2.2 - Thermopile Sensor Array with Improved Spatial Resolu¬tion, Sensitivity and Image quality

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings IRS² 2011
I2 - IR Arrays & lmaging
B. Forg, F. Herrmann, W. Leneke, J. Schieferdecker, M. Schulze, M. Simon, K. Storck - Heimann Sensor GmbH, Dresden (Germany), F. Völklein - University of Applied Sciences, Wiesbaden (Germany)
42 - 44


This year Heimann Sensor announces the new HTPA64x62 sensor. The sensor is fully pin compatible to the existing HTPA32x31. The HTPA series provides very low time constants of the elements, low noise amplifiers, serial peripheral interface and a high frame rate. Some types also provide an internal ADC.

For improved sensitivity several finite element simulations were done. We examined

- Different pixel designs
- Membrane shapes
- Number of thermopiles
- Influence of filling gas
- Mechanical stability

After simulations we have processed several pixel designs to approve the simulation findings.
The pixels were exposed to our standard packaging process and were checked on their characteristics as well as in vacuum as in different inert gases.
In example, the time constant, SNR and Sensitivity was determined in dependency of the pressure of the surrounding gas.

In fact, there were some interesting conclusions:
The sensitivity cannot be increased to the theoretical maximum, there is an optimum for the number of thermocouples. This effect is mostly due to the increased thermal conductivity of the membrane, and the increased thermal noise, if the numbers of thermocouples are increased.

We used these findings to increase the performance of our already available thermopile arrays significantly.

In example, we were able to increase the sensitivity of our HTPA32x31 with an inert gas filling by the factor of 8…10 and with a reasonable time constant of 7ms only.