What type of technology, if not in general public use, violates a person's expectation of privacy?

A thermal imager is considered a type of technology that impacts a person's reasonable expectation of privacy because it allows law enforcement to gather information that is not readily accessible to the public or through ordinary observation. While a standard camera may not violate privacy expectations since it captures images that can be seen in public, and a public security camera operates within the bounds of public areas, a thermal imager detects heat emissions from objects, which can reveal details of people’s activities or presence inside their homes without their knowledge.

This technology provides insights that individuals would not anticipate being disclosed without their consent, thus intruding upon areas of expected privacy. Drones, while they can also infringe upon privacy, are typically subject to different regulations and can operate in diverse contexts, often without the same specific technological implications as a thermal imager. The unique capability of a thermal imager to penetrate the private context of a person's home environment speaks to its potential to violate privacy expectations, highlighting why this answer is the most fitting.