Thanks MarkJ 
I can't say for certain that the OSLRF-01 will meet your requirements but it's these kinds of unusual applications that make this open source product such an exciting platform to run experiments on. There's nothing that prevents different lens combinations from being used, even to the extent of having no lenses at all! You can use a smaller lens on the laser - perhaps one of those that you get inside visible laser pointers, and you could leave the lens off the detector so that there are no parallax effects.
For short range measurements, you could also try running the laser at lower power (change the voltage regulator) to reduce electrical firing noise and also narrow the width of the laser pulse (RC network) to get a cleaner signal.
Just remember that with a smaller lens on the laser, the beam intensity goes up and you could exceed the Class1 eye safety limit. Reducing the power and pulse width of the laser will help. These kinds of modifications should be done whilst watching the expanded timebase signals on an oscilloscope. This will give you a very clear idea of how each change to the design affects the performance.
If you really want to break new ground, the OSLRF-01 circuit is capable of quasi-phase measurement, a much higher resolution method of measuring a distance. This is a pretty complicated modification and will perhaps form the basis of a future discussion!