application of polyimide kapton heater


application of polyimide kapton heater

Both instruments calibrate  data to radiance using  a two-point temperature calibration.  The strict  volume constraints imposed on SUCHI because of its satellite bus drove the design of an innovative blackbody shutter calibration system (Figure 4).  Teflon-coated, vacuum compatible iris shutters were used to minimize volume consumed by the calibration system.  The blackbody shutters are heated using low-profile Kapton heater  modules and temperature is monitored by analog temperature transducers to maintain knowledge of blackbody temperature to within 0.5° C.  SUCHI employs four shutters, two located between the interferometer and the relay optic for flat field correction, and two located at the end of the stack beyond the  objective  lens.  One shutter  of  each  pair  is actively heated,  while  the  other  will act as the  “cold” blackbody and will be temperature monitored and allowed to float at ambient.  However, all four shutters are capable of being heated for redundancy in case either of the two designated “hot” blackbodies fails.

The TIRCIS instrument is not subject to the same volume constraints so a traditional blackbody paddle scheme will be employed for radiance calibration (Figure 5).  Two paddles will be actively heated or cooled by thermoelectric modules in order to achieve ideal  “hot” and “cold” calibration temperatures determined by the  scene temperatures of interest.  A third blackbody paddle will be allowed to float at ambient and will be temperature monitored.  Cooling straps will be used to channel excess heat to the chassis in the case of vacuum operation.  A blackbody wheel containing a hot, cold, and  ambient  blackbody again  heated  and cooled  using  thermoelectric  modules  will  also  be  employed  between  the interferometer and relay lens  for flat field correction; however, a goal of this project is to improve removal of fringes from  the  paddle blackbody  data  collects  and use  these  data  for  flat  field correction  to  assess whether  the  interior blackbody can be retired from future designs

 



Wavelength calibration for both sensors to convert from optical path difference on the  detector to wavelength is done using narrow band filters.  Since the interferometer design we employ has no moving parts, once determined, wavelength calibration should  be unchanged during operation.   However, once in  orbit, the continuing  quality of  the wavelength calibration for SUCHI can be checked against the ozone feature at 9.6 microns.