help with a random sensor board how is it working? see pictures

[apbosh1]

Hi,
i'm told this board is/was used in a sliding window arrangement a bit like drive through windows auto shut/open.
I've been trying to figure out the exact workings just for education for all my efforts i cant give a confident answer on alot of things, anyway a brief of my observations:
one chip is a n555n and the other is an op amp as shown in picture i looked at spec sheet and  think i made a little sense of its characteristics.
2 dark coloured leds ? what exactly is their job? one is exposed and the other has a bit of rubber tube covering the sides also a green led which i think is just a status light OR is it influencing one of the photo diodes (its not a modulated supply to this) i've taken one of these "dark" leds out from another identical board and they produce a voltage in light so Photo diode?? or is one infer red or both?? the output pin 3 of 555 chip delivers a 1.8khz sq wave signal but the duty cycle is very high i make it only 10u seconds off time and that feeds into the rubber coated led so is this the infered signal out and when the window opens a reflector mirrors the ir back to the non covered led/photodiode and the opamp takes it to the motor control etc i've got no idea really . Why the leds? and with 10u secs off time another control board (somewhere in the auto window design) must be able to operate at 100khz in order to detect that. i suspect i've gone way off course but tell me what you think and i'll supply whatever info i can in addition. sorry the picture looks a bit big on my screen hope you can zoom out a bit if not i'll do again.
Andy   

[David_AVD]

Looks like the shrouded LED is an IR emitter (modulated by the 555) and the other dark one is a detector used with the opamp.

As you say the green LED is probably a status indicator.

The circuit looks very simple to draw out.