This is a type of photodetector that can detect a photocurrent of only one photon per second. The difference from avalanche diodes is that they can effectively control the multiplication process of photomultiplier tubes,

Therefore, there is no issue of excessive noise. The noise source of this detector comes from the flicker noise of the doubled signal. The response wavelength of the device ranges from near-infrared to near ultraviolet, mainly determined by the cathode material.

Principles for selecting photodetectors

The main criteria for selecting a photodetector are to obtain the desired light signal intensity, light background level, and required signal-to-noise ratio. The signal-to-noise ratio is determined by the required signal resolution, and in order to obtain a sufficiently large signal-to-noise ratio, detection must meet the following conditions:

① High sensitivity is required within the working frequency range.

② The noise introduced by the detector must be minimized, therefore devices with low dark current, leakage current, and parallel conductance should be selected as much as possible.

③ High reliability and good stability.

The temperature coefficient of silicon photodiodes is relatively small, making them a reliable and stable photodetector; The gain of avalanche diodes and photomultiplier tubes varies with bias voltage, especially since the gain of avalanche diodes is a function of temperature, a highly stable bias and temperature compensation device is required. The table lists the main performance of the above-mentioned photodetectors. In addition, the detector should also have the conditions of small size, easy assembly, easy coupling with optical fibers, not too high bias or bias current, and low price. The basic principle of multi-sensor information fusion technology is similar to the process of the human brain synthesizing and processing information, which involves complementing and optimizing various sensors at multiple levels and spaces to produce a consistent interpretation of the observed environment. In this process, it is necessary to fully utilize multi-source data for reasonable control and use, and the goal of information fusion is to derive more useful information based on the separated observation information obtained by each sensor through multi-level and multi-faceted combination of information. This not only takes advantage of the collaborative operation of multiple sensors, but also comprehensively processes data from other information sources to improve the intelligence of the entire sensor system.

Imported force sensors are exempt from calibration. Digital sensors can be calibrated using standard force measuring machines in production, and their output corresponds to the standard value. Due to its minimal loss in transmission engineering, the read values are the actual measured values, greatly saving time. The digital sensor can work continuously and has a fault reporting function. Once a fault occurs, it will output a signal to the instrument. The instrument can receive the signal and discard its value to automatically start the uninterrupted work mode, still ensuring a certain degree of accuracy. Users can also know which sensor needs to be replaced at any time without causing production stagnation.

Imported force sensor is a detection device that can detect the measured information and convert it into electrical signals or other required information output forms according to certain rules to meet the requirements of information transmission, processing, storage, display, recording, and control. According to the basic sensing functions of sensors, they can be divided into ten categories: thermal sensors, optical sensors, gas sensors, force sensors, magnetic sensors, humidity sensors, sound sensors, radiation sensors, color sensors, taste sensors, etc. These can be divided into three parts: physics, chemistry, and biology.

From the perspective of imported force sensors, the market share of flow sensors, pressure sensors, and temperature sensors is 21%, 19%, and 14%, respectively. From the perspective of application fields, industrial, automotive electronics, communication electronics, and consumer electronics are the sensor markets. In the field of industrial and automotive electronics in China, about 42% of sensors are growing in the automotive electronics and communication electronics markets.

At present, Chinese sensor companies are striving to catch up with foreign companies and have formed regional sensor enterprise clusters. In recent years, the development and innovation of sensor technology have mainly focused on three aspects: material, structure, and performance improvement: sensitive materials from liquid to semi-solid, and solid-state direction; The structure is developing towards miniaturization, integration, modularity, and intelligence; Wide detection range, high detection accuracy, strong anti-interference ability, and stable performance. Long expected lifespan and direction. With the development of IoT technology, new requirements have been put forward for traditional sensing technology. Products are gradually developing towards interdisciplinary integration directions such as Micro Electro Mechanical Systems (MEMS) technology (such as nanotechnology, thin film technology), wireless data transmission technology, new material technology, composite sensor technology, digital analog processors, etc.

At present, the five major application areas of sensors are industrial, medical, automotive electronics, communication electronics, and consumer electronics. Among them, industrial and automotive electronic sensors account for a large proportion in China, with the growth in the automotive electronics and communication electronics application markets. In addition, innovative applications in environmental monitoring, oil and gas pipelines, smart grids, wearable devices, and other fields will become new hotspots, and are expected to create more market demand in the future.