Through beam sensor interface with microcontroller

[goldriver]

Hi, I am looking for a sensor to be interfaced with my microcontroller for size detection of fruits for my conveyor belt packaging project. My aim is to sort the sizes of the fruits in small,medium and large by using laser sensors. The three laser sensors will be placed above each other.for example if the fruit is of medium size it will cut the middle laser ,informing the controller that the fruit is of medium size likewise for small and large size fruits. I have researched the internet on many sensors from IR SENSORS to laser sensors to Through beam sensors but i couldn't make up my mind. Also i am confused about the compatibility of the sensors with my arduino microcontroller. Please advise intelligently.

 

[cl10greg]

The main issue that you are facing if the scattering of light over a distance. A laser that is focused enough would most likely only affect the sensor it is suppose to but it may also cause false readings in the other ones. What you could do is use three different wavelengths for your sensors and sources. That would allow you to put the lights in close proximity and shine them across without having the scattering affect the other sensors. You may want to add filters in front of the sensors to block out ambient light (like TVs do). All the sensors would be used as a leg a voltage divider for your arduino analog inputs. So you would set a threshold level based on if there is light hitting the sensor or not.