Hello, new to the forum. I will not claim to be an engineer but just a very curious tradesman. I have been working with all kinds of lasers and receivers for over 35 years and have had the opportunity to work with a myriad of laser receivers. The one I have attached intrigues me very much. The glass tube that is the receiver of the laser light is what I would like to learn more about. I have been searching forever and have wound up here hoping for insight from people a lot smarter than me. This receiver is capable of readings within 0.050". I would be very appreciative of any help or leads to point me in the right direction of learning more about this receiver.