RU2635901C1 - Laser fire simulator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: laser fire simulator contains an optically coupled laser, a transparency and a lens. The transparency is installed in the focal plane of the lens and has N zones, where N is not less than 2, with dimensions of r₁<r₂<…<r_N and with the transmission coefficients in the zones of τ₁>τ₂>τ_i…>τ_N, the centres of these zones are aligned or offset from each other vertically. The transparency is made in the form of a diffractive optical element (DOE) with alternating strokes with maximum and minimum transmittance. Herewith the parameters of the strokes satisfy the conditions

, where d_i - the width of strokes with minimum transmission in the i-th zone; τ_i - the transmittance coefficient in the i-th zone; T is the period of the DOE strokes, T=λ_min/ϕ, where λ_min - the minimum working laser wavelength; ϕ - the aperture lens angle.

EFFECT: increasing the technology of the simulator and increasing the accuracy of fire simulating.

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Description

The invention relates to laser educational means and can be used to simulate shooting from small arms with imitation of defeat.

Known laser firing simulator containing optically coupled lens, pankraticheskaya optical forming system, illuminator and laser with a power source. The lesion is simulated using photodetectors placed on the target. To simulate the probability of hitting the target when setting the range, the pankratic optical forming system forms a spot of a certain (constant) size at a given range. If the range is entered correctly, provided that it is precisely aimed, the laser spot “covers” a certain number of photodetectors, which is estimated as hitting the target (Avt.Sv. USSR No. 1605673, IPC F41G 3/26, 05.26.1980).

The specified simulator has a complex structure due to the presence of a pancratic system. The simulator does not provide accuracy of simulating the probability of hitting the target, because does not provide a constant power density in the formed spot. If the radiation power density in the spot at the entered range exceeds the threshold value determined by the photodetectors, then such a beam will be detected by photodetectors at long distances, more likely due to the divergence of the beam, which contradicts the results of real shooting.

Known laser firing simulators, simulation firing of which is more close to real due to simulated input angles and the formation of spatially coded by the power density of the laser spot. In such simulators, the formation of a certain spot size at the firing range is carried out using a banner made in the form of a multilayer interference optical filter of variable optical density (RF Patent No. 2037767, IPC F41G 3/26, 02/21/1986; RF patent No. 2537872, IPC F41G 3/26 01/09/2014).

The closest in technical essence to the claimed technical solution - the prototype - is a laser firing simulator, which is part of the laser firing and destruction simulator (RF patent No. 2537872, IPC F41G 3/26, 01/09/2014).

The laser firing simulator contains an optically coupled laser, a transparency and a lens; the transparency is installed in the focal plane of the lens. The banner is made in the form of a filter of variable optical density. The banner has N zones, where N is at least 2, with sizes r ₁ <r ₂ <... <r _N and transmittance in the zones τ ₁ > τ ₂ > τ _i ....> τ _N. The centers of these zones are aligned or offset relative to each other vertically.

In addition, to simulate shelling in the simulator-prototype, an additional zone was made on the banner, covering the said zones or part of them, the transmittance of which is less than the transmittance of these zones.

A transparency with combined zone centers is applicable for imitating weapons in which ballistic accounting is uncritical, for example for melee weapons (pistols, submachine guns, etc.). To simulate the introduction of aiming angles (weapon ballistics), the transparency zones are shifted relative to each other in a vertical plane. Depending on the optical system of the firing simulator used (with or without image wrapping), the lower banner area is performed with the largest dimensions and the lowest transmittance, or, conversely, the upper zone.

The simulator generates a laser beam with a maximum angular divergence, which is necessary to ensure a certain spot size at a minimum range. An increase in the spot size at long ranges due to the divergence of radiation is accompanied by a decrease in the power density in the spot, i.e. as the range increases, a larger part of the spot is "cut off", i.e. not perceived by the radiation receiver on the target. A constant spot size is ensured by the choice of the initial distribution of the power density in the beam at a fixed threshold for the operation of the receiving device of the lesion simulator.

The correct estimation of the firing range by the shooter is controlled by evaluating the input of the aiming angle: at the minimum range, the radiation receiver on the target fires at any point of the laser spot, and at the maximum - only in its lower part.

The specified firing simulator has the following disadvantages.

1. The technological complexity of manufacturing a filter of variable optical density: first, lithography is used to make separate templates with the corresponding zones, then sequentially apply a multilayer coating in each zone. Patterns must be combined with great accuracy. At the same time, a complete repeatability of the result is not ensured; there is a scatter in the characteristics of the transparency from sample to sample.

2. Insufficient accuracy of firing simulation due to a spasmodic change in transmittance in the filter zones. It is technologically difficult to carry out a banner with a large number of zones for a smoother change in transmittance in order to ensure a smooth dependence of the radiation power density on the angle of radiation divergence (on the angular coordinate). The technological tolerances for the spread of transmittance due to coating technology are such that, with small differences in transmittance in adjacent areas, these areas may overlap. Therefore, in the interference transparency, jumps between the zones (in transmission and in the step of the aiming angle) have to be made large, and this does not allow us to achieve the required accuracy of simulating taking into account the aiming angles. Simulation of the input of aiming angles with an abrupt change in the transmittance in the zones of the filter when entering the aiming angles does not allow simulating the required range corresponding to this angle.

The objective of the invention is the creation of a laser shooting simulator with the following technical results: improving the manufacturability of a shooting simulator, improving the accuracy of a shooting simulation by providing a smoother and more stable (repeatable) distribution of the radiation power density in the spot.

The specified technical results are achieved as follows. The laser firing simulator, like the prototype, contains an optically coupled laser, a transparency and a lens, and the transparency is installed in the focal plane of the lens, while the transparency has N zones, where N is at least 2, with dimensions r ₁ <r ₂ <... <r _N and transmission coefficients in the zones τ ₁ > τ ₂ > τ _i ...> τ _N , the centers of these zones are aligned or shifted vertically relative to each other. Unlike the prototype, the transparency is made in the form of a diffractive optical element (DOE) with alternating strokes with maximum and minimum transmission, while the conditions are met

,

,

where d _i - the width of the strokes with minimal transmission in the i-th zone;

τ _i - transmittance in the i-th zone;

T - period strokes DOE,

,

,

where λ _min is the minimum working wavelength of the laser radiation;

ϕ is the aperture angle of the lens.

DOE operation is based on controlling the value of the output radiation in the zero diffraction order. Zero diffraction order does not change the direction of propagation, has no restrictions on diffraction efficiency, therefore, it is used as an outgoing one.

The light flux passing through the DOE decomposes into a number of diffraction orders into the angular spectrum. Zero order with intensity I _o does not change the direction of propagation, and the first and subsequent diffraction orders with intensity I _k propagate at angles to the optical axis (see, for example, Kukhling X. Handbook of Physics. - M .: Mir, 1982. p. 292)

where α _to - the angle of propagation of the kth order of diffraction to the optical axis;

k is the number of the diffraction order;

λ is the laser radiation wavelength;

T - period of strokes DOE.

In the scalar approximation (T >> λ), the radiation intensity in the zeroth order is described by the expression

where ϕ is the phase shift;

t is the amplitude transmittance of strokes;

Q - duty cycle strokes DOE.

DOE strokes

where d is the stroke width.

When using DOE with opaque strokes (t = 0), it follows from expressions (2, 3) that the transmittance of DOE depends on the duty cycle of DOE strokes, i.e. from geometric parameters of DOE strokes: strokes width and strokes period

Hence the width of the strokes DOE is

Based on the expression (1), the period T is selected so that the first and subsequent diffraction orders do not fall into the lens (see, for example, Kukhling X. Handbook of Physics. - M .: Mir, 1982. p. 292). This condition is stably fulfilled for a semiconductor laser if the period T is determined based on the minimum possible laser radiation wavelength, taking into account the technological and temperature spread of λ

,

,

where λ _min is the minimum working wavelength of the laser radiation;

ϕ is the aperture angle of the lens.

The number of transparency zones is determined by the range of the simulated weapon and should practically be at least two. When performing a large number of zones with a small change in the width of the DOE strokes in the zones, a smooth distribution of the power density in the target plane is achieved.

An example of a specific implementation of the device shown in the drawings.

In FIG. 1 is an optical diagram of a laser firing simulator.

In FIG. 2 shows a general view of the DOE zones.

In FIG. Figure 3 shows the relative change in transmittance over DOE zones.

The laser firing simulator contains a semiconductor laser 1 optically coupled in series, a transparency made in the form of a diffractive optical element (DOE) 2 based on a diffraction grating, and a lens 3. DOE 2 is mounted in the focal plane of the lens 3. The radiation is detected by a photodetector 4 mounted on object of defeat.

DOE 2 has four zones with zone sizes r ₁ <r ₂ <r ₃ <r ₄ and transmittance in the zones τ ₁ > τ ₂ > τ ₃ > τ ₄ . The centers of the zones are shifted vertically. The DOE zone with size r ₄ and transmittance τ ₄ has the largest upward displacement. The displacement of the centers of the zones is proportional to the angles of aiming the weapons for simulated ranges. Lens 3 wraps the DOE image and a laser spot is built in the target space, in which the zones are distributed according to the radiation power density in such a way that the power density increases with a downward vertical shift.

The period of strokes T and the width of strokes d _i in the DOE zones satisfy the following conditions:

,

,

where λ _min is the minimum working laser wavelength;

ϕ is the aperture angle of the lens.

,

,

where d _i - the width of the strokes with minimal transmission in the i-th zone;

τ _i - transmittance in the i-th zone;

T - period of strokes DOE.

The device operates as follows. The radiation of laser 1 passing through DOE 2 is decomposed into the angular spectrum into a number of diffraction orders. Zero-order radiation with an intensity of I _output propagates along the optical axis and is recorded by a photodetector 4, and the first and subsequent diffraction orders propagate at angles to the optical axis and are cut off by the lens barrel 3.

To compensate for entering the aiming angle at the maximum range, the shooter raises the weapon and directs the lower transparency zone to the target.

Technologically, the first instance of DOE is made by direct laser recording on a photoplotter, for example, of the SLWS-300 type. Subsequent copies of DOEs are made by copying a photomask. Compared with the prototype, in which each banner is made independently and it strongly depends on the “human” factor, the manufacture of a banner in the form of DOE is greatly simplified. High yield of DOE is ensured due to good repeatability of DOE parameters.

Based on DOE, it is possible to make a banner with a large number of zones with a smooth change in transmittance, which ensures a smooth dependence of the radiation power density on the beam divergence angle, accurate and repeatable, i.e. stable from sample to sample distribution of the radiation power density in the spot. The smaller discreteness of the transmission of the banner allows you to simulate a less discrete change in range, which increases the accuracy of the simulation. A semiconductor or solid state laser may be used in the device, but a semiconductor laser is practically preferred.

According to the proposed technical solution, an experimental sample of a laser firing simulator was manufactured. DOEs were made by the thermochemical method of direct laser recording using a precision recording system CLWS - 300AE. For recording, standard plates of photomasks with a chromium film were used. A lens with a focal length of 76 mm and a diameter of 22 mm was used. The aperture angle of the lens ϕ = 0.287 rad. The minimum wavelength of laser radiation, taking into account the technological and temperature spread of the values λ _min = 0.895 microns. The width of the strokes DOE in the first zone d ₁ = 2,45 μm. Received a smoother than in the prototype, the distribution of the transmittance in the areas of the transparency.

Thus, the invention improves the manufacturability of the firing simulator and the accuracy of firing simulations.

Claims (8)

A laser firing simulator containing an optically coupled laser, a transparency and a lens, the transparency is mounted in the focal plane of the lens, and the transparency has N zones, where N is at least 2, with dimensions r ₁ <r ₂ <... <r _N and with transmittances in zones τ ₁ > τ ₂ > τ _i ...> τ _N , while the centers of these zones are aligned or shifted vertically relative to each other, characterized in that the transparency is made in the form of a diffractive optical element (DOE) with alternating strokes with maximum and minimum transmission , while doing loviya

where d _i - the width of the strokes with minimal transmission in the i-th zone; τ _i - transmittance in the i-th zone; T - period strokes DOE, T = λ _min / ϕ, where λ _min is the minimum working laser wavelength; ϕ is the aperture angle of the lens.

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