Ivan G. Deyneka

Optical encoders based on imaging optical systems and two-dimensional sensor arrays have shown substantial potential for reducing measurement errors through the use of modern image processing algorithms. However, the application of two-dimensional photodiode array in optical encoders significantly reduces the update rate of positional data. This limitation is critical for wide industrial application. This study presents an optical encoder design that incorporates a high-speed linear photodiode array and an anamorphic optical system utilizing a cylindrical lens, allowing for increased update rates and reduced positional error. A Renishaw RTLC40 tape, with a grating period of 40 μm, fabrication accuracy of ±5 μm/m, and a length of 300 mm, was employed as the encoding structure. The prototype optical encoder was developed using a GL3504-BVM-NCN-AU1 linear photodetector array, a custom designed and manufactured objective (linear field in object plane of 0,84 mm, magnification 10×) with an integrated cylindrical lens and 5CEFA9F23 programmable logic device. The calculation of the object displacement is based on determining the energy centroid of the images of grating scale, which tightly mounted on the object. The error analysis of the proposed encoder prototype was determined using an XD6 LS interferometer and an LTS300/M motorized stage. Positional update frequency was measured with an MSO5074 oscilloscope. The use of a cylindrical lens amplified the irradiance projected onto the photodetector array, achieving a maximum gain factor of three. Update frequency and measurement error of the proposed optical encoder were experimentally determined and equals 10 kHz and 0,94 μm over 290 mm range, respectively. The proposed design of the optical encoder can be used as a recommendation for the development of encoders that employ cylindrical lens-based optical systems. Field-programmable gate array is recommended for grating scale displacement computation. The results obtained may prove valuable for specialists in precision displacement measurement and machine tool construction.

Subject of study. The methodology for determining the optimal operating spectral range of a Fabry–Pérot interferometer (FPI) based on chirped fiber Bragg gratings (CFBGs) is studied. Aim of study. The aim of this study is to develop and investigate a methodology for selecting the optimal operating wavelength range of a CFBG-based FPI (CFBG-FPI). Method. The proposed methodology involves the sequential tuning of the central wavelength of a vertical-cavity surface-emitting laser, followed by an analysis of the signal-to-noise ratio of the data obtained from a CFBG-FPI integrated into an experimental setup. The measurements are performed after applying pulsed acoustic excitation to a steel plate. During signal analysis, the operating spectral range is selected based on the maximum signal-to-noise ratio achieved using the setup. Main results. An original methodology for determining the optimal operating wavelength range of a CFBG-FPI is developed. A signal-to-noise ratio of 23.5 dB is achieved. Data repeatability assessments show that the standard deviation of the signal-to-noise ratio values is 0.4 dB. Practical significance. The proposed methodology can be used to develop new technological solutions, particularly for the nondestructive testing of industrial objects. Owing to their high sensitivity, CFBG-FPIs can be applied under more challenging conditions, ensuring stable registration of low-intensity acoustic measurements.

The paper discusses the problem of temperature drift compensation in a fiber-optic gyroscope, using a number of temperature sensors distributed along the gyroscope coil. An algorithm is proposed for processing the sensors’ data in the form of weighted sum of temperature values and its derivative. The results of the proposed algorithm comparison with an algorithm that uses averaged readings of sensors are presented. It is shown that the proposed algorithm increases the compensation accuracy up to 50%.

The stability of the central wavelength of the erbium‐doped fibre source (EDFS) is one of the most important parameters to ensure the accurate operation of navigation systems based on high‐accuracy fibre optic gyroscopes (FOGs). Herein, the method of stabilisation of the EDFS as a part of the FOG is presented. The main advantage of this method is the possibility of quick and simple matching of temperature‐compensating spectral filters by changing the pump ratio without modifying the optic scheme. The EDFS optic scheme is based on the double‐pass bidirectional pumping configuration. This makes it possible to obtain the world‐class stability of the central wavelength of the EDFS as a component of different devices with the spectral selectivity and set the constant value of the optic power of the output light (OL). Also, this is the first study into the dependence of the temperature coefficient of the central wavelength on the pump ratio. The proposed method allows compensating the spectral characteristics of the FOG, achieving the OL central wavelength stability around 0.7 ppm/°C and the FOG scale factor stability around 0.73 ppm/°C.