BLUE beam detector - what a heck is this?

[Matti Kaki]

Hi!

I found one strange apparatus. It has very dark blue hood
and inside there is electronics plus two _blue_ optoelectric
components about 20 cm apart. It has multiple mechanical
adjustments. It must be some kind of burglar alarm detector.
It's made in Japan and the only type is: "IS 440" and "447 100".
and "Range 100 meters". Can someone tell me what this is?

Thanks!

Matti Kaki OH2BIO