Erora opisena optical and tomography data and associated MATLAB scripts

Biophotonic nanostructures in butterfly wing scales remain fascinating examples of biological functional materials, with intriguing open questions regarding formation and evolutionary function. One particularly interesting butterfly species, Erora opisena (Lycaenidae: Theclinae), develops wing scales that contain three-dimensional photonic crystals that closely resemble a single gyroid geometry. Unlike most other gyroid-forming butterflies, E. opisena develops discrete gyroid crystallites with a pronounced size gradient hinting at a developmental sequence frozen in time. Here, we present a novel application of a hyperspectral (wavelength-resolved) microscopy technique to investigate the ultrastructural organisation of these gyroid crystallites in dry, adult wing scales. We show that reflectance corresponds to crystallite size, where larger crystallites reflect green wavelengths more intensely; this relationship could be used to infer size from the optical signal. We further successfully..., These data sets were collected using hyperspectral microscopy, microspectrophotometry and x-ray tomography. 
For hyperspectral microscopy, illumination was provided by a Zeiss Axioscope 5 microscope collimated white LED source or a halogen light source (OSL2, Thorlabs) that was passed through a collimating lens (OSL2COL, Thorlabs) and a shortpass filter (FESH0750, Thorlabs). The collimated light was passed through a tunable bandpass filter (Kurios, Thorlabs Inc.), and a quartz depolariser to counteract any polarisation effect of the liquid crystal filter (DPU-25, Thorlabs; a schematic diagram is shown in Figure 1A). The tunable bandpass filter was controlled over the serial interface by custom software written in MATLAB 2023a (The MathWorks Inc., USA). The bandwidth was set to medium, delivering a restricted spectrum of light with a full width at half-maximum (FWHM) of approximately 18 nm (Figure 1B). Samples were illuminated with wavelengths between 430–720 nm in 10 nm steps. For each ..., , # *Erora opisena* optical and tomography data and associated MATLAB scripts

[https://doi.org/10.5061/dryad.w0vt4b912](https://doi.org/10.5061/dryad.w0vt4b912)

This data set contains reflectance data of single-wing scales measured using hyperspectral microscopy and microspectrophotometry as well as two tomography data sets of a single-wing scale.

## Description of the data and file structure

Reflectance data measured using hyperspectral microscopy presented in Figure 2 is calculated using the dark data, the sample data, and the reference data which are all included in MATLAB files each containing one variable that is a three-dimensional matrix where each page is an image taken under a specific wavelength of light.

Dark data is contained within the following files:
dark_10x_HSM.mat
dark_20x_1_HSM.mat
dark_50x_1_HSM.mat

Sample data is contained within the following files:
scales_10x_HSM.mat
scales_20x_1_HSM.mat
scales_50x_1_HSM.mat

Reference data is contained within the following fi...