Wired has an article about Blade Runner, Near the bottom theres a few props shown with some explanations next to them. Here's what they say about the binoculars:
"DECKARD’S BINOCULARS Inspired by real-life military rangefinders used for spotting targets miles away. Harlocker miniaturized them, painted them red, and gave them infrared night vision and *thermal-imaging capabilities."
https://www.wired.com/2017/09/behind-the-scenes-blade-runner-2049-sequel/?mbid=nl_101017_daily_intro