Probably by detecting near infrared that is transmissive through the stovetop glass. Just like handheld infrared temperature meters. Silica glass is good at transmitting infrared that is not too far below red light frequency.
I love the knobs on this hob/stovetop.
It took me a lot of work to find an induction top with analog[1] knobs for my mum. Touch "buttons" and sliders are always a sign of absolutely shit usability/accessibility in my experience.
[1] well they were actually digital knobs not analog potentiometers: one of the knobs has a fault in the internal optical sensors or something because it can get into a state of flicking between two digital readings.
I love the knobs on this hob/stovetop.
It took me a lot of work to find an induction top with analog[1] knobs for my mum. Touch "buttons" and sliders are always a sign of absolutely shit usability/accessibility in my experience.
[1] well they were actually digital knobs not analog potentiometers: one of the knobs has a fault in the internal optical sensors or something because it can get into a state of flicking between two digital readings.