Because the speed of light is so high, it is necessary to use a high rate of modulation, typically hundreds of millions of cycles per second, in order to achieve high precision distance measurements. Unfortunately, optical detectors that can operate at such a high speed require a lot of incident light in order to work well. Hence this technique is not well suited to measurements on optically rough surfaces, which reflect only a very small fraction of the outgoing beam back to the instrument, and existing commercial systems that incorporate the technique require the use of a strongly reflecting mirror-like target in order to achieve high precision measurements.

On the other hand, an optical detector that only has to operate at a few hundred cycles per second can be up to 1000 times more sensitive. The DMR rangefinder exploits this sensitivity advantage by using a kind of optical strobe technique to allow a slow detector to track the phase shift on a beam that is modulated at a very high rate. In the same way that a stroboscope can be used to create a slow-motion representation of a high speed repetitive event, the DMR technique creates a slow-motion representation of the phase shift imposed on the measuring beam. This novel improvement allows previously untapped performance potential to be unlocked, creating a rough surface rangefinder that can outperform existing commercial systems by a factor of up to 100.

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