Optical device comprising a primary optical unit and a zoom device

Abstract

A primary optical unit (12), comprising a mechanical holding part (21) and an optical mixing part (22), the optical mixing part (22) being configured to ensure mixing of the colours of light from a light source (3) placed at a point on an axis of the primary optical unit (12), the mechanical holding part (21) being configured to be removably fastened to a mechanical interface (13).

Description

[0001] DESCRIPTION

[0002] TITLE: Optical device comprising a primary optic and a zoom device

[0003] The present invention relates to the field of optics, and in particular to assemblies comprising a color mixer and a zoom device.

[0004] It is known to use a four-chip power LED: red, green, blue, white (RGBW). This type of LED has become widely used in the event lighting market (concerts, shows, etc.) and in the architectural lighting market (facade lighting). An example of this type of LED is the Ostar Stage, manufactured by OSRAM.

[0005] It is also known to use collimating optics specially designed for this type of LED, which allow for good color mixing while preserving the geometric extent of the light beam (RGBW optics). Thus, it is known to use uncompromising optics, both very intensive and very homogeneous. These optics allow for fixed light beams, i.e. the output angle is predetermined by the optics and by the LED, it cannot be adjusted subsequently.

[0006] Furthermore, it is known to use optics with variable light beams (zoom optics), which allow the output angle to be adjusted dynamically by moving a movable optical component. Unfortunately, these zoom optics are not as efficient as optics with fixed light beams. Thus, the beam adjusted in a given zoom position is a little wider, a little less intense and noticeably less homogeneous in color than its fixed beam equivalent. Thus, there remain irreducible colorimetric defects in the projected light. If these defects were acceptable 12 years ago for the events market, they are no longer acceptable in the current architectural market, whose requirements have increased significantly over time.

[0007] It is therefore necessary to develop a new optical concept, adapted to RGBW LEDs, allowing the generation of a variable light beam, without compromise, which combines the performance of RGBW optics with fixed beams and the performance of classic zoom optics.

[0008] More precisely, an RGBW LED has four separate chips, red, green, blue, and white, respectively. With existing, unsuitable optics, there is a visible separation of the four colors in the projected light; this is due to the fact that the existing optics form a partially distorted image of the LED chips.

[0009] The invention therefore aims to propose a solution to all or part of these problems.

[0010] To this end, the present invention relates to a primary optic, comprising a mechanical holding part and an optical mixing part, the optical mixing part being configured to ensure a mixing of the colors of a light coming from a light source placed at a point on an axis of the primary optic, the mechanical holding part being configured to be removably fixed on a mechanical interface.

[0011] According to one embodiment, the invention comprises one or more of the following features, alone or in a technically acceptable combination.

[0012] According to one embodiment, the mechanical holding part and the optical mixing part, i.e. the primary optic, form a single piece. According to one embodiment, the primary optic is made of a transparent plastic material so that the primary optic can be manufactured by plastic injection in a mold.

[0013] According to one embodiment, the plastic material is a polycarbonate.

[0014] According to these provisions, the mechanical strength and thermal resistance of the material are adapted to the need.

[0015] According to one embodiment, the mechanical holding portion comprises at least one first fixing member, for example a bayonet-type fixing notch, the at least one first fixing member being configured to receive a first complementary fixing member arranged on the mechanical interface.

[0016] According to these provisions, the at least one first fixing member makes it possible to lock the position of the primary optic relative to the mechanical interface and to a collimator mounted on the mechanical interface.

[0017] According to one embodiment, the mechanical holding part further comprises at least one second fixing member, for example standardized screw holes, configured to fix the primary optic to a support of the light source.

[0018] According to one embodiment, the mechanical holding part further comprises at least one opening, for example bean-shaped, configured to evacuate heat.

[0019] According to one embodiment, the mechanical holding part has an extension transverse to the axis of the primary optic, with a bowl shape, a lower part of the bowl being closer to a light source than an upper part of the bowl, the optical mixing part being positioned on the lower part of the bowl.

[0020] According to these arrangements, the optical mixing part is thus brought closer to the light source.

[0021] According to one embodiment, the optical mixing portion comprises at least two microlens arrays, each arranged on a hemisphere centered on the point of the axis of the primary optics on which the light source is placed, a microlens of one microlens array among the at least two arrays corresponding to a corresponding microlens of another microlens array among the at least two arrays, the microlens array defining a hemispherical face of the optical mixing portion and forming a partition of said hemispherical face, without free space between two adjacent microlenses, and the other corresponding microlens array defining another hemispherical face of the optical mixing portion, and forming a partition of said other hemispherical face without free space between two adjacent corresponding microlenses.

[0022] According to one embodiment, the array of microlenses, respectively the other array of corresponding microlenses, comprises at least a first part and a second part, the first part comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face of the optical mixing part, along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optic, up to a first parallel traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optic, the second part comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part,along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optic, between the first parallel and a second parallel traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optic, a number of microlenses, respectively a number of corresponding microlenses, positioned on each successive concentric ring being adjusted so that a contour of a surface of a microlens projected onto the hemispherical face, respectively a contour of a surface of a corresponding microlens projected onto the other hemispherical face, is substantially symmetrical around an axis passing through a center of the microlens and through a center of the corresponding microlens.,

[0023] A contour of a surface is said to be substantially symmetrical around an axis if:

[0024] - the point symmetrical with respect to the axis of any point of the contour is positioned on said contour, or if

[0025] - the point symmetrical with respect to the axis of any point of the contour is at a distance from the contour less than 10% of a distance to the axis of said any point.

[0026] According to one embodiment, the array of microlenses, respectively the other array of corresponding microlenses, comprises a third part comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part, along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optic, between the second parallel and a third parallel of the optical mixing part, the third parallel being merged with a base of the hemispherical face, respectively of the other hemispherical face.According to one embodiment, the microlenses, respectively the corresponding microlenses, of the first part have a first shape and in which a distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, of the first part, comprises a curvilinear distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, which belong to two successive rings of the first part, and another curvilinear distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, of the same ring of the first part, the other curvilinear distance being equal to the curvilinear distance rounded to an integer value so that a number of adjacent microlenses, respectively a number of corresponding adjacent microlenses, of said same ring of the first part, is an integer.

[0027] According to one embodiment, the other curvilinear distance is constant.

[0028] According to one embodiment, the first shape is substantially hexagonal.

[0029] According to one embodiment, the microlenses, respectively the corresponding microlenses, of the second part have a second shape, and in which a number of the microlenses, respectively a number of the corresponding microlenses, adjacent along a crown of the second part, is a multiple of 4.

[0030] According to these provisions, the optical mixing part makes it possible to improve the luminous efficiency and the homogeneity of the color mixing, in particular when the optical mixing part is used in combination with a four-chip power LED: red, green, blue, white (RGBW), composed of a substrate on which the four chips are arranged at the four corners of a virtual square whose center passes through the mechanical axis of the LED. The LED thus has a mechanical structure decomposed into four quadrants, one quadrant per chip. If we impose that the number of microlenses of each crown within the second part is a multiple of four, then this will automatically imply that the second part also has a mechanical structure decomposed into four quadrants.The four-quadrant mechanical structure of the LED can thus be matched with the four-quadrant mechanical structure of the invention, thereby maximizing light output and color mixing quality. Empirically, it is found that any other arrangement of the microlens crowns tends to introduce asymmetries into the projected light beam, which penalize light output and color mixing quality.

[0031] According to one embodiment, the second shape is substantially hexagonal or substantially rectangular.

[0032] A substantially hexagonal shape is a regular hexagon, i.e. one which includes 6 vertices and whose two sides associated with each vertex form an angle of 120 degrees, or an irregular hexagon, i.e. one which includes 6 vertices and whose two sides associated with each vertex form an angle between 110 degrees and 130 degrees.

[0033] A substantially rectangular shape is a perfect rectangle, i.e. a quadrilateral with a right angle at each vertex, or a quadrilateral whose sides form, at each vertex, an angle between 80 degrees and 100 degrees.

[0034] According to one embodiment, the microlenses, respectively the corresponding microlenses, of the third part have a third shape, and in which a number of the microlenses, respectively a number of the corresponding microlenses, is constant from one crown to the next.

[0035] According to one embodiment, the third shape is substantially rectangular. According to these arrangements, the contours of the projected surfaces of the microlenses and the corresponding microlenses have axial symmetry with respect to an axis defined by a microlens and the corresponding microlens.

[0036] According to these arrangements, the light coming from a microlens is entirely collected by the corresponding microlens, so as to avoid the formation of light artifacts.

[0037] According to these provisions, the optical device makes it possible to generate a variable light beam, which combines the performance of fixed-beam RGBW optics, which allow colors to be mixed with an intense and homogeneous light beam, and the performance of classic zoom optics. In particular, the primary optics makes it possible to obtain:

[0038] • A luminous efficiency greater than 75%

[0039] • Excellent color mixing at any zoom setting, used in combination with and out of the primary lens, said zoom being able to range from 10° to 50°

[0040] In one embodiment, a microlens of the microlens array, located along the axis of the primary optic, collects an incident light beam from the light source and projects it toward a corresponding microlens of the other microlens array also located along the axis of the primary optic, such that the microlens projects an image of the light source onto the corresponding microlens, which projects a collimated and homogeneous emergent light beam, such that the corresponding microlens projects an image of the microlens at infinity.

[0041] According to one embodiment, a dimension of the microlens of the microlens array is adjusted to a dimension of the corresponding microlens of the other microlens array such that a geometric extent of the incident light beam is preserved and corresponds to a geometric extent of the emergent light beam.

[0042] According to one embodiment, at least one of a radius of curvature of the microlens, a radius of curvature of the corresponding microlens, a distance separating the microlens from the light source, a distance separating the microlens from the corresponding microlens, a useful optical diameter of the microlens, a useful optical diameter of the corresponding microlens, is determined as a function of a distance separating the light source and the microlens.

[0043] According to one embodiment, the distance separating the light source and the microlens is defined so that a field angle of the incident beam is less than 20 degrees on either side of the axis of the primary optic, or 40 degrees of field angle in total.

[0044] According to one embodiment, one edge of the microlens corresponds to another edge of a corresponding microlens adjacent to the corresponding microlens, and wherein one edge of the corresponding microlens corresponds to another edge of a corresponding microlens adjacent to the corresponding microlens, such that step by step a useful diameter of each microlens of the microlens array and a useful diameter of the corresponding microlens of the other microlens array are determined.

[0045] According to one aspect, the invention also relates to an optical device comprising a primary optic according to one of the embodiments described above, and a mechanical interface, the optical device further comprising a collimator, the primary optic being removably mounted on the mechanical interface, the collimator also being mounted on the mechanical interface, so that the light coming from the light source passes through the primary optic and then the collimator. According to these arrangements, the optical device has the advantage of being modular since it can be standardized and thus any mechanically compatible collimator can be fixed on the primary optic. The mechanical interface ensures coplanarity for the alignment of the collimator and the primary optic.

[0046] According to one embodiment, the invention comprises one or more of the following features, alone or in a technically acceptable combination.

[0047] According to one embodiment, the collimator comprises a collimation optic and a collimation window, the collimation window of the collimator being rotatable relative to the mechanical interface around an axis of the primary optic, the collimator being configured to provide a variable zoom function as a function of an angle of rotation of the collimation window.

[0048] According to one embodiment, the rotation angle of the collimation window is between 10 degrees and 15 degrees.

[0049] For a better understanding, an embodiment and / or implementation of the invention is described with reference to the attached drawings representing, by way of non-limiting example, an embodiment or implementation respectively of a device and / or a method according to the invention. The same references in the drawings designate similar elements or elements whose functions are similar.

[0050] [Fig. 1] is a perspective and sectional view of an optical device according to one embodiment of the invention.

[0051] [Fig. 2] is a perspective view of a primary optic of an optical device according to an embodiment of the invention

[0052] [Fig. 3] is a simplified two-dimensional representation, in a sectional plane, of an optical mixing portion of the primary optics according to an optical device according to an embodiment of the invention [Fig. 4] is a simplified three-dimensional representation of an optical mixing portion of the primary optics according to an optical device according to an embodiment of the invention.

[0053] The invention relates to a primary optic 12, shown according to an exemplary embodiment in Figure 2, designed to be interposed between a light source 3, for example an LED, shown in Figure 3, and a collimation optic 14, shown according to an exemplary embodiment in Figure 1. Said light source is not shown in Figures 1 and 2; it is positioned at a point of an axis 0, shown in Figure 3, of the primary optic 12, the optical axis 0 being transverse to an extension of the primary optic 12, the light source 3 being positioned on said optical axis 0 on one side of the extension of the primary optic 12, and the collimation optic 14 being positioned on the other side of the extension of the primary optic 12, so that the primary optic 12 is interposed between the light source 3 and the collimation optic 14.

[0054] The primary optic 12 comprises a mechanical holding part 21 and an optical mixing part 22, the optical mixing part 22 being configured to ensure mixing of the colors of the light coming from the light source 3. Thus the primary optic has an optical color mixing function and a mechanical assembly function, via a mechanical interface 13, to a more complete optical device 10, shown in FIG. 1 according to an exemplary embodiment, which notably comprises the collimation optic 14.

[0055] The optical device 10 shown in Figure 1 thus comprises the primary optics 12, the mechanical interface 13, a collimator, the primary optics 12 being removably mounted on the mechanical interface 13, the collimator also being mounted on the mechanical interface 13, so that the light coming from the light source 3 passes through the primary optics 12 and then the collimator. According to these arrangements, the optical device 10 has the major advantage of being modular since it can be standardized and thus any mechanically compatible collimator can be fixed on the primary optics. The mechanical interface ensures coplanarity for the alignment of the collimator and the primary optics.

[0056] According to a particular embodiment of the optical device 10, the collimator comprises a collimation optic 14 and a collimation window 15, the collimation window 15 of the collimator being movable in rotation relative to the mechanical interface 13 around the axis of the primary optic 12, the collimator being configured to provide a variable zoom function as a function of an angle of rotation of the collimation window 15. More particularly, the angle of rotation of the collimation window is between 10 degrees and 15 degrees.

[0057] In particular, the mechanical holding part 21 and the optical mixing part 22 of the primary optics 12 form a single, single-piece part.

[0058] According to an exemplary embodiment, the primary optic 12 is made of a transparent plastic material so that the primary optic 12 can be manufactured by plastic injection in a mold. For example, the plastic material is a polycarbonate, so that the mechanical strength and thermal resistance of the material are adapted as needed.

[0059] According to an exemplary embodiment, the mechanical holding part 21 of the primary optic 12 comprises at least one first fixing member 23, for example a bayonet-type fixing notch, the at least one first fixing member being configured to receive a first complementary fixing member arranged on the mechanical interface 13.

[0060] Thus, the at least one first fixing member makes it possible to lock the position of the primary optics relative to the mechanical interface and, consequently, also relative to the collimator mounted on the mechanical interface 13. According to a particular exemplary embodiment, the mechanical holding part 21 further comprises at least one second fixing member 24, for example standardized screw holes, configured to fix the primary optics 12 to a support, not shown in the figures, of the light source 3.

[0061] According to a more particular embodiment, the mechanical holding part 21 further comprises at least one opening 25, for example bean-shaped, configured to evacuate heat.

[0062] Optionally, the mechanical holding part 21 has an extension transverse to the axis of the primary optic 12, said extension having a bowl shape 26, a lower part of the bowl 26 being closer to the light source 3 than the upper part of the bowl 26, the optical mixing part 22 being positioned on the lower part of the bowl 26. Thus, the optical mixing part 22 is brought closer to the light source 3.

[0063] With reference to figures 3 and 4 more particularly, an exemplary embodiment of the optical mixing part 22 of the primary optics is described below.

[0064] The optical mixing portion 22 comprises two arrays 1, 2 of microlenses, each array 1, 2 being arranged respectively on a hemisphere centered on the point of the axis 0 of the primary optics 12 on which the light source 3 is placed; a microlens 5, 5b, 5c of one microlens array 1 corresponding to a corresponding microlens 6, 6b, 6c of another microlens array 2, the microlens array 1 defining a hemispherical face of the optical mixing portion 22 and forming a partition of said hemispherical face, without free space between two adjacent microlenses, and the other corresponding microlens array 2 defining another hemispherical face of the optical mixing portion 22, and forming a partition of said other hemispherical face without free space between two adjacent corresponding microlenses.More particularly, a microlens 5 of the microlens array 1, located along the axis of the primary optics 12, recovers an incident light beam 4 from the light source 3 and projects it towards a corresponding microlens 6 of the other microlens array 2 also located along the axis of the primary optics 12, so that the microlens 5 projects an image of the light source 3 onto the corresponding microlens 6, which projects a collimated and homogeneous emergent light beam 7, so that the corresponding microlens 6 projects an image of the microlens 5 to infinity.

[0065] In particular, a dimension of the microlens 5 of the microlens array 1 is adjusted to a dimension of the corresponding microlens 6 of the other microlens array 2 so that a geometric extent of the incident light beam 4 is preserved and corresponds to a geometric extent of the emerging light beam 7.

[0066] To do this, we need to know the following parameters:

[0067] - a radius of curvature (R5) of the microlens 5,

[0068] - a radius of curvature (R6) of the corresponding microlens 6,

[0069] - a distance (E5) separating the microlens 5 from the light source 3,

[0070] - a distance (E6) separating the microlens 5 from the corresponding microlens 6,

[0071] - a useful optical diameter (D5) of the microlens 5,

[0072] - a useful optical diameter (D6) of the corresponding microlens 6.

[0073] For this purpose, we use the following relationships:

[0074] A. The distance separating the microlens 5 from the light source 3 is defined arbitrarily. A value is optionally chosen which makes it possible to limit the field angle of the incident light rays as shown in Figure 3. For example, the distance separating the light source 3 and the microlens 5 is defined so that a field angle of the incident beam 4 is less than 20 degrees on either side of the axis of the primary optics 12.

[0075] B. The radius of curvature (R5) of the microlens 5 is put into an equation so as to carry out an optical conjugation (of the object / image type) between the light source 3 and the microlens 6.

[0076] C. The radius of curvature (R6) of microlens 6 is equated to perform optical conjugation (focus / infinity type) between microlens 6 and the output space.

[0077] D. The useful optical diameter (D6) of the microlens 6 is equated so that each point on the edge of the light source corresponds to each point on the edge of the microlens 6, as shown in Figure 3. This is made possible because there is a conjugation relationship between 3 and 6.

[0078] E. The right edge of microlens 6 must match the left edge of the immediately adjacent microlens 6.

[0079] F. Similarly, the right edge of microlens 5 must correspond to the left edge of the immediately adjacent microlens 5.

[0080] Relation (E) implies that, advantageously, one edge of the microlens 5 corresponds to another edge of a corresponding microlens adjacent to the corresponding microlens 5 and, relation (F) implies that, advantageously, one edge of the corresponding microlens 6 corresponds to another edge of a corresponding microlens adjacent to the corresponding microlens 6.

[0081] If this is not respected, then light from a microlens 5 could not be collected by the corresponding microlens 6 and leak elsewhere, creating light artifacts. From near to near the distance (E6) separating each microlens 5 from each microlens 6 is defined.

[0082] The useful optical diameter (D5) of each microlens 5 is defined step by step.

[0083] So that step by step a useful diameter of each microlens of the microlens array 1 and a useful diameter of the corresponding microlens of the other microlens array 2 are determined

[0084] Conditions (E) and (F) are recurrence relations that require a starting point. The recurrence relations are initiated using a “hidden” global parameter which is, for example, an opening angle O of microlenses 5 and 6; a value of the opening angle of microlens 5 is chosen, for example, to be less than 10 degrees, i.e. 5 degrees on either side of the axis that passes through a center of microlenses 5 and 6, as illustrated in Figure 3.

[0085] Thus, six unknowns (R5, R6, E5, E6, D5, D6) and six equations (A, B, C, D, E, F) make it possible to determine one by one each pair of microlenses 5 and 6 composing the complete network. The embodiment described here is not unique. There are variants where, for example, instead of defining a distance (E5) fixed a priori for each pair of microlenses, a radius of curvature (R6) fixed a priori is defined for each pair of microlenses. Advantageously, a radius of curvature (R6) fixed a priori allows the use of machining techniques which greatly simplify the manufacture of the mold, such as, for example, the use of a ball end mill calibrated to the value of the radius of curvature (R6). In all cases, an unknown is fixed, then the problem restricted to 5 unknowns and 5 equations, including 2 recurrence relations, is solved.A resolution of the problem posed above in the three dimensions of space, further leads to determining the geometric shapes of the microlenses so that the conditions (A, B, C, D, E, F) are satisfied. According to an exemplary embodiment, two additional conditions are introduced.

[0086] A first additional condition is that an outline of the projected surfaces of the microlenses 5, 5b, 5c, 6, 6b, 6c of a pair 5, 6, or 5b, 6b, or 5c, 6c of microlenses which correspond to each other on each hemisphere, is substantially symmetrical about an axis which passes through the microlens.

[0087] A contour of a surface is said to be substantially symmetrical around an axis if:

[0088] - the point symmetrical with respect to the axis of any point of the contour is positioned on said contour, or if

[0089] - the point symmetrical with respect to the axis of any point of the contour is at a distance from the contour less than 10% of a distance to the axis of said any point.

[0090] Thus, if the contour of the projected surface is for example a rectangle, a regular hexagon, a circle, or an ellipse, the axis considered passing through the center of the shape considered transversely to a plane containing said contour, then the contour is perfectly symmetrical around the axis. The contour will only be substantially symmetrical around the axis if the contour of one of these perfectly symmetrical shapes is deformed so that the symmetrical point of any point on the contour is at a distance from the contour less than 10% of a distance to the axis of said any point.

[0091] To solve in three dimensions the problem represented in two dimensions in Figure 3, the second additional condition introduced is the following: the microlenses are arranged along concentric rings around the optical axis 0 of the primary optics 12, a ring corresponding to a constant angle of emission of the light from the light source 3. Thus, as an example in Figure 4, two particular rings are represented, which delimit three portions 1, 2, 3 of surface on a hemispherical face of the optical mixing part 22. The technical effect obtained by this second additional condition is that the conditions (D, E, F) defined above are respected in the plane of Figure 3.

[0092] On each hemispherical face which composes the optical mixing part 22, along each crown thus defined, a number of microlenses is thus adjusted so that the contours of the projected surfaces of the microlenses have the axial symmetry according to the first additional condition.

[0093] Thus, according to an exemplary embodiment of the optical mixing part 22, and with reference to FIG. 4, the array of microlenses, respectively the other array of corresponding microlenses, comprises at least a first part 221 and a second part 222; the first part 221 comprises the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part 22, along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics 12; said first part 221 extends to a first parallel P1 traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics 12;the second part 2 comprises the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part 22, along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics 12, between the first parallel P1 and a second parallel P2 traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics 12;a number of microlenses, respectively a number of corresponding microlenses, positioned on each successive concentric crown being adjusted so that a contour of a surface of a microlens projected onto the hemispherical face, respectively a contour of a surface of a corresponding microlens projected onto the other hemispherical face, is substantially symmetrical around an axis passing through a center of the microlens and through a center of the corresponding microlens.;

[0094] More particularly, the array of microlenses, respectively the other array of corresponding microlenses, comprises a third part 223 comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part 22, along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics 12, between the second parallel P2 and a third parallel P3 of the optical mixing part 22, the third parallel P3 being coincident with a base of the hemispherical face, respectively of the other hemispherical face.

[0095] More particularly, the microlenses, respectively the corresponding microlenses, of the first part 221 have a first shape, for example substantially hexagonal.Furthermore, a distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, of the first part 221, comprises a curvilinear distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, which belong to two successive rings of the first part, and another curvilinear distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, of the same ring of the first part, the other curvilinear distance being equal to the curvilinear distance rounded to an integer value so that a number of adjacent microlenses, respectively a number of corresponding adjacent microlenses, of said same ring of the first part, is an integer. In particular, the other curvilinear distance is constant. By convention, a substantially hexagonal shape is a regular hexagon, i.e.which includes 6 vertices and whose two sides at each vertex form an angle of 120 degrees, or an irregular hexagon, i.e. which includes 6 vertices and whose two sides at each vertex form an angle between 110 degrees and 130 degrees.

[0096] Furthermore, the microlenses, respectively the corresponding microlenses, of the second part 222 have a second shape, for example substantially hexagonal or substantially rectangular. Furthermore, a number of the microlenses, respectively a number of the corresponding microlenses, adjacent along a crown of the second part 222, is a multiple of 4.

[0097] The technical effect of this discriminating feature is that the optical mixing part improves the light output and the homogeneity of the color mixing, especially when the optical mixing part is used in combination with a four-chip power LED: red, green, blue, white (RGBW), composed of a substrate on which the four chips are arranged at the four corners of a virtual square whose center passes through the mechanical axis of the LED. The LED thus has a mechanical structure decomposed into four quadrants, one quadrant per chip. If we impose that the number of microlenses of each crown within the second part is a multiple of four, then this will automatically imply that the second part also has a mechanical structure decomposed into four quadrants.The four-quadrant mechanical structure of the LED can thus be matched with the four-quadrant mechanical structure of the invention, thereby maximizing light output and color mixing quality. Empirically, it is found that any other arrangement of the microlens crowns tends to introduce asymmetries into the projected light beam, which penalize light output and color mixing quality.

[0098] A substantially rectangular shape is a perfect rectangle, i.e. a quadrilateral with a right angle at each vertex, or a quadrilateral whose sides form, at each vertex, an angle between 80 degrees and 100 degrees.

[0099] Even more particularly, the microlenses, respectively the corresponding microlenses, of the third part 223 have a third shape, for example substantially rectangular; a number of the microlenses, respectively a number of the corresponding microlenses, of the third part 223 is constant from one crown to the next.

[0100] According to these provisions, the optical device 10 makes it possible to generate a variable light beam, which combines the performance of fixed-beam RGBW optics, which make it possible to mix colors with an intense and homogeneous light beam, and the performance of conventional zoom optics. In particular, the primary optics makes it possible to obtain:

[0101] • A luminous efficiency greater than 75%

[0102] • Excellent color mixing at any zoom setting, used in combination with and out of the primary lens, said zoom being able to range from 10° to 50°.

[0103] The color mixing effect is obtained in particular by the fact that conditions (B) and (C) are met simultaneously. In particular, compliance with conditions (B) and (C) has the effect that the image of the light source seen through the primary optics 12 is no longer the light source but a virtual source which corresponds to a superposition of all the microlenses.

Claims

CLAIMS 1. Primary optics (12), comprising a mechanical holding portion (21) and an optical mixing portion (22), the optical mixing portion (22) being configured to ensure a mixing of the colors of a light coming from a light source (3) placed at a point of an axis of the primary optics (12), the mechanical holding portion (21) being configured to be removably fixed on a mechanical interface (13), wherein the optical mixing portion (22) comprises at least two microlens arrays (1, 2), each arranged on a hemisphere centered on the point of the axis of the primary optics (12) on which the light source is placed, a microlens (5, 5b, 5c) of a microlens array (1) among the at least two arrays (1, 2) corresponding to a corresponding microlens (6, 6b, 6c) of another microlens array (2) among the at least two arrays (1, 2),the microlens array (1) defining a hemispherical face of the optical mixing portion (22) and forming a partition of said hemispherical face, without free space between two adjacent microlenses, and the other corresponding microlens array (2) defining another hemispherical face of the optical mixing portion (22), and forming a partition of said other hemispherical face without free space between two adjacent corresponding microlenses, wherein the microlens array, respectively the other corresponding microlens array, comprises at least a first part (221) and a second part (222), the first part (221) comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face of the optical mixing portion (22), along successive concentric rings traced on the hemispherical face,respectively on the other hemispherical face, around the axis of the primary optic (12), up to a first parallel (P1) drawn on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optic (12), the second part (222) comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part (22), along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics (12), between the first parallel (P1) and a second parallel (P2) traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics (12), a number of the microlenses, respectively a number of the corresponding microlenses, positioned on each successive concentric ring being adjusted so that a contour of a surface of a microlens projected on the hemispherical face, respectively a contour of a surface of a corresponding microlens projected on the other hemispherical face,is substantially symmetrical about an axis passing through a center of the microlens and through a center of the corresponding microlens, wherein the microlenses, respectively the corresponding microlenses, of the second part (222) have a second shape, and wherein a number of the microlenses, respectively a number of the corresponding microlenses, adjacent along a crown of the second part, is a multiple of 4., 2. Primary optic (12) according to claim 1, wherein the mechanical holding portion (21) comprises at least one first fixing member (23), for example a bayonet-type fixing notch, the at least one first fixing member being configured to receive a first complementary fixing member arranged on the mechanical interface (13).

3. Primary optics (12) according to one of the preceding claims, in which the mechanical holding part (21) has an extension transverse to the axis of the primary optics, with a bowl shape (26), a lower part of the bowl (26) being closer to a light source than a higher part of the bowl (26), the optical mixing part (22) being positioned on the lower part of the bowl (26).

4. Primary optics (12) according to the preceding claim, in which the array of microlenses, respectively the other array of corresponding microlenses, comprises a third part (223) comprising the microlenses, respectively the corresponding microlenses, positioned on the hemispherical face, respectively on the other hemispherical face, of the optical mixing part (22), along successive concentric rings traced on the hemispherical face, respectively on the other hemispherical face, around the axis of the primary optics (12), between the second parallel (P2) and a third parallel (P3) of the optical mixing part (22), the third parallel (P3) being merged with a base of the hemispherical face, respectively of the other hemispherical face.

5. Primary optics (12) according to one of claims 5 or 6, in which the microlenses, respectively the corresponding microlenses, of the first part have a first shape and in which a distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, of the first part, comprises a curvilinear distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, which belong to two successive rings of the first part, and another curvilinear distance between two adjacent microlenses, respectively between two adjacent corresponding microlenses, of the same ring of the first part, the other curvilinear distance being equal to the curvilinear distance rounded to an integer value so that a number of adjacent microlenses, respectively a number of corresponding adjacent microlenses,of the said same crown of the first part, or whole., 6. Primary optics (12) according to claim 1, wherein the microlenses, respectively the corresponding microlenses, of the third part (223) have a third shape, and wherein a number of the microlenses, respectively a number of the corresponding microlenses, is constant from one crown to the next.

7. Primary optics (12) according to claim 1, wherein a microlens (5) of the microlens array (1), located along the axis of the primary optics (12), recovers an incident light beam (4) from the light source (3) and projects it towards a corresponding microlens (6) of the other microlens array (2) also located along the axis of the primary optics (12), so that the microlens (5) projects an image of the light source (3) onto the corresponding microlens (6), which projects a collimated and homogeneous emergent light beam (7), so that the corresponding microlens (6) projects an image of the microlens (5) to infinity.

8. Primary optics (12) according to the preceding claim, wherein a dimension of the microlens (5) of the microlens array (1) is adjusted to a dimension of the corresponding microlens (6) of the other microlens array (2) so that a geometric extent of the incident light beam (4) is preserved and corresponds to a geometric extent of the emerging light beam (7).

9. Primary optics (12) according to the preceding claim, in which at least one of a radius of curvature R5 of the microlens (5), a radius of curvature R6 of the corresponding microlens (6), a distance E5 separating the microlens (5) from the light source (3), a distance E6 separating the microlens (5) from the corresponding microlens (6), a useful optical diameter D5 of the microlens (5), a useful optical diameter D6 of the microlens corresponding (6), is determined as a function of a distance separating the light source (3) and the microlens (5).

10. Primary optics (12) according to the preceding claim, wherein one edge of the microlens (5) corresponds to another edge of a corresponding microlens adjacent to the corresponding microlens (5), and wherein one edge of the corresponding microlens (6) corresponds to another edge of a corresponding microlens adjacent to the corresponding microlens (6), so that step by step a useful diameter of each microlens of the microlens array (1) and a useful diameter of the corresponding microlens of the other microlens array (2) are determined.

11. An optical device (10) comprising a primary optic (12) according to one of claims 1 to 9, and a mechanical interface (13), the optical device (10) further comprising a collimator, the primary optic (12) being removably mounted on the mechanical interface (13), the collimator also being mounted on the mechanical interface (13), such that the light from the light source passes through the primary optic (12) and then the collimator.

12. Optical device (10) according to the preceding claim, wherein the collimator comprises a collimation optic (14) and a collimation window (15), the collimation window (15) of the collimator being movable in rotation relative to the mechanical interface (13) around an axis of the primary optic (12), the collimator being configured to provide a variable zoom function as a function of an angle of rotation of the collimation window (15).

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