Converting Volt to Lux using a solarimeter

[Jenkz]

Homework Statement

Hello,

I'm trying to use a solarimeter (thermopile) to measure the direct flux of solar radiation, in clear conditions, over varying solar zenith angles. The equipment has an output of volts, but I need to convert this to Lux and then convert this to watts per meter squared.

How can I go about doing this as my light source has a mix of different wavelengths?
I have also read that I can calculate the number of lumens per watt by using the luminosity function, but how could I get Watts per meter squared from this?

Thank you.

 

[Nate810]

Homework Equations N/AThe Attempt at a Solution To convert from volts to Lux, you will need to use the equation Lux = Volts x (1/sensitivity). The sensitivity of your thermopile should be specified in the product specifications. Once you have the Lux measurement, you can then use a lux-to-watts per meter squared conversion chart to get the watts per meter squared. This conversion chart will take into account the different wavelengths of light that are present in the solar spectrum. To calculate the number of lumens per watt (or luminous efficacy), you will need to use the luminosity function. This is defined as the ratio of the luminous flux (in lumens) to the radiant flux (in watts). You can then use this value to calculate watts per meter squared. To do this, you would need to divide the number of lumens per watt by the area of the source (in meters squared). I hope this helps!