mohd, start your own new thread with much more information and you will get more useful responses. Your diagrams don't have any values filled in and you haven't stated what it is that you're trying to do.
Nigel, I know this is an old thread, but one technique used for determining range with IR is to take advantage of the frequency response curve of the IR receiver while leaving the transmitter at the normal high power.
For example, a particular receiver which is sensitive at 38kHz is less sensitive at 40kHz, so the less sensitive frequencies represent shorter ranges. By transmitting through a range of frequencies while reading the response of the receiver, you can determine the distance of an object placed in front of the transmitter/detector pair.
If you're already familiar with this technique, then disregard, but i thought it may be useful for anyone reading this thread since it has been revived.