Converting Lux to Watt for Measuring Light Power

  • Thread starter Thread starter yunusx
  • Start date Start date
  • Tags Tags
    Lux Watt
AI Thread Summary
To convert lux measurements to watts for a specific wavelength, one must first understand the relationship between lux, lumens, and watts. Lux is defined as lumens per square meter, and lumens are based on human eye sensitivity, which varies by wavelength. The conversion involves using the photopic efficacy value, which indicates how many lumens correspond to one watt for a given wavelength. The proposed method involves dividing the lux value by 6830 and then adjusting for the eye sensitivity coefficient specific to the wavelength. This approach aims to yield the output in milliwatts per square centimeter, and users are encouraged to verify the accuracy of the calculations.
yunusx
Messages
10
Reaction score
0
Hi!
I need a little help. Here is my problem,
I have a light source and a monocromator that separates the white light to to its components of different wavelenght. I want to measure the power of the output light which has a single wavelenght. I am using a Lux meter to measure the illumation of the light but I don't know how to convert it into watt.

Could you please help me about this? ı am reading stuff about lux, watt and lumen but I am totally confused.
 
Engineering news on Phys.org
Lux is lumens per square meter, where lumens in turn is a weighted function based on the photopic response of the human eye. To convert from lumens to watts (or watts to lumens) you need to use the photopic efficacy relation, which can be used to define lumens/watt as a function of wavelength.

I have an SPIE field guide which has a small table with discrete values for the photopic efficacy. For example, at a wavelength of 560 nm the photopic efficacy is 680 lm/w.

https://www.amazon.com/dp/0819452947/?tag=pfamazon01-20
 
Thanks for your help. :)
 
I have finally found a way of converting lux into watt. Just for being sure can you tell me whether its tru or not?
1- First i divide the the value of light illumation which i measured in Lux by 6830.
2- Then I divide the result i found by the eye sensivity coefficient which is different for each wavelenght.
The result gives me mW/per sequare cm. Do you think there is a wrong operation?
 
Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
Thread 'Beauty of old electrical and measuring things, etc.'
Even as a kid, I saw beauty in old devices. That made me want to understand how they worked. I had lots of old things that I keep and now reviving. Old things need to work to see the beauty. Here's what I've done so far. Two views of the gadgets shelves and my small work space: Here's a close up look at the meters, gauges and other measuring things: This is what I think of as surface-mount electrical components and wiring. The components are very old and shows how...
Back
Top