When SEEK Thermal first released their "SEEK SCAN" system as a countermeasure to the Covid-19 Pandemic, I was interested to see what they had created and how they had overcome some of the challenges of a system intended to measure humans surface temperature with accuracy. Very little was published on the actual technical design at the time so I ha to guess what was inside the casings of the system. Thanks to my finding a brand new SEEK SCAN at a very good price, I will now publish a teardown so that others are no longer guessing about the SEEK Thermal design hardware that 'hides' within the casings.
What follows is my original guess as to the design from having looked at published documentation and images.... was I close, or wide of the mark ? ... let us find out.
It was clear that the SEEK SCAN designers recognised that their camera cores would not be capable of the measurement accuracy required for an application that required the accurate measurement of a humans surface temperature. Their response to this problem was excellent as they used a temperature reference in the thermal cameras field of view that could be used by software to produce very accurate temperature measurements. This technique of using a known temperature source when measuring targets temperatures is well known and understood. A thermal imaging camera normally has a specification stating a measurement accuracy of +/-2C or 2%, whichever is greater. With a temperature reference of known accuracy, this specification may be greatly improved and the level of uncertainty with measurements drops to far more precise levels. In the case of the SEEK SCAN, it is stated as making measurements with an accuracy of +/- 0.3C. Some manufacturers of Covid-19 countermeasure systems tried to operate systems without a temperature reference in the field of view and their measurements were found to be very unreliable. So from the start we see that SEEK Thermal had the right idea regarding creating an accurate temperature measurement system.
The problem with Thermal Camera temperature measurement systems intended for Covid-19 countermeasure duties is cost. The cost of the systems had to be affordable for the intended customer base and predicted sales. SEEK Thermal wanted to keep costs as low as possible to compete in the market segment and this lead to some clever decisions on their part, but more of that later. It was clear to me at the time that the rapid response to the Covid-19 Pandemic would include thermal imaging technology but that new systems would need to be designed, and supplied quickly. For manufacturers it would be both a design challenge and race to bring a product to market before competitors. This would lead to use of current building blocks in novel ways in order to reduce development time. As was seen at the time, manufacturers of thermal imaging cameras adapted their current, proven, products for Covid-19 temperature scanning duties.... some did this well, others not so well !
SEEK Thermal were no different. They already had a well populated stable of thermal imaging products and cores that could be called upon by the R&D team for Covid-19 product development. Whilst the R&D team could have opted to adapt the standard "Classic" mobile phone dongle to their needs and possible use a mobile phone host, they opted to go with a PC Host and associated software. The connectivity to the PC Host was via USB so I deduced that all they needed to do was use the guts of a "Classic" camera or a dedicated core in a new casing. The addition f a USB webcam gave their product dual spectrum capability to aid target positioning, face mask detection and identification, if required. What I was not certain of was whether SEEK Thermal had used the "CLASSIC" dongle camera style of 'open PCB' or the more compact, buy likely more expensive, MOSAIC core package. We shall soon see.
So I had guessed at a USB SEEK Thermal Core and a common USB PCB format Webcam in the SEEK SCAN head.... but it looked too large for just those two modules so maybe there was some image and/or situational processing going on at the camera head ?
Now to the temperature reference.... these are normally called a Black Body temperature reference, source or emitter. They create a known temperature at their emission plate and have known emissivity. As such they may be used to test a thermal cameras temperature measurement accuracy, calibrate a cameras measurement systems or act as a temperature reference in a live measurement system. The challenge when designing such a temperature reference is in creating a unit that remains accurate in varying operating conditions. The units emission plate must stay at the set temperature and be resistant to ambient temperature changes, air movements etc. Modern PID temperature controllers can easily manage the temperature of the emission plate but you do need a decent quality PID controller for the task. The effects of ambient temperature and air movements can be somewhat harder to deal with for the Black Body designer and sometimes compromises are made. The designer may stipulate correct deployment and use of the Black Body in order that it remains accurate, rather than trying to design a Black Body that can cope with anything thrown at it. I was interested to see how SEEK Thermal had addressed this challenge but I could find no information on their Black Body temperature reference. The unit looked very compact and neat but I could not see the construction used within it. I was left to guess that the unit contained a painted aluminium plate on the rear of which a polyimide foil heater was attached and driven by some form of electronic temperature controller. The temperature controller needs to be very accurate in this application so I thought it unlikely to be analogue in nature. A small microcontroller reading a thermistor via its internal ADC, and an output PWM driving the heater via a transistor, came to mind. The unit is fixed temperature so a small microcontroller could easily meet the needs of the unit. The problem I had with the SEEK Thermal design was the lack of depth to the unit. There does not appear to be enough depth to the plate section for insulation around and behind it, to aid temperature stability, and the very open front design does nothing to mitigate air currents impacting heat loss of the emission plate. I was left doubting the real world performance of eth SEEK Thermal Black Body reference design. I was very keen to find out what his within that Black Body's casing but never saw a teardown on line or a description of the design from the owner of such I would have to wait until today to get the answers to some of my questions. The design is not quite as I expected but more of that later
I am not going to delve into the software aspects of this SEEK SCAN system in this teardown as this is a hardware teardown to show how SEEK Thermal created a human body temperature measurement system in a short period of time whilst ensuring that its measurements were useful, rather than the "best guess" of some lesser designs.
Now I am going to be cruel to you, dear reader, it is late here in the UK so I am an going to delay uploading the teardown images until tomorrow .... don't you just hate it when people do this !
Teardown pictures to follow
Fraser
Home
Help
Search
Login
Register
