Challenges, constraints and results of lens design in 8-12micron waveband for bolometer-FPAs having a pixel pitch 12micron

Norbert Schuster; John Franks

doi:10.1117/12.2021637

18 June 2013 Challenges, constraints and results of lens design in 8-12micron waveband for bolometer-FPAs having a pixel pitch 12micron

Norbert Schuster, John Franks

Author Affiliations +

Proceedings Volume 8704, Infrared Technology and Applications XXXIX; 870424 (2013) https://doi.org/10.1117/12.2021637
Event: SPIE Defense, Security, and Sensing, 2013, Baltimore, Maryland, United States

Abstract

In the 8-12 micron waveband Focal Plane Arrays (FPA) are available with a pixel pitch of 12 microns or less. High resolution FPAs with VGA, XGA and SXGA resolution should become available at a reasonable price. These will require new lens designs to give the required fields of view. The challenge for the Optical Designer is to design lenses when the pixel pitch of the detector is the same as the wavelength of the light imaged. The lens specification will need to give more thought to the resolution required by the system. A smaller pixel pitch detector defines a requirement for a shorter focal length to give the same field of view. This will have a number of effects upon the lens design. Geometrical aberrations decrease proportionally with the focal length. Reverse telephoto layouts will become more common, particularly when the system has a shutter. The increase in pixel count will require wide field of view lenses which present particular challenges. The impact of diffraction effects on the lens design is considerably increased. The fast F-number causes an increase in the diffraction limit of the system, but also increases geometric aberrations by a cube law. Therefore the balance between the diffraction limited and the aberration limited performance becomes more difficult. The first approach of the designer is to re-use proven designs originally intended for use with 17micron detectors. Some of these designs will have adequate performance at the Nyquist limit of the 12 micron detectors. Even smaller detector pitches, such as 10 micron, will demand new approaches to Infra Red lens design. The traditional approach will quickly increase the number of elements to 3 or even more. This could lead to the lenses with medium fields of view driving the system cost. A close cooperation between the camera developer and lens designer will become necessary in order to explore alternate approaches, such as wavefront coding, in order to reach the most cost effective solution.

Citation Download Citation

Norbert Schuster and John Franks "Challenges, constraints and results of lens design in 8-12micron waveband for bolometer-FPAs having a pixel pitch 12micron", Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 870424 (18 June 2013); https://doi.org/10.1117/12.2021637

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