Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instrumentation for solar spectropolarimetry: state of the art and
  prospects   Given its unchallenged capabilities in terms of sensitivity and spatial
resolution, the combination of imaging spectropolarimetry and numeric Stokes
inversion represents the dominant technique currently used to remotely sense
the physical properties of the solar atmosphere and, in particular, its
important driving magnetic field. Solar magnetism manifests itself in a wide
range of spatial, temporal, and energetic scales. The ubiquitous but relatively
small and weak fields of the so-called quiet Sun are believed today to be
crucial for answering many open questions in solar physics, some of which have
substantial practical relevance due to the strong Sun-Earth connection.
However, such fields are very challenging to detect because they require
spectropolarimetric measurements with high spatial (sub-arcsec), spectral (<100
mA), and temporal (<10 s) resolution along with high polarimetric sensitivity
(<0.001 of the intensity). We collect and discuss both well-established and
upcoming instrumental solutions developed during the last decades to push solar
observations toward the above-mentioned parameter regime. This typically
involves design trade-offs due to the high dimensionality of the data and
signal-to-noise-ratio considerations, among others. We focus on the main three
components that form a spectro-polarimeter, namely, wavelength discriminators,
the devices employed to encode the incoming polarization state into intensity
images (polarization modulators), and the sensor technologies used to register
them. We consider the instrumental solutions introduced to perform this kind of
measurements at different optical wavelengths and from various observing
locations, i.e., ground-based, from the stratosphere or near space.

21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat