Line-of-sight module

This module takes several Spectrum objects as an input and combines then along the line-of-sight (SerialSlabs()) or at the same spatial position (MergeSlabs()), to reproduce line-of-sight experiments

How to combine slabs?

Along the line-of-sight

Use the SerialSlabs() function:

s1 = calc_spectrum(...)
s2 = calc_spectrum(...)
s3 = SerialSlabs(s1, s2)

You can also use the > operator. The previous line is equivalent to:

s3 = s1 > s2

At the same spatial position

Use the MergeSlabs() function:

Merge two spectra calculated with different species (true only if broadening coefficient dont change much):

from radis import calc_spectrum, MergeSlabs
s1 = calc_spectrum(...)
s2 = calc_spectrum(...)
s3 = MergeSlabs(s1, s2)

You can also use the // operator. The previous line is equivalent to:

s3 = s1 // s2

Practical Examples

Below are some practical examples of the use of the Line-of-sight module:

Build a large spectrum

If you want to calculate a spectrum on a very large spectral range which cannot be handled in memory at once, you can calculate partial, non-overlapping spectral ranges and use MergeSlabs() to combine them. In that case, we tell MergeSlabs() to use the full spectral range and that the partial spectra are transparent outside of their definition range:

from radis import load_spec, MergeSlabs
spectra = []
for f in ['spec1.spec', 'spec2.spec', ...]:  # precomputed spectra
    spectra.append(load_spec(f))
s = MergeSlabs(*spectra, resample='full', out='transparent')
s.plot()

Get the contribution of each slab along the LOS

Let’s say you have a total line of sight:

s_los = s1 > s2 > s3

If you want to get the contribution of s2 to the line-of-sight emission, you need to discard the emission of s3 but take into account its absorption. This is done using the PerfectAbsorber() function, which returns a new Spectrum with all the emission features set to 0:

from radis import PerfectAbsorber
(s2 > PerfectAbsorber(s3)).plot('radiance_noslit')

And the contribution of s1 would be:

(s1 > PerfectAbsorber(s2>s3)).plot('radiance_noslit')