The objective of the present method and apparatus is to provide a portable diagnosis system for a quick and reliable method to examine the conditions of a human eye-lens. The method provides precise and safe technique for the early diagnosis of Alzheimer's Disease (AD) which is not involved brain surgery or biopsy. The detection of deposited layers of amyloid plaque in the eyes of the patient has been discovered to be a possible diagnosis solution. The disclosed method uses terahertz waves instead of laser for scanning the eye of the AD patient to precisely image the amyloid layer non-evasively in real time and to map the deposited plaque with high resolution which can easily distinguish the abnormality of an AD patient with the comparison of the patient eye-lens test to the available signature of a normal person and the signature of a person with common age-related cataracts.