Green Laser pen

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Will
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Re: Green Laser pen

Post by Will » Tue Sep 27, 2005 6:56 pm

OK Chris, You liken me to someone you consider to be a stupid person and then follow it with " Sorry, no offence meant " Now who looks stupid ?.
This is what we know about you now . . (i) You do not understand the English language (ii) You do not understand the language of engineering (iii) You plagiarize the works of others and present them as your own. (iv) It is questionable as to whether or not you can perform any engineering calculations because you didn't put up by furnishing three of the four answers to questions you originally outlined.
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Chris Smith
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Re: Green Laser pen

Post by Chris Smith » Tue Sep 27, 2005 7:51 pm

Have you always had problems with the English language Will? <p>We already know your still having problems with Physics, “Mass” in particular. <p>You seem to think that mass has something to do with size?

Well Will, if you get that simple one wrong, yes, you are capable of getting so much more wrong, [like the English language] and while the night is still young, why don’t you take center stage and give us a proper show?<p>Were you trying to attach this..... “Sorry, and I mean no offence, but your learning curve is simply hindered by your complete lack of logic“ .....to the whole paragraph, instead of applying it to the line that it actually applied to? <p>Your mistake. <p>And "Liken you to the guy I heard on the Radio", Yes. I do. <p>However one line and statement is not mutual to the other.<p>[ September 27, 2005: Message edited by: Chris Smith ]</p>

Will
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Re: Green Laser pen

Post by Will » Wed Sep 28, 2005 12:07 pm

OK Guys!
I give up. From now on, While I may read and enjoy Chris' ludicrous, comic offereings, because it is a complete and utter waste of time, I am never again going to respond to any contribution/statement of Chris'
Who else wants to make the same motion ?
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Chris Smith
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Re: Green Laser pen

Post by Chris Smith » Wed Sep 28, 2005 2:52 pm

So that how one becomes ignorant? I didn’t know? Thanks for the tip.
Ill remember to never place my head in the sand, it could come back to bite me. <p>You should take it on the road Will.

rshayes
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Re: Green Laser pen

Post by rshayes » Wed Sep 28, 2005 6:00 pm

I think that everyone will agree that Chris does not have his head in the sand.

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Chris Smith
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Re: Green Laser pen

Post by Chris Smith » Wed Sep 28, 2005 6:15 pm

Steven, The circus officially left town. Did you miss your bus? Sand any one? <p>I was just reading one of your short sighted posts, I will use it later to show how small thinking comes up short every time. <p>If you dont mind that is? <p>a preview...<p>“The highest peak brightness will probably occur at about the current where the diode is entering the resistive region. This assumes that the duty cycle is reduced to keep the junction temperature constant. I would expect that the pulse width at this point would be in the 1 to 10 millisecond range as a rough guess.”<p>
*******
This is valid thinking if you don’t consider all the physics involved in the die or chip located inside any led. Metallurgy states than you can super heat metals to a plasma state, emitting greats amounts of light, and still let it cool down to start over, losing only a small amount of material if its not contained. <p>Like any light bulb however, the led is contained so no oxygen is mixed or involved to “oxidize” the metal, hence recover is almost total with little or no degradation to the die material. <p>If you heat it up quickly, it cools down fairly fast as well, because only a few surface atoms at a time are involved. Current does not flow in a conventional manner with anything fast. Same goes for HF where the skin effect takes over and current does not flow deep into the structure. This also increases the Energy density because only a few atoms are involved with all the current, and thus the ratio is increased. <p>But those Few atoms are in a state of plasma, one of the highest energy levels in the known universe, so proportionally they emit far more energy than any conventional way of producing light. On the order of thousands. What you can do here, has been done for more than 30 years now.....

rshayes
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Re: Green Laser pen

Post by rshayes » Wed Sep 28, 2005 8:08 pm

It's called an arc lamp. It was used for street lighting in the late 1800's.

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Chris Smith
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Re: Green Laser pen

Post by Chris Smith » Wed Sep 28, 2005 8:14 pm

Actually its called the LED, oops? <p>http://lists.gnu.org/archive/html/avr-c ... 00078.html<p>“Fig 7 shows the response of an LED to a digital modulation signal. The electrical signal shown is the type generated by more sophisticated LED driver circuits such as that shown in Figure 6c. Starting at time zero, we first see the digital signal go to a logic level 1. The most remarkable part of this event is the strong overshoot seen on the electrical drive signal. This overshoot may be two times the steady state logic 1 drive current. This overshoot accelerates the turn-on time or rise time of the LED. Even so, we see that the optical output lags behind the electrical signal. Typical values for very high-performance LED’’s and driver circuits would be 0.7 ns rise time of the electrical signal and 1.5 ns optical rise time. Later, when the digital signal goes back to a logic 0, we see the same process repeated. The electrical signal has a strong undershoot component which acts to accelerate the turn-off of the LED. The undershoot serves to reverse bias the LED, sweeping out the carriers. Even so, the turn-off time of most LED’’s is always slower than the turn-on time. Typical values for turn-off times are 0.7 ns for the electrical signal and 2.5 ns for the optical signal. Note that while in a logic 0 state, the drive current does not quite go to zero. It is common to provide a small amount of pre-bias current, typically a few percent of the peak drive current, to keep the LED forward biased and improve dynamic response.
All of these tricks together can increase the operating speed of the LED and driver circuit to about 270 Mb/s. There have been numerous laboratory tests and prototype circuits that have achieved rates to 500-1000 Mb/s, but none of these have ever made it into mass production. Typically these levels of performance require a great deal of custom tweaking on each part to achieve the high data rates.”

VIRAND
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Re: Green Laser pen

Post by VIRAND » Fri Sep 30, 2005 1:04 am

In the west, the red lasers are restricted, because they are on guns, and if you see a red dot on yourself, you are going to get shot. The green ones are for aiming telescopes at the stars.<p>In the east, we have red and green lasers. If you believe anyone was arrested for playing with them, throw your television in the trash and start reading "my pet goat". Try to hit a flying pigeon with a laser and then tell me you can blind a pilot 20 miles away with one!

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Chris Smith
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Re: Green Laser pen

Post by Chris Smith » Fri Sep 30, 2005 8:59 am

Gas lasers are far more powerful than laser diodes. <p>With a set up like my "Big Bertha" all you have to do is look through the gun scope mounted on it and put the cross hairs where you want them. Just aim at the strobe light on the air plane and you will hit the air plane. Then flip the switch. <p>The beam divergence at 20 miles is enough to hit the entire plane, and still be bright enough to blind the pilot temporarily.<p>Big Bertha threw a beam over 40 mile and still was more than impressive, and it was TINY compared to a one watt argon laser. It was thousands of time more powerful than a 5mw red diode laser.<p>To the moon and back is what lasers can do, very easily.

zotdoc
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Re: Green Laser pen

Post by zotdoc » Mon Oct 03, 2005 2:23 pm

Hi everyone. I remember in the 80's there was a brokerage in downtown New Orleans that occupied 2 buildings and they used some type of green laser to transmit their data through the air from one to the other. It didn't last very long, I don't know why, perhaps pigeons tried to land on the green "wire", disrupting the data transfer. Nice story - my question is, can you see the beam from a green laser pointer from the side, does it look like the contraption I'm describing back in N.O.? Or, is it just a dot on the board like the red pointers

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Chris Smith
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Re: Green Laser pen

Post by Chris Smith » Mon Oct 03, 2005 2:33 pm

In most circumstances, you cant see any of the Laser beam from the side angles. Only when moisture or pollution [dust, smog, smoke etc] is in the air, you see the beam bounce off the particulate involved. The only time you can see the beam is from the frontal position and it just looks like a bright light. <p>If you have a laser pointer, lay it down sideways and sprinkle some talc or blow cigarette smoke on the beam position, and it will come to light.

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