Patent Application
20130182121
The present invention relates to a mirror, a casing and an infrared device and to a method of manufacturing the mirror and a method of manufacturing a casing comprising such a mirror.
Infrared or thermal image cameras are increasingly used like, for example, for localizing heat insulation leaks in a building. Lenses made of special materials are employed in the optics for infrared or thermal image cameras, since glasses for the visible range of light absorb long-wavelength infrared radiation. Zinc-selenium, germanium or silicon compounds are frequently used when, for example, manufacturing infrared optics for wavelengths from 8 μM to 14 μm.
Recently, special glasses made on the basis of germanium, like Amtir® or Gasir®, are employed when manufacturing the optics for infrared cameras. Due to the usage of these materials or glasses, the lenses can be pressed so that the production process is cheaper than when using zinc-selenium, germanium or silicon compounds, however, the basic materials required, like, for example, germanium, still are relatively expensive. Another way of reducing the manufacturing costs for infrared or thermal image cameras is employing reflective optics, like, for example, a mirror, in the infrared optics instead of refractive optics, like, for example, a lens. When using conventional mirrors for manufacturing infrared or thermal image cameras, no significant advantages as to costs result since mirror optics for such systems employed in the infrared range are produced by processing a surface by means of grinding or turning, diamonds being employed here as tools. These manufacturing processes are very expensive due to the tools necessary, so that the manufacturing costs for such mirrors and/or mirror optics are high.
It is the object of the present invention to provide a mirror, a casing comprising a mirror, and an infrared device which can be manufactured in a cost-effective way, and a method of manufacturing same.
This object is achieved by a mirror of claim 1, a casing of claim 9, an infrared device of claim 21, a method of claim 27 and a method of claim 29.
The present invention provides a mirror having a doubly curved surface formed by pressing or casting.
Furthermore, the present invention provides a casing comprising a mirror having a doubly curved surface formed by pressing or casting.
In addition, the present invention provides an infrared device comprising an infrared sensor or an infrared source and a mirror having a doubly curved surface formed by pressing or casting.
Additionally, the present invention provides a method of manufacturing a mirror having a doubly curved surface which includes pressing or casting a pressing or casting material into a mold.
Also, the present invention provides a method of manufacturing a casing comprising a mirror having a doubly curved surface formed inside the casing, the method including pressing or casting a pressing or casting material into a mold such that the doubly curved surface will form inside the casing.
The present invention is based on the realization that a mirror having a doubly curved surface, which is, for example, suitable for being used in an infrared system, may comprise a higher surface roughness than a conventional mirror, so that this mirror may be formed by pressing or casting. That is how the manufacturing costs for such mirrors can be reduced, thereby lowering the manufacturing costs for infrared or thermal image cameras.
It is of particular advantage in infrared systems or thermal image cameras which are frequently employed in wavelength ranges of 3 μm to 5 μm and/or 8 μm to 14 μm that surface precisions in a range of one eighth, or 12.5%, to one fourth, or 25%, of the respective wavelength are sufficient to produce imaging optics adequate for the field of application so that a mirror for such a usage in an infrared device can be pressed or cast in a cost-effective manner. A surface precision achieved when pressing or casting, which, for example, is in a range from 0.3 μm to 3 μm and/or at roughly 1 μm, is sufficient for a mirror employed in an infrared system so that such a mirror of considerably reduced manufacturing costs can be employed in an infrared device. The roughness or surface roughness indicates to which extent the shape of the surface is allowed to deviate from the ideal shape.
Such infrared systems are provided with optics comprising at least one mirror having a doubly curved surface. However, two or even more mirrors are arranged in embodiments of other infrared systems, since they allow an additional degree of freedom when constructing the optics, which is accompanied by an increased flexibility when designing the setup of the optics. At the same time, imaging characteristics can be improved by using several mirrors in an infrared system and/or casing which is, for example, used in an infrared system. Due to the fact that two or more mirrors are used in embodiments of infrared systems of this kind, the cost proportion of mirrors in such systems is increased. In infrared systems of this kind, the manufacturing costs may be reduced by forming the mirrors having the doubly curved surface by means of pressing or casting, wherein the cost reduction, in proportion, manifests itself to an even greater extent in the overall manufacturing costs. Thus, the manufacturing costs for such infrared systems may, proportionally, be reduced even more.
It is of further advantage that free-form areas may be used for rectifying or correcting higher-order imaging errors when forming the mirrors, wherein bodies having such free-form areas may be formed easily by pressing or casting and only manufacturing such a pressing mold or casting mold entails increased costs, whereas a plurality of suitably set-up mirrors having corresponding free-form areas may be manufactured by the pressing or casting molds produced in this way. Thus, the manufacturing costs for such infrared systems may be reduced to a particularly noticeable extent. This results from the fact that a conventional production of mirrors by means of turning or grinding is very complicated and expensive, whereas, when using a corresponding pressing or casting mold when producing, the manufacturing costs may be reduced such that they are equivalent to that of mirrors the shape of which can be described by a single curve, or singly curved mirrors.
Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:
Thus, the interior of the infrared optics 11 is protected from penetrating humidity or dirt particles, wherein penetrating humidity or dirt particles might impede the functionality of the infrared optics. An infrared sensor 17 is arranged on the second side wall in which the second opening 13b is formed, the infrared sensor 17 serving for detecting impinging infrared radiation or thermal radiation in its intensity or position.
A surface of the casing 13 facing the interior of the infrared optics 11 forms a first mirror 19 characterized by a doubly curved surface, the surface being curved relative to two mutually perpendicular axes. Furthermore, the surface of the casing 13 facing the interior of the infrared optics 11 is, in another region, characterized by a double curvature so that a second mirror 21 is formed in the other region of the surface. The double curvature of the surface or inner surface of the casing 13 in the region of the mirrors 19, 21 is also characterized by a curvature or linear curve relative to two mutually perpendicular axes.
An infrared ray L1 entering the interior of the casing through the transparent lid 15 or in the incidence region of the casing 13 impinges on and is deflected by the first mirror 19 such that, in its further course, it impinges on 21 and is deflected by the second mirror such that it reaches, in its further course, the infrared sensor 17. The infrared sensor 17 detects and captures the impinging first infrared ray L1. In addition, a second infrared ray L2 entering through the transparent lid 15 is deflected by the first mirror 19 and the second mirror 21 to the infrared sensor 17 such that the sensor 17 detects the second infrared ray L2, too.
The infrared optics 11 according to an embodiment of the present invention shown in
Of particular advantage in the infrared optics according to a first embodiment of the present invention is the fact that the mirrors 19, 21, in contrast to a telescope setup, which will be discussed in an embodiment of infrared optics below, are not opposite each other, so that the non-opposite mirror areas may be manufactured by casting or pressing a suitable material into a corresponding mold. Since the mirror areas are not opposite each other, simple molds may be used for realizing the double curvature of the surfaces. The mutually offset mirrors 19, 21 are also referred to as offset mirrors.
In addition, it is of particular advantage in the setup of the infrared optics 11 that the first mirror 19 is opposite the first opening 13a and the second mirror 21 is opposite the second opening 13b. Thus, the infrared optics 11 may be manufactured easily by pressing or casting a plastic material into a precast mold and by subsequently vapor-depositing a metal, like, for example, aluminum, onto a surface facing the interior of the casing through the first opening 13a or the second opening 13b, so that a reflective layer of the aluminum material will form on the surface of the casing in a region of the first mirror 19 and a region of the second mirror 21, respectively.
A cross-sectional view of further infrared optics 31 in accordance with a second embodiment of the present invention is discussed in
In contrast to the infrared optics 11 in accordance with a first embodiment of the present invention shown in
In contrast to the infrared optics 11 in accordance with a first embodiment of the present invention shown in
In contrast to the infrared optics 11 shown in
The back wall mirror 57 is exemplarily embodied by a reflective layer deposited on a surface of the back wall of the casing 13 facing the interior of the casing, or the back wall 13 itself is made of a reflective material. The surface of the back wall mirror 57 has a double curvature or curvature relative to two mutually perpendicular axes, wherein the surface can be produced easily by pressing or casting the back wall material into a mold. An interior mirror 59 the surface of which also has a double curvature is arranged in the interior of the casing 13.
The infrared rays L1, L2 are incident on the interior of the casing 13 through the first transparent cap 53a and the second transparent cap 53b and impinge on the surface of the back wall mirror 57. From there, they are deflected to the surface of the interior mirror 59 and, from there, are influenced in their course or deflected such that they impinge on the infrared sensor 17 arranged over the back wall opening 55. The infrared optics shown in
Apart from the infrared optics 11, 31, 51 discussed in
The infrared optics 71 comprise a window 73 which is mounted in a recess of the front side wall of the casing 13, and a mirror 75 deposited on a surface of the back side wall of the casing 13 facing the interior of the casing. A surface of the mirror region 75 is doubly curved or comprises a curvature relative to two mutually perpendicular axes, wherein the mirror region, similarly to the mirrors 19, 21, 57, 59, is produced by applying a reflective layer onto the back wall of the casing, or is formed by pressing or casting a reflective material, like, for example, aluminum, into a mold so that the casing 13 forms.
The surface of the mirror region 75 is shaped such that the infrared rays L1, L2 incident through the incident region or window 73 impinge on and are deflected or reflected by the surface of the mirror region 75 facing the interior of the casing such that they impinge on the sensitive region of the infrared sensor 17. The arrangement of the infrared optics 71 shown in
After having shown above four embodiments of infrared optics in accordance with the present invention, a setup of a mold 80 for manufacturing the casing 13 for the infrared optics 11 will be discussed in
Furthermore, in one embodiment of the mold 80, the surfaces or inner faces of the mold 80 are of a double curvature such that a doubly curved surface is produced or formed in a subsequent step of pressing or casting.
For manufacturing the infrared optics 11, a casting material, like, for example, plastic, is cast or pressed into the mold 80 serving as a tool such that the setup of the infrared optics 11 shown will form. Depending on the material, the surfaces serving as mirrors are metallized following pressing or casting. Metallization exemplarily takes place by means of vapor-depositing aluminum on the surface. If, however, the casing itself is made of a reflective material, like, for example, aluminum, this step will no longer be required.
After manufacturing the casing 13, the infrared sensor or image sensor or the transparent lid 15 or protective lid is mounted to the casing 13 and thus connected thereto. The infrared sensor 17 or the lid 15 may be mounted to the casing 13 in a cheap manner by means of molding-in, gluing or clicking-in.
In the infrared optics 11, 31, 51, 71, one or two mirrors 19, 21, 57, 59, 75 are arranged inside the casing 13. However, any numbers of mirrors serving to deflect the infrared rays L1, L2 may be used alternatively. The mirrors 19, 21, 57, 59, 75 have a doubly curved surface, wherein a ratio of the radii of curvature relative to mutually perpendicular axes may exemplarily be in a range from 0.1 to 10. Reflectivity of the mirrors 19, 21, 57, 59, 75 may exemplarily be in a range of greater than 0.9 or range of more than 90%. However, any ratios of the radii of curvature to each other and any reflectivity values would be conceivable in further embodiments of the mirrors. It would also be conceivable for the mirrors 19, 21, 57, 59, 75 to have a curvature of their surfaces relative to two different, not mutually perpendicular axes.
The mirrors 19, 21, 57, 59, 75 may be implemented such that they reflect infrared radiation of a wavelength in a range from 3 μm to 5 μm or 8 μm to 14 μm, which means that the reflectivity for infrared rays in this range of wavelengths has a value of greater than 0.9, wherein the reflectance value for a light ray of a wavelength of less than 0.7 μm may exemplarily also be in a range below 0.5. However, any characteristics of the mirrors 19, 21, 57, 59, 75 may be used alternatively in dependence on a wavelength of the infrared radiation or light.
A surface roughness of the mirrors 19, 21, 57, 59, 75 exemplarily is in a range from 0.3 μm to 3 μm or 0.125 times to 0.25 times a wavelength of a reflected infrared ray flux the wavelength of which exemplarily is in a range from 3 μm to 5 μm or a range from 8 μm to 14 μm, however, any mirror surface roughness values may be used alternatively. The mirrors 19, 21, 57, 59, 75 are manufactured such that they exemplarily are embodied to be integral with the casing 13 by forming the casing 13 of, for example, a reflective material, like aluminum, tin, glass or plastic, or vapor-depositing a reflective layer onto the inner face of the casing, wherein the reflective layer may exemplarily be embodied to be made of an aluminum material, a silver material or a glass material. However, any methods of manufacturing the mirrors 19, 21, 57, 59, 75 or the casing 13 comprising the mirrors mentioned which comprise a step of pressing or casting may be used alternatively. Methods of manufacturing the mirrors in which the mirrors are not deposited onto an inner face of a casing but are produced on any doubly curved surface by means of any step of depositing, such as gluing or vapor-depositing, are also conceivable. A reflective foil may, for example, be glued onto the doubly curved surface of a basic body, the reflective layer may be deposited by means of sputtering, or a reflective material may be deposited onto the doubly curved surface by means of galvanizing. It would even be conceivable to produce the mirror by means of depositing a dye onto the curved surface.
The lid 15, the transparent caps 53a, 53b or the window 73 is/are made of a translucent or infrared-transparent material which may exemplarily also differ from a material of the casing 13. Any materials of which the lid 15, the transparent caps 53a, 53b and the window 73 may be made are also conceivable. In the infrared optics 11, 31, the first side wall and the second side wall are arranged such that they are in parallel orientation to each other or such that the surfaces thereof enclose an angle in a range from 170 to 190°. The same also applies to an orientation of the front wall and the back wall in the infrared optics 51 and the front side wall and the back side wall in the infrared optics 71, respectively. However, in other infrared optics according to further embodiments of the present invention, any arrangements to one another of the walls mentioned are conceivable.
In the infrared optics 11, 31, the third side wall is arranged to be perpendicular to the first side wall or the second side wall or arranged such that the surfaces of the third side wall and the first side wall or the second side wall enclose an angle of 80° to 100°. However, any arrangements of the third side wall to the first side wall or the second side wall are conceivable in further embodiments of the infrared optics 11, 31.
In the infrared optics 11, 31, 51, 71, the lids 15, 33, 53a, 53b, 73 are mounted to the side wall of the casing 13 by means of molding-in, gluing or clicking-in, however, any methods of mounting the lid to the casing 13 are conceivable. Also, in further embodiments of the infrared optics 11, 31, 51, 71, the infrared sensor 17 may be mounted completely inside the casing 13, in a recess in the wall of the casing or to the side wall of the casing 13.
The mirrors 13, 19 in the infrared optics 11, 31 are arranged such that they are offset to each other, however, any arrangements of the mirrors 19, 21 may be used alternatively. In addition, the mirrors 19, 21 in the infrared optics 11, 31 are arranged such that they are arranged opposite the openings 13a, 13b and overlap same in a line of vision perpendicular to the side wall of the casing 13, however, any arrangements of the mirrors 19, 21 in the casing 13 may be used alternatively.
The casing 13 and/or the mirrors 19, 21, 57, 75 are exemplarily manufactured by pressing or casting a pressing material or a casting material into the mold 80. The mold 80 here includes the two parts or pieces 81, 83 which comprise the projecting portions 85, 87. However, any configurations of the pieces 81, 83 and any setups of the mold 80, like, for example, in one piece, are conceivable.
Embodying the windows and/or lids 15, 73 or caps 53a, 53b in the infrared optics 11, 31, 51, 71 such that they are able to influence the optical path of the infrared rays L1, L2 and may thus be used as correction plates would also be conceivable. The window may be produced of silicon, a plastic material or any material transparent for the infrared radiation. Here, the lid 15, 73 may also be embodied to be a lens, like, for example, a Fresnel lens.
In the casing 13, a region of the surface inside the casing may be patterned such that a reflectance for an infrared ray flux impinging on the patterned region on the surface is less than for an infrared ray flux impinging on the mirror 19, 21, 57, 59, 75, wherein grooves may exemplarily be arranged in the region of the patterned surface. Thus, a ratio of the reflectance of the surface in the patterned region and a reflectance in the region of the mirror 19, 21, 57, 59, 75 in an impinging infrared ray flux, the wavelength of which exemplarily is in a range of 3 μm to 5 μm or a range of 8 μm to 14 μm, may be between 0.1 and 0.7. However, any embodiments of the surface inside the casing 13 may be used alternatively.
This application is a national phase entry of PCT Patent Application Serial No. PCT/EP2007/004062, filed 8 May 2007, and is incorporated herein in its entirety by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2007/004062 | 5/8/2007 | WO | 00 | 3/5/2010 |
