How to obtain beam spread angle of a parabolic reflector?

In summary, the conversation discusses designing a parabolic light reflector for an LED array, with a desired beam spread angle of 70 degrees. The individual is seeking equations to relate the reflector's diameter and height to achieve the desired angle. Nonimaging optics is mentioned as a separate field, and a book and online resources are suggested for further information. The Mangin-Chikolev equation is also mentioned as a potential resource for designing searchlights.
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czh133
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Hi i am new to the forum and hopefully i can get some help.

I am trying to design a small parabolic light reflector that can be used with an LED array as being the source of light. The diameter of the LED array is 18.75mm. I am trying to obtain equations that would relate the diameter and height of the reflector with the beam spread angle. This way i can change the dimensions of the reflector to affect the angle i want to achieve. As an example i want to achieve a total of 70 degrees beam spread with the source being 18.75mm and placed on the focus point of the reflector. How can i find the diameter and height of the reflector with this information? any help is appreciated. thanks
 
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  • #2
Nonimaging optics is practically it's own branch of science, essentially disconnected from everything else.

http://en.wikipedia.org/wiki/Nonimaging_optics

This book (http://books.google.com/books?id=ykk1xQc25c0C&dq=Anidolic&source=gbs_navlinks_s) seems to be the primary resource in the field.

You may find some useful information here:
http://reflector-design.com/files/Computer_Aided_Optical_Design_Kusch_Oleg.pdf

It sounds like what you are asking relates to the design of searchlights, so look around for work based on the Mangin-Chikolev equation. Good luck...
 

1. What is a parabolic reflector?

A parabolic reflector is a curved surface that reflects light or other radiation to a single point, creating a highly focused beam of energy. It is often used in telescopes, satellite dishes, and other devices that require highly concentrated beams of light or radiation.

2. How is beam spread angle defined?

Beam spread angle is the measure of how much the beam from a parabolic reflector spreads out as it travels away from the focal point. It is typically measured in degrees and can range from very narrow beams to wider, more diffuse beams.

3. What factors affect the beam spread angle of a parabolic reflector?

The beam spread angle of a parabolic reflector is affected by several factors, including the size and shape of the reflector, the distance from the focal point, and the wavelength of the radiation being reflected. In general, larger reflectors and shorter distances from the focal point will result in narrower beam spread angles.

4. How can I calculate the beam spread angle of a parabolic reflector?

The beam spread angle of a parabolic reflector can be calculated using the formula θ = 2 × arctan (L / 2f), where θ is the beam spread angle, L is the diameter of the reflector, and f is the focal length. Alternatively, there are many online calculators and software programs that can calculate the beam spread angle for a given parabolic reflector.

5. Can the beam spread angle of a parabolic reflector be adjusted?

Yes, the beam spread angle of a parabolic reflector can be adjusted by changing the shape or size of the reflector, or by adjusting the distance from the focal point. Additionally, using a secondary reflector or lens can also alter the beam spread angle. However, these adjustments may also affect other aspects of the reflector's performance, so careful consideration is needed when making changes.

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