IR Laser Detector Help

Hey all, Hope you're all well.

I've been looking over the past few days for a specific type of IR Laser detector system I require for a design project underway.

To explain quickly what I need is basically a system (as small as possible) that can detect an IR laser (in multiple wavelengths) and in turn, once this IR laser has been shone over this "receiver" ill call it, it causes a small LED to switch on, until the IR laser moves on, or is no longer detected.

For example, there's a powerful IR laser, shining 1200 meters let's say, automatically sweeping left to right constantly, when the laser sweeps over the specific area where this "receiver" is placed 1200 meters away, the small LED light turns on, then off once the laser sweeps back the other way the LED switches off.

Can anyone help link a series of parts that exist to make this happen or specific parts that I could assemble together in a circuit to make this happen?

Many thanks for your help!

My first thought would be a pyroelectric infrared sensor with some form of automatic background adjustment to compensate the ambient reading; plus possibly an appropriate IR filter to block longer wavelength IR.

An IR laser should cause a measurable increase in the output from such a sensor? You could try that with a basic IR thermometer, this style of thing:

If the laser was modulated a different system would be more appropriate, but for a simple solution and an unmodulated source the pyroelectric type is the only thing that comes to mind.

Thanks for that rjenkinsgb, ill look into that, but ideally id want the actual system that's inside the body of the gun, in a smaller size, inside like a 50mmx50mmx55m (lxwxh) box which would be amazing.