CITATION INFORMATION Title: 3D-printed fused silica polished to sub-nanometre roughness for lightweight telescope mirrors Lead researcher: Lawrence Bissell[1,2] Co-Investigators: Marta Maria Civitani[2] and Gabriele Vecchi[2] Contributing researchers: Gregory Lister[1,3] and Davide Sisana[2] Principal Investigator: Carolyn Atkins[1] [1] - STFC UK Astronomy Technology Centre, Royal Observatory Edinburgh, EH9 3HJ, UK [2] - INAF Astronomical Observatory of Brera, Merate, 23807 (LC), Italy [3] - University of Manchester, Dept of Mechanical & Aerospace Engineering, M13 9PL, UK Year: 2026 Funder: - UKRI Future Leaders Fellowship ‘Printing the future of space telescopes’ under grants # MR/T042230/1 and MR/Z000238/1 - INAF Mini-Grant "Development of astronomical mirrors by 3D printing of silica glass", Project Code C72B25000150005 One line summary: Data supporting the characterisation (surface roughness and surface form error) of 3D-printed fused silica for future lightweight telescope applications. --- LICENCE CC-BY-NC --- DATA AND FILE OVERVIEW - File tree ## Overview This dataset contains measurements from two complementary experimental studies: - **Comparative study** of the surface roughness of 3D printed fused silica with conventional silica glass when the materials undergo the same lapping and polishing processes - **Lightweight study** of three identical lightweight mirror substrates incorporating a surface-based lattice that were polished and evaluated at different spatial scales. Data includes: - Design files and FEA - Optical microscopy and photography - Surface roughness measurements (multiple instruments) - Surface form measurements (multiple instruments) ## File tree structure #### Key structure logic 01 Comparative -> **Measurement technique** -> **Processing stage** -> **Sample** - **Sample**: - 01 HOQ310 Sample 1 - 02 HOQ310 Sample 2 - 03 Spectrosil 2000 Sample 1 - 04 Spectrosil 2000 Sample 2 - 05 Glassomer Sample 1 - 06 Glassomer Sample 2 An "- Empty" suffix to the folder indicates no measurements were taken. - **Processing stage**: - 01 Initial - 02 Lapping 20T - 03 Lapping 9T - 04 Polishing SC1663 Run 1 - 05 Polishing SC1663 Run 2 - 06 Polishing SC1663 Run 3 - 07 Polishing Opaline - 08 Polishing Suposil Nano Polish These stages correspond to the lapping and polishing runs as defined in the paper's supplementary information. N.B., the prefix is determined by the processing stage rather than the location in the file tree. - **Measurement technique** - 01 Design Files This contains the .step file of the design of the 3D printed sample. - 02 Microscope Images Each data subfolder contains 2x .jpg image files. The folder location within the file tree provides metadata of the processing stage and the sample measured. The suffix (x100 or x500) indicates the magnification of the microscope objective used. - 03 Photos Each data subfolder contains a .heic image file of the samples. The folder location within the file tree provides metadata of the processing stage of the image. - 04 Surface Roughness - SurfTest SJ-210 Each data subfolder contains 10x .txt files. The folder location within the file tree provides metadata of the processing stage and the sample measured. - 05 Surface Roughness - MFT Each data subfolder contains 3x .txt files. The folder location within the file tree provides metadata of the processing stage and the sample measured. The suffix indicates the measurement location on the sample: Pos1 (central); Pos2 (intermediate); Pos3 (near edge). N.B., for the "05 Polishing SC1663 Run 1" processing stage, for samples in set 1 (prefixes: 01, 03, 05), only one measurement was taken (at Pos1). A single measurement was sufficient to show the polishing duration was insufficient. N.B., for the "05 Polishing SC1663 Run 1" and "06 Polishing SC1663 Run 2" processing stages, for samples in set 2 (prefixes: 02, 04, 06), no measurements were taken. Instead, measurements were only taken after Run 3, once the polishing with SC1663 was completed. - 06 Surface Roughness - AFM Each data subfolder contains 3x .txt files. The folder location within the file tree provides metadata of the processing stage and the sample measured. The suffix (100um, 10um, 1um) indicates the field-of-view of the measurement. - 07 Surface Form - CUP Each data subfolder contains 1x .txt file. The folder location within the file tree provides metadata of the processing stage and the sample measured. --- 02 Lightweighted -> **Measurement technique** -> **Processing stage** -> **Sample** - **Sample**: - 01 Sample 1 - 02 Sample 2 - 03 Sample 3 An "- Empty" suffix to the folder indicates no measurements were taken. - **Processing stage**: - 01 Initial - 02 Lapping 20T - 03 Lapping 9T - 04 Polishing SC1663 Run 1 - 05 Polishing SC1663 Run 2 - 06 Polishing SC1663 Run 2 (Ultrasonic Cleaning) - 07 Polishing SC1663 Run 3 - 08 Polishing SC1663 Run 4 - 09 Polishing SC1663 Run 5 - 10 Polishing SC1663 Run 6 - 11 Polishing SC1663 Run 7 - 12 Polishing SC1663 Run 8 - 13 Polishing SC1663 Run 9 - 14 Polishing Opaline - 15 Polishing NanoCERI These stages correspond to the lapping and polishing runs as defined in the paper's supplementary information. N.B., the prefix is determined by the processing stage rather than the location in the file tree. - **Measurement technique** - 01 Design FEA This contains 1x .stl file, 1x .pdf file, and 1x .csv file. - 02 Microscope Images Each data subfolder contains .jpg image files (various numbers). The folder location within the file tree provides metadata of the processing stage and the sample measured. - 03 Photos Each data subfolder contains a .heic image file of the samples. The folder location within the file tree provides metadata of the processing stage of the image. - 04 Surface Roughness - SurfTest SJ-210 Each data subfolder contains 10x .txt files. The folder location within the file tree provides metadata of the processing stage and the sample measured. - 05 Surface Roughness - MFT Each data subfolder contains 3x .txt files. The folder location within the file tree provides metadata of the processing stage and the sample measured. The suffix indicates the measurement location on the sample: 1_avgXX (central); 2_avgXX (intermediate); 3_avgXX (near edge), where XX is either 32 or 64 corresponding to the number of measurements that were averaged. - 06 Surface Form - CUP Each data subfolder contains 1x .txt file. The folder location within the file tree provides metadata of the processing stage and the sample measured. - 07 Surface Form - Zygo Each data subfolder contains 1x .datx file. The folder location within the file tree provides metadata of the processing stage and the sample measured. DATA AND FILE OVERVIEW - File types .step - universal CAD format .stl - universal file format for 3D printing .csv - comma separated variable .pdf - portable document format .jpg - joint photographic expert group .heic - high efficiency image container .txt - text file document --- METHODOLOGICAL INFORMATION - Sample design and manufacture Comparative samples - Year of manufacture/purchase: 2024 - Location: STFC UK Astronomy Technology Centre, Royal Observatory Edinburgh, EH9 3HJ, UK - Materials and suppliers: - 3D printed fused silica (Glassomer GmbH, Germany) - fused quartz (HOQ310; Heraeus, Germany) - fused silica (Spectrosil 2000; Heraeus, Germany) - Design software: COMSOL Multiphysics CAD module (COMSOL Multiphysics, USA) - Sample dimensions: 50 mm diameter, 5 mm thick - Number of samples: - x2 3D printed fused silica - x2 fused quartz - x2 fused silica - Optical prescription: flat Lightweight samples - Year of manufacture/purchase: 2024 - Location: STFC UK Astronomy Technology Centre, Royal Observatory Edinburgh, EH9 3HJ, UK - Materials and suppliers: - 3D printed fused silica (Glassomer GmbH, Germany) - Design software: nTopology (nTopology, USA) - Sample dimensions: 52 mm diameter, 9 mm thick, - Lightweight structure: TPMS diamond lattice with a cubic cell map (10 mm × 10 mm × 10 mm) and a wall thickness of 1 mm. - Number of samples: - x3 3D printed fused silica - Optical prescription: flat - Reference: Lister, G. et al. 2024 - https://doi.org/10.1117/12.3019053 METHODOLOGICAL INFORMATION - Post-processing Comparative samples - Year of post-processing: 2025 - Location: INAF Astronomical Observatory of Brera, Merate, 23807 (LC), Italy - Lapping - Equipment: M.M.8400 lapper/polisher (LAM PLAN, France) + NEW 299 LAM®M’M’ BLUE lapping plate - Abrasive (consumable, stage 1): Microgrit Al2O3 20T (Micro Abrasives Corporation, USA) - Abrasive (consumable, stage 2): Microgrit Al2O3 9T (Micro Abrasives Corporation, USA) - Polishing (stage 1) - Equipment: M.M.8400 lapper/polisher (LAM PLAN, France) + TOUCHLAM®1PU4 polyurethane polishing pad - Abrasive (consumable, stage 1): Super CEROX 1663 CeO2 (Solvay, Belgium) - Polishing (stage 2) - Equipment: M.M.8400 lapper/polisher (LAM PLAN, France) + TOUCHLAM®2TS1 satin woven polishing pad - Abrasive (consumable, stage 2.1): Opaline®CeO2 (Solvay, Belgium) - Abrasive (consumable, stage 2.2): Suposil Nano Polish CeO2 (Pieplow & Brandt GmbH, Germany) Lightweight samples - Year of post-processing: 2024 - Location: INAF Astronomical Observatory of Brera, Merate, 23807 (LC), Italy - Lapping - Equipment: M.M.8400 lapper/polisher (LAM PLAN, France) + NEW 299 LAM®M’M’ BLUE lapping plate - Abrasive (consumable, stage 1): Microgrit Al2O3 20T (Micro Abrasives Corporation, USA) - Abrasive (consumable, stage 2): Microgrit Al2O3 9T (Micro Abrasives Corporation, USA) - Polishing (stage 1) - Equipment: M.M.8400 lapper/polisher (LAM PLAN, France) + TOUCHLAM®1PU4 polyurethane polishing pad - Abrasive (consumable, stage 1): Super CEROX 1663 CeO2 (Solvay, Belgium) - Polishing (stage 2) - Equipment: M.M.8400 lapper/polisher (LAM PLAN, France) + TOUCHLAM®2TS1 satin woven polishing pad - Abrasive (consumable, stage 2.1): Opaline®CeO2 (Solvay, Belgium) - Abrasive (consumable, stage 2.2): Nano-CERI PB CeO2 (Pieplow & Brandt GmbH, Germany) METHODOLOGICAL INFORMATION - Evaluation Comparative samples - Year of evaluation: 2025 - Location [Metrology]: INAF Astronomical Observatory of Brera, Merate, 23807 (LC), Italy - Location [Analysis - Python]: STFC UK Astronomy Technology Centre, Royal Observatory Edinburgh, EH9 3HJ, UK - Inspection equipment: - Keyence digital microscope (Keyence, Japan) - VHX-E100 objective - VHX-E500 objective - Surface roughness: - SurfTest SJ-210 portable surface roughness tester 310 (Mitutoyo, Japan) - λc = 0.8 mm - λs = 2.5 µm - Evaluation length = 4 mm - Point spacing = 0.5 µm - Sampling length = 0.8 mm - Number of sample length = 5 - MicroFinish Topographer (MFT; Optical Perspectives Group, USA) - 10x objective - FOV = 1.100 mm × 0.825 mm - Number of measurements averaged per surface map - 32 for intermediate lapping/polishing runs - 64 for final polishing run - Analysis software: MATLAB - Analysis: removal of 12 square Zernike polynominals and calculate the RMS of the surface height. - Nanosurf FlexAFM (Nanosurf, Switzerland) + C3000 326 control software - FOV (square): 100 µm, 10 µm, and 1 µm - Data sampling: - 512 points per line - 0.5 seconds per line - Tip vibration: - Frequency = 160kHz - Amplitude = 500 mV - Analysis software: Gwyddion data analysis and visualisation software (Department of Nanometrology, Czech Metrology Institute) - Analysis: Standard line alignment correction provided within Gwyddion - Surface Form error: - Characterization Universal Profilometer (Astronomical Observatory of Brera, IT) - Reference: Civitani, M. et al. 2010 - https://doi.org/10.1117/12.863879 - FOV = 45 mm diameter - Sampling grid: 47 × 47 - Analysis software: Python - Analysis: piston, tip, and tilt removal Lightweight samples - Year of evaluation: 2024 - 2026 - Location [Finite element analysis]: University of Manchester, Dept of Mechanical & Aerospace Engineering, M13 9PL, UK - Location [Metrology]: INAF Astronomical Observatory of Brera, Merate, 23807 (LC), Italy - Location [Analysis - Python]: STFC UK Astronomy Technology Centre, Royal Observatory Edinburgh, EH9 3HJ, UK - Finite element analysis: - nTopology (nTopology, USA) - mesh, average element length = 0.25 mm - Material properties: - Young's modulus = 72GPa - Poisson’s ratio = 0.17 - Applied pressure = 3500 Pa (on reflective surface, negative z direction) - Boundary conditions - Base fixed in z - Two edges fixed to prevent rotation - Analysis software: Python with Prysm and Numpy libraries - Analysis: - Z1 to Z3 Zernike removal - Z1 to Z300 Zernike removal - Power spectral density - Inspection equipment: - Keyence digital microscope (Keyence, Japan) - VHX-E100 objective - VHX-E500 objective - Surface roughness: - SurfTest SJ-210 portable surface roughness tester 310 (Mitutoyo, Japan) - λc = 0.8 mm - λs = 2.5 µm - Evaluation length = 4 mm - Point spacing = 0.5 µm - Sampling length = 0.8 mm - Number of sample length = 5 - MicroFinish Topographer (MFT; Optical Perspectives Group, USA) - 10x objective - FOV = 1.100 mm × 0.825 mm - Number of measurements averaged per surface map - 32 for intermediate lapping/polishing runs - 64 for final polishing run - Analysis software: MATLAB - Analysis: removal of 12 square Zernike polynominals and calculate the RMS of the surface height. - Surface Form error: - Characterization Universal Profilometer (Astronomical Observatory of Brera, IT) - Reference: Civitani, M. et al. 2010 - https://doi.org/10.1117/12.863879 - FOV = 45 mm diameter - Sampling grid: 47 × 47 - Analysis software: Python - Analysis: piston, tip, and tilt removal - Zygo 4 inch GPI XP/D 633 nm He:Ne interferometer (Zygo, USA) - Transmission flat: XONOX 4+ PRIME f/∞ (XONOX, Germany) - Mask = 49.6 mm diameter - Analysis software: Python with Prysm library - Analysis: - Z1 to Z3 Zernike removal - Z1 to Z300 Zernike removal --- End of file