I have a GY-906 breakout board with a MLX90614 infrared sensor that I want to use on my robot to detect humans and animals at range by comparing the ambient temperature and the temperature of object in front of the sensor (both measurements are provided by GY-906).
GY-906 picture: https://ae01.alicdn.com/kf/HTB1mioEaGagSKJjy0Fgq6ARqFXaz.jpg
The datasheet for MLX90614: https://www.sparkfun.com/datasheets/Sensors/Temperature/MLX90614_rev001.pdf
Problem is, this sensor has a wide field of view, and it's object-temperature measurement is the average temperature of everything that is within that FOV cone. Meaning that it becomes unreliable to detect a heat source (such as a hand) more than 20-30 cm away, because it only takes up a small part of it's field of view.
What I want to do is reduce the field of view of this sensor, so that it takes measurements within a cone of just a few degrees, and in effect, would be able to detect changes in temperature much further away.
There is a similar sensor that has some kind of a tube on top of it:
Problem is, it costs 5 times more than the one I have, and I'm kind of reluctant to spend that much money when IR sensors are pretty damn expensive to begin with. I can't find a datasheet to determine what kind of tube this thing has on top, and I'm wondering if this is something that I could make myself. Something that would limit the field of view.
I tried out simple things like using a straw or a rolled strip of paper to make a tube and put it on the sensor I have, but it seems to raise it's object detection temperature, and the sensor doesn't detect much past the end of the tube.
Can anyone give any suggestions how to achieve this?
EDIT: I was trying to post this in the Sensors sub-forum... I have no idea how it ended up here. I can't seem to delete or move it myself. Can someone from the moderators please move this topic to Sensors section? Sorry