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As a Fresnel lens it would be only a few millimeters thick. A space sunshade or sunshield is something that diverts or otherwise reduces some of the Sun's radiation, preventing it from hitting the Earth and thereby reducing its insolation, which results in reduced heating. Light can be diverted by different methods.
2 insulation vs. insolation. 3 ... 2 comments. 6 Sun-Earth L1 Distances. 3 comments. 7 Number of Sunshades required for 2% reduction. ... 11 Proposal to merge with ...
Unlike a standard lens, a binary zone plate produces intensity maxima along the axis of the plate at odd fractions (f/3, f/5, f/7, etc.).Although these contain less energy (counts of the spot) than the principal focus (because it is wider), they have the same maximum intensity (counts/m 2).
The temperature differences between the hot and cold sides of the James Webb Space Telescope five-layer sunshield. The sunshield acts as large parasol allowing the main mirror, optics, and instruments to passively cool to 40 kelvins (−233 °C; −388 °F) or cooler, [6] and is one of the enabling technologies that will allow the JWST to operate. [10]
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A Fresnel imager is a proposed ultra-lightweight design for a space telescope that uses a Fresnel array as primary optics instead of a typical lens. It focuses light with a thin opaque foil sheet punched with specially shaped holes, thus focusing light on a certain point by using the phenomenon of diffraction .
The Fresnel equations ... where Z 0 is the impedance of free space and i = 1, 2. Making this substitution, we obtain equations using the refractive indices: ...
Fresnel zone: D is the distance between the transmitter and the receiver; r is the radius of the first Fresnel zone (n=1) at point P. P is d1 away from the transmitter, and d2 away from the receiver. The concept of Fresnel zone clearance may be used to analyze interference by obstacles near the path of a radio beam. The first zone must be kept ...