This page contains a database of all requirements defined for FINCH. What is currently viewable on this page is a subset of these requirements that are pertinent to the Optics subsystem. Some of these requirements are not finalized, or otherwise well-defined. A graphical representation of requirements concerning optics is presented first, followed by the database.
The FINCH EYE hyperspectral imager takes and aims to deliver on Basic Performance Specifications from Science. These specifications influence the quality and resolution of the images our instrument is able to gather, and directly affect the statistical significance of inferences made from the data we downlink. Since the payload must be compatible with the satellite, it also faces several Footprint and Environmental Constraints, informed by Thermal and Mechanical. Other subsystems, such as Data Processing and ADCS, have requirements that are relevant to the optical system, but do not directly impact the design of the payload.
In order to satisfy the environmental and performance specifications, Optics must carefully design the Basic Design Parameters listed below. These are essentially variables or degrees of freedom that we may control. The basic design parameters are called this way because their determination can be done analytically, without resorting to advanced modelling and simulation software. Once the basic parameters are determined, we still need to validate the system’s performance with simulation software. We can then determine the so-called Advanced Design Parameters by utilizing a suite of powerful analysis functions in the simulation software, which are fairly important for a rigorous qualification of an optical system. These analyses will inform a determination of more “detailed” degrees of freedom which necessary for the final design of the system.
Perhaps to assist your imagination, it would be instructive to list what degrees of freedom an optical engineer may have at their disposal. For example, with lenses, one can simply describe a lens by its focal length and diameter. However, there are substantially more details that go into the manufacturing of a lens. For example, how thick should this lens be, and what curvature should the surfaces be polished to? How smoothly does the surface have to be polished? What glass material should be used? Over what temperature and wavelength ranges is this lens meant to operate over? What are the requirements on aberrations? The list goes on. You may appreciate that for the GRISM, objective, and camera, there are many more “degrees of freedom” that must be considered, hence the challenging nature of optical design.
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<aside> 🛠 Visit TreeViz to visualize an up-to-date requirements model.
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