Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An off-axis, wide-field, diffraction-limited, reflective Schmidt
  Telescope   Off-axis telescopes with unobstructed pupils offer great advantages in terms
of emissivity, throughput, and diffractionlimited energy concentration. For
most telescope designs, implementation of an off-axis configuration imposes
enormous penalties in terms of cost, optical difficulty and performance, and
for this reason off-axis telescopes are rarely constructed. However, for the
reflective Schmidt design, implementation of an off-axis configuration is very
straightforward, and involves only a modest optical penalty. Moreover, the
reflective Schmidt gets particular benefits, avoiding the obstruction of its
large focal plane and support column, and gaining a highly accessible,
gravity-invariant prime focus, capable of accommodating very large
instrumentation. We present an off-axis f/8 reflective Schmidt design for the
proposed 'KDUST' Chinese infrared telescope at Dome A on the Antarctic plateau,
which offers simultaneous diffraction-limited NIR imaging over 1 degree, and
close to diffraction-limited imaging out to 2 degrees for fibre-fed NIR
spectroscopy.

25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th