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arxiv: 2604.15530 · v1 · submitted 2026-04-16 · 🌌 astro-ph.IM

Sequential and non-sequential Zemax Dynamic Link Libraries for generating image slicer integral field units

Ellen Lee This is my paper

Pith reviewed 2026-05-10 09:19 UTC · model grok-4.3

classification 🌌 astro-ph.IM
keywords image slicerintegral field unitZemaxdynamic link libraryoptical designspectrographIFUSPECTRE
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0 comments X

The pith

Dynamic link libraries let Zemax model image slicer IFUs by transforming surfaces to match fabrication processes.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper implements sequential and non-sequential Dynamic Link Libraries for Zemax OpticStudio to model image slicer integral field units. The DLLs use surface manipulation parameters chosen to match how these slicers are fabricated in practice. They enable accurate modeling of diffraction and full instrument description in a single file rather than many separate configurations. The libraries exactly reproduce the surfaces created by native Zemax transformations. They have been used to replicate the 36-slice image slicer design of the SPECTRE spectrograph for the NASA Infrared Telescope Facility and can also handle transmission and arbitrary grids of surfaces.

Core claim

The paper's core discovery is the implementation of DLLs that efficiently model image slicer IFUs in Zemax. By selecting parameters that align with fabrication processes, the DLLs identically reproduce natively transformed surfaces. This approach has been validated by replicating the SPECTRE facility spectrograph's 36-slice design, and it supports both sequential and non-sequential modes as well as transmission applications.

What carries the argument

Sequential and non-sequential Dynamic Link Libraries (DLLs) that manipulate mirror surfaces to form the image slicer array according to fabrication-matched parameters.

If this is right

  • Full instrument models including diffraction can be kept in one Zemax file.
  • The same method can model other applications requiring grids of surfaces.
  • Optical design of IFUs can start from basic requirements in future tools.
  • Existing designs like SPECTRE can be replicated and verified quickly.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Designers of future integral field spectrographs could reduce time spent switching between configurations.
  • The DLL approach might be extended to other complex optical elements in astronomical instruments.
  • If made available publicly, it could lower the barrier for creating custom IFU designs in Zemax.
  • Further validation on different slice numbers would test scalability beyond 36 slices.

Load-bearing premise

The surface manipulation parameters chosen for the DLLs accurately correspond to real-world fabrication processes and the code works reliably for grids beyond the tested cases.

What would settle it

Running the same image slicer design with native Zemax transformations and with the DLLs and finding mismatches in the resulting spot diagrams, wavefront errors, or diffraction patterns.

Figures

Figures reproduced from arXiv: 2604.15530 by Ellen Lee.

Figure 1
Figure 1. Figure 1: The basic function of an image slicer IFU is to reformat the focal plane into one or more [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Zemax ray trace of SPECTRE’s image slicer IFU. a) The image slicer is placed at the input [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Image and pupil planes in SPECTRE’s IFU. a) At the input focal plane, the positions of the [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Parameters used to define a single slice. All rotations are about the global coordinate system. [PITH_FULL_IMAGE:figures/full_fig_p008_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Comparison of spot diagrams generated for a tilted off-axis parabolic mirror. Units on the x [PITH_FULL_IMAGE:figures/full_fig_p011_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Sag of the SPECTRE’s image slicer IFU generated by the DLLs. A rectangle aperture is [PITH_FULL_IMAGE:figures/full_fig_p012_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Spot diagrams for selected field angles at the focal plane of SPECTRE’s near-infrared [PITH_FULL_IMAGE:figures/full_fig_p013_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Diffraction in SPECTRE’s IFU simulated by physical optics propagation. The intensity [PITH_FULL_IMAGE:figures/full_fig_p014_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Scattering and reflections off of steps in an image slicer generated by the non-sequential [PITH_FULL_IMAGE:figures/full_fig_p015_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Lenslet array with increasing focal lengths at each ring of lenses generated with custom [PITH_FULL_IMAGE:figures/full_fig_p016_10.png] view at source ↗
Figure 12
Figure 12. Figure 12: Conversion between the off-axis angle α and the OAD y0. The red star marks the focal point of the conic and z ′ is the sag at (0, y0), which is computed using equation (1). y0 can be written in terms of α and d shown in the diagram. The same process can be used to find x0 from β. α = 90◦ and β = 90◦ are not considered because the optical path would be deflected by 180◦ , which is unphysical. For κ = −1, t… view at source ↗
Figure 13
Figure 13. Figure 13: Slicer indices defined in equations (52) to (54) and corresponding angles α and β in standard mode. This diagram shows an image slicer with 9 sections of three slices each viewed face on. α is incremented row-wise while β is incremented column-wise. nc is the column index, nr the row index, ns the slice index within a column, and ns,r the slice index within the row. Slices within a given (nc, nr) correspo… view at source ↗
Figure 14
Figure 14. Figure 14: Two of four available angle switching modes. The left shows the surface sag evaluated [PITH_FULL_IMAGE:figures/full_fig_p025_14.png] view at source ↗
Figure 15
Figure 15. Figure 15: Same as Fig [PITH_FULL_IMAGE:figures/full_fig_p026_15.png] view at source ↗
Figure 16
Figure 16. Figure 16: Algorithm for determining which surface is intersected by an incoming ray. This involves [PITH_FULL_IMAGE:figures/full_fig_p028_16.png] view at source ↗
Figure 17
Figure 17. Figure 17: Different cases that are handled by the ray tracing algorithm, shown along one axis for ease [PITH_FULL_IMAGE:figures/full_fig_p029_17.png] view at source ↗
Figure 18
Figure 18. Figure 18: Criteria for determining whether a ray could have hit the image slicer. Let [PITH_FULL_IMAGE:figures/full_fig_p032_18.png] view at source ↗
Figure 19
Figure 19. Figure 19: Diagram showing how to determine whether a ray has intersected a wall between slices. [PITH_FULL_IMAGE:figures/full_fig_p033_19.png] view at source ↗
Figure 20
Figure 20. Figure 20: Surface generated by one of the non-sequential DLLs. The surface is composed of a series [PITH_FULL_IMAGE:figures/full_fig_p037_20.png] view at source ↗
Figure 21
Figure 21. Figure 21: Slice approximated by twelve facets (Nx = 4, Ny = 3). Each facet is composed of two triangles. Prior to generating the triangles, a grid of (x, y, z) coordinates for every slice is calculated and stored. The triangles are then generated by iterating through every facet on the grid and selecting the coordinates at the corners of each facet. Then, those coordinates are sent to a function that will create tw… view at source ↗
read the original abstract

In astronomy, image slicer integral field units (IFUs) are often used in integral field spectrographs to simultaneously record spatial and spectral information. The majority of astronomical instruments, including integral field spectrographs, are designed using the Zemax OpticStudio optical design software. Modeling an image slicer IFU in Zemax traditionally requires using many separate configurations, which is slow, cannot accurately model diffraction, and can prevent one from fully describing their instrument within a single file. This paper presents the implementation of sequential and non-sequential Dynamic Link Libraries (DLLs) that efficiently model image slicer IFUs with a known design. The parameters used to manipulate the surfaces are chosen to match fabrication processes. The DLLs identically reproduce natively transformed surfaces in Zemax and have also been used to replicate the design of SPECTRE, a facility spectrograph with a 36-slice image slicer for the NASA Infrared Telescope Facility. The DLLs also work in transmission and can be used in other applications that require modeling a nearly arbitrary grid of surfaces. In the future, this work may facilitate the creation of an optical design tool for IFUs that starts from basic system requirements.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper presents sequential and non-sequential Dynamic Link Libraries (DLLs) for Zemax OpticStudio that model image slicer integral field units (IFUs) by applying surface manipulations chosen to match fabrication processes. It claims the DLLs identically reproduce native Zemax surface transformations (tilt, decenter, and grid operations) and demonstrates this by replicating the 36-slice image slicer design of the SPECTRE facility spectrograph for the NASA Infrared Telescope Facility. Additional claims include functionality in transmission and applicability to nearly arbitrary grids of surfaces, with potential future use in requirement-driven IFU design tools.

Significance. If the reproduction accuracy holds, the DLLs would offer a practical improvement for astronomical optical design by enabling single-file, diffraction-capable models of complex IFUs, reducing reliance on multiple configurations and supporting instruments like SPECTRE. This addresses a common workflow limitation in Zemax for integral field spectrographs.

major comments (2)
  1. [Abstract] Abstract: the claim that the DLLs 'identically reproduce natively transformed surfaces' is presented without any quantitative validation (e.g., surface RMS error, ray-trace spot diagrams, or wavefront comparisons between DLL and native Zemax models). This absence makes the central reproduction claim unverifiable from the manuscript.
  2. [SPECTRE replication] SPECTRE replication description: no performance metrics, surface coordinate tables, or optical throughput/image quality comparisons are provided to confirm that the DLL-generated 36-slice model matches the original SPECTRE design within fabrication tolerances.
minor comments (2)
  1. The manuscript would benefit from a dedicated section or appendix with pseudocode or key implementation details for the surface transformation algorithms to support reproducibility.
  2. Clarify the range of tested surface grid sizes and any limitations encountered beyond the SPECTRE case.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive review and for identifying areas where additional quantitative evidence would strengthen the manuscript. We address each major comment below and will incorporate the requested validations in the revised version.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the claim that the DLLs 'identically reproduce natively transformed surfaces' is presented without any quantitative validation (e.g., surface RMS error, ray-trace spot diagrams, or wavefront comparisons between DLL and native Zemax models). This absence makes the central reproduction claim unverifiable from the manuscript.

    Authors: We agree that quantitative validation is required to make the central claim verifiable. In the revised manuscript we will add explicit comparisons, including surface RMS error values, ray-trace spot diagrams, and wavefront error metrics, between the DLL-generated surfaces and equivalent native Zemax tilt/decenter/grid transformations. revision: yes

  2. Referee: [SPECTRE replication] SPECTRE replication description: no performance metrics, surface coordinate tables, or optical throughput/image quality comparisons are provided to confirm that the DLL-generated 36-slice model matches the original SPECTRE design within fabrication tolerances.

    Authors: We acknowledge the need for these metrics. The revised manuscript will include surface coordinate tables for the 36-slice model together with optical throughput and image-quality comparisons (spot sizes, ensquared energy) demonstrating agreement with the original SPECTRE design within stated fabrication tolerances. revision: yes

Circularity Check

0 steps flagged

No significant circularity; software implementation paper

full rationale

The paper describes the creation and testing of sequential and non-sequential DLLs for Zemax to model image-slicer IFUs. It states that parameters are chosen to match fabrication processes, that the DLLs reproduce native Zemax surface transformations, and that they have been applied to replicate the SPECTRE 36-slice design. No equations, fitted parameters, or predictions are presented that reduce to the inputs by construction. No self-citations are used to justify uniqueness or load-bearing premises. The work is a self-contained software tool description verified against external benchmarks (Zemax native behavior and an existing instrument design), so the derivation chain contains no circular steps.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The central claim rests on the assumption that surface parameters can be chosen to match fabrication without introducing unmodeled errors and that the DLL approach generalizes beyond the SPECTRE case. No free parameters are explicitly fitted to data in the abstract; the work is an implementation rather than a derivation.

pith-pipeline@v0.9.0 · 5500 in / 1143 out tokens · 40618 ms · 2026-05-10T09:19:40.705405+00:00 · methodology

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Reference graph

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