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In Star Trek, they use the terms scanner and sensor a lot.

Is there any technical difference in the meaning of the two terms? Or are they 100% interchangeable? If there is a difference, what is it?

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  • Some examples: camera, infrared, radio telescope : sensors. X-Ray, radar, sonar : scanners
    – flq
    Jan 14 '17 at 8:36
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A sensor is a device that measures a physical quantity - photons, molecular movement (temperature), magnetic fields, electric current ...

A scanner is a sensor coupled with an emitter for the physical phenomenon to measure. Since the environment will change the emitted signal, that change can be used to make assumptions about the environment. Depending on the variety of scanner signals and computational power, these assumptions can get arbitrary close to reality.

A sensor scan refers to to the ability of some sensors to sense for an adjustable smaller range (usually photon frequencies). Changing the range continuously (for example from infrared to ultraviolet for "visible" light, or from 89.0 MHz to 104 MHz for radio broadcasting), is called scanning, too.

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    And.... source?
    – Mowzer
    Jan 15 '17 at 4:08
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    These are the common definitions (in my own words) for sensor, scanner, and sensor scan. The usage in Star Trek is fully in line with this.
    – nibra
    Jan 16 '17 at 10:54
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In Star Trek, the difference is in scale. A device that was used at the scale of an entire ship to probe for input was called a "sensor". Ships had sensor probes and sensor arrays, and even performed "sensor scans" on planetary or bigger scales.

The hand-held devices used by various science and medical personnel were "scanners". These were also called "hand scanners", and there were several types. There were also, in certain settings, larger mounted scanners that might be the size of a tablet or even a small computer console, but still small enough for a single person to manually operate the device.

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    Do you have any canonical sources for this information? Or is this strictly your own personal observations and opinion?
    – Mowzer
    Jan 14 '17 at 3:07
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    I believe measurements tools that were used internally within the ship were also sensors if I recall. There's the occasional mention of internal sensors picking up something or being down.
    – Ellesedil
    Jan 14 '17 at 5:51
  • "Sensor scans" you mean actively scanning what sensors tje adversary uses?
    – flq
    Jan 14 '17 at 8:31
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Summary from comments:

  • Scanners: active
  • Sensors: passive
@Ixrec wrote:

I believe "scanning" refers to active technologies that do something to the thing being scanned, while "sensors" normally means passive technologies that just listen to things emitted or left behind. My only evidence is that Star Trek characters often seem to know when they're being "scanned" by someone, but nobody ever says they're being "sensed" by someone, only that someone's sensors should or should not pick them up.

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  • In RL, scanners can be passive too, e.g., a "police scanner". Jan 15 '17 at 22:50

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