1975-2015: 40 years ago the company "Eltec Instruments", the U.S.A., manufactured the world's first pyroelectric detector based on a single crystal such as lithium tantalate. A new thermal capacity equation for obtaining the thickness of a crystal in the voltage mode is given. A new boundary condition for the equation is given as well. Geometry of the crystal in both voltage and current mode is compared.
Ключові слова: pyroelectric detector, optimization, time constants, heat flux