Time delay can be determined using a device such as an optical time-domain reflectometer.
From the en.wikipedia.org
Bad contacts or shorts are especially difficult to diagnose, though a time-domain reflectometer will find most problems quickly.
From the en.wikipedia.org
Similar to basic wire faults, a Time-domain reflectometer is used to identify the distance to the fault from a specific site.
From the en.wikipedia.org
Since then, they have reviewed more than 6 million recordings by the electron reflectometer and found amid the data some 13,000 signals with an electron peak indicative of an aurora.
From the sciencedaily.com
The reflectivity of the mirror coating can be measured using a reflectometer and for a particular metal it will be different for different wavelengths of light.
From the en.wikipedia.org
The scientists measured sun exposure by comparing pigmentation of underarm skin, which is usually not exposed to sunlight, with forehead pigmentation, which is, using a portable reflectometer.
From the sciencedaily.com
More examples
A meter that measures the reflectance of a surface
(reflectometry) The science of the design and use of reflectometers
Downward-facing pyranometer used for measuring reflected solar radiation.