Power of laser chart? and another question

[Tw15t3r]

Hey I was wondering: well, most of you have seen the chart for laser pointers sold by Nova lasers. The chart says what the laser can do at each power, i.e. 75mw, viewable beam indoors with light on, etc. The problem is that, that chart is for green lasers. Anyone know a similar chart for red lasers? It would help those without a laser power meter to roughly guage the power of the laser.

If there is no such chart available, maybe those who have laser power meters and lasers can chip in so we can create one ourselves. I won't mind collating the data.

2nd question, I've managed to get my laser diode working, and wow, (@100mA) it's really nice to see a dot that is as bright as the dot of the sun when focused with a magnifying glass. My laser diode is from an 18x burner, and it's a closed can one. So how far should I push it with a proper heatsink? (like the ones by Jayrob)

 

[ElektroFreak]

A lasers destructive power should be the same no matter what the color.. The output power of a 100mW laser is 100mW no matter what the color, and it's the mW that do the burning, popping, etc. Therefore the chart will work for any color laser.

I'm not familiar with your diode specifically, but I'd say an 18X diode should be able to handle 200-250 mA
without too much trouble.

 

[691175002]

Wavelength makes a huge difference for what you can see. Even 200mW of 405 would not be visible with lights on.

Burning ability can also vary with wavelength. While the power behind the beam is always the same, the material does not always absorb the same amount. For example, a red sheet of paper would be very difficult to cut with a red laser but a piece of cake for green.

I would be skeptical of a charts usefulness. I can see 50% error in trying to gauge a lasers power this way just because there are so many external factors. For example, in my house we have HEPA air filters which can make it hard to see the beam. Someone else may be in a dusty closet. The lighting in a room can vary considerably, burning power relies far more on proper focus than laser power, etc. I wouldn't even try to gauge a laser like this.

 

[Tw15t3r]

Hmm, I do agree on it being difficult to guage the power of the laser from looks, but it should be easy to tell if it is surely above a certain mW.

And no, a green chart cannot work for red lasers. I'd disagree on that because green is more visable than red. So although burning capabilities may be the same, visability would greatly differ. If a red beam appears as bright as a green beam, obviously the red is more powerful.

My idea for a chart is more like:
If you're able to burn matches (dark) within a meter, while having ur laser focused at infinity, then ur laser is at least x mW

If you can pop black balloons (party, not water bomb ones), and it must be within an inch from ur pointer, while giving max focus, then your laser is at least x mW

That's the kind of thing I'm thinking about. It's more of an at least chart.

[edit]Hey I have an idea! Maybe we can see how many tissues a laser can penetrate and guage it's power from there! (that is, if the laser doesn't burn the tissue) Conditions could be like: Focused at infinity, tissues held at around 1m, standard 2 ply.[/edit]

 

[ElektroFreak]

In terms of destructive power ONLY (not beam visiblilty) a laser's power output is the same no matter what the color (with some dependence at low powers on the color of the object being burned). As I said before, a mW is a mW whether it is green, blue, red, purple, orange or any other color you can think of. Beam visibility doesn't tell you anything about the power of the laser at all. A laser in a room with a certain amount of particles in the air will look brighter than the same laser in a different room with less particles in the air, so unless you can find two places in the world with exactly the same air purity then one person may see a beam while another in a different room may not. Also the diameter of the beam plays a big role in beam visibility. A narrower beam will be more visible than a wider beam of the same total power output.

I agree with 691175002 in that a chart of this type is no way to determine the output of a laser. The only proper way is to use an LPM. Anything other than that is just highly inaccurate guesswork..

 

[randomlugia]

I have to agree with Electrofreak about the beam visability. It's impossible to tell. Some nights I can see my 5mW red beam perfectly, some I can't see the beam with the laser pointed right at me. Air particles differ from time to time, and from space to space.
Also, some people can see laser beams better than others. Some can see blu-ray so well it hurts their eyes to look at in a lit room, other people can barely make it out in the dark. I'm probably someone who sees it well, because I am blinded by any kind of blacklight while other people think it's really dim... :-?

Plus, it depends on the exact object you're burning. "Popping a black balloon" won't work, because different companies make different thicknesses, or material.
This chart is a bad idea.

 

[billg519]

If your lasers are less than 120mw or so, ebay vendor (and member) lasersbee has a power meter module for use with your DMM for low $$$. This will be far more accurate than any chart based approach. If you really like lasers, consider getting a thermal power meter.

 

[Tw15t3r]

Hmm I see....
I was thinking there could be some way that one might guage power by using common household tests. But I guess maybe not after all. Thanks for the replies guys!