For long distances and large objects:
* Radar: Uses radio waves to detect objects and their distance. While it doesn't show a visual image, it can provide information on approaching objects on a screen.
* Air traffic control radar: Specifically designed for detecting and tracking aircraft. It displays a visual representation of the airspace, showing approaching aircraft and their trajectories.
* Military radar: Advanced radar systems used for detecting and tracking various objects, including aircraft, ships, and missiles.
For shorter distances and everyday applications:
* Security cameras with motion detection: These cameras can alert you to moving objects within their field of view and record them. You can view this footage on a screen.
* Autonomous vehicle sensors: Self-driving cars use a variety of sensors, including lidar and cameras, to detect objects in their surroundings and display them on a screen for the driver or for internal navigation.
* Ultrasonic sensors: Used in some robotic applications and obstacle avoidance devices, they can detect objects using sound waves and display the information on a screen.
Other considerations:
* The size and type of objects: Are you looking for large objects like cars and airplanes, or smaller objects like people or animals?
* The distance: Do you need to detect objects that are close or far away?
* The environment: Is the apparatus being used indoors or outdoors? Is there a lot of interference?
* The level of detail required: Do you need to see the objects in high resolution or just their presence?
It's important to understand your specific needs and consider the different options available.
