RU2033570C1 - Imitator of illumination source - Google Patents

Abstract

FIELD: instruments. SUBSTANCE: device has n lasers 1-3, n laser power supply units 4- 6, two light guides 10 and 11, lens 12, filter 13 which density varies in radial direction, photodetector 14, differential amplifier 15, n rotating devices for lasers 27-29. EFFECT: increased functional capabilities. 9 dwg

Description

S
The invention relates to optical instrumentation, to radiation simulators; used for a variety of purposes, for example, for testing goniometric optical devices, optoelectronic goniometric orientation devices.

 A known simulator containing a laser and a two-lens laser beam expander, consisting of short-focus and long-focus lenses with aligned focal planes.

This simulator has the following disadvantages. The unevenness of illumination in the output light beam behind the telephoto lens reproduces the unevenness of illumination in the cross section of the laser beam. It reaches great values. For a single-mode beam, the non-uniformity is described by a Gaussian curve, and for a multi-mode beam, the irregularity of illumination reaches 100%. In a simulator with a two-lens extender, the beam divergence decreases (f ₂ / f ₁ ) times, where f ₁ and f _{2 are the} focal lengths of short-focus and telephoto lenses. The long-focus lens at the exit has a large diameter, with f ₂ >> f ₁ . But the simulator of the radiation source must ensure the divergence of the light beam is the same as that of the natural light source. For example, a beam of light from a solar simulator should have a divergence of ≈32 '. The divergence of the light beam of gas and solid-state crystal lasers is units of angular minutes, and after a two-lens expander, the divergence will be many times reduced, and the whole device is generally unacceptable.

 Violations in the uniformity of illumination in the cross section of the light beam of the simulator lead to incorrect estimates of the goniometric instrumental error of the verified precision orientation device.

 In addition, gas and solid-state crystal lasers have flow pulsations, which are eliminated, for example, by feedback, by installing a photodetector in the output beam connected to an amplifier and a laser power supply.

 A simulator is known in which the radially uneven distribution of illumination in a weakly diverging light beam is eliminated by an assembly of three lenses, in which the first and third lenses are glass and the second is concave-convex, formed by a gap between the first and third lenses filled with translucent gelatin.

 The disadvantage of this device is the instability in operation (time, temperature and other influences) of the optical characteristics of organic gelatin, as a result of which the uniformity of illumination is violated. In addition, the specific form of the gap between the lenses and the optical characteristics of gelatins do not allow for accurate alignment of the unevenness of illumination in the beam with an arbitrary law in the radial direction.

 The closest in technical essence to the proposed device is a simulator containing a radiation source and a light beam diffuser in the form of a plane-parallel package of glass fibers.

(1) Если источник света (например, лазер) излучает слаборасходящийся пучок света диаметром d, а диаметр d₁ волокон в волоконном пакете d₁ << d, то формула (1) для расходимости θ справедлива, если волокна в пакете разложены упорядоченно. Однако получить большой поток в рабочем пучке имитатора невозможно, так как поступающий на входную плоскость волоконной пластины мощный поток даст быстрый и большой (на сотни градусов) разогрев пластины из-за поглощения на оболочках волокон и межволоконных зазорах. Если же расширять диаметр d лазерного пучка света, чтобы уменьшить входную освещенность на пластине, то увеличится расходимость θ. Кроме того, излучение многих типов лазеров является поляризованным, а свет от натурных источников (Солнце, звезды и др.) неполяризованный.The disadvantages of this simulator are as follows. It is impossible to simultaneously provide the necessary divergence of the working beam of the simulator and a large flow. Let us illustrate this with an example. Let a lens be mounted behind the fiber bag, the focus of which is located on the output surface of the fiber bag. The divergence θ of the working light beam behind the lens is determined by the diameter d of the light spot at the focus of the lens and its focal length f ₂ :
θ arctg

(1) If a light source (for example, a laser) emits a weakly diverging light beam of diameter d, and the diameter d _{1 of the} fibers in the fiber packet is d ₁ << d, then formula (1) for the divergence θ is valid if the fibers in the packet are arranged in an orderly manner. However, it is impossible to obtain a large flux in the working beam of the simulator, since the powerful flux entering the input plane of the fiber plate will give a fast and large (hundreds of degrees) heating of the plate due to absorption on the fiber sheaths and interfiber gaps. If we expand the diameter d of the laser light beam to reduce the input illumination on the plate, then the divergence θ will increase. In addition, the radiation of many types of lasers is polarized, and light from field sources (the Sun, stars, etc.) is unpolarized.

 The aim of the invention is to provide the necessary divergence in the working light beam of the simulator, increasing the flux and creating an unpolarized light beam.

(2˙r₁ ) > t
r₁ радиус сердцевины волоконной жилы;
t размер зеркала на излучающем торце лазера;
Δ₁ расстояние от зеркала лазера до входного торца жилы;
(2˙Ψ₁) расходимость лазерного пучка света, а выходные n торцов волоконных жил соединены осесимметрично вместе, находятся в одной плоскости и направлены в одну сторону, причем сердцевины выходных торцов волокон расположены в круге с радиусом r₂, второй светопровод выполнен с одним светопроводящим каналом с радиусом r₃, r₃ > > r₂, входной торец второго светопровода расположен осесимметрично с выходным торцом первого светопровода с условием
Ψ₂>Ψ₃ где Ψ₂= arctg

,
Δ₂ расстояние между входным торцом второго светопровода и выходным торцом первого светопровода;
Ψ₃ апертурный угол волоконной жилы в первом светопроводе;
Ψ₃= arcsin

,
n_с показатель преломления сердцевины волоконной жилы в первом светопроводе,
n_о показатель преломления оболочки волоконной жилы в первом светопроводе, кроме того, выходной торец второго светопровода установлен в фокусе объектива, фокусное расстояние f объектива находится из условия
f

где θ- требуемая расходимость рабочего пучка света имитатора, а все n пар лазер входной конец жилы первого светопровода установлены соответственно в n поворотных устройствах с возможностью поворота каждой пары на угол от 0 до 90^о вокруг оси, перпендикулярной излучающему зеркалу лазера.This is achieved by the fact that the proposed simulator contains a light source connected to a power supply unit, a light guide whose output end is located in the focus of the lens, a filter with a radial density change mounted axisymmetrically behind the lens, a photodetector installed in the light beam outside the working area of the light beam section moreover, the photodetector is connected to a differential amplifier connected to the power supply unit of the radiation source, n lasers connected to n power supply units of the lasers, a second light guide is inserted into it, and the first fiber is formed of n single fiber cores, the input end of the i-th fiber core is optically connected to the emitting mirror of the i-th laser, where 1≅i≅n, with the condition
Ψ> Ψ ₁ , where Ψ arctg

(2˙r ₁ )> t
r ₁ radius of the core of the fiber core;
t is the size of the mirror at the emitting end of the laser;
Δ ₁ distance from the laser mirror to the input end of the core;
(2˙Ψ ₁ ) the divergence of the laser light beam, and the output n ends of the fiber strands are connected axisymmetrically together, are in the same plane and directed in one direction, with the cores of the output ends of the fibers located in a circle with a radius r ₂ , the second light guide is made with one light guide channel with a radius of r ₃ , r ₃ >> r ₂ , the input end of the second fiber is located axisymmetrically with the output end of the first fiber with the condition
Ψ ₂ > Ψ ₃ where Ψ ₂ = arctg

,
Δ _{2 the} distance between the input end of the second light guide and the output end of the first light guide;
Ψ ₃ aperture angle of the fiber core in the first light guide;
Ψ ₃ = arcsin

,
n _with the refractive index of the core of the fiber core in the first light guide,
n _about the refractive index of the sheath of the fiber core in the first light guide, in addition, the output end of the second light guide is installed in the focus of the lens, the focal length f of the lens is found from the condition
f

where θ is the required divergence of the working light beam of the simulator, and all n pairs of laser input end of the first fiber core are installed in n rotary devices, respectively, with the ability to rotate each pair at an angle from 0 to 90 ^{about an} axis perpendicular to the emitting laser mirror.

 Thus, the proposed technical solution is a combination of essential features that, in comparison with the prototype, have novelty.

 The use of a (fiber) light guide for transmitting a light beam from a light source to the focal plane of a lens is known. However, the use of the connection of two light guides, the first of which is branched to collect light beams from several lasers, and the second with one light guide channel for mixing light beams emerging from the first light guide, is not known.

 Thus, such a technical solution has significant differences.

 Ensuring a high value of the light flux in the working beam of the simulator and the necessary divergence of the working light beam is carried out by the required number of lasers (i.e., the necessary number of branches in the first light guide); selection of the focal length of the lens, taking into account the diameter of the second light guide; ensuring the geometry of the junction of the ends of the veins of the first light guide with light sources and the ends of the first and second light guides.

 The creation of an unpolarized light beam is provided by the turns of the lasers and the input ends of the fiber cores of the first light guide.

 Thus, the proposed technical solution allows to obtain a new positive effect.

 In FIG. 1 shows a block diagram of a simulator; in FIG. 2 schematically shows a semiconductor laser with its light emitting end; in FIG. 3 the location of the input end of one of the veins of the first light guide relative to the emitting end of the laser; in FIG. 4 output end of the first light guide; in FIG. 5 the relative position of the output end of the first light guide and the input end of the second light guide; in FIG. 6 indicatrix of laser radiation in XY planes perpendicular to the pn junction of the laser; in FIG. 7 indicatrix of laser radiation in the ZY plane parallel to the pn junction of the laser; in FIG. 8 projection of the laser mirror on the core core of the input end of the first light guide; in FIG. 9 is a specific example of a differential amplifier feedback loop.

 The simulator contains n light sources (semiconductor lasers) 1, 2, 3, powered from n power supplies 4, 5, 6, the first branched optical fiber of n single fiber cores with input ends 7, 8, 9, and a common output end 10, the second light guide 11 with one light guide channel. The approximate number of lasers emitting 0.5 W each is n≈10. Each light source 1, 2, 3, is located axisymmetrically relative to the input ends of the cores 7, 8, 9, The output end 10 is located axisymmetrically relative to the input end of the light guide 11. The output end of the light guide 11 is located in the focus of the lens 12 having a focal length f. Behind the lens 12 is an optical filter 13 with a radial density change. In the light beam behind the output end of the light guide 11, a photodetector 14 is mounted connected to a differential amplifier 15, the output of which is connected to one or more power supplies of the light source (s). Figure 1 is a power supply 6.

A semiconductor laser has an emitting mirror size of 16 (txq). In FIG. Figure 2 also shows the XYZ coordinate system attached to the laser emitting mirror. To this coordinate system, the indicatrixes of laser radiation are linked in the XY and XZ planes. A single fiber core 7 (8, 9,) of the first light guide consists of a core 17 and a sheath 18 and has a flat end 19. The radius of the core r ₁ . The flat output end face 20 of the output end 10 of the light guide unites the n ends of the cores 7, 8, 9, using, for example, epoxy glue 21. The core cores are enclosed within a circle of radius r ₂ . The second light guide 11 can be performed, for example, either as a fiber core with a core 22, a sheath 23 and with a flat end 24 (see Fig. 5), or in the form of a hollow mirror channel.

The output end of the light guide 11 is also flat. The ends of the cores of all optical fibers are perpendicular (up to ± 3 ^° ) to the axes of the wires near the ends. The mutual arrangement of the ends 20 and 24 is axisymmetric with respect to the axis 25. The middle of the output end of the light guide 11 is located in the focus of the lens 12. The filter 13, the lens 12 and the output end of the light guide 11 are axisymmetric. The axis 26 is the axis of symmetry at the docking of the mirror 16 and the end face 19 for each of the n joints of the fiber-laser lasers. Each pair of conductor laser inlet end (1-7, 2-8, 3-9) can rotate around the axis 26 by an angle from 0 to ⁹⁰ by means of devices 27, 28, 29, These reversals can be carried out either only lasers or turn along with the lasers and the input ends of the cores 7, 8, 9, The last option is more convenient, since the aligned connection of the laser and the fiber core will not be disturbed.

. Излучение этого лазера стабильно, без пульсаций. В этом отношении определяется стабильностью блока питания. В качестве блоков питания могут использоваться покупные, например, ТЕС-15. Размер зеркала лазера t x q (100 мкм) х (1 мкм).We will consider the operation of the device using the example of a Sun simulator. The most suitable light source for a solar simulator is a gallium arsenide semiconductor laser. Laser radiation power up to 0.5 W at a wavelength of light of 0.8 microns. Power linearly depends on the supply current. The coefficient of performance is 0.3. Working temperature 10-15 ° ^C. At room temperature, the radiation capacity adhered to the massive (copper) heat sink of the semiconductor laser is reduced by 30% Typical indicatrix laser in XY and XZ planes are shown respectively in figure 6, 7. The laser radiation is polarized by 90% in the XY plane. Width of the emitted spectrum 20

. The radiation from this laser is stable, without ripple. In this regard, it is determined by the stability of the power supply. As power supplies, purchased, for example, TEC-15, can be used. Laser mirror size txq (100 μm) x (1 μm).

, (1) где n_c, n_o показатели преломления сердцевины и оболочки волоконной жилы.One of the properties of a fiber core is that the output light beam from the output end of the core fills (axisymmetrically) the entire conical space defined by the aperture, regardless of the angle of incidence of light and its convergence at the input end (within a cone with a double aperture angle in the axial section ) The aperture angle is
arcsin

, (1) where n _c , n _{o are} the refractive indices of the core and sheath of the fiber core.

Sunlight is natural, not polarized. Laser radiation is polarized. Fiber core 7 (8, 9,) does not completely depolarize laser radiation. Let us explain this with an experimental example. We investigated the fiber core with a quartz core diameter of 130 microns and a polymeric shell, with the aperture angle 25 ^of 700 mm in length. A slightly diverging beam of light with a 100% polarization at a zero angle of incidence (i.e., along the axis 26) was sent to the input end. A polarizer and a photodetector were installed behind the output end. Photocell fixed, and a polarizer is rotated around the axis 26 by an angle φot 0 to ^about 90. In this case, the signal U from the photodetector at some arbitrary angles φ changed from the maximum U _max to the minimum U _min .

(2) оказался у 10 волоконных жил равным 0,3-0,7.Depolarization coefficient

(2) it turned out at 10 fiber veins equal to 0.3-0.7.

The specific value of the angles φ, at which the signal U takes at each core the values of U _max and U _min , depends on the length of the core, the deviation of the core diameter along the length of the core, the bends of the core.

 The following facts were experimentally confirmed.

If at the input end of the core rotate the plane of polarization by the angle Δ φ, then the angles of rotation of the polarizer behind the output end of the core, at which the signal from the photodetector is U _max and U _min , also change by the angle Δ φ.

 This is preserved both when the plane of polarization of light is rotated relative to the input end of the core, and when the plane of polarization and the input end of the core are rotated together.

, от лазера 3 при угле φ 2·

, от лазера i при угле φ (i-1)·

.Thus, so that the working light beam 30 is almost completely freed from the influence of the depolarization coefficient (2), it is necessary to make such individual turns of the pairs of lasers (1, 2, 3,) and the input ends (7, 8, 9,) so that the signals U _max (or U _min ) from each laser, measured by the photodetector behind the output end 10 through the polarizer, took place at angles of rotation of the polarizer: from laser 1 at an angle φ = 0 ^о , from laser 2 at an angle φ

, from laser 3 at an angle of φ 2

, from laser i at angle φ (i-1)

.

 Then the polarizer and the photodetector behind the output end face are removed and the ends are docked 20, 24.

 The second light guide 11 does not change the depolarized state of the light coming from the output end of the first light guide.

 The second light guide 11 mixes n light beams emerging from the end face 20 of the first light guide.

A large flux in the working light beam 30 is provided by a large radiated flux (up to 0.5 W) from each semiconductor laser; a set of the required number of lasers and the corresponding number of cores in the first light guide; the correct joints of the lasers with the input ends of the veins of the first optical fiber and the ends 20, 24 of the first and second optical fibers; by clearing optical surfaces to a reflection coefficient much less than 1%. This succeeds because the clearing is monochromatic. In addition, the core of the second light guide 11 can be conical with a slight extension towards the lens 12. For example, the radius of the core 22 at the end 24 is r ₃ , and at the end facing the lens 12 is r ₄ , and r ₄ > r ₃ .

где L длина светопровода 11.In this case, the divergence of the light beam at the exit from the light guide 11 will be less than the double aperture angle by
2 · arctg

where L is the length of the light guide 11.

 The conical design of the light guide 11 can be recommended in the case when the light beam entering the lens 12 is larger in diameter than the diameter of the lens 12 to introduce the entire stream into the lens.

 The magnitude of the flux in the light beam 30 is also affected by the required value of the diameter of the beam 30 (required for devices checked in the light beam), i.e. and the diameter of the lens 12. In addition, there are technological limitations in the manufacture of lenses with spherical surfaces (the focal length should be ≈1.5 times the diameter of the lenses). The latter circumstances will need to be taken into account while ensuring the necessary divergence of the working light beam.

For maximum transfer of the flux from the laser to the core of the first fiber, it is necessary that the distance Δ ₁ (see Fig. 3) ensures the complete entry of the diverging beam from the laser into the core of the core. The core core diameter should be larger than the size of the laser emitting mirror. The aperture angle of the core must be not less than the angle of divergence of the laser beam.

, (3) где 2˙ r₁ > t;
r₁ радиус сердцевины волоконной жилы первого светопровода;
t размер зеркала на излучающем торце лазера;
Δ₁ расстояние от зеркала до входного торца жилы, причем должно быть
Ψ>(Ψ_1макс), (4) Максимальное значение угла расходимости (Ψ_1макс) в лазерном пучке света составляет (см. фиг.6, 7) в плоскости XY±25^о, а в плоскости XZ±3^о.In FIG. 3 shows the geometry of the docking of the laser and the core in the XZ plane. These conditions are represented by the formula
Ψ arctg

, (3) where 2˙ r ₁ >t;
r _{1 the} radius of the core of the fiber core of the first light guide;
t is the size of the mirror at the emitting end of the laser;
Δ _{1 the} distance from the mirror to the input end of the core, and should be
Ψ> (Ψ _1max ), (4) The maximum value of the divergence angle (Ψ _1max ) in the laser light beam is (see Fig. 6, 7) in the XY plane ± 25 ^о , and in the XZ plane ± 3 ^о .

56^°18′ причем 56^o18' >> 3^o, т.е. условие (4) выполнено.We verify condition (3) for the XZ plane at r ₁ 65 μm, Δ ₁ 10 μm, t 100 μm:
Ψ arctg

56 ^° 18 ′ with 56 ^o 18 '>> 3 ^o , i.e. condition (4) is satisfied.

мкм 41/5 мкм. Условие (3) приобретает вид
Ψ arctg

arctg

76^°18′, причем 76^o18' > 25^о, т.е. условие (4) выполнено.In the perpendicular direction, the XY plane is not subject to verification, but parallel to it and passing through the end of the laser mirror, i.e. spaced from the XY plane at a distance of t / 2 (see Fig. 8), since l <r ₁ , but it is desirable to provide condition (3) for all points of the mirror with dimensions txq (100 μm) x (1 μm). We find
l

μm 41/5 μm. Condition (3) takes the form
Ψ arctg

arctg

76 ^° 18 ′, with 76 ^o 18 '> 25 ^o , i.e. condition (4) is satisfied.

(6)
Ψ₃ апертурный угол первого светопровода,
n_c, n_o показатели преломления сердцевины и оболочки волоконной жилы в первом светопроводе;
Ψ₂ arctg

(7)
Δ₂ расстояние между входным торцом 24 второго светопровода и выходным торцом 20 первого светопровода.The condition for joining the second light guide with the first (see Fig. 5) for maximum transmission of the light flux is recorded for angles Ψ ₂ and Ψ ₃ :
Ψ ₂ ≥Ψ ₃ (5)
Ψ ₃ = arcsin

(6)
Ψ ₃ aperture angle of the first light guide,
n _c , n _o the refractive indices of the core and the sheath of the fiber core in the first light guide;
Ψ ₂ arctg

(7)
Δ _{2 the} distance between the input end 24 of the second light guide and the output end 20 of the first light guide.

Let us verify the fulfillment of condition (5) using an example. Let r ₂ 350 microns, r ₃ = 360 microns, Δ ₂ = 20 microns (see figure 5).

arctg 0,5 26^°31′. Следовательно, условие (5) выполнено, так как апертурный угол Ψ₃ 25^одля волоконной жилы с кварцевой сердцевиной и полимерной оболочкой.Find from expression (7)
Ψ ₂ arctg

arctg 0.5 26 ^° 31 ′. Therefore, condition (5) is satisfied, since the aperture angle is Ψ ₃ 25 ^о for a fiber core with a quartz core and a polymer shell.

(8) в которой θ= 32' расходимость рабочего пучка света, равная солнечной. Получим
f

77,5 мм (9) Зададимся большим диаметром рабочего пучка 30 света, равным 60 мм. Площадь Р поперечного сечения пучка (круга диаметром 60 мм) равна Р 28 см².The focal length of the lens 12 is determined from the formula
f

(8) in which θ = 32 'the divergence of the working light beam is equal to the solar one. We get
f

77.5 mm (9) Let us set a large diameter of the working beam 30 of light equal to 60 mm. The cross-sectional area P of the beam (circle with a diameter of 60 mm) is equal to P 28 cm ² .

2·arctg

2· (21^°12′) (10) Если апертурный угол Ψ₄ второго волоконного светопровода равен Ψ₄= Ψ₃= ±25^о, то коэффициент "захвата" μпотока объективом 12 приблизительно равен μ

0,8.The angle (2˙Ω) at the top of the cone, formed by light rays from the output end of the light guide 11 (i.e., from the focus of the lens 12) to the edges of the lens 12, is
(2Ω) 2Arctg

2 · arctg

2 · (21 ^° 12 ′) (10) If the aperture angle Ψ _{4 of the} second fiber optic fiber is Ψ ₄ = Ψ ₃ = ± 25 ^о , then the “capture” coefficient μ of the flux of lens 12 is approximately equal to μ

0.8.

0,0091 Вт/см² (11) где τ₁=τ₂= 0,9 пропускание света первым и вторым светопроводами с просветленными торцами;
μ= 0,8;
τ_ф 0,7 пропускание фильтра 13 с радиальным изменением плотности.From one laser in the working beam 30, the illumination E _{1 is} obtained:
E ₁ =

0.0091 W / cm ² (11) where τ ₁ = τ ₂ = 0.9 light transmission by the first and second light guides with enlightened ends;
μ = 0.8;
τ _f 0.7 transmission filter 13 with a radial change in density.

10 шт. Поскольку лазерное излучение с длиной волны 0,8 мкм приходится на максимум спектральной чувствительности кремниевого фотодиода, то для получения от фотодиода сигнала, равного при засветке от Солнца, потребуется меньше десяти лазеров ( ≈8 лазеров).In solar orientation devices, silicon photodiodes are usually used, the spectral sensitivity of which is from 0.4 to 1.1 microns. The extra-atmospheric solar constant in this spectrum is
E ₂ 0.09 W / cm ² (12) Therefore, the required number n of lasers to ensure the value of (12) is
n

10 pieces. Since laser radiation with a wavelength of 0.8 μm falls on the maximum spectral sensitivity of a silicon photodiode, it will take less than ten lasers (≈8 lasers) to obtain a signal from the photodiode, which is equal when illuminated from the Sun.

 In FIG. 9 shows a specific example of a feedback circuit with a differential amplifier 15 receiving a signal from a photodiode 14 to stabilize the level of flux in the working light beam 30. This refers to stabilization for several hours or more.

Structurally, the photodetector 14 can be mounted as shown in FIG. 1 or elsewhere. For example, outside a conical beam of light with an angle (2˙Ω) reaching the lens 12, but in the light reflected from the front surface of the lens 12. To do this, do not lighten a small portion of the front surface (≈2x2 mm ² ) on the edge of the lens to which light from the light guide 11 enters, and install the photodetector in a beam of light reflected from this unenlightened portion of the front surface of the lens. In another embodiment, the radiation can be attributed to the lens using an additional fiber core, so that it is possible to position the photodetector and differential amplifier in a temperature-stabilized heat chamber.

 Figure 9 shows an example feedback loop. The photodiode 14 (for example, silicon, type FD20KP) is shunted by a low-resistance resistor 31 with a nominal value of 1 kΩ so that the photodiode's operating mode is valve. The reference voltage is provided by a silicon Zener diode 32 type D818E. Using resistors 33, 34, the signals at the inputs of the differential amplifier 15 are aligned with the necessary level of illumination in the working light beam of the simulator and with the initial value of the temperature in the room in which the simulator is located.

The differential amplifier 15 is executed on the 544UD1A microcircuit. Resistors 35, 36 have a nominal value of R ₁ 9.1 kOhm; resistors 37, 38 have a nominal value of R ₂ 130 kOhm.

 The power supply 6 consists of a current stabilizer 39 and an emitter follower 40.

 The quality of stabilization of the flux in the working light beam 30 using the feedback circuit depends on the temperature stability of three elements: a photodetector 14, a differential amplifier 15, a zener diode 32.

4,3 /^°C (13) Изменение чувствительности кремниевых фотодиодов (ФД20КП и других) менее
0,4%/^oC (14) Стабильность уровня напряжения стабилитрона Д818Е равна
±0,001% /K (15) Выходное напряжение U_вых с дифференциального усилителя равно
U_вых= (U₂-U₁)·

, где U₂ снимается с делителя из резисторов 33, 34,
U₁ снимается с фотодиода 14. Оценим стабильность дифференциального усилителя 15.The temperature coefficient of variation of the flow from the laser is in the range from 15 to 22 ^about

4.3 / ^° C (13) Sensitivity change of silicon photodiodes (FD20KP and others) less
0.4% / ^o C (14) The stability of the voltage level of the Zener diode D818E is
± 0.001% / K (15) The output voltage U _o from the differential amplifier is
U _o = (U ₂ -U ₁ )

where U ₂ is removed from the divider from the resistors 33, 34,
U ₁ is removed from photodiode 14. Let us evaluate the stability of the differential amplifier 15.

dR₁ +

dR

(U₂-U₁)·

dR₁ +

dR

. Запишем соотношение резисторов R₁ и R₂ как R₂= k˙R₁, где k const. Тогда
U_вых (U₂- U₁)·

-

dR₁+

(k·dR₁)

0 (16)
Дифференциальный усилитель не вносит дополнительной нестабильности, если резисторы R₁ и R₂ однотипные.dU o _out = (U ₂ -U ₁ )

dR ₁ +

dR

(U ₂ -U ₁ )

dR ₁ +

dR

. We write the ratio of resistors R ₁ and R ₂ as R ₂ = k˙R ₁ , where k const. Then
U _o (U ₂ - U ₁ )

-

dR ₁ +

(kdR ₁ )

0 (16)
A differential amplifier does not introduce additional instability if the resistors R ₁ and R _{2 are of the} same type.

Since the quantities (14), (15), (16) are much less than the values (13), the feedback circuit really plays a stabilizing role. Stabilization of the flow will be even better if the photodiode 14, the zener diode 32, amplifier 15 placed in a thermostat, for example, type SZHML-19 / 2.5 I1, TU 16-531.539-75 providing preservation temperature in the range 30-250 ^{° C} with an accuracy ± 0.02 ^about C.

In cases where it is desirable to seal the laser, the transmission of radiation from the laser to the input end 19 can be carried out using a microlens. The front focus of the microlens is combined with the laser mirror 16, and for the image of the mirror 16 in the back focus of the microlens in condition (4), the physical meaning of the quantities changes: Ψ _1max is the convergence of the light beam behind the microlens; t is the size of the image of the mirror in the back focus of the microlens; Δ _{1 is the} distance from the image of the mirror to the input end of the core. A microlens actually consists of two lenses to transfer an image from one focus to another. Instead of microlenses and lens 12, reflective optics (ellipsoids, paraboloids, etc.) can be used.

 Thus, the proposed simulator has small dimensions due to the small number of lasers, their small size and high efficiency, which makes it possible to dispense with small power supplies and the small focal length of the lens to ensure solar divergence in the light beam 30, since the core diameter of the second light guide is small. Using lasers with radiation at different wavelengths of light, it is possible to carry out certification (orientation instruments) in a wide spectral region. The resource of semiconductor lasers is 500-1000 h, while the lamp life of ubiquitous at the enterprises of the Sun simulators with xenon lamps is ≈50 h.

Claims (1)

A RADIATION SOURCE SIMULATOR comprising a light source connected to a power supply unit, a light guide whose output end is located at the focus of the lens, a filter with a radial density change mounted axisymmetrically behind the lens, a photodetector installed in the light beam outside the working area of the light beam section, the photodetector being connected to the differential amplifier connected to the radiation source power supply, characterized in that the simulator contains n lasers connected to n laser power supplies, a second etoprivod, wherein the first svetoprivod fiber formed of n single fiber strands, the inlet end of the i-th optical fiber conductor coupled to the radiating mirror i-th laser where 1 ≅ i ≅ n, with the proviso Ψ> Ψ ₁

2 · r ₁ >t;
r ₁ radius of the core of the fiber core;
t is the size of the mirror at the emitting end of the laser;
Δ ₁ distance from the laser mirror to the input end of the core;
(2 · Ψ ₁ ) the divergence of the laser light beam,
and the output n ends of the fiber strands are connected axisymmetrically together, are in the same plane and directed in one direction, with the cores of the output ends of the fibers located in a circle of radius r ₂ , the second light guide is made with one light guide channel of radius r ₃ (r ₃ > r ₂ ), the input end of the second optical fiber is located axisymmetrically with the output end of the first optical fiber with the condition Ψ ₂ > Ψ ₃ ,

Δ _{2 the} distance between the input end of the second light guide and the output end of the first light guide;
Ψ ₃ aperture angle of the fiber core in the first light guide,

η _s , η _o the refractive indices of the core and the sheath of the fiber core in the first light guide,
in addition, the output end of the second light guide is installed in the focus of the lens, the focal length f of the lens is found from the condition

where q is the required divergence of the working light beam of the simulator,
and all n pairs of laser input end of the fiber core of the first light drive are installed respectively in n rotary devices with the ability to rotate each pair at an angle from 0 to 90 ^o around an axis perpendicular to the emitting laser mirror.

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