I'm testing a way to protect IR sensor from bad weathers (rain, humidity, freeze) to keep the lens as dry as possible.
Some times bad conditions can affect and skew its sensitivity.
Here are some screenshots indoor and outdoor, today weather is cool and dry (around 12 °C)
1- As we can see the heater indoor can rise to a high level
2- A measure on the glass of the lens (indoor)
3-Now outside, as shown the heater ensures goog warm, in this test all the components are totally outside, inside a box the protection would be better
4- outside with the multimeter directly on the lens, the temperature is maintained to a good level
Hope it will help, i plan to use this heater (5v/1w bought from Aliexpress) with a toggle switch i would set to off during summer an on during winter.