SPOT AND LINEAR FRESNEL LENSES
Both can be used for solar cooking and solar hot water heating. There are three types of Fresnel lenses, linear, spot, an continuous linear. Linear and spot lenses look similar in terms of the circular Fresnel pattern but a spot lens may appear more transparent. Spot lenses produce a very small tight beam at the optimal focal length and are generally more powerful size for size. Linear lenses produce a longer flat beam ranging from 1 inch high by 3 inches wide up to 1" x 12".
Continuous linear lenses are rarely used and produce a beam the length of the lens much like a parabolic trough. Optically stable UV inhibitors are required for lenses experiencing solar exposure to the sun or the materials will deteriorate rapidly with sun exposure.
Linear Fresnel Lens Advantages:
• Less chance of damaging equipment if liquid evaporates
• Long beam can be spread the length of a pipe
• Powers a Steam Engine slower but more safely
Disadvantages:
• More opaque due to physical nature, less light (power) transferred to project
• Cannot be used for melting metals

Beam NOT continuous Linear like a trough (1" tall x 3" - 6" wide optimal)
Spot Fresnel Lens Advantages:
• High power heat transfer (available in Crystal Clear Acrylic perfection cutting)
• Can be set to less of a focal length (ideal for cooking)
• Melts copper and many other materials
• Powers a Sterling Engine and Steam Engine
Disadvantages:
• Instant flame and work hazard
• Equipment damage
• Does not spread over a pipe surface evenly










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