Optical Design of a Reflecting Telescope for CubeSat

Jin, Ho; Lim, Juhee; Kim, Young‐Ju; Kim, Sanghyuk

doi:10.3807/josk.2013.17.6.533

Cited by 17 publications

(7 citation statements)

References 8 publications

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“…An infrared optical system with four spherical lenses is selected whose basic specification is listed in Table 1 [22][23][24]. There is no reflector in this camera, and every refracted surface figure is spherical.…”

Section: Results Of Focused Infrared Telescopementioning

confidence: 99%

Parameterized Modeling of Spatially Varying PSF for Lens Aberration and Defocus

Wang

Chen

Jia

et al. 2015

Journal of the Optical Society of Korea

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Image deblurring by a deconvolution method requires accurate knowledge of the blur kernel. Existing point spread function (PSF) models in the literature corresponding to lens aberrations and defocus are either parameterized and spatially invariant or spatially varying but discretely defined. In this paper, a parameterized model is developed and presented for a PSF which is spatially varying due to lens aberrations and defocus in an imaging system. The model is established from the Seidel third-order aberration coefficient and the Hu moment. A skew normal Gauss model is selected for parameterized PSF geometry structure. The accuracy of the model is demonstrated with simulations and measurements for a defocused infrared camera and a single spherical lens digital camera. Compared with optical software Code V, the visual results of two optical systems validate our analysis and proposed method in size, shape and direction. Quantitative evaluation results reveal the excellent accuracy of the blur kernel model.

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Section: Results Of Focused Infrared Telescopementioning

confidence: 99%

Parameterized Modeling of Spatially Varying PSF for Lens Aberration and Defocus

Wang

Chen

Jia

et al. 2015

Journal of the Optical Society of Korea

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“…Basing on data available from missions such as [11] and analyses of 6U cubesats available in literature (e.g. [7]), one can expect a certain periodicity in the thermal fluctuations of the structure and bus of about 100min for a LEO orbit. We assume operating temperatures to be centered around 270-275 K, and…”

Section: System Feasibilitymentioning

confidence: 99%

A calibration cover for multi-spectral space instruments

Baccichet¹,

Aló²,

Gulde³

et al. 2021

International Conference on Space Optics — ICSO 2020

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The study of many astrophysical objects relies on repeated measurements of specific areas of the sky to allow, for example, the identification of transient phenomena, or of targets of interest extracted automatically from a large set of observations. A key aspect coming to play in these cases, is the stability of the measurement system that allows data to be traceable and comparable over time, which in turn leads to the necessity of a reliable and stable calibration.Observations from space allows for an intrinsically more stable environment due to the absence of ground-generated disturbances, leading to a less complex calibration system to correct for effects such as ageing of optics/detectors or temperature variations in the instrument. In this context, making use of external sources reduces further the need for internal devices, minimizing the impact of calibration in the design of a spacecraft.In this paper we present the performance of a device that takes advantage of these aspects and makes use of the sun to passively generate calibration scenes at visible and infrared wavelengths, with a single part. It consists on a movable cover placed at the entrance pupil of a telescope, with pinhole inserts and a black-coated internal surface. Sunlight passing through the pinholes is used to generate a flat field at visible wavelengths, while by heating the inner surface an infrared uniform scene can be formed.We apply this concept to a case-study for a small-sized satellite (e.g. 6U CubeSat) showing a good relative stability with such system in both IR and VIS bands, over the course of a 2-3 years mission.

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“…Figure 5B shows the 4 U FluidCam payload. The optical telescope has been redesigned from the first generation and consists of a proprietary square-aperture Nasmyth focus Ritchey-Chretien reflecting telescope based on a design proposed by Jin et al (2013).…”

Section: Fluidcam Instrument and Airborne Field Campaignsmentioning

confidence: 99%

Next-Generation Optical Sensing Technologies for Exploring Ocean Worlds—NASA FluidCam, MiDAR, and NeMO-Net

Chirayath

2019

Front. Mar. Sci.

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We highlight three emerging NASA optical technologies that enhance our ability to remotely sense, analyze, and explore ocean worlds-FluidCam and fluid lensing, MiDAR, and NeMO-Net. Fluid lensing is the first remote sensing technology capable of imaging through ocean waves without distortions in 3D at sub-cm resolutions. Fluid lensing and the purpose-built FluidCam CubeSat instruments have been used to provide refraction-corrected 3D multispectral imagery of shallow marine systems from unmanned aerial vehicles (UAVs). Results from repeat 2013 and 2016 airborne fluid lensing campaigns over coral reefs in American Samoa present a promising new tool for monitoring fine-scale ecological dynamics in shallow aquatic systems tens of square kilometers in area. MiDAR is a recently-patented active multispectral remote sensing and optical communications instrument which evolved from FluidCam. MiDAR is being tested on UAVs and autonomous underwater vehicles (AUVs) to remotely sense living and non-living structures in light-limited and analog planetary science environments. MiDAR illuminates targets with high-intensity narrowband structured optical radiation to measure an object's spectral reflectance while simultaneously transmitting data. MiDAR is capable of remotely sensing reflectance at fine spatial and temporal scales, with a signal-to-noise ratio 10-10 3 times higher than passive airborne and spaceborne remote sensing systems, enabling high-framerate multispectral sensing across the ultraviolet, visible, and near-infrared spectrum. Preliminary results from a 2018 mission to Guam show encouraging applications of MiDAR to imaging coral from airborne and underwater platforms whilst transmitting data across the air-water interface. Finally, we share NeMO-Net, the Neural Multi-Modal Observation & Training Network for Global Coral Reef Assessment. NeMO-Net is a machine learning technology under development that exploits high-resolution data from FluidCam and MiDAR for augmentation of low-resolution airborne and satellite remote sensing. NeMO-Net is intended to harmonize the growing diversity of 2D and 3D remote sensing with in situ data into a single open-source platform for assessing shallow marine ecosystems globally Chirayath and Li NASA FluidCam, MiDAR, and NeMO-Net using active learning for citizen-science based training. Preliminary results from four-class coral classification have an accuracy of 94.4%. Together, these maturing technologies present promising scalable, practical, and cost-efficient innovations that address current observational and technological challenges in optical sensing of marine systems.

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Optical Design of a Reflecting Telescope for CubeSat

Cited by 17 publications

References 8 publications

Parameterized Modeling of Spatially Varying PSF for Lens Aberration and Defocus

Parameterized Modeling of Spatially Varying PSF for Lens Aberration and Defocus

A calibration cover for multi-spectral space instruments

Next-Generation Optical Sensing Technologies for Exploring Ocean Worlds—NASA FluidCam, MiDAR, and NeMO-Net

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