מד טווח לייזר מבוסס על מקלט אופטי קוהרנטי

Laser range-finder based on a coherent optical receiver

Laser range-finders are central for defense and civilian applications. The form the basis of laser radars (or lidars), which are key sensors in three-dimensional imaging, machine vision and autonomous vehicles. The signal-to-noise ratio of laser ranging measurements scales inversely with the fourth power of distance. For example, when measurements are taken at 1 km range, with a receiver aperture of few-cm diameter, only one in ten billion transmitted photons is collected back! Hence range-finder receivers must handle extremely weak input power levels.

One possible solution for this challenge is coherent optical detection, in which the weak incident waveform is interfered with a much stronger local oscillator, which a much stronger copy of the transmitter light source that is retained as part of the receiver. The signal-to-noise ratios of coherent detection may be orders-of-magnitude higher than those of direct (or incoherent) detection. The principle is widely employed in modern-day optical fiber communications. It is also being explored in the context of laser range-finders and lidars. Our group has been conducting research on laser range-finders over the last 3 years. Research is funded by the Ministry of Defense (MAFAT).

The objective of the project is to model, simulate and construct experimentally a coherent laser range-finder setup, and to characterize its performance. Measurements will use weak reflections over optical fibers for the emulation of weak targets. Coherent detection will be tested against the transmission of single, intense and isolated pulses, and also using extended sequences.

Research tasks include the performance and noise analysis of coherent detection in laser range-finders, a numerical simulation of a transmitter and receiver over matlab code, the assembly of an experimental setup, the definition of experimental procedures, collection of data and analysis.

Milestones and formal requirements include:

• A written mid-term report (to be submitted March 2018, in English)
• Mid-term presentation in the Zadok group meeting (to be given March 2018, in Hebrew)
• A final report (to be submitted no later than September 2018, in English)
• An oral defense and presentation of the project, in front of an examination committee consisted of the project advisors and external experts (to be given in Hebrew, no later than October 2018).

דרישות:

• Electro-optics track (mandatory);
• Elective class "Advanced Topics in Optical Communications" (83648), to be taken during spring term 2018 (mandatory);
• Signal processing track (advantage).

מקורות:

Nadav Arbel, "Continuously opearting laser range finder based on incoherent compression of periodic sequences," M.Sc. Thesis, Faculty of Engineering, Bar-Ilan Univ., Ramat-Gan, Israel, 2015. http://www.eng.biu.ac.il/zadoka/files/2015/11/msc_thesis_Nadav_Arbel.pdf