Analogue input filter

I am trying to program a positioning system based on laser positioning sensors, and a thought occured to me~:
What happens if there is a sudden fleeting obstruction to the laser light? Is there a simple(ish)way of filtering the analogue signal in the ladder code? There is no filtering available in the configuration for the card (GE Fanuc IC693 ALG221)and I have no manuals as yet for the position transmitters to see if it can be done there. Any ideas?

Try this:

http://www.plctalk.net/qanda/showthread.php?s=&threadid=7740&highlight=digital+filtering

most distancing sensers will have a range of exclusion