ref_index is a Python tool for calculating refractive index of air, under varying atmospheric conditions. Functions for conversion of wave length of light in vacuum to that in air, and vice-versa are also defined.
The code is based on the documentation for the NIST online refractive index of air calculator.
Examples
Refractive index can be calculated using two different equations: one due to Edlén and another due to Ciddor.
>>> ref_index.ciddor(wave=633.0, t=20, p=101325, rh=20)
1.0002716285340578
>>> ref_index.edlen(wave=633.0, t=20, p=101325, rh=20)
1.0002716291691649
>>> ref_index.edlen(wave=633.0, t=20, p=101325, rh=80)
1.0002711197635226
>>> ref_index.ciddor(wave=633.0, t=20, p=101325, rh=80)
1.0002711183472626
>>> ref_index.edlen(wave=633.0, t=60, p=101325, rh=80)
1.0002339748542823
>>> ref_index.ciddor(wave=633.0, t=60, p=101325, rh=80)
1.0002340241754055
Conversion of wave length of light in vacuum to that in air, and vice-versa. Both of these functions use the Ciddor equation, as implemented in ciddor_ri() and ciddor().
>>> ref_index.vac2air(633.0)
632.82500476826874
>>> ref_index.air2vac(632.82500476826874)
633.00000139949032
>>> ref_index.vac2air(np.array([633.0, 550.0, 400.0]))
array([ 632.82500477, 549.84723175, 399.88692724])
>>> x = ref_index.vac2air(np.array([633.0, 550.0, 400.0]))
>>> ref_index.air2vac(x)
array([ 633.0000014 , 550.00000164, 400.00000243])
Note that the reversibility of air2vac() is ~1e-5nm.
Default temperature is 15∘C, pressure is 101325Pa, relative humidity is 0, and CO2 concentration is 450µmole/mole. All these can be changed.
>>> ref_index.vac2air(633.0, t=20, p=100000.0, rh=50)
632.83051710791892
>>> ref_index.air2vac(632.83051710791892, t=20, p=100000.0, rh=50)
633.00000131884678
For more details please see the docstring for the module. Detailed description of the equations can be found in the NIST documentation.
Installation
The module can be installed using pip and easy_install.
pip install ref_index
or,
easy_install ref_index
Requirements:
- Python
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