. Here's his quote from the interview:
"I went through the catalogs of available laboratory lamps, and calculated the effective brightness rather than being concerned with the size or the joules delivered, because my calculations showed that, within reason, the size of the ruby would not be important. And as I screened them and isolated them, there were only three lamps that had enough brightness to do it. All three of them were made by General Electric and all three of them where quartz helices. I bought a few versions of all three: FT503, FT506 and FT624 (a monster, designed for aerial photography). They all had enough brightness. So my first laser used the smallest, a GE FT506 lamp. The ruby was about 1 centimeter in diameter by 2 cm long, just filling the lamp spiral.
"That brings up a humorous anecdote. When the Hughes public relations people took the photographs of my first laser, they used the FT503 flashlamp because it was more photogenic. So when the press release got circulated, everybody thought that was the lamp I used. There was a run on those lamps. All of the reproductions of the ruby laser made in other labs used the FT503."
Maiman's first laser was 1 centimeter in diameter. Here's his quote from the interview:
"I went through the catalogs of available laboratory lamps, and calculated the effective brightness rather than being concerned with the size or the joules delivered, because my calculations showed that, within reason, the size of the ruby would not be important. And as I screened them and isolated them, there were only three lamps that had enough brightness to do it. All three of them were made by General Electric and all three of them where quartz helices. I bought a few versions of all three: FT503, FT506 and FT624 (a monster, designed for aerial photography). They all had enough brightness. So my first laser used the smallest, a GE FT506 lamp. The ruby was about 1 centimeter in diameter by 2 cm long, just filling the lamp spiral.
"That brings up a humorous anecdote. When the Hughes public relations people took the photographs of my first laser, they used the FT503 flashlamp because it was more photogenic. So when the press release got circulated, everybody thought that was the lamp I used. There was a run on those lamps. All of the reproductions of the ruby laser made in other labs used the FT503."
Here is a fun wikipedia page with more fun and highly accurate measurements 
http://en.wikipedia.org/wiki/List_of_strange_units_of_measurement
http://en.wikipedia.org/wiki/List_of_strange_units_of_measurement
I'll leave the measurements to the physicists among us, but when you said the Gillette razors were "synonymous" with the company, I think you meant "eponymous." And that should be in the Trivia Geek's area of expertise!
I'd like to add that the original (in this sense) Gillette was King Gillette, who started the razor company that bears his name. (I'd like to think it was named for Penn Jillette-with-a-J, but alas...)
Gillette is synonymous with razors. Lou Gehrig is eponymous with Lou Gehrig disease. Synonymous was the right term.
Since the original laser operated in pulses, and I don't know the length of those pulses (assuming the "gillette" measure was how many blades a single pulse could burn through), it's impossible to convert to watts, since watts are calories per second. (Would need the time measurement to do a real conversion.)
Beyond that, it's a pretty straightforward measurement.
First, we need the albedo of a gillette razorblade. That's the ratio of light absorbed vs light reflected. (I did an online search, but couldn't find this.) Assuming an albedo of .9 (polished metal surfaces are pretty reflective), that means that your laser's energy will be 90% reflected, 10% absorbed.
Then we need the specific heat of a gillette razor. How many calories does it take to heat one gram by one degree Celcius? Steel varies in this regard depending on its carbon content and other components. Iron is .11, so I'll assume it's around that amount.
Then we need the number of grams of metal we're talking about burning through. Let's assume half a gram for now. (7-9 grams/cubic centimeter for various grades of steel; the desired hole would be about 1 cm wide I'm guessing, and less than 1 mm thick, which would make it approx .1 cubic centimeter, or about .7 grams.)
Boiling point is around 3,000 degrees C. So, we need to heat .5 grams of steel to 3,000 degrees, specific heat of .11, heat of vaporization around 340/gram, from about 30 degrees. 163.35 to 3000, 170 to vaporize, call it 340 calories. Then, because of the albedo factor, we have to multiply that by 10 (90% reflected) = 3,400 calories. If we're talking about a 1 second pulse, that's 3,400 watts/gillette. If it's a .1 second pulse, that's 34,000 watts. If it's a 2 second pulse, it's 1,700 watts. Just depends on the length of the pulse.
(Please note that the actual heat, density and albedo characteristics of steel may vary from what I've assumed, but the math is still solid.)
So, yes, it is possible to convert from gillettes to watts.
If there are errors in this, blame it on the fact that it's been nearly 20 years since high school physics.
Beyond that, it's a pretty straightforward measurement.
First, we need the albedo of a gillette razorblade. That's the ratio of light absorbed vs light reflected. (I did an online search, but couldn't find this.) Assuming an albedo of .9 (polished metal surfaces are pretty reflective), that means that your laser's energy will be 90% reflected, 10% absorbed.
Then we need the specific heat of a gillette razor. How many calories does it take to heat one gram by one degree Celcius? Steel varies in this regard depending on its carbon content and other components. Iron is .11, so I'll assume it's around that amount.
Then we need the number of grams of metal we're talking about burning through. Let's assume half a gram for now. (7-9 grams/cubic centimeter for various grades of steel; the desired hole would be about 1 cm wide I'm guessing, and less than 1 mm thick, which would make it approx .1 cubic centimeter, or about .7 grams.)
Boiling point is around 3,000 degrees C. So, we need to heat .5 grams of steel to 3,000 degrees, specific heat of .11, heat of vaporization around 340/gram, from about 30 degrees. 163.35 to 3000, 170 to vaporize, call it 340 calories. Then, because of the albedo factor, we have to multiply that by 10 (90% reflected) = 3,400 calories. If we're talking about a 1 second pulse, that's 3,400 watts/gillette. If it's a .1 second pulse, that's 34,000 watts. If it's a 2 second pulse, it's 1,700 watts. Just depends on the length of the pulse.
(Please note that the actual heat, density and albedo characteristics of steel may vary from what I've assumed, but the math is still solid.)
So, yes, it is possible to convert from gillettes to watts.
If there are errors in this, blame it on the fact that it's been nearly 20 years since high school physics.
Okay, gsquared, private message me a shipping address and contact number, and I'll get your swag out to you ASAP!
...by the fact that gsquared got no points credit for a fine calculation, and the Geek got 50k just for accepting it as valid!
According to
http://www.press.uchicago.edu/Misc/Chicago/284158_townes.html
The pulse was a 'few milliseconds'. So given the calculations above and assuming a few is 3 (1 is 'a millisecond', 2 is 'a couple of milliseconds), this puts our conversion at around 1MW/gillette. 3 is also supported by the plethora of ruby laser specs on the web regarding hair removal
http://www.press.uchicago.edu/Misc/Chicago/284158_townes.html
The pulse was a 'few milliseconds'. So given the calculations above and assuming a few is 3 (1 is 'a millisecond', 2 is 'a couple of milliseconds), this puts our conversion at around 1MW/gillette. 3 is also supported by the plethora of ruby laser specs on the web regarding hair removal
Those of us who have been around long enough to remember what the blades actually looked like at that time would tell you that they were a dark blue in color. I don't believe that they became silver colored until well after the "Gillette" unit of measure was devised. Your albedo would be much lower and you would therefore need much less power (consistant with the laser outputs of the time).
cheers,
chuck...
cheers,
chuck...
The calculations depend on the conversion of cal/sec to watts/sec.
1 watt = 1 Joule/sec and 1 cal = 4.184 J
So, 1 cal/sec = 4.184 watts.
With a 1-second pulse, 1 gillette = (3400 cal/sec)*(4.184 J/cal) ~= 14 kW
26 years have passed since my last physics course so I won't be surprised to learn that I'm mistaken.
1 watt = 1 Joule/sec and 1 cal = 4.184 J
So, 1 cal/sec = 4.184 watts.
With a 1-second pulse, 1 gillette = (3400 cal/sec)*(4.184 J/cal) ~= 14 kW
26 years have passed since my last physics course so I won't be surprised to learn that I'm mistaken.
Actually, the result of your calculations results in Gillette-Seconds/Watt.
There is no equivalance between Gillettes and Watts without including a standard unit of Time.
There is no equivalance between Gillettes and Watts without including a standard unit of Time.
In Australia a common comparative measure of water volume is the SydHarb. This measure is the volume of water contained in Sydney Harbour. This unit first became popular during the construction of the Snowy River Hydroelectic scheme during the 1950s and 60s. Many new dams were built in remote locations in the mountains and were of such size that it was easier to relate their size to a familiar body of water (ie Sydney Harbour) than to quote a very large number of acre-feet, cubic feet or gigalitres. The volume of a SydHarb (at high tide) was recently calculated to be 562,000 megalitres.
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