Photo-Source (OLED)& Photo-sensor (pTFT)

[niikos]

Hello to everybody. This is my first post.

I have a trouble calculating the light illuminance that senses a light sensor.

Analytically. I have a light source (OLED) that is at the same surface as the light sensor (polysilicon-TFT). Also, the emitting area of the source is three or four times larges that the area of the senor. For the light source it is given the luminance from a figure of cd/m^2 to Voltages applied to it. For the light-sensor i have a equation that uses lux (lx) to calculate the production of current from it.
I need to calculate how much of light (in lux) is sensing the light-sensor from the light source. (assuming that there isn't another light source)

1st Question: The light source is emmitting light to any direction or only straight forward?
2nd : if straightforward what is the steradian of the emmition? (if it is at any direction, the steredian of the emmition is 2pi)
3rd : depending of the answer of the 1st question, is the light-sensor sensing any light?

So,
I know that cd/m^2=lm/m^2.sr=lux/sr. if the steradian of the light source is 2pi and the emmitting light luminance is A cd/m^2 the sensed light illumination of the sensor is A*2pi ? Am i right?

 

[niikos]

If the source gives 10cd of light to any direction. A sensor of area 100x100um how many lux does it read?

So, the lumens are 10*4pi lm , and the illuminance: 10*4pi/(100um*100um) lux?
Am i right?

 

[m2003]

Hello, and welcome to the forum! It sounds like you are working on a interesting project involving OLED light sources and polysilicon-TFT light sensors. To answer your questions:

1. The light source is emitting light in all directions, but the intensity of the light will be strongest in the direction that is directly facing the sensor. This is known as the "normal angle," and it is typically the direction that is perpendicular to the surface of the OLED.

2. The steradian of the emission will depend on the design of the specific OLED light source you are using. Some OLEDs may have a more focused emission angle, while others may have a wider angle. It is important to consult the specifications of your particular OLED to determine the steradian of the emission.

3. Yes, the light sensor will be able to sense light from the OLED as long as it is within the sensor's field of view. The amount of light that is sensed will depend on the distance between the OLED and the sensor, as well as the intensity and angle of the emission.

In regards to your last question, the amount of light that is sensed by the sensor will not necessarily be equal to the luminance of the OLED multiplied by the steradian. Other factors, such as the distance between the OLED and the sensor, will also play a role in the amount of light that is sensed. It is important to use the equation that you have for calculating the production of current from the sensor, and to take into account all relevant variables in your calculations.

I hope this helps and good luck with your project!