FR2549242A1 - Method and optical device for concentrating radiant energy onto a receiver element, and application to the capture of energy, such as solar energy. - Google Patents

Abstract

THE INVENTION CONCERNS THE CAPTURE OF THE RADIANT ENERGY EMITTED BY A SOURCE AND ITS CONCENTRATION ON A RECEIVING ELEMENT IN A TASK OF DETERMINED EXTENT. THE DEVICE INCLUDES A CONCENTRATOR SYSTEM, FOR EXAMPLE A LENS 1, FOLLOWED BY A DECONCENTRATOR SYSTEM, FOR EXAMPLE A GUIDE 3 OF TRUNCONIC SHAPE WHOSE SIDE SURFACE IS INTERNALLY REFLECTIVE, THIS GUIDE GIVING BIRTH FROM THE TACUS LENS 1 ON ITS INPUT SECTION 4 HAS A WIDER SPOT OF SUITABLE CONCENTRATION AT THE LEVEL OF ITS OUTPUT SECTION 6 WHERE THE RECEIVER ELEMENT 7. IS PLACED. APPLICATION TO THE CONVERSION OF SOLAR ENERGY INTO ELECTRICAL ENERGY.

Description

METHOD AND OPTICAL DEVICE FOR CONCENTRATING ENERGY
RADIANT ON A RECEIVER ELEMENT, AND APPLICATION TO THE CAPTATION OF ANERGY SUCH AS THE SOLAR ENERCY.

 It is conventional to concentrate the radiation by means of convergent lenses or convergent mirrors forming an image or at least a concentrated spot from rays from the radiation source.

 A perfectly correct and homogeneous concentration requires forming an image under the conditions of aplanetism.

This image is called Gauss image. If the optical system is not aplanatic, the most correct part of the image or the concentrated spot obtained is always approximately inscribed in the theoretical aplanatic contour of the Gauss image. So is it for condensers, ordinary lenses or
Fresnel, spherical or parabolic mirrors.

 If one wants to stick to this central spot the most correct, it follows several disadvantages. First we are led to adopt a focal length usually too long. For example, the well-known formula i = Foc (where i is the diameter of the Gaussian image spot, F the focal length of the convergent system and the apparent angle, in radians, under which the radiation is captured), leads, for a receiver of 1 cm, in the case of solar radiation CX = 1/100 radian), at a focal length of 1 m.

Then, the concentration is imposed by the opening of the convergent system, F / N, N being equal, as we know, the ratio of the focal length to the diameter of the entrance pupil of the system. The concentration in the Gauss image is indeed equal to 1 / N2 ~ 2. If one uses, for example, as is usual to do, an aperture lens F / 1, the central theoretical concentration will be of the order of 10,000 suns. This is much too much for the usual applications. In addition, the concentrated spot obtained is much too small considering the size of the receiver which can be, for example, a photo voltaic cell.

 To obtain, under these conditions, a Gauss image of usually adequate size, it would be necessary to reduce the opening of the lens. By keeping its diameter, in order to capture the same flow, it would be necessary to increase its focal length. To fix the ideas, a lens of opening F / 1 and of 30 cm of diameter, capturing the solar radiation, theoretically provides a concentration of the order of 10 000 suns in the center of a Gauss image of 3 mm of diameter . To obtain, for example, a concentration of 1 COO suns in a circle of 1 cm in diameter, it would be necessary that the focal length of the lens is about 1 meter (we find the sizing already reported). Such a length can be considered as prohibitive, a traditional solution was to ex-focus the receiver. But then, the distribution of illumination on this receiver became very inhomogeneous, having a dark area in the center that was mostly unacceptable.

In the example that has just been mentioned, the image spot considered is that called Gauss, which corresponds to the case where the maximum illumination is sought by accepting to lose the scattered flux around this image spot of the makes aberrations of the optical system. One can also, and this is another case, seek to limit this loss of flow by agreeing to obtain a lower average illumination. We then take a spot-image covering, for example, a surface double that of the image of
Gauss. With an F / 1 aperture lens, the theoretical average concentration will be on the order of a few thousand suns. The distribution of the illumination will be very inhomogeneous, presenting a much brighter area in the center. We will also try to ex-focus the receiver; but we shall not succeed, as experience shows, in a more satisfactory distribution than in the first case.

 Various other solutions are possible, either by calculating special lenses or mirrors, or by using concentrator-additional devices such as those described in the French patents in the name of Malifaud No. 1,543,165 of May 6, 1964 and No. 1,587,607 of June 12, 1968. All these solutions are the sole process of concentration.

 The present invention relates to a different design method for optimally adjusting the concentration of a radiant energy on a receiver element.

This method consists of following a concentration of the radiant energy in a spot-image, for example a picture of
Gauss, a partial deconcentration leading, from said spot image, to a radiation spot providing a predetermined extent and distribution on the receiving element. Such a combination of concentration and partial deconcentration makes it possible to adjust the overall concentration factor and the distribution of energy on the receiving element in any desired manner.

 The invention also relates to a device for implementing the method defined above. This device, intended to form in a plane, from a radiation source, a concentrated spot of predetermined extent, comprises, in addition to a concentrator optical system, a deconcentrating optical system placed after the losses concentrator system, and constituted by an optical guide whose interiorly reflecting lateral surface flares in the direction of propagation of the radiation and whose input section is situated substantially in the plane of the image spot provided by the concentrator system, its output section being closely adjacent to the receiving element.

 This device furthermore has the advantage of reducing the entrance pupil acting as an exchange surface between the internal medium and the external medium, which reduces the radiation losses.

 The inlet and outlet sections of the guide may have respective contours for two convex, polygonal or curvilinear plane lines, its lateral surface being defined by a straight or substantially straight generating line, contained in a plane passing through a straight line which constitutes an axis optical medium for the guide, this generating line based on the contours of the input and output sections.

Preferably, the planes of the input and output sections are parallel and the line taken into account the average optical axis of the guide is perpendicular to these planes. In advantageous performance forces, the lateral surface of the guide has a pyramidoidal or pyramidal shape, or a conical or conical shape. Here we mean by conold or pyramidoidal form the drill of the lateral surface of a geometric solid limited by two extreme bases, parallel to each other and of real areal, the cross section of this solid growing gradually from the small base to the large one. base, the two bases being connected by adjoining lateral faces and this geometric solid admitting at least two symmetry planes perpendicular to the bases. The intersection of these planes of symmetry constitutes the average optical axis of the conoldal or pyramidoidal guide. By pyramidoide is meant more particularly a volume of this kind in which the bases are substantially polygonal and the lateral faces are flat or substantially flat, that is to say slightly curved or warped. Unlike a cone or a pyramid, a conoid or a pyranidoid does not generally have a single vertex where its ridges join; in addition, its generators can be slightly curved or warped.

où dl et d2 sont les largeurs respectives des sections d'entrée et de sortie (soit leurs diamètres si ces sections sont circulaires), 1/N le rapport du diamètre de la pupille frontale du système concentrateur à sa distance focale, et- n l'indice du milieu intérieur du guide.Plus précisément, lorsque le guide a la forme d'un tronc de cône de révolution, sa hauteur h peut etre choisie telle que

The height h given to the guide should satisfy the condition:

where d1 and d2 are the respective widths of the inlet and outlet sections (ie their diameters if these sections are circular), 1 / N the ratio of the front pupil diameter of the concentrator system to its focal length, and n index of the inner environment of the guide.More precisely, when the guide has the shape of a truncated cone of revolution, its height h can be chosen such that

In all cases where the guide has a circular exit section, whatever the shape of its inlet section, its height h can also be chosen such that

 It can be provided, in order to obtain a weakening (desired in certain cases) of the illumination in the central part of the concentrated spot provided by the device, that the guide comprises, in the center of its inlet section and / or a small element disturbing the ray operation.When the guide is made by molding in the form of a solid guide transparent material, the small disturbing element may advantageously be constituted by a protuberance appearing in the center of the section d ' # input and / or output as a result of the molding process.

 To reduce the pointing accuracy required in the case of a moving radiation source, the contour of the input section of the guide may be chosen larger than that of the image spot formed by the concentrator system. If the moving source moves with a regular movement in a plane containing the device, it is advantageous that the contour of the input section of the guide is oblong in the direction of said plane.

 The contour of the input section of the guide may also coincide substantially with that of the image spot formed by the concentrator system. In all cases, when the source is mobile, the device may advantageously comprise, overcoming the inlet section of the guide, a collecting mirror increasing the apparent surface of said inlet section, which increases the sensor area of the device In an advantageous embodiment intended for the case of a moving source which moves with a regular movement in a plane containing the device, the collecting mirror has a trace, in said plane, of the side where the risk of more commonly a misalignment of the device, a convex curved line calculated so that the incidence-limiting radii, in the direction of misalignment, which fall on the corresponding part of the collector mirror are returned to the opposite point of the contour of the section of entry of the guide, this curved line being connected by a rectilinear segment to the point adjacent the contour of said inlet section, and, on the opposite side, a concave curved line calculated for that the incidence-limiting rays in the opposite direction to the misalignment which fall on the part corresponding to said rectilinear segment and are reflected by it are returned to the point of the contour of the inlet section of the guide to which the said segment is connected straight.

 It is within the scope of the invention to apply the method or the device defined above to the excitation of a photosensitive receiver element, such as a photo voltaic cell, by radiation originating from a source such as the sun, this element being placed substantially coincidental with the outflow section of the deconcentrator system. The invention also comprises the application to the heating at a given temperature of a receiving element, such as a body capable of thermal dissociation, by radiation from a source, such as the sun, this element being placed in the vicinity the outlet section of the deconcentrator system.

 Other features and advantages of the invention will emerge more clearly from the description which follows, with reference to the accompanying drawings, of non-limiting exemplary embodiments.

 Figures 1 and 2 show schematically a device according to the invention, its concentrator system being respectively constituted by a lens and a concave mirror.

 Figures 3 and 4 show two limiting cases relating to the design of the optical guide, the latter being respectively in the form of a hollow mirror and a solid transparent.

 Figures 5 and 6 illustrate two particular cases of sizing the optical guide.

 FIG. 7 represents an example of distribution of the illumination in the vicinity of the exit section of the optical guide.

 Figure 8 illustrates a case of misalignment of the device in a given direction and Figure 9 the shape that can be given to the input section of the guide to obviate such misalignment.

 Figure 10 shows the shape of a collector mirror placed in front of the guide to obviate similarly a misalignment in a specific direction.

 In the device shown in FIG. 1, the concentrator optical system consists of a single convergent lens 1. It may be a Fresnel lens; it could also be a condenser with two lenses, etc ... This lens captures radiation from a source that may be the sun or any other source, for example a jet engine or engine emitting infrared radiation. It concentrates this radiation in the plane 2 of its focus defined by its focal length F. A frustoconical optical guide 3 is disposed along the same optical axis 20 so that its small section 4 coincides substantially with the most concentrated part of the spot. image formed in the plane of focus 2.This frustoconical guide may be glass (or any other refracting material appropriate to the wavelengths of the captured radiation), its lateral surface 5 acting as mirror by total reflection. It can also be hollow, made for example of shiny aluminum, and be conoidal, pyramidal or pyramidoidal, possibly with non-rectilinear generators.

 The radiation travels in the guide 3 by reflections on its side wall 5 and its mistrust concentration in inverse ratio to the areas of the straight sections reached, to the exit by the large section 6. The area of this section is determined so that the ratio between the area of the inlet section 4 and the area of this section 6 is equal to the desired deconcentration factor. For example, in the case of a capture of the solar radiation, if the concentration in the entry section 4 is of 10 000 suns and that one wishes to obtain a concentration of 1000 suns, the deconcentration factor sought is 1 / 10.

The area of section 6 will be ten times larger than that of section 4. The receiver 7, for example a photo voltaic cell, will be arranged in the vicinity of the outlet section 6, so that the additional deconcentration undergone by the diverging beam of radiation emerging from the guide 3 is negligible. If this were not the case, the area of section 6 would be reduced so that the final concentration on the receiver would be the one ultimately desired.

In the case where the concentrator optical system 1 provides a very aberrant image spot, for example if it is a Fresnel lens (such a lens providing an almost random overlay of Gauss images affected by various aberrations) , the most concentrated central part of this spot-image that is judged good to capture in the inlet section 4 of the frustoconical guide 3 may be much larger than the so-called Gauss image (whose area corresponds to that of the image that would provide an aplanatic optical system of the same diameter and the same relative opening as said lens of
Fresnel). To take this fact into account, the deconcentration factor characterizing the frustoconical guide will be significantly reduced.

 FIG. 2 shows a similar device where the concentrator optical system is a spherical (or parabolic) mirror 8.

 The ratio between the areas S 1 and S 2 of the circular sections 4 and 6 of radii r 1 and r 2 of the frustoconical guide being taken equal to the desired deconcentration factor, the height h of this truncated cone and, hence, its half-angle at the apex (y = Arc r2-r I tg-h) can have very different values. In any case, however, the value of the height h can not be chosen lower than a minimum value below which the frustoconical deconcentrator mirror could no longer play any role. For example (see FIG. hollow frustoconical 3a, capturing in its small section 4a of radius ri a concentrated radiation reaching it under an angle of maximum incidence i. If the desired deconcentration factor is 1 / C, the value of the radius r2 of its output section 6a is set by r12 / r22 = 1 / C.

avec l'ouverture relative de la lentille 1 étant F/N.When the half-angle at the vertex r of the guide is equal (in the case of FIG. 3) or greater than C, none of the rays coming from the concentrator system 1 are reflected on the lateral wall of the frustoconical guide. In this limiting case, the height ho of the guide is equal to r2 - ri
tg #
In other words, the minimum value condition by the height h of the optical guide is therefore

with the relative opening of the lens 1 being F / N.

If the frustoconical guide consists of a truncated cone 3b in glass of refractive index n acting by total reflections (FIG. 4), the refractive angle 'corresponding to the maximum angle of incidence Q is equal to Arc sin 1 / 2nN. The indicated condition then becomes

For the sake of clarity, the following example may be considered as an example: convergent optics 1 is a lens 270 mm in diameter, open at P e = 30 apt for solar radiation; the outlet section of the glass frustoconical guide of index 1.5 is associated with a photovoltatic cell # that likewise diantre 2 r2 = 10 mm; the desired final concentration is about 1000 suns. If we capture in the small section of the guide the image of Gauss, we have
270 x 0.01
rl = - = 1.35 mm.

2
It is then necessary, according to relation (1): h> 10.4 mm.

 If the convergent optics is a Fresnel lens, which provides a superposition of Gauss images enlarging the brightest central portion of the concentrated spot, it may be necessary to take, for example, ri = 2 mm. -It will then h> 9.4 nia.

 This condition of a minimum value for the height h of the truncated cone is respected, we can choose the value of h and hence that of y, depending on the characteristics we want to obtain for the illumination produced in the section outlet of the frustoconical guide and in its immediate vicinity, in particular according to the more or less homogeneous distribution of this illumination.

If one desires the greatest homogeneity, one can use the optimizations of the sizing of the frustoconical mirror described in the following French patents, in the name of Malifaud:
No 1 587 607 of 12 June 1968
No 1 602 203 of 19 July 1968
No 2,224,769 of 03 April 1973
No. 2,224,770 of April 3rd. 1973.

 If it desires a non-homogeneous distribution of a particular type, it is possible to resort to the modulations of the parameters of the dimensioning relations involved in these French patents, in particular in the patent No. 1,602,203, and also in another French patent with the same name. , No. 1,543,165 of 6.05.64.

 A non-homogeneous type of distribution, desired in some cases, is represented by the curve of FIG. 7; it comprises a weakening of the illumination E in the central region of the outlet section of diameter d2 = 2 r2 of the frustoconical mirror. This attenuation is much less than that which would result from a simple ex-focussed arrangement of the receiver 7 behind the convergent lens 1, in order to reduce the degree of concentration without the use of an optical guide.

 To obtain a distribution of this type, it is possible to use the fact that the rays captured by the frustoconical mirror are divided into discontinuous families according to the number of reflections they undergo on the conical lateral surface. As a result, at the outlet of the truncated cone a homogeneous distribution into more or less brilliant rings alternately. The optimum distribution may, according to the invention, be experimentally sought by varying the height h of the guide and choosing the one which provides the frustoconical distribution closest to that sought. It is also possible to use the considerations developed in this regard in French Patent No. 1,543,165, already mentioned, and to modulate the parameters accordingly, if necessary by programming a computer for this purpose.

 Independently of these modes of determination, two examples of combinations according to the invention are described below, by way of indication and in no way limiting.

placé derrière une lentille convergente 1 d'ouverture F/N.First example (Fig. 59) The frustoconical guide 3c is a hollow mirror of height

placed behind a convergent lens 1 F / N opening.

 In the plane of the figure, all the rays coming from the points such as Li situated on the peripheral edge of the lens 1 undergo a reflection in the guide ~ c. Half of the rays from a point such as L2 undergo reflection. The rays coming from the central part of the lens between the points such as L3 and the center Lo do not undergo any reflexion in the frustoconical mirror, the points L2 and L3 sharing the Lo Li segment into three roughly equivalent parts.

Pour ri = 1,35 mm et r2 =5 mm, on trouve alors h# - 18 iman, et, pour ri = 2 mm et r2 = 5, h ~ 20 mm. The construction. determining a glass frustoconical guide of index 1.5 would be obtained by drawing the refracted rays at the entrance of the truncated cone. In that case

For ri = 1.35 mm and r2 = 5 mm, there is then h # - 18 iman, and for ri = 2 mm and r2 = 5, h ~ 20 mm.

 Under these conditions, a significant portion (which may be of the order of one-half) of the flow provided by the convergent lens undergoes at least one reflection in the frustoconical guide. This flow corresponds to a peripheral annular zone of the lens.

Second example (Figure 6). The frustoconical guide 3d is a hollow guide and L4 points are chosen at a distance from the center
Lo and edges of the lens 1. The height h of the 3d guide is then given, according to the plot of the figure, by the formula

qui donne, pour r2 - 4,23 mm, h z 23 mm.In the case of a glass guide of index 1.5, its height h is determined by the formula

which gives, for r2 - 4.23 mm, hz 23 mm.

 It will be observed that, in the formulas of this second example, the radius r 1 of the input section of the guide does not intervene. Furthermore, it can be seen in the figure that the flux coming from a peripheral annular zone of the lens, bounded by the points L4, undergoes reflection in the optical guide 3d. In a general manner, the means according to FIG. invention with a very slight ex-focalisation of the section envere of the deconcentrator guide relative to the focal plane of the converging system providing the first very concentrated image spot.

 Finally, another means according to the invention to obtain a distribution of the type shown in FIG. 7 may consist in providing in the center of the inlet section of the frustoconical guide and / or in the center of the outlet section a zone diffusing the radiation, for example by roughening a central area in the case of a full glass guide. In this way, the radiation undergoes at the input a disturbance whose effect is reflected in the output by weakening the illumination in the center. In the particular case of a glass guide obtained by molding or pressing, it can be made advantage of, according to the invention, the fact that the molding blank can have an injection point in the form of a small protrusion which disperses the radiation.On can be made so that this dispersive point is located-for example in the center of the inlet section of the frustoconical guide (or in the center of the outlet section, as appropriate). Thus, the desired distribution is obtained with a weakening in the center, taking advantage of an inevitable defect that is usually removed by expensive grinding and polishing, hence here a double advantage, technically and financially.

 Another important problem which arises in the case of the concentration of solar energy is that posed by the need to keep the axis 20 of the optical device in the direction of the sun. In order to reduce the precision required at this point, it is proposed according to the invention to increase the area of the inlet section of the frustoconical guide. Taking again the example developed above, a very simple calculation indicates how much it is necessary to increase the diameter d1 of the inlet section of the frustoconical guide so that a misalignment of given value does not affect the capture by this guide of the concentrated image spot.

 The convergent lens 1 having a diameter of 270 mm and the angle of incidence of the rays captured at the entrance of the frustoconical guide 3 being about 300, the triangle ABF (FIG 8) which is based on the diameter of the lens and for vertex its focus (in the center of the entrance section) is equilateral. For an angular misalignment 6, the displacement PP 'of the point of incidence in the focal plane is equal to 270 mm multiplied by tg G and divided by the cosine of 300.

For a misalignment E = 10, 30 'or 15', the increase of ri must thus be respectively 5.4 mm, 2.7 mm or 1.35 mm.

 The misalignment, caused rather generally by a late lag of the tracking system relative to the apparent movement of the sun is always produced in the same direction. The exact score corresponding to a circular image spot of diameter PQ (FIGS 8 and 9), it is necessary to increase this diameter of the length PP 'to continue to correctly capture the radiation during misalignment.

We will give PP 'the value

 It is preferable, according to the invention, to increase the input diameter only in the direction of displacement 9 of the stain isage (see Figure 9). The inlet section of the frustoconical guide then takes the form indicated in the figure, which stobtient by connecting by two tangents semicircles corresponding to the extreme positions of the image spot during misalignment. The output section, associated with the receiver, remains the same, circular. The deconcentrator guide 3 is then of conararle shape, its reflective lateral surface connecting the contour shown in FIG. 9 to the circular contour of the outlet section. The height of the conical trunk is determined according to the invention as described above (second example ), only involving the radius r1 of the captured spot. In the case, for example, of a molded glass deconcentrator, the manufacture of such a conoid, once the mold is made, operates exactly like that of a truncated cone of ordinary revolution.

 The advantage of such a conoidal mirror is to adapt closer to the capture of the radiation to the displacement of the image spot, which has the effect of disrupting the optical deconcentration process to a minimum and to lead to a piece of dimensions and weight less than with a truncated cone of revolution retaining a circular shape at the flow inlet section.

 Another way, according to the invention, of decreasing the precision required when pointing towards a source of moving radiation is to overcome the inlet section 4 of the frustoconical conical guide 3 of another collecting mirror 10 (see FIG. role is to capture the rays that would not reach said entrance because of the misalignment, and reflect these rays to this entry.

 The plan. of the figure is the plane containing the mean center of the entrance pupil 4 and the apparent trajectory of the center of the sun during such day considered.

 Taking again the type of example already described above, a convergent lens concentrates the solar radiation and forms in its focal plane a PQ image spot. In case of misalignment in the direction of the arrow 9, the limit radii such as 11, 12 converging at the point P converge at the point P '. Rays such as 13, 14, 15, 16 converging at P 'are collected by a convex layer 10a of the mirror 10 and concentrated by it at the point Q.

The radii such as -17 and 18 passing between P and P 'meet a conical web 10b which sends them, via a third concave web 10c, into the entry section PQ of the guide 3. Thus, everything happens as if the section The inlet of the guide extended, in the direction 9, the length P'Q and not the length PQ. The precise profile of the plies 10a, lob, 10c is established in each case by geometrically constructing in the vicinity of each of their points the direction of the tangent allowing the reflection defined above according to the invention and connecting all these tangents.

 It is also possible for a computer to define the profiles of these sheets by programming them according to the spirit of the invention.

 In the meridian plane perpendicular to that of the figure, the profiles are reduced to segments of line, the misalignment being supposed nonexistent. The side surface of the collector mirror 10 connects continuously the profiles shown and said right segments.

Claims (18)

 A method for optimally achieving the concentration of radiant energy on a receiver element, characterized by first concentrating the radiant energy into an image spot, and then partial deconcentration leading, from said spot image, to a radiation spot providing a predetermined extent and distribution on the receiving element.  2. Device for carrying out the method according to claim 1, intended to form in a plane, from a radiation source, a concentrated spot of predetermined extent, this device comprising a concentrator optical system, characterized by the it further comprises, placed as a result of the concentrator system (1), a deconcentrating optical system consisting of an optical guide (3) whose interiorly reflecting lateral surface flares in the direction of propagation of the radiation and whose input section (4) is located substantially in the plane of the image spot provided by the concentrator system (1), its output section (6) being closely adjacent to the receiving element (7).  3. Device according to claim 2, characterized in that the inlet and outlet sections of the guide have respective contours two convex flat lines # s, polygonal or curvilinear, and that the lateral surface of the guide is defined by a line generator right or substantially straight, contained in a plane passing through a straight line which constitutes a mean optical axis for the guide, this generating line based on the contours of the inlet and outlet sections.  4. Device according to claim 3, characterized in that the planes of the input and output sections are parallel and the line taken as the mean axis of the guide is perpendicular to these planes.  5. Device according to claim 4, characterized in that the lateral surface of the guide has a pyramidal or pyramidal shape.  6. Device according to claim 4, characterized in that the lateral surface of the guide has a conical or conoidal shape.  7. Device according to any one of claims 4 to 6, characterized in that the height h of the guide fulfills the condition

 or d1 and d2 are the respective widths of the inlet and outlet sections, 1 / N is the ratio of the front pupil diameter of the concentrator system to its focal length, and n is the index of the interior medium of the guide.  8. Device according to claim 7, characterized in that, the guide having the shape of a truncated cone of revolution, its height h is chosen such that

 9. Device according to claim 7, characterized in that, the guide having a circular outlet section, its height h is chosen such that

 10. Device according to any one of claims 2 to 9, characterized in that the guide comprises, in the center of its inlet section and / or outlet, a small element disturbing the ray arches.  11. Device according to claim 10, characterized in that the guide is made by molding in the form of a solid guide in transparent material and that the small disturbing element is a protuberance appearing in the center of the inlet section and / or output as a result of the molding process.  12. Device according to any one of claims 2 to 11, characterized in that the contour of the input section is larger than that of the image spot formed by the concentrator system.  13. Device according to claim 12, for concentrating the radiant energy of a moving source which moves with a regular movement in a plane containing the device, characterized in that the contour of the inlet section of the guide is oblong in the direction of said movement.  14. Device according to any one of claims 2 to 11, characterized in that the contour of the input section coincides substantially with that of the image spot formed by the concentrator system.  15. Device according to any one of claims 2 to 14, characterized in that it comprises, overcoming the input section (4) of the guide (3), a collector mirror (10) increasing the apparent surface of said inlet section.  16. Device according to claim 15, for concentrating the radiant energy of a moving source which moves with a regular movement in a plane containing the device, characterized in that the collecting mirror (10) has a trace in said plane, on the side where there is a risk of a misalignment of the device (arrow 9), a convex curved line (10a) calculated so that the radii (13 to 16) of incidence-limit in the direction of the misalignment which fall on the corresponding part of the collector mirror (10) are returned to the opposite point (Q) of the contour of the input section (4) of the guide, this curved line (10a) being connected by a rectilinear segment (10b) to the adjacent point ( P) of the contour of said inlet section, and, on the opposite side, a concave curved line (10c) calculated so that the incidence-limiting rays (17, 18) in the opposite direction to the misalignment which fall on the part corresponding to said rectilinear segment (10c) are to the point (P) of the contour of the inlet section of the guide to which said rectilinear segment is connected.  17. Application of the method according to claim 1 or the device according to any one of claims 2 to 16 to the excitation of a photosensitive receiving element (7), such as a photo-voltaic cell, by the radiation coming from a source, such as the sun, this element being placed substantially in coincidence with the outlet section (6) of the deconcentrator system (3).  18. Application of the method according to claim 1 or the device according to any one of claims 2 to 16 to the heating at a given temperature of a receiving element, such as a body capable of thermal dissociation, by radiation from a source, such as the sun, this element being placed in the vicinity of the outlet section (6) of the deconcentrator system (3).