Sensor and double integration method for capturing thermal patterns

A method for capturing a thermal pattern by a sensor comprising a plurality of pixels each comprising at least one heat-sensitive measuring element, the sensor further comprising:

• at least one heating element configured to heat said at least one heat-sensitive measuring element of at least one pixel of the plurality of pixels during a measurement by said at least one heat-sensitive measuring element of said at least one pixel;
• at least one reading circuit configured to read the electrical charges outputted by said at least one pixel during a measurement by said at least one heat-sensitive measuring element of said at least one pixel;
• the method comprising, for each pixel of the plurality of pixels, the implementation of at least the following steps:
• heating said at least one heat-sensitive measuring element of said each pixel during a heating duration starting at a time t0 and ending at a time t2 later than the time t0;
• first reading of the electrical charges outputted by said each pixel during a first measurement duration starting at a time t1 and ending at a time t3 later than the time t1, and giving a first measurement value x1 corresponding to the electrical charges read during the first measurement duration t3−t1;
• second reading of the electrical charges outputted by said each pixel during a second measurement duration starting at a time t4, later than the time t3, and ending at a time t5 later than the time t4, and giving a second measurement value x2 corresponding to the electrical charges read during the second measurement duration t5−t4;
• calculating a difference x1−α·x2, with a corresponding to a positive real number,
• wherein more than half of the heating duration is implemented during the first measurement duration and less than half of the heating duration is implemented during the second measurement duration, and wherein the time t2 occurs before the time t5 such that the second reading of electrical charges outputted by said each pixel is implemented at least partly during a cooling of said each pixel.