6/12/2018 Thermal and Multispectral Imaging Optics Lecture 3: - PDF document

6/12/2018 Thermal and Multispectral Imaging Optics Lecture 3: Sensors and Cameras Jörgen Ahlberg Lens, focal plane, focal length Lens, focal plane, focal length Lens materials Transmittance • Transmittance • Durability • Refractive index • Dispersion • Thermal sensitivity • Cost • Weight 1

6/12/2018 Durability: Knoop Hardness Refractive index • High n d -> Thin lens. • VNIR: <2. • TIR: 2-4. Dispersion -> chromatic aberrations Achromatic tuplet Thermal sensitivity Lens materials: Germanium • Expansion • Good for MWIR and LWIR (with AR coating) • Transmittance • Durable (KH 780) • High refractive index (4.0) • Transmittance drops with temperature! 2

6/12/2018 Lens materials: Zinc Selenide Lens materials: Sapphire • Transmits even better than Germanium! • Durable (KH 2200). • KH 120  • Good transmittance in VIS-MWIR. • Toxic Sensor materials Sensors Image sensor – focal plane array (FPA) Calibration and NUC 3

6/12/2018 Narcissus Multi/hyperspectral cameras The data cube Aqcuiring the data cube • Push-broom • Wisk-broom • Staring • Scanning Filter mosaics Multispectral cameras 4

6/12/2018 16-band sensor from IMEC Filter wheels Multi-layer sensors Hyperspectral cameras Diffraction grating Specim 5

6/12/2018 Interferometer Linear variable optical band-pass filter Misalignment & smile Limitations Spectral Spatial Misalignment & keystone Spectral Spatial 6

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