simonfrfr

Resistance in an LDR is a highly nonlinear function typically, and CANNOT be used as "Intensity" (Which I am pretty sure you mean irradiance here). Irradiance is simply Unit of Power per Unit Area per Solid Angle. So if you look at some of the SPIE Radiometry Field Guides, they should help you to understand briefly how to go about calculating this. And yes you can use approximations, but they need to be the correct ones and you will need to make certain assumptions about your incoming light. (Field Guide to RadiometryBarbara G. Grant)What I mean by spectral efficiency is not of the light emitted, but of the detector. If you know the Quantum Efficiency of your Photodiode or your general Spectral efficiency of your LDR, then you can level the signal properly. This is generally a...

Resistance in an LDR is a highly nonlinear function typically, and CANNOT be used as "Intensity" (Which I am pretty sure you mean irradiance here). Irradiance is simply Unit of Power per Unit Area per Solid Angle. So if you look at some of the SPIE Radiometry Field Guides, they should help you to understand briefly how to go about calculating this. And yes you can use approximations, but they need to be the correct ones and you will need to make certain assumptions about your incoming light. (Field Guide to RadiometryBarbara G. Grant)What I mean by spectral efficiency is not of the light emitted, but of the detector. If you know the Quantum Efficiency of your Photodiode or your general Spectral efficiency of your LDR, then you can level the signal properly. This is generally a very nonlinear function. Think of the Human Eye We see more Green than we do blue or red. Green has a higher Also, Curious side note, If I were to make a Kit would you be interested? Because I had wanted to make one a few years ago, but I hadn't the time.(Instructables does not alert me when I get a new message for some reason sorry about the long wait)

Hi,This instructable doesn't exactly do calibration any justice. So what you are going to need to do is, find the spectral efficiency curve, and multiply the values from this curve to your data. You probably will want only a few, so find your LED's wavelengths. I recommend using an RGB LED so that you can select which wavelength you are using. Then you can use a Look Up Table to be able to determine wavelength. Next, after that, you MUST model the nonlinear function for light irradiance. So if you just took your values and took the ratio, then you wouldn't get anywhere because the operation curves of the photodiodes, phototransistors and LDRs are nonlinear. Finally, I would recommend using the entire detector area to ensure you are measuring the irradiance.Just a few thoughts I had this...

Hi,This instructable doesn't exactly do calibration any justice. So what you are going to need to do is, find the spectral efficiency curve, and multiply the values from this curve to your data. You probably will want only a few, so find your LED's wavelengths. I recommend using an RGB LED so that you can select which wavelength you are using. Then you can use a Look Up Table to be able to determine wavelength. Next, after that, you MUST model the nonlinear function for light irradiance. So if you just took your values and took the ratio, then you wouldn't get anywhere because the operation curves of the photodiodes, phototransistors and LDRs are nonlinear. Finally, I would recommend using the entire detector area to ensure you are measuring the irradiance.Just a few thoughts I had this morning,Good luck!Simon

You put a Processing Sketch (A different program than Arduino) in the Arduino IDE. to download the software for that program, visit: processing.org

There is a USB to serial converter that is wired up to the UART pins of the MSP430G2553 (Then its a COM port)