01-11-2018, 01:24 PM
"What kind are those?"
I'll answer your question for EOU here Me2. In a previous life I started a company that developed a new approach to an old idea called differential phase for the purpose of distance measurement. Three members of that old team are still here at EOU in one capacity or another. We adapted the principle to work in conjunction with laser diodes that were modulated at high frequency (100mghz). In fact, a single laser diode might be modulated at up to 4 different frequencies i.e 99, 99.2,99.4,99.6 during a single measurement event. The phases of both transmitted (via beam splitter) and received light, at each frequency, were compared to each other and then a reference frequency that was fixed at a very precise 455 Khz. The further the light had to travel (round trip) the greater the shift in phase. Sold the technology about a dozen years ago.
I'll answer your question for EOU here Me2. In a previous life I started a company that developed a new approach to an old idea called differential phase for the purpose of distance measurement. Three members of that old team are still here at EOU in one capacity or another. We adapted the principle to work in conjunction with laser diodes that were modulated at high frequency (100mghz). In fact, a single laser diode might be modulated at up to 4 different frequencies i.e 99, 99.2,99.4,99.6 during a single measurement event. The phases of both transmitted (via beam splitter) and received light, at each frequency, were compared to each other and then a reference frequency that was fixed at a very precise 455 Khz. The further the light had to travel (round trip) the greater the shift in phase. Sold the technology about a dozen years ago.