Vachon

I am an electronics newbie (took all of that chemistry/calculus stuff in college), and am in need of some assistance. As part of my research, I currently measure large quantities of oil well casing "down-the-bore", using a laser distance meter. Right now, I must utilize an assistant who holds a target (translucent material) and yells to me that I am on target before I actually take the measurement. These pipes are 4 - 10 inchces in diameter and up to 46 feet long. Often the noise at the sites makes it very difficult to hear each other at the distances involved. Is there a way to use a solar cell or other light activated component to trigger a relay or activate a 6 or 12 volt circuit to shine a light or sound a buzzer while I am on the target? I know that the laser beam does create a small voltage on a small solar cell I have tried, but I wonder if one of those 4 - 5 inch circular chips would make a suitable target or if something else would be more appropriate. I would very much appreciate any feedback or suggestions. Thanks!