Abstract:
A system and method for measuring radiation. In one embodiment, a radiometer includes an inlet port, a light sensor operatively coupled to the inlet port, and a direction sensor adapted to detect the orientation of the inlet port. In another aspect, a radiometer has a base, a housing pivotally mounted to the base, an aperture in the housing, a radiation sensor in communication with the aperture, and a direction sensor adapted to detect the orientation of the housing relative to the base. In yet another aspect, a radiometer has a housing including at least one aperture, and a radiation sensor adapted to detect the irradiance and direction of origin of radiation entering the aperture. A method is disclosed for detecting the irradiance of radiant energy from a source in at least two dimensions. The method involves the steps of providing a radiometer of the present invention and positioning the radiometer in the path of radiant energy emitted from the source.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to the field of radiometry, with common but by no means exclusive application to radiometric measurement of manufacturing apparata for curing reactive materials. For greater clarity, when used herein, reference to “curable” and “reactive” materials and variations thereof is intended to mean polymeric materials which chemically transform with the application of sufficient energy, unless a contrary intention is apparent.  
         BACKGROUND OF THE INVENTION  
         [0002]    Manufacturing objects containing reactive materials commonly requires consistent power levels and distribution of curing radiation. This is particularly the case if the objects to be cured have narrow tolerance requirements for high quality control, often where reliability for safety or high performance is necessary.  
           [0003]    Curing three dimensional objects raises additional difficulties in terms of measuring the power levels and distribution of the curing radiation in three dimensions.  
           [0004]    Accordingly, the inventors have recognized a need for a system and method which are capable of measuring radiation distribution in at least two dimensions.  
         SUMMARY OF THE INVENTION  
         [0005]    This invention is directed towards a radiometer.  
           [0006]    The radiometer includes an inlet port, a light sensor operatively coupled to the inlet port, and a direction sensor adapted to detect the orientation of the inlet port.  
           [0007]    The invention is further directed towards a radiometer having a base, a housing pivotally mounted to the base, an aperture in the housing, a radiation sensor in communication with the aperture, and a direction sensor adapted to detect the orientation of the housing relative to the base.  
           [0008]    In yet another aspect, the invention is also directed towards a radiometer having a housing comprising at least one aperture, and a radiation sensor adapted to detect the irradiance and direction of origin of radiation entering the aperture.  
           [0009]    In a different aspect, the invention is also directed towards a method of detecting the irradiance of radiant energy from a source in at least two dimensions. The method involves the steps of providing a radiometer of the present invention and positioning the radiometer in the path of radiant energy emitted from the source. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The present invention will now be described, by way of example only, with reference to the following drawings, in which like reference numerals refer to like parts and in which:  
         [0011]    [0011]FIG. 1 is a side schematic view of a first embodiment of the radiometry system made in accordance with the present invention.  
         [0012]    [0012]FIG. 2 a top perspective view of a curing system configured to emit radiation in an arc of approximately 360°.  
         [0013]    [0013]FIG. 3A is a logical flow diagram of a multi-step curing method employed in using the curing system made in accordance with the present invention.  
         [0014]    [0014]FIG. 3B is a side schematic view of the radiometry system of FIG. 6, in use.  
         [0015]    [0015]FIG. 4 is a graph of the measured irradiance of radiation correlated to angle of origin emitted by the curing system of FIG. 2 as detected by the radiometry system of FIG. 1.  
         [0016]    [0016]FIG. 5A is a side schematic view of a second embodiment of the radiometry system made in accordance with the present invention.  
         [0017]    [0017]FIG. 5B is a close-up schematic view of an alternate configuration of a reflector which may be used in the radiometry system of FIG. 5A.  
         [0018]    [0018]FIG. 6 is a side schematic view of a third embodiment of the radiometry system made in accordance with the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Illustrated in FIG. 1 is a first embodiment of the radiometry system of the subject invention. The radiometry system, shown generally as  10 , includes a housing  12 , an inlet port  14 , a radiation sensor  16 , a controller  18  and a display  20 .  
         [0020]    The housing  12  is generally cylindrical in shape and comprises an upper assembly  22  rotatably mounted to a rotation stage  24 . Preferably the housing  12  is made of metal or other materials which are substantially unaffected by radiation of the type intended to be used in association with the radiometry system  10 . As will be understood, the rotation stage  24  functions as a direction sensor and detects the orientation of the upper assembly  22  (preferably correlated specifically to the inlet port  14 ) relative to the rotation stage  24 , and generates corresponding orientation data which is received by the controller  18 . As well, the rotation stage  24  preferably also comprises orientation markings (not shown) to assist the user in correlating the orientation of the upper assembly  22  relative to the rotation stage  24 . The inlet port  14  generally comprises a radiation passageway through the housing  12  in the upper assembly  22 , typically in the form of an aperture.  
         [0021]    The upper assembly  22  comprises a substantially tubular interior chamber  26  which contains a cladded glass rod waveguide  28  having a centred longitudinal axis  30  and fixed in position within the chamber  26 , for example through the use of a set-screw  32  through the housing  12 . The waveguide  28  is typically tubular, and more preferably substantially cylindrical. As will be understood, while the waveguide  28  has been described as being made of cladded glass, other materials suitable for acting as a waveguide may be used. Proximate the inlet port  14 , the waveguide  28  comprises an angled face  34 , facing away from the inlet port  14 , as illustrated in FIG. 1.  
         [0022]    As will be understood, the angle  38  of the face  34  (relative to the longitudinal axis  30 ) is selected based on the index of refraction of the material forming the waveguide  28  and the angle of the radiation entering the inlet port  14  (represented by vector  36 ). The angle  38  must be formed such that the angle that the incident radiation  36  makes with the normal of the face  34  is beyond the critical angle for the glass-air interface. In the instant example in which the waveguide  28  is of cladded glass and the incident radiation  36  is perpendicular to the longitudinal axis  30 , the angle  38  of the face  34  is 45°, such that the incident radiation  36  is reflected  900  upwards towards the radiation sensor  16  by total internal reflection.  
         [0023]    As well, the face  34  preferably comprises a diffusing surface, such as through the application of a diffusion coating, to obtain an isotropic irradiance measurement, as will be understood by one skilled in the art.  
         [0024]    The upper assembly  22  may also comprise a recessed region  40  which is sized and shaped to receive a radiation emitting apparatus, such as the curing cylinder  200  illustrated in and discussed in relation to FIG. 2. At the indented portion, the housing  12  is generally narrow in diameter. Preferably the recessed region  40  is sized to enable the inlet port  14  to be positioned proximate the radiation emitter ports on the radiation emitting apparatus, while still allowing the upper assembly  22  to rotate with respect to the radiation emitting apparatus. As well, the recessed region  40  typically extends completely around the housing  12 . As will be understood, the curing cylinder  200  or other radiation emitting apparatus to be tested by the radiometry system  10  is fixed in position relative to the rotation stage  24 .  
         [0025]    The upper assembly  22  may further comprise two upper assembly segments  22   A  and  22   B . The upper segment  22   A  is detachably mountable to the lower segment  22   B , such as by threaded mounting or friction fitting the two segments  22   A  and  22   B  together at the top of the recessed region  40 . Such a configuration facilitates the positioning of the radiometry system  10  within a small location such as the radiation chamber  214  of the curing cylinder  200 , discussed below in relation to FIG. 2.  
         [0026]    The radiation sensor  16  may typically comprise a photodiode or an array of photodiodes or other devices capable of detecting irradiance and generating corresponding irradiance data. As will be understood, the controller  18  comprises memory storage and a suitably programmed CPU configured to receive and correlate orientation data and irradiance data from the rotation stage  24  and radiation sensor  16 , respectively. The display  20  is operationally coupled to the controller  18  and may comprise a display screen, printer or other suitable device for presenting the correlated orientation and irradiance data to the user.  
         [0027]    As will be understood, the angular resolution of the radiometry system  10  may be varied by altering the cross-sectional size of the inlet port  14 . As will also be understood, the housing  12  and other components of the system  10  may be very compact in size, enabling the system  10  to take radiometry measurements within narrow spaces.  
         [0028]    It should also be noted that when the upper assembly  22  is rotated by the rotation stage  24 , the inlet port  14  transcribes a circular arc. Accordingly, as will be understood the radiometry system  10  may be used to detect the irradiance of curing radiation impinging on the surface of an object to be cured (such as a syringe or fibre optic cabling), having a circumference substantially equivalent to the circular arc transcribed by the inlet port  14 . Correspondingly, the diameter of the housing  12  proximate the inlet port  14  may be sized to closely match the diameter of specific objects being cured.  
         [0029]    Referring now to FIG. 2, illustrated therein is a cylindrical curing apparatus illustrated generally as  200 , and which may be similar to the curing apparatus illustrated and described in co-pending U.S. patent application Ser. No. 98/873,199. The curing cylinder  200  has a housing  210  and an inlet port  212  for receiving radiation from a radiation emitting device (such as a light guide). The curing cylinder  200  also typically has several emitter ports positioned on the interior wall of the irradiation chamber  214 . The irradiation chamber  214  is generally a tubular passageway into which objects to be cured may be inserted. As will be understood, the emitter ports are operatively coupled to the inlet port  212  and are configured to emit the received radiation radially inwardly and substantially about an arc of 360°. As noted above, the irradiation chamber  214  may closely match the dimensions of the recessed region  40  of the radiometry system  10 .  
         [0030]    [0030]FIG. 3A depicts the method, shown generally as  300 , employed in using the radiometry device  10 ,  600  (discussed below in relation to FIG. 6) of the present invention to test the uniformity of radiation emitted by a radiation source. In use, the radiation emitting apparatus (such as the curing cylinder  200 ) is positioned with its emitter port(s) proximate the inlet port  14 ,  614  typically by detaching the upper segment  22   A ,  622   A  from the lower segment  22   B ,  622   B  and inserting the lower segment  22   B ,  622   B  within the irradiation chamber  214 , and rejoining the upper and lower segments  22   A ,  622   A ,  22   B ,  622   B . Preferably, the upper assembly  22 ,  622  is concentrically positioned within the irradiation chamber. (Block  302 ) The radiation emitting apparatus is then fixed in relation to the rotation stage  24 ,  624  while allowing the upper assembly  22  to freely rotate. (Block  304 )  
         [0031]    The radiation emitting apparatus is then caused to emit radiation through its emitter port(s). (Block  306 ) While the apparatus continues to emit radiation, radiation is received by the inlet port and directed to the radiation sensor  16 , which senses the power of the received radiation, and generates corresponding irradiance data (based on the cross-sectional area of the inlet port  14 ,  614 ) which is received by the controller  18 . (Block  308 ) The upper assembly  22 ,  622  is then rotated to enable the inlet port  14 ,  614  to receive radiation from different orientations (and preferably over a range of orientations) relative to the emitting apparatus, and the rotation stage  24 ,  624  generates orientation data which is received by the controller  18 ,  618 . In the case of the curing cylinder  200  which is configured to emit radiation substantially about an arc of 360°, the upper assembly  22 ,  622  is preferably rotated through 3600°. (Block  310 ) In the case of the radiometry system  600 , the jack stage  625  may then be raised (or lowered as appropriate) to different vertical positions. At each vertical position, the rotation stage  624  may be rotated as discussed in relation to Block  310 . (Block  311 ) The controller  18 ,  618  then correlates the orientation and irradiance data (and the vertical position data, in the case of controller  618 ), which are displayed to the user by the display  20 ,  620 . (Block  312 )  
         [0032]    Illustrated in FIG. 3B is a side schematic view of a radiometry system  600  (described in greater detail in relation to FIG. 6, below) in use. The upper assembly  22  of the radiometry system  600  is positioned within the irradiation chamber  214  of a curing cylinder  200 . The curing cylinder  200  is held in fixed position relative to the radiometry system  600  through the use of a clamp  250 . The clamp  250  and radiometry system  600  are both preferably mounted to a workbench  252  or other suitable working surface. A radiation generating apparatus  260  is also provided, having a waveguide  262 , such as a liquid light guide, coupled to the inlet port  212  of the curing cylinder  200 .  
         [0033]    Referring now to FIG. 4, illustrated therein is a graph illustrating irradiance correlated to orientation, detected by a radiometry device  10  from a curing cylinder  200 . On the graph, the irradiance data has been normalized in a range from 0 to 1, and has been captured in  100  increments (as indicated by the square data points). As indicated on the graph, the curing cylinder  200  tested by the radiometry device  10  has eight emitter ports (represented by peaks A-H), approximately evenly distributed around the irradiation chamber  214 . However, the irradiance data also indicates a lack of uniformity in the levels of irradiance emitted by the various emitter ports A-H. As can be seen, the irradiance levels indicated for emitter ports B, C are approximately only 75% of the irradiance at emitter port G. This lack of uniformity may be sufficient to indicate that the curing cylinder  200  is defective.  
         [0034]    Illustrated in FIG. 5A is a second embodiment of the radiometry system of the subject invention. The radiometry system, shown generally as  500 , includes a housing  512 , an inlet port  514 , a radiation sensor  516 , a controller  518  and a display  520 .  
         [0035]    The housing  512  is roughly cylindrical in shape and preferably is made of metal or other materials which are substantially unaffected by radiation of the type intended to be used in association with the radiometry system  500 . The housing comprises an upper assembly  522  detachably mounted to a base  524 , as will be explained in greater detail below.  
         [0036]    The inlet port  514  generally comprises a radiation passageway through the housing  512 , typically in the form of an annular aperture circumscribing all or a substantial portion of the housing  512  perimeter. However, as will be understood, the passageway could comprise radiation transmissive material such as glass or plastic which has been selected to transmit the radiation. The inlet port  514  could also comprise a plurality of apertures which collectively extend substantially around all or a substantial portion of the periphery of the housing  512 . As will be understood, the configuration of the inlet port  512  may be selected to correspond to the emission pattern of a radiation emitting device.  
         [0037]    The housing  512  comprises a tubular interior chamber  526  which contains a cladded glass rod waveguide  528  having a longitudinal axis  530  and fixed in position within the chamber  526 , for example through the use of a set-screw  532  through the housing  512 . The waveguide  528  is typically tubular, and more preferably substantially cylindrical. As will be understood, while the waveguide  528  has been described as being made of cladded glass, other materials suitable for acting as a waveguide may be used.  
         [0038]    A substantially conical reflector  535  is positioned proximate the inlet port  514 . The reflector  535  may be made of polished aluminum and is preferably a right circular cone positioned proximate the inlet port  514  and aligned with the longitudinal axis  530 . A radiation transmissive support sleeve  537  may be adhered to the bottom of the waveguide  528  and also to the outer periphery of the reflector  535  near its base. The support sleeve  537  is made of a material such as plastic which provides sufficient structural integrity to support the weight of the upper assembly  522 . The reflector  535  may in turn be mounted to a support  539  which may be detachably mountable to the base  524 , typically by friction fitting or by threading into a socket in the base  524 . As will be understood, the angle  538  of the reflector  535  is selected based on the angle of the radiation entering the input port  514  (represented by vectors  536 ). In the instant example in which the incident radiation  536  is substantially perpendicular to the longitudinal axis  530 , the angle  538  of the reflector  535  is 45°, such that the incident radiation  536  is reflected 90° upwards towards the radiation sensor  516 .  
         [0039]    The upper assembly  522  may also comprise an indented portion  540  which is sized and shaped to receive a radiation emitting apparatus, such as the curing cylinder  200  illustrated in and discussed in relation to FIG. 2. At the indented portion, the housing  512  is generally narrow in diameter. Preferably the recessed region  540  is sized to enable the inlet port  14  to be positioned proximate the emitter ports on the curing cylinder  200 . As will be understood, the curing cylinder  200  or other radiation emitting apparatus to be tested by the radiometry system  10  is fixed in position relative to the upper assembly  522 . As will also be understood, the recessed region  540  may be inserted within the irradiation chamber of the curing cylinder  200  by detaching the upper assembly  522  from the base  524 .  
         [0040]    The radiation sensor  516  will preferably comprise an array of photodiodes or other devices capable of detecting irradiance and generating corresponding irradiance data. As will be understood, each photodiode in the array will correlate to angle of orientation from which the incident radiation  536  has entered the inlet port  514 . The controller  518  comprises memory storage and a suitably programmed CPU configured to receive irradiance data from each photodiode in the radiation sensor  516  array, and determine the corresponding orientation data. The display  520  is operationally coupled to the controller  518  and may comprise a display screen, printer or other suitable device for presenting the correlated orientation and irradiance data to the user.  
         [0041]    In use, the inlet port  514  is positioned proximate the emitter port(s) of a radiation emitting apparatus (such as the curing cylinder  200 ). This is typically accomplished by detaching the upper assembly  522  from the base  524 , and inserting the indented portion  540  within the irradiation chamber  214 , and remounting the upper assembly  522  to the base  524 . The radiation emitting apparatus is then fixed in relation to the housing  512 .  
         [0042]    The radiation emitting apparatus is then caused to emit radiation through its emitter port(s). The emitted radiation is received by the inlet port and directed to the array of photodiodes in the radiation sensor  516 , which senses the power of the received radiation impinging on each photodiode, and generates corresponding irradiance data correlated to each photodiode which is received by the controller  518 . The irradiance data is calculated through correlating the field of view of each photodiode to the corresponding portion of the inlet port  514 . The controller  518  then determines orientation data based on the location of each photodiode in the array and correlates the orientation and irradiance data, which are displayed to the user by the display  520 . As will be understood, the radiation sensor  516  and the controller  518  may also be adapted to detect the total irradiance of received radiation  536  (from all angles) and display data to the user on the display  520  correlated to the total power of the radiation  536 .  
         [0043]    Illustrated in FIG. 5B is an alternate configuration of a reflective cone and surrounding components which may be used in the second embodiment of the radiometry system  500 . To improve the quantity of radiation detected by the radiation sensor  516 , a conical reflector  535 ′ having a concave surface capable of reflecting incident radiation  536 ′ from a broader range of angles than substantially perpendicular to the longitudinal axis  530 . The curve of the concave surface may preferably be parabolic or elliptical. The inlet port  514 ′ may also be beveled to allow a broader angular range of radiation to be received. The surface of the cone  535 ′ may be adapted to diffuse the incident radiation  536 ′, to obtain an isotropic irradiance measurement by the radiation sensor  516 . Additionally, to improve the signal-to-noise ratio of the radiation detected by the sensor  516 , the waveguide  528  may be replaced with a lens  541  or other imaging optics to focus the incident radiation  536 ′.  
         [0044]    With appropriate changes to the controller  518 , the radiometry system  500  may also include a jack stage similar to the jack stage  625  discussed with respect to FIG. 6, below.  
         [0045]    Referring now to FIG. 6, illustrated therein is a third embodiment of the radiometry system, shown generally as  600 . The system  600  is generally similar to the radiometry system  10 , illustrated in FIG. 1, and includes a housing  612 , an inlet port  614 , a radiation sensor  616 , a controller  618  and a display  620 .  
         [0046]    The housing  612  is generally cylindrical in shape, preferably without a recessed region  40  of the type illustrated in FIG. 1. In addition to having an upper assembly  622  rotatably mounted to a rotation stage  624 , the rotation stage  624  is also mounted to a jack stage  625 , which is capable of raising and lowering the upper assembly  622 . As will be understood, the jack stage  625  functions as an elevation sensor and detects the relative vertical position of the upper assembly  622  (preferably correlated specifically to the inlet port  614 ), and generates corresponding vertical positioning data which is received by the controller  618 .  
         [0047]    The upper assembly  622  comprises a substantially tubular interior chamber  626  which contains a cladded glass rod waveguide  628  having a longitudinal axis  630  and fixed in position within the chamber  626 .  
         [0048]    The upper assembly  622  may further comprise two upper assembly segments  622   A  and  622   B . The upper segment  622   A  is detachably mountable to the lower segment  622   B , such as by threaded mounting or friction fitting the two segments  622   A  and  622   B  together. Such a configuration facilitates the positioning of the radiometry system  10  within a small location such as the radiation chamber  214  of the curing cylinder  200 .  
         [0049]    As will be understood, the controller  618  comprises memory storage and a suitably programmed CPU configured to receive and correlate vertical position data, orientation data and irradiance data from the jack stage  625 , the rotation stage  624  and radiation sensor  616 , respectively.  
         [0050]    Thus, while what is shown and described herein constitute preferred embodiments of the subject invention, it should be understood that various changes can be made without departing from the subject invention, the scope of which is defined in the appended claims.