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Grism-based Spectrograph Modeling
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:Version: |version| of |today|
:Author: Yannick Copin Figure: Modeling of 5×5 sources in the detector plane at 10 individual wavelengths, using the SNIFS-R optical configuration. Orders -1 (very top), 0 (undispersed), 1 (middle) and 2 (bottom) are represented. The size of the symbol somehow encodes the blaze function of the spectrograph.
.. raw:: latex \begin{figure}[htbp] \centering \includegraphics{../../_static/SNIFS-R} \caption{\textbf{Figure:} Modeling of 5×5 sources in the detector plane at 10 individual wavelengths, using the SNIFS-R optical configuration. Orders -1 (very top), 0 (undispersed), 1 (middle) and 2 (bottom) are represented. The size of the symbol somehow encodes the blaze function of the spectrograph.} \end{figure} .. .. figure:: _static/SNIFS-R.* .. .. **Figure:** Modeling of 5×5 sources in the detector plane at 10 individual .. wavelengths, using the SNIFS-R optical configuration. Orders -1 (very top), .. 0 (undispersed), 1 (middle) and 2 (bottom) are represented. The size of the .. symbol somehow encodes the blaze function of the spectrograph. Positions and directions ------------------------ * A 2D-position :math:`(x, y)` is encoded in complex number :math:`x + jy = r\,\exp(j\varphi)`. * A 2D-direction :math:`(\theta, \phi)` -- where :math:`\theta` is the angle between the optical axis :math:`Oz` and the propagation direction, and :math:`\phi` the phase in the transverse plane :math:`(Oxy)` -- is encoded in complex number :math:`\tan(\theta)\,\exp(j\phi)`. * A 3D-direction is encoded by the coordinates of the unit-vector :math:`(x, y, z)`. Distortions ----------- * A :class:`distortion.StructuredGrid` is a structured grid of (complex) 2D-positions, with plotting and distortion-adjustment facilities. * :class:`distortion.GeometricDistortion` implements the full Brown-Conrady (achromatic) distortion model, including radial and tangential components of arbitrary orders. * :class:`distortion.ChromaticDistortion` is a minimal lateral-color distortion implementation. Near Infrared Spectrometer and Photometer (NISP) ================================================ Zemax simulations ----------------- The :mod:`spectrogrism` optical model is used to simulate the *Near Infrared Spectrometer and Photometer* (NISP) of EUCLID, mimicking full sky-to-detector Zemax spectroscopic and photometric simulations for a nominal NISP configuration (courtesy J. Zoubian). .. raw:: html :file: _static/run_190315.html .. raw:: htmlFigure: Zemax sky-to-detector multi-order simulation of 17×17 sources in the detector plane at 13 individual wavelengths (outlined symbols) and minimally 1st-order-adjusted optical model using nominal NISP parameters (filled symbols), along with associated 0th- and 2nd-order predictions.
.. raw:: latex \begin{figure}[htbp] \centering \includegraphics{../../_static/run_190315_fit} \caption{\textbf{Figure:} Zemax sky-to-detector multi-order simulation of 17×17 sources in the detector plane at 13 individual wavelengths (\emph{outlines symbols}) and minimally-adjusted optical model using nominal NISP parameters (\emph{large symbols}), along with 0th- and 2nd-order predictions.} \end{figure} .. .. figure:: _static/run_190315_fit.* .. .. **Figure:** Zemax sky-to-detector 1st-order simulation of 17×17 sources in .. the detector plane at 13 individual wavelengths (*small symbols*) and .. minimally-adjusted optical model using nominal NISP parameters (*large .. symbols*). .. topic:: Questions regarding the current Zemax simulation: * input y-coordinates are offset by +0.85 deg * output y-coordinates are not centered: (dx, dy) = (+0.7, 179.8) mm, corresponding to (+0.7, -4.2) mm for centered y-coordinates * input position (+0.4, +1.25) is missing the 1.85 µm wavelength NISP optical design ------------------- The NISP optical design is presented in [Grupp12]_ and updated in [Grupp14]_ (see :numref:`fig#nisp_optdesign`). .. _fig#nisp_optdesign: .. figure:: _static/NISP_optdesign.png :width: 60% :align: center The EUCLID f#20 to f#10 relay system including filter and grating position (from [Grupp12]_). It consists of: 0. an *f/20* 1.2 m diameter Korsch type three mirror telescope in off-axis configuration 1. the Corrector Lens assembly CoLA (fused silica) 2. depending on the observing mode: **photometric mode (NISP-P)**: a filter with mildly powered spherical entrance surface and flat exit surface (fused silica) **spectroscopic mode (NISP-S)**: a grism with mildly powered spherical entrance surface and binary optic (curved line) grating exit surface (fused silica) These intrinsically static elements are placed in filter/grism wheels with limited position repeatibility. 3. the Camera Lens assembly CaLA (CaF2/S-FTM16/S-FTM16), providing an *f/10* beam. 4. 16 2k×2k IR detectors The objective of this work is to assess the possibility to model in an effective way the NISP-S optical scheme in order to be able to predict multi-order spectrum locations from photometric catalogs. References ========== * :download:`SNIFS optical parametrization <_static/SNFactory-SNIFS-02-002.pdf>` (SNfactory Technical Documentation) * :download:`Redefinition of the blue grating <_static/SNFactory-SNIFS-02-004.pdf>` (SNfactory Technical Documentation) * `Euclid Mission Database