Calculate optical power output of LEDs

In summary, the conversation discusses the process of calculating the optical power output of a set of LEDs using a photodiode and the formula R (A/W) = I/P. The speaker expresses confusion about obtaining small values despite having the responsivity curve of the photodiode and measuring the photocurrent. They question if their method is correct and request help.
  • #1
Sophie MC
1
0
Hi guys,

I have to calculate de optical power output of a set of LEDs. For that I used a photodiode to measure the photocurrent at each wavelength and then calculate the optical power at each wavelength using the following formula:

R (A/W) = I/P,

where R is the responsivity of the photodiode at each wavelength,
I is the photocurrent measure with the photodiode at each wavelength and
P is the optical power output at each wavelength that I want to measure.

I have de responsivity curve of my photodiode and I have measure the photocurrent. However when calculating de optical power output I obtain very small values.

For example, for a LED with typical 17000 mlm (from datasheet), I only obtain 0,027 mW (summation of all wavelegths) of optical power. I think that this is a very small value comparing with the value in lumens (17000 mlm).

Can any on help with this? Am I right? Am I wrong? Is this the right way of calculate optical power?

Thank you so much
 
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  • #2
We would have to see your raw data and your methods to comment.

Are you using a sum where an integral is needed?
 

FAQ: Calculate optical power output of LEDs

How do I calculate the optical power output of an LED?

To calculate the optical power output of an LED, you will need to know the luminous flux (measured in lumens) and the luminous efficacy (measured in lumens per watt) of the LED. You can then use the formula: Optical Power Output = Luminous Flux x Luminous Efficacy. This will give you the optical power output in watts.

What is luminous flux?

Luminous flux is the measure of the total amount of visible light emitted by an LED. It is measured in lumens (lm).

What is luminous efficacy?

Luminous efficacy is the measure of how efficiently an LED converts electrical energy into visible light. It is measured in lumens per watt (lm/W).

How do I find the luminous flux and luminous efficacy of an LED?

The luminous flux and luminous efficacy of an LED can usually be found in the manufacturer's specifications or datasheet. If this information is not readily available, you can also measure the luminous flux using a photometer and calculate the luminous efficacy using the formula: Luminous Efficacy = Luminous Flux / Power Input.

Are there any other factors that can affect the optical power output of an LED?

Yes, there are other factors that can affect the optical power output of an LED, such as the ambient temperature, current and voltage levels, and the age of the LED. It is important to consider these factors when calculating the optical power output of an LED to ensure accurate results.

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