Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Approximate magnifying perfect lens with positive refraction   We propose a device with a positive isotropic refractive index that creates
an approximate magnified perfect real image of an optically homogeneous
three-dimensional region of space within geometrical optics. Its key ingredient
is a new refractive index profile that can work as an approximate perfect lens
on its own, having a very moderate index range.

7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph