How to estimate the power of a laser pointer

In summary, a 500mW laser pointer can potentially cause eye damage if shone into the eye. It is not very powerful, and is not likely fake.
  • #1
CookieSalesman
103
5
Not sure if this is the right place, but I'm hoping to ask two questions:
1. I shine a laser pointer at a mirror at night, and the reflecting beam glaces off of my eye. Obviously it's quite bright, and I want to know if this has caused any serious damage. Of course I shut my eye, but apparently only 5mW is safe for eyes.

2. Does anyone know how to estimate the power of this pointer?
All that's said on the laser is that its max power output is less than 1000 milliwatts. That's obvious.
The model is apparently a "JD-303". I looked that up, and it's a 500mW laser, which doesn't seem right.

From this video , it seems that 500 mW should be able to burn anything, from my eyeball to my bedsheets- which mine can't do.
It's quite bright- At night, if I shine it out of my window, it (the whole beam, not the dot) clearly goes for quite a few kilometers. (allowing me to point it into hotel rooms and such.)

The battery in the laser:
"BRC 18650 4800mAh
3.7Volts lithium ion battery"
Perhaps that helps.

is it just that my laser has a bad focus/lens, since it's apparently not very powerful?

Perhaps the battery stats can help explain the power output of this laser. Will I need to see a doc...?oh. and I bought this laser off the street... In China. I honestly don't know if it's a fake, but from what I can tell, so far it is actually quite authentic. I don't think that just because I purchased this off the street that it should be considered fake, although it's a possibility. I'm not sure if street peddlers can really sell fake lasers though.
 
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  • #2
You wrote,

"
All that's said on the laser is that its max power output is less than 1000 milliwatts. That's obvious.
The model is apparently a "JD-303". I looked that up, and it's a 500mW laser, which doesn't seem right."

Why don't you believe that number, I would?

To estimate power use a volt/amp meter to determine current passing out of the battery and the battery voltage while the laser is working, this will likely require some jury rigging. Current times voltage gives power. Google the efficiency of solid state lasers?

https://www.google.com/search?sourc...id state lasers&aqs=chrome..69i57j0.11126j0j8

Notice anything wrong with your vision?

Be careful with dangerous tools.
 
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  • #3
I don't believe it because it's far from burning matches, or paper.

I unfortunately don't have the items or ability to measure this sort of stuff.

I don't think anything is wrong with my vision... I suppose I wouldn't be asking here if there was something wrong.
 
  • #4
CookieSalesman said:
I don't believe it because it's far from burning matches, or paper.
To burn things, you need high intensity, not high power. How much Watt higher do you think the lamp in your room has, and you are still alive?
 
  • #5
Ok...
Well the beam seems pretty darn well like a laser beam...

I can't possibly focus it more than it already is. And I feel absolutely no heat even if I stick the laser on my hand. ??
 
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  • #6
Yes, taking even a low-intensity laser hit in your eye can start to create damage. Please do your best to avoid that. It would be a good idea for you to have an eye exam, and talk to the doctor about laser safety.

And why are you shining your laser into hotel rooms? That can earn you an assault or battery charge if you are caught...
 
  • #7
CookieSalesman said:
1. I shine a laser pointer at a mirror at night, and the reflecting beam glaces off of my eye. Obviously it's quite bright, and I want to know if this has caused any serious damage.
This is impossible to tell based on that description.
CookieSalesman said:
(allowing me to point it into hotel rooms and such.)
To ruin other's vision? ...

The power drawn from the batteries is probably a good start - it gives a very hard upper limit on laser power and allows to make a reasonable estimate.
An even better idea is to not use lasers of unknown power.
 
  • #8
berkeman said:
Yes, taking even a low-intensity laser hit in your eye can start to create damage. Please do your best to avoid that. It would be a good idea for you to have an eye exam, and talk to the doctor about laser safety.

And why are you shining your laser into hotel rooms? That can earn you an assault or battery charge if you are caught...
Yep. I'll try to avoid that... I assure you I didn't stick my eye in front of the laser...

I assure you, if it was your first time getting a neat laser like that you wouldn't be able to resist doing that.
But I'm also not in the US, people don't get beat up for small things like this :-]
 
  • #9
Thread is done.
 

1. How do I determine the power of a laser pointer?

To estimate the power of a laser pointer, you will need a few pieces of information. First, you will need to know the wavelength of the laser, which can typically be found on the label or in the product specifications. You will also need to measure the beam diameter and the beam divergence. With these measurements, you can use the formula P = I x A x θ to calculate the power, where P is power, I is intensity, A is the cross-sectional area of the beam, and θ is the beam divergence angle.

2. What is the unit of measurement for laser power?

The unit of measurement for laser power is watts (W). This is a unit of energy per unit time, and is used to measure the rate at which the laser beam delivers energy.

3. Can I estimate the power of a laser pointer without any special equipment?

It is possible to estimate the power of a laser pointer without any special equipment, but it may not be very accurate. You can use a laser power meter, which is specifically designed for measuring laser power, or you can use a regular power meter and a calibrated filter that blocks out all light except for the laser's specific wavelength. Without these tools, it is difficult to get an accurate estimation of laser power.

4. How does the power of a laser pointer affect its safety?

The power of a laser pointer directly affects its safety. Laser pointers with higher power outputs can cause permanent eye damage, while lower power outputs may only cause temporary vision disturbances. It is important to always follow the safety guidelines and regulations for the specific power of your laser pointer.

5. Is there a maximum power limit for laser pointers?

Yes, there are maximum power limits for laser pointers. The FDA has set a limit of 5 mW for handheld laser pointers, as this is considered the highest level of laser power that is safe for use by the general public. Any laser pointer with a power output higher than 5 mW is considered a Class 3B or Class 4 laser and should only be used by trained professionals in controlled environments.

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