Are there sensor components that can determine the distance to other objects in their immediate vicinity?

[unixdaemon]

I am wondering if there are sensors that can measure distance to other objects up to 2-3 inches out?

For example, the sensor might use reflected light, or radio signal that is reflected by some other nearby part to determine distance between them.

 

[BradtheRad]

There are proximity detector circuits. Bring your hand close and it triggers. The method might operate on capacitance or static charge. It senses arbitrary distance, not a definite measurement.

 

[KlausST]

Hi,

This is too broad a question.

Objects: What size, material, optical features, electrical features...
Dust particles? Or a human hand? Soap bubble? Metal, glass? A thread of a spider web?

What if there is not only one object? How to behave when there are 10 of them?

How fast? A bullet?
How accurate and precise? Only a single distance (to what reference?) Or 3D coordinates?

Does the sensor need to be in the center of the "area"? Or maybe 3 cameras watching from outside? What sensor size?
Full 360° area in all 3 dimensions?

--> you need ti give a lot more informations.