Hallo
See data sheet. I have a few questions about Laser Power, current and voltage. Example calculation: If I Calculate Laser current x Laser Voltage = 50mA x 2V = 100mW Where is the Calculation Error? Laser diode has a maximum power P = 5mW. What Voltage and Current is present at the Laser Diode?
So Power loss is around 100mW? Why isn't Power loss listed in the Data sheet?
What does Monitor Current mean in the Data Sheet?
Gruss Chris
See data sheet. I have a few questions about Laser Power, current and voltage. Example calculation: If I Calculate Laser current x Laser Voltage = 50mA x 2V = 100mW Where is the Calculation Error? Laser diode has a maximum power P = 5mW. What Voltage and Current is present at the Laser Diode?
So Power loss is around 100mW? Why isn't Power loss listed in the Data sheet?
What does Monitor Current mean in the Data Sheet?
Gruss Chris
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The difference is optical power (as measured with a Laser Power Meter) that is radiated as light, vs. electrical power that heats up the diode junction. So the efficiency is low, just like that of a LED. The monitor current is the current generated by the split laser light on the reverse biased internal photodiode. This is my interpretation, but I am not an expert either.
I am also interested how could I measure the emitted light power of a Philips CDM-1 laser. I measured the actual current and it is around 50 mA, but the eye pattern is a bit weak. I haven't got acces to a laser power meter
I am also interested how could I measure the emitted light power of a Philips CDM-1 laser. I measured the actual current and it is around 50 mA, but the eye pattern is a bit weak. I haven't got acces to a laser power meter
Thanks For Infos.
Maybe this is useful UNI-T UT385 ?
https://de.aliexpress.com/item/1005004005259168.html
Maybe this is useful UNI-T UT385 ?
https://de.aliexpress.com/item/1005004005259168.html
Sure it must be good, but the price...
I found this alternative:
https://overseas.sanwa-meter.co.jp/products/laser_power-environment/lp10.html
I found this alternative:
https://overseas.sanwa-meter.co.jp/products/laser_power-environment/lp10.html
There is a big risk of getting such tools if you have high-end players at home. But I'm also a saver, it has to be cheap.
Maybe I'll buy it at some point.
Greetings Chris
Maybe I'll buy it at some point.
Greetings Chris
Some hints:
5mw is nominal power output, but it can deliver more, 8 or 10mw aprox.
2V datasheet is max reverse laser diode reverse voltage.
Why power loss or power of power efficiency is not detailed in datasheet? Because is a irrelevant data.
Laser diode substrate is like a square, a box, it emites for two sides, one side to the laser diode ouput, andthe other for the monitor diode, it helps to perform it a way it keeps a constant power.
There is as data that is not well known but it is very important for CD readers, is S/N. Laser diode emites a light that is very pure in frequency and in PHASE. Phase performance is the most important characterisc.
If you repair or experiments with CD players, you have noticed that when a laser diode is older, exhaust or run out, though laser power emited is maintained(meassured with a laser power meter), laser current haver soar and RF signal have lowered.
Why RF signal is low though laser power keeps its power?
I think it is laser diode have lost phase purity, the laser diode has lost Laser characteristics, it emites, but emites energy out of phase.
In the workshop, when you get a cd player with low RF, you instintly up power laser. But surely, if you measure the laser power diode, it keeps its nominal power.
When you up the laser power, you compenstes the lost of Laser phase propierties.
It should be interesting to analyze an exhausted laser diode in a spetrum analyzer, I'm sure you could see a lot of differences respect a new laser diode.
Responding the thread, monitor diodes is a photodiode that captures the oposites laser diode emision, it is a in reverse polarized diode, and it helps to know how power is emitting the laser diode, and if you desigh a proper circuit, you can emit a laser diode with constant power, avoiding temperature or other factors that makes power is not constant.
5mw is nominal power output, but it can deliver more, 8 or 10mw aprox.
2V datasheet is max reverse laser diode reverse voltage.
Why power loss or power of power efficiency is not detailed in datasheet? Because is a irrelevant data.
Laser diode substrate is like a square, a box, it emites for two sides, one side to the laser diode ouput, andthe other for the monitor diode, it helps to perform it a way it keeps a constant power.
There is as data that is not well known but it is very important for CD readers, is S/N. Laser diode emites a light that is very pure in frequency and in PHASE. Phase performance is the most important characterisc.
If you repair or experiments with CD players, you have noticed that when a laser diode is older, exhaust or run out, though laser power emited is maintained(meassured with a laser power meter), laser current haver soar and RF signal have lowered.
Why RF signal is low though laser power keeps its power?
I think it is laser diode have lost phase purity, the laser diode has lost Laser characteristics, it emites, but emites energy out of phase.
In the workshop, when you get a cd player with low RF, you instintly up power laser. But surely, if you measure the laser power diode, it keeps its nominal power.
When you up the laser power, you compenstes the lost of Laser phase propierties.
It should be interesting to analyze an exhausted laser diode in a spetrum analyzer, I'm sure you could see a lot of differences respect a new laser diode.
Responding the thread, monitor diodes is a photodiode that captures the oposites laser diode emision, it is a in reverse polarized diode, and it helps to know how power is emitting the laser diode, and if you desigh a proper circuit, you can emit a laser diode with constant power, avoiding temperature or other factors that makes power is not constant.
I believed Less RF = Less Laser Current = Less power delivered . But I'm not a professional, I have to understand this first.
Thanks for the Info
Greetings Chris
Thanks for the Info
Greetings Chris
Less RF = Less Laser Current = Less power delivered
Yes, it is true, though I'd change the order
Less Laser Current => Less power delivered => Less RF
But, when the laser diode gets older, or is run out, it needs more current for the same amount of light, and this light have lost "laser properties", and RF signal drop down.
Yes, it is true, though I'd change the order
Less Laser Current => Less power delivered => Less RF
But, when the laser diode gets older, or is run out, it needs more current for the same amount of light, and this light have lost "laser properties", and RF signal drop down.