Dave Plowman (News) wrote:


It's a damn sight more accurate than those clip on thermometers...

You can fool yourself with some of them as there's a parallax error
between the laser spot antdthe sensor.

It was only when I noticed implausible readings that I started
investigating and discoverd just how misaligned the two beams are when
you're targetting a small object ( like a pipe ) at close range.

I found that if I scanned the thermometer across the bit of black tape
stuck to the pipe and observed the readings, the peak happened with the
laser more than 1cm past the pipe.

Once you know the direction and amount of the misalignment, it's dead
easy to aim accordingly. Aligning the laser and sensor along the pipe
reduces the error, but you can still end up missing the bit of black
tape if you're using some.