I’m not a great tea drinker but there are plenty of people I know who are seriously into brewing their optimal ‘cuppa’.
Today’s invention is a pretty simple way to ensure that they get a beverage which is neither insipid nor stewed.
A waterproofed LED is held by a clip at a fixed distance from a small mirror which reflects light back to a sensor beside the light source. All of this is clipped to the inside of one’s cup. Having added a teabag and some hot water, to cover the sensor, the user waits for the tea to reduce the optical transmissability of the water -to a degree known to correspond to the preferred taste of the drink. This setting can be changed for different users, of course. A similar setup could be used for any infusion-based drink (eg coffee).
Then add milk (if necessary).