Education of the republic of uzbekistan tashkent state technical university named after islam karimov

Research of reflectometric sensors 
 
Amplitude fiber-optic (WATER) pressure sensors have a number of advantages over 
strain-resistant and capacitive ones, such as insensitivity to electromagnetic fields, fire, 
explosion and electrical safety. This is due to their principle of operation, which consists in the 

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Electrical and Computer Engineering
205 
redistribution of the luminous flux between the emitting and receiving optical fibers due to the 
movement of the micro-mirror under the action of the measured pressure [8-10]. 
General issues of designing amplitude pressure waters were considered in [8-12]. 
The transformative characteristic of amplitude pressure waters of the reflectometric type 
has the structure: 
∪= 𝐹3{𝐹2[𝐹1(𝑃]]}
(1) 
where F1, F2, F3 are partial conversion functions that correspond to three stages of 
conversion: pressure into displacement of the micro-mirror, displacement of the micro-mirror 
into a change in the luminous flux and a change in the luminous flux into an electrical signal; p 
is the measured pressure [10-15]. 
To date, the features of the F2 transformation function and their effect on measurement 
errors have been studied in detail [10-14]. In pressure sensors, it is necessary to additionally 
take into account the nonlinearity of the partial conversion function F1 and optimize the 
parameters of the entire optomechanical node (optical fiber + micro mirror), which has not yet 
been described in detail. 
We have conducted studies of the influence of external mechanical loads on low-mode 
optical fibers with the preservation of polarization in order to develop mosaic multi-sensor 
fiber-optic pressure sensors for medical use. Figure 4. Figure (1) shows a graph of the change 
in optical power in the receiving fiber of the sensor depending on the distance to the mirror 
membrane (in mm) for a standard reflectometric sensor with separated optical channels based 
on two identical multimode light guides with a core thickness of 200 microns. The figure (2) 
indicates a graph for a new fiber-optic sensor using a radiating single-mode fiber (core diameter 
8 microns) and a receiving multimode fiber (core diameter 200 microns) manufactured using 
vacuum technologies. 
Fig
. 4. Graph of changes in the relative optical power in 
the sensor receiving fiber depending on the distance to the mirror membrane 
The graph clearly shows that there are two quasi-linear sections. The first one is from 1.5 
mm to 3.5. The second one is from 3.5 to 9 mm. The sensitivity of the sensor is a fraction of a 
micron. Compared to a standard fiber-optic sensor, the sensitivity of the new sensor has been 
improved by 3 times, the dynamic range has been significantly (more than twice) increased and 
the characteristic of the signal dependence on the measured distance has become more linear.