Calibration via the Service menu. - Page 1
Forum section: electronics / general

author: peppy88
author_rank: Regular Contributor
timestamp: July 14, 2023, 03:59:31 pm
content: Has anyone performed a calibration using the service menu of a FLIR camera. I have a few cameras that I can access via ip and use the standard flir creds.I also have a black body calibrator that goes to 500C. I am not versed in how this process works but if I am not mistaken, they basically calculate the RBF values at certain temps?I also see where you can switch calibrations so im guessing you can revert to old calibrations if need be

author: Fraser
author_rank: Super Contributor
timestamp: July 14, 2023, 04:46:17 pm
content: Calibration of FLIR cameras is not normally an option made available to end users of their cameras unless working with a OEM core or a science camera. FLIR like to charge for calibration ! For cameras that FLIR permit user calibration, they detail the process in the supporting document set, as found for TAU when fine tuning the camera for different lenses.For the cameras that I have worked on, calibration takes different forms that are dictated by the performance of the camera and manufacturers calibration routines. Some cameras only require a low and high temperature black body to align the Radiance to a temperature unit curve. This is called a “2 Point” calibration for obvious reasons and is adequate to align a Radiance to temperature conversion curve for non critical temperature measurement applications. Without that calibration present, the camera normally reports “Counts” that are a value of Radiance but not a temperature unit. The temperature that needs to be set on the black body calibration sources is detailed by the manufacturer in the calibration routine. In some cases it might be +10 Celsius and +120 Celsius but in other cases very different temperatures may be needed for high temperature ranges or manufacturers preferences. Some FLIR cameras, such as the SC4000, allow the user to set whatever sensible temperatures they desire on the Blackbodies for a particular temperature range, and then the user tells the calibration software the temperature that is in its field of view. This is great as it provides great freedom when it comes to the black bodies that may be used. Some are variable, whilst others can be fixed temperature or incapable of the temperatures specified by some manufacturers, such as 100 Celsius BB and a calibration routine needing 120 Celsius.I know this does not answer your question but the requirements for calibration differ between FLIR models and FLIR advise of the required temperatures for setting the BB. The SC4000 calibration routine is comprehensive whilst a TAU calibration is quite simple. A science camera calibration routine will often permit the user to create many black body calibration points to correctly align the Radiance to Temperature conversion curve across a temperature range. The result is a very accurate temperature measurement capability. The multiple calibration points are stored in the camera and assigned to the range settings used at the time of calibration. Each range in a camera requires a set of calibration points. In the SC4000 and SC6000 there are many adjustments that may be made to the cameras configuration so a calibration run and associated calibration table is needed for each configuration. There are 4 factory calibration tables that are supposedly fixed (they aren’t) and 4 user calibration tables that may be changed at will. When connected to ResearchIR 4 MAX there are infinite calibration tables available and stored within the PC software that may then be uploaded to the camera at will.I hope this helps a little.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: July 14, 2023, 05:15:49 pm
content: Further to my last……If a camera or core has more than one temperature range, there will be multiple calibration tables that align with those ranges. Manufacturers may populate only the calibration tables that a given camera needs for the provided temperature ranges. This means that temperature ranges that are not enabled in the specific camera may not have an associated calibration table. This means that if the additional temperature range is enabled though manipulation of the cameras configuration, the camera will report “Counts” until such time as a calibration table for that range is created with the calibration routine. We have seen that some FLIR cameras have additional ranges that were not enabled at the time of sale, E30 being an example, yet there is a calibration table present for them. This permits users to enable the additional ranges (through unsanctioned changes to the camera configuration) without needing to go through a calibration routine.Calibration routines can be part of a cameras firmware, as was the case with many FLIR cameras, or an external software application that was heavily controlled and supplied only to official service agents. Without the calibration routine access permissions or external software utilities, it is not normally possible to carry out the calibration of a core or camera. FLIR has removed the calibration routines from recent firmware buildsFraser

author: IR_Geek
author_rank: Regular Contributor
timestamp: July 15, 2023, 12:52:15 pm
content: One of the better books on the topic is "Thermal Infrared Characterization of Ground Targets and Backgrounds" By Pieter A. Jacobs · 2006 There is an earlier version from 1996. There is an entire chapter devoted to calibration depending on your setup. Also "The Art of Radiometry" By James M. Palmer, Barbara Grant · 2010 ... Check google books for free previews.I for one rarely use 'factory' calibrations as I've found them to be lacking for most of my applications. Multiple sensors from multiple vendors with wide variety of optics. As long as you are working within the linear region of your digital counts, then mapping temperature or radiance to counts is straight forward. Radiance should be linear, while temperature will be curved. Depending on your digital bit depth (8, 12, 14) you will have 256, 4096, or 16,384 to work with. If the sensor is setup properly, then staying away from the top and bottom 10% of counts usually works. Remember that digital bit depth DOES NOT equal sensor linear region.Jacob's gives equations for multiple setups such as target and calibration at equal distances and different distances. Really depends on your setup and needs ... apparent or absolute temperature/exitance? I for one like to have the sources and target at the same distance so I can 'cancel' out the atmosphere from the equation.