Research interests

• Solar energy
• Nonimaging optics
• Numerical optimization

Journal papers

• H. J. D. Johnsen, J. C. Miñano, and J. Torgersen, “Line-focus solar concentration 10 times higher than the 2D thermodynamic limit”, in Optics Express, 2022.
• H. J. D. Johnsen, A. Aksnes, and J. Torgersen, “Beyond the 2D limit: Étendue-squeezing line-focus solar concentrators”, in Optics Letters, 2020.
• H. J. D. Johnsen, A. Aksnes, and J. Torgersen, “High-performance stationary solar tracking through multi-objective optimization of beam-steering lens arrays”, in Optics Express, 2020.

Conference papers

• V. Stubberud, A. Santamaría, H. J. D. Johnsen, “Designing freeform Fresnel lenses with continuous facets,” in Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XIX, 2024.
• W. Cassarly, H. J. D. Johnsen, “Mixing rod with embedded mirrors,” in Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XIX, 2024.
• V. Stubberud, M. Steinert, and H. J. D. Johnsen, “Democratising dry adhesion development with consumer-grade AM”, in Proceedings of the Design Society, 2024.
• H. J. D. Johnsen, J. Torgersen, “High-concentration freeform microtracking concentrators with single-axis external tracking,” in AIP Conference Proceedings 2841, 2023
• H. J. D. Johnsen, J. C. Miñano, “In search of a sharper line focus: Rotating the étendue,” in Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XVIII, 2022.
• H. J. D. Johnsen, A. Aksnes, and J. Torgersen, “Pushing the limits of beam-steering lens arrays,” in Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XVI, 2019.
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “High-concentration wide-angle tracking integration with stacked lens arrays,” in 15th International Conference on Concentrator Photovoltaic Systems (CPV-15), 2019.
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “Solar tracking using beam-steering lens arrays,” in Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XV, 2018.

Teaching

• TMM4150 Machine Design and Mechatronics (fall 2024)
• TPK4125 Mechatronics (spring 2024, spring 2023)
• MAST2001 Machine Elements 1 (fall 2022)
• TMM4112 Machine Elements (part of spring semester 2022)

Awards

• “Young Scientist Award” at The 18th International Conference on Concentrator Photovoltaics (CPV-18), 2022.

Other work

• H. J. D. Johnsen, “A visual tour through the nonimaging optics literature,” SPIE Optics + Photonics 2024, 2024. (Presentation. Recording)
• H. J. D. Johnsen, “Freeform beam-down secondary concentrators for heliostat fields,” SPIE Optics + Photonics 2024, 2024. (Presentation. Recording)
• H. J. D. Johnsen, “Non-imaging Secondary Mirrors for Heliostat Fields,” Norwegian Electro-Optics Meeting, May 23, 2024. (Presentation)
• H. J. D. Johnsen, J. C. Miñano, “Rethinking the Secondary Concentrator: A High-Concentration Retrofit for Linear Solar Collectors,” SolarPACES 2022, 2022. (Presentation)
• H. J. D. Johnsen, “The fascinating optics behind solar concentration,” TRANSNET Project Workshop. Zaragoza, Spain, 2022. (Invited Presentation)
• H. J. D. Johnsen, “Improved line-focus solar concentration through étendue rotation,” Norwegian Electro-Optics Meeting, 2022. (Presentation)
• H. J. D. Johnsen, J. C. Miñano, “In search of a sharper line focus: Rotating the étendue,” SPIE Optics + Photonics 2022, 2022. (Presentation)
• H. J. D. Johnsen, and J. Torgersen, “High-Concentration Freeform Microtracking Concentrators with Single-Axis External Tracking,” The 18th International Conference on Concentrator Photovoltaics (CPV-18), 2022. (Presentation. Slides)
• H. J. D. Johnsen, J. C. Miñano, and J. Torgersen, “Towards a High-Concentration Line-Focus Concentrator: Étendue-Squeezing and Tracking Integration?,” SolarPACES 2021, 2021. (Poster. Recording, PDF)
• H. J. D. Johnsen, “New approaches to solar tracking and concentration through numerical optimization of lens arrays,” PhD Defence Presentation, 2020. (Presentation. Recording)
• H. J. D. Johnsen, “Using the coldness of space: radiative cooling and power conversion,” PhD Defence Trial Lecture, 2020. (Presentation. Recording)
• H. J. D. Johnsen, A. Aksnes, and J. Torgersen, “Beam-steering lens arrays and ètendue-squeezing: a pathway towards a new class of solar concentrators?,” SPIE Optics + Photonics 2020, 2020. (Presentation. Recording, Slides)
• H. J. D. Johnsen, A. Aksnes, and J. Torgersen, “Pushing the limits of beam-steering lens arrays,” SPIE Optics + Photonics 2019, 2019. (Presentation. Recording, Slides)
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “Design and fabrication of beam steering lens arrays through raytracing and maskless grayscale lithography,” 10th Annual Workshop of the Norwegian PhD Network on Nanotechnology for Microsystems, 2019. (Presentation)
• H. J. D. Johnsen, A. Aksnes, and J. Torgersen, “High-Concentration Wide-Angle Tracking Integration with Stacked Lens Arrays,” The 15th International Conference on Concentrator Photovoltaics (CPV-15), 2019. (Presentation. Slides)
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “Tracking-Integrated Solar Energy Using Stacked Lens Arrays,” Norwegian Solar Cell Conference (NSCC) 2019, 2019. (Poster)
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “Beam-steering lens arrays for solar tracking,” First NTNU Young Researcher Clean Energy Symposium, 2019. (Presentation)
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “Beam-steering lens arrays for solar tracking,” NTNU Nano Symposium 2018, 2018. (Presentation)
• H. J. D. Johnsen, J. Torgersen, and A. Aksnes, “Solar tracking using beam-steering lens arrays,” SPIE Optics + Photonics 2018, 2018. (Presentation. Recording)
• H. J. D. Johnsen, “Interview: Håkon J. Dugstad Johnsen – Beam steering lens array for solar cooking,” SunPod podcast, 2018. (Podcast Interview)
• H. J. D. Johnsen, J. Torgersen, and O. J. Nydal, “Beam Steering Lens Array for Solar Cooking,” The 10th International SolarZentrum Conference for food quality, solar cooking, drying, farming, and gardening, 2018. (Invited Presentation)
• H. J. D. Johnsen, J. Torgersen, and O. J. Nydal, “Beam Steering Lens Array for Solar Cooking,” Consolfood 2018, 2018. (Presentation. Slides)