Blu ray at 24mA

[killmore231]

I have a blu ray running at 24mA, so that should be <5mW correct? Im just wondering if the "safe laser" is always <5mW, or if it is different for different colors. :thinking: It also still seems VERY bright when hitting fluorescent objects. Tried searching but didnt come up with much on if blu ray is different from red in terms of power.

EDIT: It also is over 5mW as it is smoking dark colored plastic. Curious as to the output of this, and if this is normal of a PHR.

 

[mfo]

I have a blu ray running at 24mA, so that should be <5mW correct? Im just wondering if the "safe laser" is always <5mW, or if it is different for different colors. :thinking: It also still seems VERY bright when hitting fluorescent objects. Tried searching but didnt come up with much on if blu ray is different from red in terms of power.

Depends on the diode. The only real way to know is to measure it with a LPM. Also, the fluorescence you speak of is normal.

 

[daguin]

I have a blu ray running at 24mA, so that should be <5mW correct? Im just wondering if the "safe laser" is always <5mW, or if it is different for different colors. :thinking: It also still seems VERY bright when hitting fluorescent objects. Tried searching but didnt come up with much on if blu ray is different from red in terms of power.

5mW of light is 5mW of light. Although there are some more subtle differences because of wavelength, the mW ratings are equal regardless of the color of the laser. Even IR and UV which you cannot "see" is measured the same way. Even 5mW of invisible light is still 5mW.

Peace,
dave

 

[killmore231]

Depends on the diode. The only real way to know is to measure it with a LPM. Also, the fluorescence you speak of is normal.

Yea, just tried to burn a piece of dark plastic, and to my surprise it did! Measuring 24mA but no way to measure the output of the laser, but it has to be >5mA.

 

[pullbangdead]

Most of the PHRs I've used wouldn't even be lasing at 24mA, much less burning plastic.

Not saying that I'm doubting your measurement, but I'm doubting your measurement .

How are you measuring the current?

 

[matrixcs]

i guess he uses a different test load for it... at 24mA??? can burn?? and a PHR does not light at 24mA....

 

[killmore231]

Im using a 1ohm resistor with a DLL driver to get the reading. Im going to verify it today with a different DMM, mine acts up sometimes.

 

[pullbangdead]

So you're using a DDL driver with a PHR...

What is your sense resistor on the DDL? As in, what is the resistance of the resistor that is soldered between the pins on the LM317 chip? This should be very easy to measure.

And then describe your measurement procedure more precisely. Do you have a 1 ohm resistor in series with the laser diode, and then are you measuring the voltage across that resistor while the laser id running? What voltage is your meter telling you when you measure the voltage across the 1-ohm resistor with the laser on?

 

[killmore231]

Alright, I had the pot between the lm317 set at 53 ohms (got 52 ohms on good multimeter) and it still burned dark plastic. The one ohm resistor is in series with the laser diode. It was reading 35mV with a good DMM(not 24mV like my DMM reads), but as soon as I took the reading, the laser dimmed drastically. I turned the pot down to 15 ohms and while I don't remember what it said for mV, it was about the same brightness as it was before again. Maybe damage to the LM317? Got it all built into a flashlight host now with the same DLL driver, and it still works so it may not have been the diode, but a bad LM317, or my DMM. Or I could have made a mistake, but I don't think that it would have dimmed when I checked it tho.

 

[Cyparagon]

Strictly speaking, the MPE is different for different wavelengths. For example, MPE for a UVC laser is less than 5mW and for MIR wavelengths (>2 microns or so), substantially more than 5mW.

But for just about everything you'll encounter, <5mW is commonly understood as safe.