1. A method for early diagnosis of Alzheimer, comprising: a) generate a Terahertz signal; b) split the Terahertz signal to a scanning system and an optical arrangement; c) feed a signal passing though the optical arrangement to a Terahertz detector; d) illuminate the eye lens with a focused scanning Terahertz beam from the scanning system; e) redirecting the reflection of the eye lens into the Terahertz detector; f) inserting the output of the Terahertz detector to an amplifier; g) inserting the output of the amplifier to a control and display system; h) wherein the method measures the amyloid layer of the eye and provides an early diagnosis of Alzheimer's disease.