Yes and no.
Police can use technology to supplant their ability to engage in typical police observations, but they can’t use it to enhance their abilities beyond what would otherwise be possible.
Example: pole cameras. I worked a drug case once where the police installed a video camera on the top of a utility pole and then focused it directly on the front door of a dealer’s house so they could record the comings and goings of the residents. That was legal, even though it was recording 24/7 for weeks, since it would have been permissible for the police to have an officer stand across the street and watch the door (never mind that a cop is far more obvious than a camera, or that the camera makes constant surveillance so much easier).
But, the cops would not have been able to use the camera to look over the fence and into the backyard, since that’s not an observation available to a passing pedestrian.
So, cops wouldn’t be able to use infrared to look into the home without any warrant.
What about a flyover? It might be OK, I’m guessing (and I’m sure that there’s law on this), since you don’t have the ability to shield the area above your house from airplanes. Basically, it’s plain view, albeit from a different angle.
Then again, a person flying overhead isn’t normally close enough to see the details of your backyard, so maybe it would not be acceptable.
(There are lots of permutations of this. What about if cops put up a ladder and climb it to look into the yard? Not sure; people will debate and disagree. This is why each case is different, and lawyers get to make arguments).
And there are workarounds, too. The utility police camera raised the fact that the utility company can consent to allow the police to use their infrastructure to assist with an investigation. That same cooperation also extends to utility rates, and so cops may, for example, get a search warrant based off the fact that a house is using way more electricity than would be expected, thereby providing evidence of a marijuana grow. Believe it or not, how much you pay the electric company is information that they have and can share without your knowledge or consent.