Investigation and design of tunable zoom lenses in the near infrared (NIR) imaging application

Abstract

Optical zoom systems have been found to make ways into many

applications. They have been developed for better flexibility. They have found an

many fields including military systems, machine vision and others. Infrared

radiations are invisible radiation ranging from about 750 nanometres, just longer

than red in the visible spectrum, to Irnillimeter, shorter than the micro waves. It is

classified into Near-infrared, Short-wavelength Infrared, Mid-wavelength Infrared,

Long-wavelength Infrared and Far-infrared.

According to the ISO specifications, Near Infrared (NIR) ranges from 750

nanometres to 3000 nanometres. For more than two decades research has been

made in Mid and Far Infrared Imaging. Since then there have been many

advancements in this field. Due to the recent developments in the field of detectors

for SWIR range, there has been an importance for zoom lenses in this range.

Commercially available systems for the NIR Imaging applications are mostly Fixed

Focal Length Lenses or Non-Continuous Variable Focal Length Lenses. Hence, a

Tuneable Zoom Lenses are necessary. Currently, intense research is being made to

develop a system which has a variable zoom for Short wavelength Infrared.

The main aim of this dissertation is to successfully design and develop a

continuous Zoom lens system which will work in the Near Infrared wavelength

range with the optical elements available for the visible spectrum using ZEMAX

software and to investigate the Optical performance such as Modulation Transfer

Function (MTF) and spot radius.