Design method research of a radiation-resistant zoom

XXG

1. Introduction
With the enrichment of zoom optical system design theory and
the continuous improvement of mechanical processing capabilities, the
imaging quality of the zoom optical system is basically comparable to
that of a fixed focus lens [1,2]. In the zoom optical system, adjusting
the cam can continuously change the focal length of the system to make
the imaging magnification of the object change continuously, which
can not only search the interested target in a large range but also track
and observe the object precisely [3,4]. Hence, zoom optical system has
been widely used in many fields, such as target tracking, photography,
and security monitoring [5–7].
In the process of the zoom optical system design, the imaging
quality of the optical system at all focal lengths needs to be considered.
Therefore, the aberration correction of the zoom optical system is often
difficult, especially the chromatic aberration and spherical aberration
at the long focal length [8]. The larger the zoom ratio of the zoom
optical system, the more difficult it is to correct the aberrations of the
optical system. Therefore, in the process of the zoom optical system
design, low-dispersion lenses, aspheric lenses, and diffractive elements
are generally used to improve the image quality. Zhang et al. proposed
to use the harmonic diffractive lens and new aspheric lens for aber
ration correction [9]. Using four harmonic diffractive lenses and four
new aspheric lenses, and using a multi-component full-motion zoomstructure, a 300× visible light zoom optical system was designed; Hou
et al. designed a large aperture zoom projection optical system with
five-element structure, which used two aspheric lenses [10]; Ma et al.
designed a three-step underwater zoom optical system, which used two
aspheric lenses for aberration correction [11]. However, all the lenses
of these zoom optical systems are made of conventional glass materials,
so the life of these zoom lenses is extremely short in the strong radiation
environment.
There are few kinds of radiation-resistant glass materials compared
with conventional glass materials, which is extremely disadvantageous
for the chromatic aberration correction of the zoom optical system. In
addition, there are few reports on the design of zoom optical systems
with specific two kinds of glass materials. Therefore, in order to in
crease the life of the zoom lens in the strong radiation environment,
this paper proposes a method to design a zoom optical system using spe
cific radiation-resistant materials. Aiming at the difficulty of chromatic
aberration correction of the radiation-resistant zoom optical system,
this paper analyzes the configuration selection and initial configuration
established method of the zoom optical system. A 6× continuous zoom
optical system with only two radiation-resistant glass materials Silica
and ZF506 is designed by using the design method proposed in this
paper. The imaging experiment shows that the system has high imaging
quality