Aplanatic THz imaging

Steven T. Griffin; Keith A. Krapels

doi:10.1117/12.777087

15 April 2008 Aplanatic THz imaging

Steven T. Griffin, Keith A. Krapels

Proceedings Volume 6949, Terahertz for Military and Security Applications VI; 69490H (2008) https://doi.org/10.1117/12.777087
Event: SPIE Defense and Security Symposium, 2008, Orlando, Florida, United States

Abstract

Optical systems for THz imaging frequently consist of readily available components - typically a single spherical or parabolic surface. For THz imaging applications, the range is short, due to limitations associated with atmospheric attenuation. For these applications, single spherical and parabolic surfaces are neither stigmatic, aplanatic nor Herschel. As a result, many THz imaging systems exhibit significant image degradation caused by primary aberrations. Further, the short range limitations frequently result in image degradation due to near violation of the paraxial assumption. For improved imaging, an aplanatic system is required. To achieve aplanatism, a minimum of two aspheric surfaces is required. Aplanatism requires stigmatic performance which dictates surfaces that are conic sections of revolution. A minimum of two are required to exhibit stigmatism and meet the sine condition. An improvement of receiver form factor allows for a decrease in optical image distance and an increase in system magnification factor. This significantly improves a number of THz imaging characteristics such as depth-of-field while maintaining the diffraction-limit resolution and reducing the primary objective diameter. Reduction of objective diameter reduces signal strength - principally at the expense of specular reflections. This paper summarizes the results of the optical system design and its incorporation into THz imagers containing THz receivers with improved form factors. Efforts at incorporation of optical zoom will be presented.

Citation Download Citation

Steven T. Griffin and Keith A. Krapels "Aplanatic THz imaging", Proc. SPIE 6949, Terahertz for Military and Security Applications VI, 69490H (15 April 2008); https://doi.org/10.1117/12.777087

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available