High-brightness, integrated sphere compatible with vacuum or ambient environments

Abstract

HIGH-LUMINANCE INTEGRATING SPHERE COMPATIBLE WITH VACUUM OR AMBIENT ENVIRONMENT The invention relates to an integrating sphere comprising a body delimiting an integration chamber and having at least two access windows to the integration chamber from outside the body. According to the invention, the body of the integrating sphere includes at least one cooling channel for the circulation of a heat transfer fluid. Figure for the abstract: Figure 2

Description

Title of the invention: INTEGRATING HIGH-LUMINANCE SPHERE COMPATIBLE WITH VACUUM OR AMBIENT MEDIUM

[0001] The present invention relates to a high-luminance integrating sphere usable in ambient air or in a vacuum chamber.

[0002] An integrating sphere, also known as an Ulbricht sphere, is an optical component comprising an integrating chamber or cavity whose internal surface is coated with a material having a high diffuse reflectance for the wavelengths of interest. The sphere further comprises relatively small input and output ports compared to the dimensions of the integrating chamber. Most often, the integrating chamber has a spherical shape so that light beams originating from any point on the internal surface of the integrating chamber are distributed, due to the multiple diffuse reflections they experience, equally to all other points on the sphere, regardless of the direction from which the light originates.

[0003] Thus, an integrating sphere can be considered as a diffuser that retains the power but destroys the spatial formation. Integrating spheres are used either as a light source or as a system for measuring the optical power of a light source.

[0004] In a preferred application, the invention relates to an integrating sphere used as a light source. Such an integrating sphere comprises, at a minimum, an access window to the integrating chamber from the outside for the placement of a light source, such as an incandescent bulb, inside the integrating chamber. The integrating sphere further comprises an access window to the integrating chamber open to the outside, allowing the light radiation to exit. This exit window then forms a light source with a uniform apparent light intensity in all directions within its opening.

[0005] When a high or even very high light intensity is desired at the exit window, it is necessary to have one or more high-power light sources inside the integration chamber. The dimensions of the integrating sphere, and more specifically of its integration chamber, are then a limiting factor, given the heat power that can be dissipated by the light sources placed within it. Therefore, it is not possible to reliably and permanently achieve the desired high light intensities. Indeed, the high temperatures prevailing within the integration chamber when several very powerful light sources are used affect the lifespan. of these light sources and therefore the reliability of the system. High temperatures also affect the internal coating of the integration chamber, so that the lifespan and optical performance of this coating are significantly impacted.

[0006] It therefore arose the need for a new type of integrating sphere which would allow high or even very high luminous powers to be achieved while offering satisfactory reliability guarantees.

[0007] In order to achieve this objective, the invention relates to an integrating sphere comprising a body delimiting an integration chamber and being provided with at least two access windows to the integration chamber from outside the body characterized in that the body comprises at least one cooling channel for the circulation of a heat transfer fluid.

[0008] The implementation of a cooling channel within the body of the integrating sphere makes it possible to control the temperature well and more particularly to efficiently evacuate the heat generated by the light sources arranged inside the integration chamber.

[0009] According to one feature of the invention, the body comprises at least two complementary half-bodies, each comprising a portion of the integration chamber and at least one cooling channel.

[0010] Such an embodiment makes it easier to assemble and maintain the integrating sphere according to the invention, in particular for the application of the coating to the internal surface of the integration chamber.

[0011] According to another feature of the invention, a cooling channel extends inside the body over at least part of the periphery of the integration chamber.

[0012] Positioning part of the cooling channel in the immediate vicinity of the internal surface of the integration chamber optimizes heat exchange with the latter

[0013] According to yet another feature of the invention, the integrating sphere body comprises at least one cooling chamber which is connected to the cooling channel, which extends over at least a part of the periphery of the integrating chamber.

[0014] The implementation of such a cooling chamber at the periphery of the integration chamber helps to increase the contact area between the heat transfer fluid and the wall delimiting the integration chamber.

[0015] According to a variant of this feature, the cooling chamber defines with a wall of the integration chamber a double-skin type structure.

[0016] According to another variant of this feature, the cooling chamber comprises at least one structure permeable to the heat transfer fluid connecting two opposite internal faces of the cooling chamber.

[0017] The implementation of the permeable structure linking the two opposite inner faces of the cooling chamber makes it possible to increase the contact surface between the heat transfer fluid and the body of the integrating sphere according to the invention.

[0018] In this variant, the permeable structure can be made in any suitable way, such as, for example, fins defining a maze for the circulation of the heat transfer fluid or in the form of a mesh or porous structure permeable to the heat transfer fluid.

[0019] According to a feature of the invention, the integration chamber is partially gas-tight.

[0020] According to another feature of the invention, the sphere includes at least one channel for managing the internal atmosphere of the integration chamber.

[0021] The possibility of controlling the nature of the internal atmosphere of the integration chamber makes it possible to reduce the humidity of the latter and in particular to be able to lower the temperature below the dew point when the sphere is used in air.

[0022] According to one feature of the invention, the body of the integrating sphere is made of a thermally conductive material.

[0023] According to a preferred embodiment, the body of the integrating sphere is manufactured by additive machining.

[0024] According to another feature of the invention, one of the windows of the integrating sphere is intended for the placement of a light source and the body includes at the level of this window a mounting seat for a socket supporting a lamp constituting the light source.

[0025] The presence of such a mounting seat at the level of the body of the integrating sphere makes it easier to set up and maintain light sources.

[0026] According to a variant of this feature, the integral sphere includes a lamp support socket, this socket being removably adapted onto the mounting seat.

[0027] According to another variant of this feature, the socket comprises a body including at least two connection blocks each intended to receive a power supply pin of the lamp.

[0028] According to a preferred embodiment of this variant, each connection block comprises a connection channel for receiving a lamp power supply pin and equipped with a pin clamping jaw that is servo-controlled in the clamping position by a spring supplemented by a suitable pressure screw to reversibly immobilize the jaw in the clamping position of the feed spindle.

[0029] According to another variant of this feature the body of the socket is made of thermally conductive and electrically insulating material.

[0030] The different features, variants and embodiments of the invention can be combined with each other in various ways insofar as they are compatible with each other.

[0031] Furthermore, various other features of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0032] [Fig.1] [Fig.1] is a schematic perspective of an integrating sphere according to the invention.

[0033] [Fig.2] the [Fig.2] a schematic cross-section of the integrating sphere illustrated in [Fig.1] according to plan II-II of the latter.

[0034] [Fig.3] [Fig.3] is a perspective partially torn from half a body upper part of the integrating sphere illustrated in [Fig.1].

[0035] [Fig.4] [Fig.4] is a schematic perspective of a socket holding a light bulb intended to form a light source equipping the integrating sphere as illustrated in [Fig. 1],

[0036] [Fig.5] [Fig.5] is a perspective analogous to [Fig.4] on which a hood of the The socket was removed in such a way as to show part of the inside.

[0037] [Fig.6] [Fig.6] is a schematic elevation of a lamp intended to form a light source for the integrating sphere illustrated in [Fig.1].

[0038] [Fig.7] [Fig.7] is a schematic cross-section of a connecting block constituting the socket illustrated in figures 4 and 5.

[0039] An integrating sphere according to the invention, as illustrated in figures 1 and 2 and designated as a whole by reference 1, comprises a body 2 equipped with at least one and, according to the illustrated example, four sockets 3 each provided with a light source formed by a bulb 4.

[0040] In the present case, the body 2 comprises two half-bodies, lower 10 and upper 11, which are complementary and which together delimit an integration chamber 12. Thus, the lower half-body 10 and the upper half-body 11 form two half-shells which, assembled, constitute the hollow integrating sphere 1.

[0041] The integration chamber 12 has, according to the illustrated example, a spherical or substantially spherical shape, it being understood that it could have another suitable shape depending on the applications.

[0042] Body 2 comprises at least two and, according to the illustrated example, five access windows into the interior of integration chamber 12, of which only three are visible to [Fig.2]. In the present case, four windows 15 are intended for the installation of a bulb 4 constituting a light source while the fifth window 16 is intended to allow an exit of the light emitted by the bulbs 4 after back scattering on the wall of the integration chamber 12.

[0043] In this regard, it should be noted that the wall of the integration chamber is covered with a reflective and diffusing coating adapted to the nature of the light radiation emitted from the light sources 4. Thus, for radiation in the visible spectrum, a white barium sulfate-based paint will be used, for example, while for radiation in the infrared range, a gold-based coating will be used. Since those skilled in the art know how to adapt the reflective coating to the nature of the light radiation used, it is unnecessary to describe further the possible variations in the choice of coating covering the inner surface of the integration chamber 12.

[0044] In accordance with an essential feature of the invention, the body 2 of the integrating sphere includes at least one cooling channel for the circulation of a heat transfer fluid. In the present case, the body 2 includes two channels 20 and 21 respectively arranged in the lower half-body 10 and the upper half-body 11. In order to allow optimal temperature control within the integration chamber 12 and more particularly to dissipate the heat produced by light sources 4, each channel 20, 21 includes at least a portion which extends over at least a part of the periphery of the integration chamber 12 as shown more particularly in [Fig. 2].

[0045] The objective is then to maximize, as far as possible, the exchange surface area between the peripheral wall of the integration chamber 12 and each channel 20, 21. This objective can be achieved in various ways, such as, for example, by creating within each channel 20, 21 a network of secondary channels extending over a large portion of the periphery of the wall of the integration chamber 12 outside of the latter. The channels are then designed so that the wall thickness separating the interior of each channel from the peripheral face of the integration chamber 12 is as reduced as possible, taking into account the mechanical stresses to which the entire system, and more particularly the body 2 and its constituent elements, must withstand.

[0046] In a preferred embodiment, and as can be seen in Figures 2 and 3, each channel 20, 21 comprises a cooling chamber 25 extending over at least a portion of the periphery of the corresponding portion of the integration chamber 12. The purpose of this cooling chamber 25 is to create a double cooling skin around the integration chamber 12. Thus, the cooling chamber 25 defines a circulation volume of the cooling fluid which has a shape generally analogous to that of the peripheral wall of the integration chamber 12. As previously stated, the cooling chamber is arranged, in each of the corresponding half-bodies, so that the wall thickness which separates the interior of the cooling chamber from the peripheral face of the integration chamber is as reduced as possible, taking into account, of course, the mechanical constraints.

[0047] In a preferred but not exclusive embodiment, in order to increase the exchange surface between the body 2 or the half-bodies 11 which constitute it and the heat transfer fluid circulating therein, the cooling chamber 25 comprises a structure, permeable to the heat transfer fluid, connecting the two opposite internal faces of said cooling chamber 25. This structure is made of the same material as the body 2 and, preferably, forms a single unit with the latter so that the continuity of material ensures good thermal conductivity between this structure and the rest of the body 2.

[0048] The heat exchange structure 25 can have different shapes depending in particular on the nature of the heat transfer fluid used. Thus, the heat exchange structure 25 can be formed by fins connecting the opposite walls of the cooling chamber 25. In the present case, and as shown in detail in [Fig. 3], the heat exchange structure 25 is formed by a set of prismatic elements constituting a porous structure through which the heat transfer fluid can pass.

[0049] To ensure continuity between the heat exchange structure 25 and the body 2 or the half-bodies 10, 11 that constitute it, the body 2 is preferably manufactured using an additive manufacturing process, also known as 3D printing, with materials having good thermal conductivity, such as aluminum, stainless steel, copper, or ceramics. This manufacturing method also ensures perfect sealing of the cooling circuits formed by the channels 20, 21 and the cooling chambers 25.

[0050] In order to optimize the cooling of the entire system constituting the integral sphere and including the body equipped with the light sources, the invention proposes to implement specific sockets 3 to carry and ensure the electrical supply of the lamps 4.

[0051] As can be seen from Figures 4 and 5, each socket 3 comprises a body 30 closed by a cover 31. The socket body 30 has at its base a mounting plate 32 which has a shape complementary to that of a mounting seat 33 arranged on the corresponding body 2 or half-body 10 or 11 at each window 15 for installing a light source. The complementarity of the plate 32 and the mounting seat 33 is achieved such that the socket 3 forms a means of closing the integration chamber 12. Of course, the plate 32 and the seat of Mounting 33 are configured to allow removable adaptation of the socket 3 onto the body of the integrating sphere.

[0052] Each socket 3 includes means for supplying power to the light source 4 it supports. In the present case, and as shown in [Fig. 6], each light source 4 is formed by a bulb comprising two straight power supply pins 34, also called pins. The power supply means then comprise two connection blocks 35, one for each pin 34.

[0053] Each connection block 35 is made of an electrically conductive material, such as copper, while the body 30 of the socket is preferably made of a thermally conductive but electrically insulating material such as an aluminum nitride type ceramic.

[0054] As shown in [Fig. 7], each connection block 35 includes a connection channel 36 for receiving a power supply pin 34. The connection channel 36 is equipped with a clamping jaw 37 for pressing the pin 34 against a wall of the channel 36. In the illustrated example, the clamping jaw 37 is held in the clamping position by a spring 38. "Held in the clamping position" means that the spring 38 pushes the jaw 37 towards the wall of the channel 36 so as to clamp the pin 34 when it is in position there. The spring 38 is complemented by a set screw 39 which is adapted to reversibly lock the jaw in the clamping position of the pin 34 and thus ensure perfect electrical contact between the pin 34 and the connection block 35.

[0055] The implementation of the spring 38 makes it easier to mount the lamp 4 on the socket 3 insofar as the pressure exerted by the spring makes it possible to immobilize the lamp on the socket before tightening the corresponding screw.

[0056] During the implementation of the integrating sphere 1 and its constituent elements as described above, the sockets 3 are, before their assembly, fitted with the lamps 4 and then fixed to the body 2 with the interposition of a thermal paste or seal compatible with a vacuum system. This thermal paste or seal ensures good heat conduction between each socket 3 and the body 2 and thus allows efficient heat dissipation from each socket 3 by the cooling circuit of the integrating sphere 1.

[0057] It should be noted that such a paste or thermal seal is preferably implemented at the level of all the junction surfaces of the different constituents of the integrating sphere 1 according to the invention.

[0058] As previously stated, the sleeves 3 ensure the closure of the windows 15. It is then possible to control the internal atmosphere of the integration chamber 12 by means, for example, of a continuous gas injection, and for this purpose the body 2 includes a channel 41 intended to be connected to a unit not shown adapted to ensure this management. This internal atmosphere management unit of integration chamber 12 can, for example but not exclusively, include a purified gas source.

[0059] During the implementation of the integrating sphere 1 according to the invention and as described above, the cooling circuit, formed in particular by the channels 20, 21, is connected to a cooling unit, not shown, which ensures the supply and circulation of the heat transfer fluid, which can be of any suitable liquid or gaseous nature depending on the application. The heat transfer fluid is then chosen according to the power and operating conditions.

[0060] According to the example described above, the body of the integral sphere 1 is made in two parts. However, the implementation of additive manufacturing makes it possible to consider manufacturing this body 2 in a single block.

[0061] Of course, various other embodiments of the integrating sphere according to the invention can be envisaged within the scope of the annexed claims.

Claims

Demands

1. Integrating sphere comprising a body (2) delimiting an integration chamber and being provided with at least two windows (15, 16) for access to the integration chamber (12) from outside the body (2) characterized in that the body (2) comprises at least one cooling channel (20, 21) for the circulation of a heat transfer fluid.

2. Integrating sphere according to claim 1, characterized in that the body (2) comprises at least two complementary half-bodies (10, 11) which each comprise a part of the integration chamber (12) and at least one cooling channel (20, 21).

3. Integrating sphere according to claim 1 or 2, characterized in that at least one cooling channel extends inside the body (2) over at least a part of the periphery of the integrating chamber (12).

4. Integrating sphere according to any one of claims 1 to 3, characterized in that it comprises at least one cooling chamber (25) which is connected to the cooling channel (20, 21), and which extends over at least a part of the periphery of the integrating chamber (12).

5. Integrating sphere according to the preceding claim, characterized in that the cooling chamber (25) defines with a wall of the integration chamber (12) a double-skin type structure.

6. Integrating sphere according to claim 4 or 5, characterized in that the cooling chamber (25) comprises at least one structure (26) permeable to the heat transfer fluid connecting two opposite internal faces of the cooling chamber (25).

7. Integrating sphere according to claim 6, characterized in that the permeable structure (26) comprises a mesh or porous structure permeable to the heat transfer fluid.

8. Integrating sphere according to any one of the preceding claims, characterized in that the sphere (1) comprises at least one channel for managing the internal atmosphere of the integrating chamber (12)

9. Integrating sphere according to any one of the preceding claims, characterized in that the body (2) is made of a thermally conductive material.

10. Integrating sphere according to any one of the preceding claims characterized in that the body (2) is manufactured by additive machining.

11. Integrating sphere according to one of the preceding claims, characterized in that one of the windows (15) is intended for the installation of a light source (4) and in that the body (2) includes at the level of this window a seat (33) for mounting a socket (3) for supporting a lamp constituting (4) of the light source.

12. Integral sphere according to the preceding claim, characterized in that it comprises a socket (3) for supporting a lamp (4), this socket being removably adapted to the mounting seat.

13. Integrating sphere according to claim 11 or 12, characterized in that the socket (3) comprises a body (30) comprising at least two connection blocks (35) each intended to receive a power supply pin (34) for the lamp (4).

14. Integrating sphere according to claim 13, characterized in that each connection block (35) comprises a connection channel (36) intended to receive a lamp supply pin (34) and equipped with a clamping jaw (37) of the pin locked in clamping position by a spring (38) completed by a pressure screw (39) adapted to reversibly immobilize the jaw (37) in the clamping position of the supply pin (34).

15. Integrating sphere according to any one of claims 12 to 14, characterized in that the body of the socket is made of thermally conductive and electrically insulating material.

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