SU1774304A1 - Prismatic corner reflector - Google Patents

Description

The invention relates to location technology and optical instrumentation and can be used as a reflective element in navigation signs, buoys, interferometers, markers, rangefinders, in the control of movement and vibration, in aviation, astronautics, meteorology.

Known rectangular triangular corner reflector operating in the total internal reflection mode. However, this reflector has a small axial reflected light force.

The closest to the proposed technical essence and the achieved result is a corner reflector made in the form of a trihedral pyramid with side edges of equal length, two dihedral angles of which are equal to the right one, and the third dihedral angle is made equal to jt / 2 [2 (s + 1) J, where s is a positive integer. However, this reflector also has insufficient axial reflected light strength.

The purpose of the invention is to increase the axial force of the reflected light while maintaining the overall and weight characteristics of the corner reflector.

This goal is achieved by the fact that in a prismatic corner reflector made in the form of a trihedral pyramid, the two dihedral angles of which between the lateral reflective faces are equal to n / 2, the third dihedral angle is equal to π [2 (e + 1)]. where s = 1,2,

1774304 A1

3, according to the invention, the front face of the reflector limits the lengths of its lateral ribs in relation to

Ri: R2: R3 = a: a: 1 (1) where the value a related to the edges of right dihedral angles is determined through the refractive index of the material η as follows for s = 1>a> 1.994η ² -7.207η + 7.115 at 1.361 <η <1.495;

a = 70.098η ³ - 326.011 η ² + 505.312η - 260.211 at 1.495 <η <1.59;

a = 0.283η ⁴ - 2.532η ³ + 8.393η ² - 12.038η + 7.108 at 1.59 <η <2.5;

for s = 2

1>a> - 1.570η ³ + 8.666η ² - 16.533η + 11.453 at 1.390 <η <1.773;

a = 2.426η ³ - 14.150η ² + 26.955η - 16.155 at 1.773 <η <2.145, a = 6.159η ³ - 44.025η ² + 105.059η - 82.854 at 2.145 <η <2.5;

for s = 3

1>a> -0.453η ⁵ + 4.833η ⁴ - 20.709η ³ + + 44.784η ² - 49.449η + 23.149 with 1.401 <η ^ 2.5:

The claimed device meets the criterion of novelty since it is characterized by the presence of a new feature, namely, a special selection, depending on the refractive index, of the lengths of the lateral edges of the reflector,

Comparison of the proposed technical solution with other technical solutions shows that it meets the criterion of significant differences, since the introduction of a new feature leads to the manifestation of a new property by the device, the formation of reflected radiation with a greater axial force.

The invention is illustrated in Fig.1-5, Fig.1 shows a General view of the proposed device. It is made in the form of a trihedral pyramid 1 with three lateral reflective faces 2, 3 and 4 and an entrance front face 5. The dihedral angles between faces 2 and 4. 3 and 4 are equal to π / 2, and between faces 2 and 3 -? R / [ 2 (s + 1)]. On edges 2,3 and 4, the light experiences total internal reflection. The length of the side edge 6 between faces 2 and 4 is equal to Ri, the edge 7 between faces 3 and 4 is R2, the edge 8 between faces 2 and 3 is R3. The lengths of the lateral ribs 6,7 and 8 are related by the ratio (1). The set of points of entry and exit of light from reflector 1 forms its working aperture 9 (the border of the working aperture is highlighted by a thick line), which is an elongated symmetric hexagon located on the frontal face 5. It is obtained as the common part of the intersection of the frontal face 5 and its mirror image -symmetric image relative to the entry point of the central ray (the base of the perpendicular, lowered from the top of the triangular angle to the front face 5). Working aperture 9 consists of a set of 4s + 6 sectors, the boundaries between which coincide with the projections onto the frontal face 5, in the direction perpendicular to it, of the lateral edges 6, 7 and 8 of the reflector and their mirror images in the lateral faces 2, 3 and 4. On Fig. 2 in parentheses shows the sequence of light passing the side edges 2, 3 and 4 when leaving the corresponding sector of the working aperture. Fig. 3, 4 and 5 show curves 10, 11, 12. characterizing the design of the inventive reflector, i.e. dependence (limiting at 1.361 <η <1.495 for s = 1; at 1.390 <η <<1.773 for s = 2; at 1.401 <η <2.5 for s = 3) the ratio of the lengths of the side edges R1 / R3 on the refractive index η reflector material, in accordance with formula (1).

The device works as follows.

The incident collimated light beam enters the reflector 1 through its working aperture 9 and, after 2s + 3 total internal reflections from faces 2, 3, and 4, leaves the reflector in the direction opposite to the direction of incidence. With a fully illuminated working aperture 9, the incident beam is divided in the reflector into 4s + 6 partial beams, which propagate in it in different ways.In accordance with this, the output beam is a superposition of 4s + 6 spatially separated beams. With total internal reflections from side faces 2, 3, and 4, the amplitude-phase characteristics of the wave change. These changes depend on the refractive index of the reflector material, the state of polarization of the incident light, the set of angles of incidence of waves on the reflecting faces (the geometry of the reflector), as well as on the sequence of re-reflection of waves from the faces. Therefore, the sectors of the working aperture of the reflector act as separate optical elements that form waves with different states of polarization. The energy distribution of the reflected radiation relative to the line of sight in the Fraunhofer diffraction zone, which determines the efficiency of the prism

Structurally, depending on the retained overall and weight characteristics, it is performed as follows:

corner reflector in optical devices and location systems, due to the interference of 4s + 6 partial beams. Axial luminous intensity, i.e. the intensity at the center of the diffraction pattern is equal in magnitude to the square of the modulus of the Jones vector of the output radiation averaged over the aperture area ®Si_ Л S _o

Esi s + 6q.

Σ-V I = 1 Oo

where So is the area of the entire working aperture 9, Si is the area of the I-ro sector of the working aperture, 15 E _s i and E _P i are the orthogonal components of the Jones vector of the wave coming out of the i-ro sector. The parameters of the proposed device (the ratio of the lengths of the side ribs) are optimized in such a way that it forms reflected radiation with the maximum possible axial force, regardless of the polarization state of the incident wave, while maintaining the overall and weight characteristics of the prototype, for s = 1 at 25 η > 1.495 and for s = 2 at η> 1.773. For other refractive indices (1.361 <η <1.495 for s = 1.1390 <n <1.773 for s = 2, the entire region 1.401 <η <2.5 for s = 3) the maxima of the axial intensity of the reflected light 30 fall on the breakdown points total internal reflection mode. In these cases, the geometry of the reflector is given by a continuous continuum of edge length ratios from equal to each other to these critical 35 points, not including them (inequalities in (1) for a). The preservation of the overall and weight characteristics means the fulfillment of one of six conditions (Fig. 1):

1) maintaining the mass (volume) of the Voabc reflector:

2) preserving the area of the reflective edges

So-p = Soab + Soac + Sobc:

3) preservation of the area of the frontal 45 facet Sabc;

4) preservation of the area of the working aperture Sdefghj;

5) maintaining the useful volume of the reflector 50

Upol = Voabc - Vcdei - Vahkj - Vbglf:

6) preservation of usable area of reflective edges

Srion = Soto- SAHK 'SaKJ * SbgL Sbfl- ScDI - ScEl.

As an example of execution, consider a prismatic corner reflector (tg / 2, lg / 2, l / 4) (s = 1). made of glass with a refractive index η = 1.55.

1) Ri = R ₂ = 0.934 L, R ₃ = 1.145 L;

2) Ri = R ₂ = 0.926 L, R ₃ = 1.135 L:

3) Ri = R ₂ = 0.942 L, R ₃ = 1.154 L;

4) Ri = R ₂ = 0.874 L, R ₃ = 1.071 L; (OL = OK = 0.409 L, 01 = 0.609 L

5) Ri = R ₂ = 0.897 L, R ₃ = 1.099 L; (OL = OK = 0.420 L. 01 = 0.625 L)

6) Ri = R2 = 0.893 L, R ₃ = 1.094 L; (OL = OK = 0.418 L, 01 = 0.622 L).

In all cases, the ratio Ri / R ₃ = 0.816 satisfies (1), and the axial luminous intensity according to (2) is 1 = 0.676, which is the maximum possible value for a given refractive index and is 5% more than that of the prototype (Rt. = R ₂ = R3 = L, Ιπροτ = 0.646). Fig. 3, 4 and 5 show the values of I depending on η for the inventive device (curves 13, 14 and 15 for, respectively, s = 1,2,3). Curves 16, 17 and 18 correspond to a similar relationship for the prototype. From Figs 3, 4, 5 it is directly seen that the achieved increase in axial force is especially significant at some values of the refractive indices, for example, for s = 1 at 1.4 <η <1.6 (η = 1.45, I = 0.641 , Ιπροτ = 0.600, an increase of 7%).

Thus, the proposed prismatic corner reflector reduces the divergence of the reflected radiation. This leads to an increase in the range of the location systems and increases the clarity of the image formed by optical devices, in which the reflector is used as a retroreflective element.

Claims (1)

Claim A prismatic corner reflector made in the form of a trihedral pyramid, the two dihedral angles of which between the lateral reflective faces are equal to n72, the third dihedral angle is Jt / [2 (S + 1)]. where S = 1, 2, 3, characterized in that, in order to increase the axial force of the reflected light while maintaining the overall and weight characteristics, the lengths of the edges of the triangular angle opposite the front face are referred to as a: a: 1, where the value is a. related to the edges of right dihedral angles is related to the refractive index of the material as follows: for s = 1 5 1>a> 1.994η ² - 7.207n + 7.115 at 1.361 <n S 1.495: .a = 70.098n ³ - 326.011η ² + 505.312η - 260.211 at 1.495 <η <1.59: a = 0.283p ⁴ - 2.532p ³ + 8.393η ² - 12.038p + 7.108 10 at 1.59 <η <2.5; for s = 2 1>a> - 1.570n ³ + 8.666η ² - 16.533n + 11.453 at 1.390 <n S 1.773; a = 2.426η ³ - 14.150n ² + 26.955n-16.155 at 1.773 <η <2.145; a = 6.159η ³ - 44.025η ² + 105.059η - 82.854 at 2.145 <η <2.5: for s = 3 1>a> -0.453η ⁵ + 4.833η ⁴ - 20.709n ³ + + 44.784P ² - 49.449n + 23.149 at 1.40Κ η <2.5. Fig L inr. 3 1.5 2 2.5 Editor S. Kulakova 4ig. 5 Compiled by A. Titov Tehred M. Morgenthal Corrector S. Baker Order 3926 Circulation Subscription VNIIPI of the State Committee for Inventions and Discoveries under the USSR State Committee for Science and Technology 113035, Moscow. Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhgorod, Gagarin str., 101