Reference temperature ranges and the possibility of filters/attenuators etc.
My industrial PM5xx and 6xx cameras have two temperature ranges plus the option of a third
Range 1 covers -40C to +120C
Range 2 covers +80C to +500C
Range 3 covers +500 to +1500C or +2000C depending on fitted filter/attenuator.
The change between Range 1 and Range 2 initiates a full auto-recalibration cycle with the NUC shutter engaged.
No additional filter or attenuator is inserted in the optical path.
Changing to Range 3 activates the
mechanical insertion of a high temperature filter/attenuator to extend the measuring capability to 1500C or 2000C depending upon the filter/attenuator fitted. The camera then carries out a full auto calibration with NUC shutter activated
IIRC the additional filter/attenuator sits between the NUC shutter and the Micro-bolometer. I will upload an image of the PM series optical block so that readers may see the implementation.
Update: Image of PM570 optical block added.
In the image the parts are as follows, from left to right:
Micro-bolometer block / Hi Temp filter & mechanism / NUC shutter & mechanism / Focus Lens / Primary Lens.
The Hi Temp filter mechanism is operated by a motor via the silver disc that has a wire crossing its face. The NUC shutter is operated by a solenoid driven bell crank rotating a horizontal shaft to which the shutter is attached. Hence the loud 'Clunk' when these cameras operate the NUC. These industrial cameras are built to last in extreme conditions so are very much over engineered when compared to something like the Ex series. The NUC shutter is so much simpler in more modern consumer grade cameras ..... hence no loud 'Clunk'
the focus lens is internal to the PM series cameras and controlled via a joystick and motorised linear actuator. The PM695 is the same mechanics but has a 'through the lens' auto focusing capability as well.
Finally..... the 1500C high temperature optional filter is fitted to all PM series cameras when manufactured. It is enabled through a software upgrade. An expensive mechanism to provide in every camera and then not use, but then these cameras cost a great deal of money and the activation of the Hi Temp option was an eye watering cost for just a software setting.