Metal spring thermal expansion

I am attempting to figure out why a laser layout tool I have is drifting over time. It was designed with a small adjustment mechanism that relies on a spring to apply pressure to a fulcrum that rotates the entire laser. A screw is used to apply and release pressure on the spring thus moving the laser very small amounts left and right.

I am getting a drift in the lasers horizontal position of about 1/2inch at 100 feet over the course of several hours. I am doing this test at night and there is about a 15 degree Fahrenheit temperature from when I start the test to when it is complete.

I made a Sketch-Up model of the device and determined that 5 micron change in position (at the end of the fulcrum) is all it would take to move the laser 1/2 inch at 100ft.

My question is it possible that my spring is expanding and contracting 5 microns with a 15 degree temperature change?

I am not an engineer and am looking for some speculation just to rule in or rule out the general possibility.

The spring looks similar to this:

The diameter of the entire spring is about 1/4 inch. The diameter of the coiled metal wire is about 1/6 inch. The spring length is about 1/2" uncompressed. It consists of about 8 loops.

I do not know the metal it is made of, speculation on different scenarios would be helpful as, again, I'm just trying to rule in or out the possibility.

• diameter of the coiled metal wire is about 1/6 inch - did you mean 1/16"? Also, a picture or diagram of your setup would be helpful to point out possible sources of drift. Right now we're only guessing at what your setup looks like. – grfrazee Aug 28 '15 at 14:15
• It would be very helpful if you could post an image of the SketchUp that you made. Are you sure that the alignment device depends on the spring for alignment? Most laser alignment devices (adjustable mirrors, stages, etc.) only use the spring to maintain contact between the movable part and an adjustable screw drive. At any rate, 0.5 mrad isn't an exceptionally large thermal drift. – Chris Mueller Aug 28 '15 at 14:38
• Could you artificially heat the spring (and surrounding area) in a shorter time period to ascertain whether it's thermal expansion of that section causing the issue? – Jonathan R Swift Apr 18 '18 at 21:05