RU2420746C1 - Procedure for change of acceleration at micro- and nano-shifts - Google Patents

Abstract

FIELD: machine building. ^ SUBSTANCE: procedure consists in lightning object with optical radiation, in conversion of reflected signal into autodyne signal and in recording its power. Further the signal is digitised and analysed. Value of object acceleration is determined by solving an inverse problem defining minimum of functional: where a is linear acceleration of an object, Pexsp are experimental values of the autodyne signal, Ptheor are theoretical values of the autodyne signal, is phase incursion of the autodyne signal, t is time interval of the autodyne signal. The exact value of global minimum is found by the method of descent along sought-for parametres and a. ^ EFFECT: measurement of acceleration at micro-shifts in wide dynamic range of accelerations and upgraded accuracy of absolute acceleration measurement within limits meeting modern precision devices. ^ 4 dwg

Description

The invention relates to the field of measurement technology and can find wide application in precision engineering and electronic engineering. Increased measurement accuracy, in particular, will allow you to control the process of developing precision devices in computer technology, in micro- and nanoelectronics.

A known method that implements the principle of measuring acceleration using an electron-optical converter, matching device, inertial mass, optoelectronic converter and computer. The method consists in the fact that under the action of acceleration, the inertial mass moves relative to the initial position and exerts pressure on the segments of the optical fiber. The intensity of the light flux in these segments changes due to the appearance of microbends, which introduce losses in the transmitted light, and the intensity of the output light depends on the pressure of the inertial mass on the fiber sections passing inside the housing. The change in light intensity determines the acceleration value (see patent RU No. 2010235, IPC G01P 15/08).

The disadvantage of this method and its implementing devices is the measurement error associated with a change in the properties and destruction of the optical fiber as a result of multiple microbends.

There is also a method of measuring acceleration using an inertial mass in the form of a ball and displacement sensors. The method consists in the fact that under the action of the measured acceleration, the inertial mass begins to move, which leads to a corresponding change in the deformation of the membranes. A change in the deformation of the membranes leads to a change in the gaps between the bases of the prisms and the light absorbing layers. A change in the gaps entails a change in the intensity of the light flux reflected from the bases of the prisms. In this case, the relative displacements of the membranes located in the slots of the opposite sides of the housing will have different signs (see patent RU No. 2017159, IPC G01P 15/08).

The disadvantage of this method is the low threshold sensitivity, determined by the rigidity of the deformed membranes and the value of the inertial mass.

Closest to the proposed solution is a method that implements the principle of measuring acceleration using a coherent radiation source, two optical fibers and a photodetector. The method consists in generating an interference pulsed optical signal, the parameters of which determine the acceleration (see patent RU No. 2156979, IPC G01P 15/08).

The disadvantage of this method is the dependence of the transmission time of the radiation in the fiber from the refractive index of the medium. In addition, with multiple passage of light in the fiber, it attenuates. The introduction of an additional optical amplifier complicates the measurement device.

The objective of the present invention is to determine the acceleration of the object at micro and nanodisplacement using a semiconductor laser operating in autodyne mode.

The technical result consists in providing the ability to measure acceleration at micro- and nano-displacements in a wide range of measured accelerations; in increasing the accuracy of measuring absolute acceleration within the limits that satisfy modern precision devices.

The problem is solved due to the fact that the object is illuminated with optical radiation, the reflected signal is converted into an autodyne signal, its power is recorded, after which the signal is digitized and analyzed. The acceleration value of the object is determined by solving the inverse problem.

The invention is illustrated by drawings. In Fig.1 shows a theoretical view of the function of the autodyne signal with uniformly accelerated movement of the external reflector, Fig.2 shows a diagram of the installation for implementing the proposed method, Fig.3 is a measured autodyne signal with uniformly accelerated movement of an object, Fig.4 is a view of the experimental curve, smoothed by means of MathCad, where 1 is a semiconductor laser, 2, 4 are stabilized current sources, 3 is an object (electromagnetic relay armature), 5 is a holder, 6 is a photo detector, 7 is an amplifier, 8 is an analog-to-digital converter, 9 is a computer.

The method is implemented as follows.

Computer simulation of the autodyne signal of a semiconductor laser is carried out with uniformly accelerated motion of the external reflector. The variable component of the autodyne signal in the proposed model is written in the form:

where θ is the phase incursion of the autodyne signal, λ ₀ is the wavelength of laser radiation, a is the linear acceleration of the external reflector, V ₀ is the initial velocity of a moving object, t is the time interval of the observed autodyne signal.

The theoretical form of the function of the autodyne signal P (t) at values of a = 0.000001 m / s ^{2 is} shown as an example in FIG. 1.

The unknown parameters θ and a are determined from the solution of the inverse problem. In this case, the solution to the problem is to determine the minimum of functional (2) obtained by summing the squared deviations of the experimental P _exp and theoretical P _{theory of the} values of the autodyne signal (1) for different time intervals.

When solving equation (2), the problem arises of determining the global minimum in the presence of several local minima. To search and analyze the minimum of interest, one can use numerical methods of unconditional optimization. We, to find solution (2), determined the type and number of local minima in a given range of desired values. Then, the region of the global minimum was determined, the exact value of which was found by the method of descent using the desired parameters θ and a .

To obtain P _exp values, the object 3 is irradiated with optical radiation from a semiconductor laser 1 operating in the autodyne mode. The autodyne signal is recorded, for example, by photodetector 6, while the output autodyne signal from the photodetector is amplified by amplifier 7, converted into a digital code and stored in computer memory 9 for subsequent processing.

The proposed method was implemented as an example of measuring the acceleration of the armature of an electromagnetic relay 3. The radiation of a semiconductor laser 1 stabilized by a current source 2 was directed to an electromagnetic relay 3, which was fed by a current source 4. The fixing of the relay was provided by mechanism 5. A part of the radiation reflected from the relay armature was returned to the cavity of the semiconductor laser 1, the change in the output power of which was detected by the photodetector 6. The signal from the photodetector 6 was fed through an amplifier 7 to an analog-digital pre photoelectret 8, data are stored in the memory of the computer 9. The stored data file after the recording to a computer analyzed in MathCad mathematical package. The type of measured autodyne signal with uniformly accelerated object movement is shown in Fig.3. The experimental curve, smoothed by means of MathCad, is shown in FIG. 4.

Experimental studies were carried out using a laser diode RLD-650 on quantum-dimensional structures with a diffraction-limited single spatial mode and characteristics: radiation power of 5 mV, wavelength of 654 nm. As an object of research, a switching electromagnetic relay type 904.3747 was chosen. During measurements, laser radiation was directed to the freely moving relay armature. In this case, the form of the autodyne signal reflected from the surface of the armature was recorded and stored on a computer.

The moment of the beginning of the movement of the armature was synchronized with the launch of the sweep of the storage oscilloscope. The saved data file was written to a computer and analyzed in the mathematical package MathCad.

The average acceleration value calculated as a result of solving the inverse problem was a = 0.215 × 10 ^-7 m / s ² . The distance traveled during the observation time of 3 s was l = 96 nm.

Claims (1)

A method of measuring the acceleration of an object at micro- and nano-displacements, characterized in that they illuminate the object with optical radiation, convert the reflected signal into an autodyne signal, record its power, after which the signal is digitized and analyzed, the acceleration value of the object is determined by solving the inverse problem, which consists in determining the minimum functional:

where a is the linear acceleration of the object;
P _exp - the power value of the recorded autodyne signal;
P _theory - theoretical values of the power of the autodyne signal;
θ is the phase incursion of the autodyne signal;
t is the time interval of the autodyne signal, and the exact value of the global minimum is found by the method of descent according to the desired parameters θ and a.

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