I often play Counter Strike and once I decided to measure the full latency of my computer, just to understand how much it is. One more reason - because I play on the laptop, it might be higher compared to the PC if the laptop isn’t configured properly.
Quick googling gave me a few videos about LDAT, and also about Reflex Analyzer which is basically the same tool built-in to the monitors. Here is the page about original device: Nvidia LDAT
But there is a huge problem with these monitors: there are quite few options available and they cost much more compared to regular monitors even with high refresh rate like 240+ hz. I decided that the task is quite simple and I can build a LDAT-like device on my own, because the algorithm is very simple.