fig1 is a schematic illustration of a system using an infrared camera 12 which includes the baffle 10 of the present invention . the camera 12 receives light at its entrance aperture 14 from an optical device 16 which , for purposes of simplicity , is depicted in fig1 as a lens . the optical device 16 is typically a reflecting or refracting telescope . when the camera 12 is used to detect infrared light , the telescope 16 is either a reflecting telescope or a special infrared refracting telescope whose optics are specially designed to pass infrared light . the baffle 10 of the invention will be described below as used in an infrared camera 12 . it will be understood that the baffle 10 is applicable to other imaging systems . the camera 12 is positioned such that the array of infrared detectors 20 is positioned at the image plane 22 of the telescope 16 . light 24 travels from the telescope 16 through the aperture 14 of the camera 12 and then enters the baffle 10 through the baffle input aperture 26 . the aperture 14 of the camera includes a window 18 made of a material such as zinc selenide ( znse ) which is transparent to infrared radiation . the window 18 can also be coated with an optical coating which filters the light 24 by allowing only certain wavelengths of light to reach the detector array 20 . reference numeral 30 refers to the envelope of light rays which travel through the shroud portion 32 of the baffle 10 to strike the detector array 20 . the shroud portion 32 of the baffle 10 is shaped such that it just encloses the envelope 30 of light . that is , space between the inner surface 61 of shroud 32 and the envelope 30 is minimized . the baffle 10 also has an opening or exit aperture 36 at the detector end of the baffle 10 . this opening allows the light to impinge on the detector array 20 at the image plane 22 . the baffle 10 and detector array 20 are enclosed within a vacuum chamber 38 by an enclosure 13 such as a dewar case . the case 13 comprises a valve 44 which can be opened to interface the chamber 38 with a vacuum system 40 via a vacuum line 42 . when the valve 44 is open , the vacuum system 40 is used to evacuate the chamber 38 . when the chamber 38 is evacuated to a desired pressure , the valve 44 is closed and the vacuum system 40 is disconnected from the camera 12 . the detector array 20 is mounted to the top side of a thermally conductive mounting plate or chip carrier 34 . the baffle 10 is also mounted to the chip carrier 34 via a mounting surface 35 of the baffle 10 . four bolts 33 mount the mounting surface 35 of the baffle 10 to the chip carrier 34 via through holes 67 in the mounting surface 35 ( see fig2 ). the chip carrier 34 is physically mounted to the base plate 39 of the case 13 via rigid posts 57 which are typically made of a thermal non - conductive material such as a composite of fiber and glass . a helium cryostat refrigeration subsystem 45 is mounted to the back side of the base plate 39 of the case 13 . the refrigeration subsystem 45 cools the detector array 20 and baffle 10 via its cold finger 46 . the cold finger 46 is physically coupled to the chip carrier 34 by a thermally conductive spring 48 which is connected at one end to the cold finger 46 . when the camera 12 is assembled , the opposite end of the spring 48 contacts the chip carrier 34 . the thermally conductive spring 48 and cold finger 46 conduct heat away from the detector array 20 and baffle 10 . the spring 48 is used instead of direct physical contact between the cold finger 46 and the mounting plate 34 to prevent expansion and contraction effects due to temperature fluctuations from altering the relative physical locations of the detector array 20 and telescope 16 and to prevent stressing the array 20 . electrical signals from the detector array 20 are coupled via lines 50 through a hermetically sealed connector 52 to a processing system 54 which receives and processes signals indicative of light detected by the array 20 . the top portion 41 of the dewar case 13 , which includes the filter window 18 , is secured to the base plate 39 via bolts 11 . an o - ring 43 seals the top 41 to the base plate 39 . a flange 51 of the cryogenic refrigerator 45 is bolted to the base plate 39 of the dewar case 13 by bolts 47 . an o - ring 49 seals the flange 51 to the base plate 39 . as mentioned previously , all warm objects radiate low - energy photons which can be detected by the array 20 . specifically , the inner surfaces of the walls of the dewar case 13 are warm and emit infrared radiation . if the baffle 10 was not present , the infrared photons would strike the detector array 20 and destroy its imaging capability . however , even though the photons are prevented from striking the detector array 20 , they can still strike the outer surface 60 of the baffle 10 . the photons which are absorbed by the baffle 10 heat the baffle 10 and result in an increased load on the refrigerator 45 . to reduce this effect , the outer surface 60 of the baffle 10 is polished and / or coated with a reflective material such as gold to reduce photon absorption by the baffle 10 . the photons are reflected away from the baffle 10 rather than being absorbed by it . it is possible that stray photons can enter the aperture 26 of the baffle 10 . to prevent them from reaching the detector array 20 , the inner surface 61 of the baffle is roughened and blackened so that any photons striking it will be absorbed . fig2 is a perspective view of the embodiment of the baffle 10 of the present invention used in the camera 12 of fig1 . the exit end of the baffle 10 is connected to a mounting surface 35 at the exit aperture 36 . the mounting surface 35 includes four mounting bolt holes 68 used to mount the baffle 10 to the chip carrier 34 shown in fig1 . the baffle 10 is made of a thermally conductive material such as oxygen - free high - conductivity copper ( ofhc ) which is gold plated on its outside surface 60 to make it reflective . the inner surface 61 of the shroud 32 is roughened and blackened such that it absorbs stray photons which enter the baffle 10 . in fig1 dashed lines 71 define the stray light boundary for the camera 12 using the baffle 10 . any stray light rays within this boundary will pass through the window 18 of the dewar case 13 and will strike the detector array 20 . this minimal amount of stray light is acceptable for many applications . however , fig3 illustrates a system which substantially eliminates stray light from the detector array 20 . fig3 is a schematic illustration of another infrared camera 112 using another embodiment 110 of the baffle of the present invention . this camera 112 is placed beyond the image plane 22 of the telescope 16 . rather than a simple ir - transparent window , the camera 112 uses a reimaging lens 111 to alter the path of light at the entrance aperture 114 of the camera 112 . the reimaging lens 111 forms an image of the focal plane 22 of the telescope 16 on the detector array 120 . thus , an image of the telescope far field is rescaled by the reimaging lens 111 and is formed on the detector array 120 . the reimaging lens 111 also forms an image of the aperture of the telescope 16 at the baffle entrance aperture 126 located approximately at the focal point of the lens 111 . thus , the entrance aperture 126 of the baffle 110 is a cold pupil image of the aperture of the telescope 16 . because of the reimaging lens 111 , the shape of the envelope 130 of light rays passing through the camera 112 is different from that of the previous embodiment . as in the previously described embodiment , the shroud 132 of the baffle 110 is shaped to just enclose the envelope 130 of the light rays . this reduces the overall surface area of the baffle 110 , resulting in substantially reduced cooling load . the baffle 110 includes a zinc selenide window 128 across its entrance aperture 126 . as described above , the window 128 is transparent to infrared radiation . in addition , if desired , the window 128 can be coated with an optical coating which provides for selective filtering . the coating is chosen such that the window will pass only desired wavelengths of radiation . the exit aperture 136 of the baffle 110 couples the light to the detector array 120 . the infrared camera 112 is similar to the camera 12 of the previously described embodiment . the detector array 120 and the baffle 110 are both mounted to a chip carrier or mounting plate 134 . the baffle 110 is mounted to the plate 134 by bolts 33 and is enclosed within a dewar case 113 which includes a valve 144 coupled to a vacuum system 40 via a vacuum line 42 . the vacuum system 40 partially evacuates the chamber 138 of the case 113 . the valve 144 is then closed and the camera 112 is detached from the vacuum system 40 . the chip carrier 134 is mounted to the base plate 139 of the dewar case 113 via rigid posts 142 preferably made of a thermally insulating material such as fiberglass . signals from the array 120 are coupled to a processing system 54 via electrical wires 150 which pass through the base plate 139 via a hermetically sealed connector 152 . the top portion 141 of the dewar case 113 , which includes the reimaging lens 111 , is secured to the base plate 139 via bolts 11 . an o - ring 43 seals the top 141 to the base plate 139 . a flange 51 of the cryogenic refrigerator 45 is bolted to the base plate 139 of the dewar case 113 by bolts 47 . an o - ring 49 seals the flange 51 to the base plate 139 . the cold finger 46 of the refrigerator 45 is coupled to chip carrier 134 via the thermally conductive spring 48 . as in the previously described system , this eliminates movement of the detector array 120 relative to the system due to expansion and contraction effects . as with the previous baffle , the inner surface 161 of the baffle 110 is roughened and blackened to absorb stray light photons which enter the baffle 110 . in addition , the outer surface 160 of the baffle 110 is polished and / or coated with a reflective material such as gold to reflect photons which strike the outer surface . the surface area of the baffle 110 is minimized . thus , the number of photons from the warm dewar case walls striking the baffle 110 is minimized . once again , this reduces the refrigerator burden . in addition , the mass of the baffle 110 is also minimized by the shape of the shroud 132 . this also contributes to the reduction in refrigerator burden . fig4 is a schematic perspective view of the baffle 110 used in the camera 112 of fig3 . the baffle 110 comprises the input aperture 126 having the filter window 128 . in addition , a mounting surface 135 at the output aperture 136 is used to mount the baffle 110 to the chip carrier mounting plate 134 via bolt holes 168 . as previously described , the inner surface 161 of the shroud portion 132 is blackened and roughened to absorb stray light photons . the outside surface 160 is polished and / or coated with a reflective material such as gold to reflect photons . it should be noted that the baffles 10 and 110 described herein are directed to a camera having a linear detector array 20 and 120 , that is , a detector array having many times more detectors in one dimension than in an orthogonal dimension . this is most clearly illustrated by the elongated shape of the exit apertures 36 and 136 of the baffles 10 and 110 respectively . such linear arrays are useful in very common scanning systems which move across a scene and image the scene by viewing only a small strip at a time . it should be noted , however , that the baffles of the invention are applicable to two - dimensional arrays of detectors . in systems using such arrays , the size and shape of the exit aperture and shroud of the baffle would be different than those shown in the embodiments described in . for example , in the case of a square detector array , the exit aperture of the baffle would be square . in that case , the shroud portion of the baffle would be approximately conical in shape . the shroud would taper from the circular entrance aperture to the square exit aperture . while this invention has been particularly shown and described with references to preferred embodiments thereof , it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims .