\[fig:wavelength\] shows the isolated wavelengths identified from the Th-Ar reference frames. These wavelengths and the corresponding Echelle orders are given as input to Zemax using a Python interface. Coordinate breaks in Zemax are placed in such a way that each optic is perturbed separately about the local axis of the component. Then a known perturbation (in positive and negative direction separately) is applied to each optical component in the Zemax model and the perturbed X, Y centroid position is estimated [@zemaxmatlab].

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A common practice is to consider the translational and rotational degrees of freedom for sensitivity analysis. However, the optical components (prism, grating, etc.) of the spectrograph are in the collimated beam, and they are less sensitive to translational perturbation in $X, Y, Z$ directions. Hence, we have analyzed only rotational perturbations. A tilt of $\pm$0.01$^\circ$ in $X, Y,$ and $Z$ direction is considered for this analysis. The rotational perturbations with respect to the slit are given as follows:

-   $X$ perturbation: Movement across the slit length

-   $Y$ perturbation: Movement across the slit width

-   $Z$ perturbation: Movement across the normal to the slit.

Results - RV sensitivity from individual components
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The isolated wavelengths obtained from Th-Ar 