For the current photoelectric mixing technology, there are many problems such as small array size, high noise level and poor receiving stability. Combined with the idea of microwave photonic down-conversion technology, this paper proposes a new photoelectric mixing technology based on electro-optical modulation. Using high-resolution, low-cost, mature 2D sensors and electro-optical modulators to perform mixed-frequency demodulation at the optical level, not only overcomes the limitations of array size on image resolution, but also has the advantages of high energy utilization and high signal-to-noise ratio. A mathematics model was set up with the mixing efficiency and mixing signal-to-noise ratio as the key performance parameters. The influence of the operating point offset, modulation depth, and incident optical power on the performance parameters was analyzed. The results show that taking into account the mixing efficiency, IF signal amplitude and mixing signal-to-noise ratio, the electro-optic modulator works best when the modulation depth is at the maximum at the standard operating point, which are laying a theoretical foundation for the further research.
Silicon photomultiplier (SiPM)-based optoelectronic mixing (OEM) is studied for the first time. The validity of SiPM-based OEM is experimentally verified. Compared with the avalanche photodiodes-based OEM, the SiPM-based OEM is less noisy and easy to realize for its low voltage operation and high responsivity.
Vanishing point is an important concept in the sensors’ self-calibration method. For traditional self-calibration method
based on vanishing point, it's computationally intensive, real-time not high and noise sensitive. A novel method of sensor
self-calibration based on rectangular vanishing point characteristics is proposed to solve all these problems mentioned
above. Firstly, four template images are captured from different angles and locations. Subsequently, the vanishing points
are calculated by using the coordinates of the four vertices in rectangle. Finally, the novel sensor parameter equation is
proposed by using the geometry properties of rectangle and the vanishing points. Some numerical simulations are made
to test the validity and robustness of the proposed algorithm.
The purpose of this paper is to present the prototype of the laser diode transmitter for the laser radar based on
frequency-modulated (FM) ranging principles. It belongs to the time-of-flight measurement category. In this case, the
time-of-flight is converted to a beat frequency proportional to the range to be measured. This conversion is realized with
intensity modulation of the laser power by a linear FM continuous wave. FM ranging theory and the principle of
operation are described to show the application of FM radar principles in laser radar. The design of laser diode
illuminator and the key techniques in the transmitter are discussed, including the generation technique of the wideband
radio-frequency (RF) chirp signal, design of the transmitter module and the laser beam collimation optics. The possible
factors that may limit the performance the laser radar system are discussed.