If you are an engineer or a student of engineering, you know what waves are.
Waves are an important part of many of the technologies you use every day, from radio signals to ultrasound imaging.
But have you ever thought about what these waves do as they move away from where they start? This is where the idea of beam spread comes in.
Beam spread is the angle at which an electromagnetic or acoustic beam moves away from its center axis as it moves through a material.
Understanding beam spread is important for designing and making the best use of many engineering systems, like lighting, sonar, and lasers.
So, I'll talk about beam spread and why it's important in the field of engineering in this article.
Introduction to Beam Spread
Formal definition:
The angle of divergence from the central axis of an electromagnetic or acoustic beam as it travels through a material.
Beam spread is the amount that an electromagnetic or acoustic beam moves away from its center axis as it moves through a material.
It is usually measured in degrees and shows how wide the beam is from the source at a certain distance.
In engineering, beam spread is an important idea that helps figure out how strong and in which direction light, sound, and radio waves are.
Beam Spread in Lighting
In lighting, beam spread is a way to measure how far light from a source with a reflector, like a light bulb, goes.
It measures how wide the beam is, which is important to know if you want to decide how much light to shine on an object or surface.
Depending on how big they are, reflector lamps either have a spot beam or a wide beam.
The width of the beam is what makes a spot beam different from a flood beam.
Use this simple formula to find the width of a light beam from a given distance: Beam Spread = Angle of Beam x.018 x Distance.
For example, if you want to know how far a 120-degree floodlight's light will reach from 15 feet away, you can just plug the numbers into this formula.
Spot lights and flood lights are often described by manufacturers in slightly different ways.
Knowing how beam spread works will help you choose the right outdoor light for your project.
For longer distances, a narrower beam that goes farther will work best.
If you want to use wider-beam lights to create an atmosphere, the distance between the lights should be equal to or greater than the diameter of the light's beam spread.
Beam Spread in Acoustic Waves
Beam spread can also happen in ultrasound transducers, where it is measured as the angle between the main lobe of the sound beam in the far field and the main lobe itself.
The beam divergence is another way to measure how much sound energy spreads out as it moves away from its source.
It depends a lot on how often the transducer is used and how big it is.
An applet can be used to get a rough estimate of the beam divergence angle, which is half of the beam spread angle.
This is done by taking into account the diameter (D), frequency (F), and sound speed (V) in a liquid or solid medium.
Why Beam Spread is No Laughing Matter in Engineering
Still hard to understand? Let me change the point of view a bit:
Who needs to worry about pesky things like beam spread anyway? Just let your light or sound waves fly willy-nilly and hope for the best! After all, who needs precision or accuracy in engineering applications, right?
Of course, this is not true at all, as any engineer or engineering student knows.
When designing and optimizing different technologies, beam spread is one of the most important things to think about.
But sometimes we need a little bit of ironic humor to understand how important a concept like beam spread is.
Now let's go back to the explanation.
Factors Affecting Beam Spread
The things that affect the way electromagnetic and acoustic waves spread out depend on the type of material they are traveling through.
When choosing a transducer for ultrasound, beam angle is an important thing to think about.
Beam spread makes reflections less loud because sound energy is spread out over a larger area.
The frequency and diameter of the transducer have a lot to do with how wide the beam is.
When a low frequency transducer is used, the beam spread is wider than when a high frequency transducer is used.
As the transducer's diameter grows, the beam spread will shrink.
When sound beams don't spread, the rate at which they spread is determined by the diffraction coefficient D, which is related to the curvature of the isofrequency surface.
The choice of transducer has a big effect on sensitivity, resolution, penetration, and beam spread.
Changing the operating frequency or waveform has a small effect.
Factors Affecting Beam Spread in Light Waves
Refraction is what happens when a light wave moves from one material to another and changes speed and direction.
How much the light wave bends depends on the angle at which it hits the surface and the refractive indices of the two materials.
The refractive index shows how much a material slows down light compared to a vacuum.
When light goes through a prism, it is bent twice: once as it goes in and again as it comes out.
How much light bends depends on its wavelength, so different colors bend at different angles.
This is called dispersion.
When light goes through a piece of glass, some of it bounces off the surface and some of it goes straight through.
How much light is reflected depends on the angle at which it hits the surface and on how air and glass bend light.
The index of refraction of glass is higher than that of air, so when light goes from air into glass, it slows down and bends towards the normal (an imaginary line perpendicular to the surface).
When light goes from glass to air, it speeds up and bends away from the normal.
In short, the properties of the medium the wave is traveling through, as well as the frequency and size of the transducer, are the main things that affect the spread of electromagnetic and acoustic waves.
Refraction changes the speed and direction of light waves as they pass through different materials.
This affects how far apart the light waves are.
Knowing what affects beam spread is important for choosing the right equipment and getting the results you want in different engineering applications.
Uses of Beam Spread
Beam spread is an important part of many engineering applications, such as lighting, sonar systems, underwater sensing technologies, and more.
It is important to know how beam spread affects these technologies so that you can choose the right equipment and get the results you want.
Beam Spread in Lighting
In lighting, the angle at which light comes out of a fixture is called its beam spread.
More area is lit up with less light intensity if the beam is wider.
On the other hand, a beam spread that is narrower puts more light in a smaller area.
With multi-beam spread track heads, the beam angle can be changed on the spot by moving the lens.
Flood beam spreads can be used to light up a large area, while spot beam spreads can be used to highlight certain parts of a room.
Different kinds of lights have different patterns for how their light spreads, which are made for different reasons.
Spread beam lights have a wider beam pattern than spotlights, which produce a more focused light beam that can travel farther ahead of the vehicle.
Fog lights can shine through layers of fog, rain, snow, or dust on the road because they have a wide horizontal spread but a narrow vertical cut-off.
NEMA Beam Spread Classification System
The National Electrical Manufacturers Association (NEMA) came up with a way to classify how light is spread.
This system is called the NEMA beam spread.
It refers to the two edges where light intensity spreads horizontally and vertically to 10% of the maximum beam intensity and correlates to whether the light output is very narrow, very wide, or somewhere in between.
Angles of horizontal and vertical beam spread are used to tell the difference between NEMA types.
The standardized NEMA beam angle classification system gives everyone in the industry a consistent way to figure out how fixtures spread light.
The six types named by NEMA are used for different things.
You can get the right light distribution for your project by using fixtures with the right NEMA classification.
Beam Spread in Sonar Systems
In sonar systems, beam spread refers to the coverage area of sound waves emitted by a transducer.
Multibeam sonar sends out multiple sonar beams at the same time in a fan-shaped pattern that looks under the ship and to each side.
Compared to single-beam sonar, this makes it possible to scan a larger area of the seabed faster and with more accuracy.
Different frequencies reveal different levels of detail in sonar data.
High-frequency pulses show a lot of detail but can't go deep into water.
Low-frequency pulses, on the other hand, go deeper into water but show less detail.
Beam Spread in Underwater Sensing Technologies
Beam spread also affects technologies for underwater sensing, such as visible light communication (UVLC).
UVLC uses a frequency range between 450 and 550 nm because radio frequency signals lose their strength much more quickly in seawater.
This makes it possible for people to talk underwater, even though seawater isn't always the same temperature and the hull moves when waves hit it.
In short, beam spread is an important thing to think about in many engineering applications, such as lighting, sonar systems, and technologies for sensing what's going on underwater.
It is important to know how beam spread affects these technologies so that you can choose the right equipment and get the results you want.
What methods can be used to control or change the spread of a beam in different situations?
Beam shaping and steering
Beam shaping and steering is an important technique that is used in many modern devices, like camera lenses and optical tweezers.
In this method, the beam is changed in different ways to get the spread that is wanted.
One popular way to change the shape of the beam is to use diffractive optical elements (DOEs).
The DOEs can change how the beam is spread out in terms of phase and amplitude to get the beam spread that is needed.
Also, holographic optical tweezers use holograms made by a computer to shape and direct light beams to make traps in 3D space.
Dielectric metasurfaces
Dielectric metasurfaces are thin, man-made layers of structures smaller than a wavelength that can change the way light behaves based on its refractive index, period, incident angle, and cross-section shape.
They can change the beam's strength, phase, and polarization, which lets them make complex beam patterns.
Lenses, reflectors, and diffraction gratings
In some situations, lenses, reflectors, or diffraction gratings can be used to control how far a beam spreads.
Lenses can change the shape of the beam to make it narrower or wider, and reflectors can turn the beam in a certain direction.
Diffraction gratings can split the beam into more than one beam or bend it into a certain pattern.
Aperture or iris
By changing the size of the opening, an aperture or iris can be used to change the size of the beam.
In photography, this method is often used to control how much light gets into the camera and to get the right depth of field.
Moving the workpiece or the laser
When using a laser to cut or weld, for example, the beam can be changed by moving the workpiece or the laser.
This method is used to make cuts or welds that are very precise and to control how far the beam spreads.
Particle accelerators
Particle accelerators can control or change beam spread in a number of ways.
These include injection and extraction methods, beam cooling, spin transport, polarization, first turn analysis, closest tune approach, compensating the sum resonance, and emittance near coupling resonance.
These methods are used to make sure that the beam is steady, well-focused, and in the right place.
In conclusion, there are many ways to control or change the way a beam spreads, and the best way to do it depends on the application and needs.
It is important to choose the right technique to get the beam spread you want and make sure the application works.
Techniques for Controlling and Manipulating Beam Spread
Beam spread is a critical factor in many engineering applications, including lighting, sonar systems, and particle accelerators.
Different applications call for different ways to control or change beam spread.
Calculating Beam Spread
You can easily figure out the right beam spread for your lighting design by multiplying the angle of the beam by a constant value of 0.018 and then by the distance.
For example, if you want to figure out the coverage area (spot size) of a 10° beam that is mounted 25 feet above the deck (the throw distance), you can use this formula: 10° x 0.018 x 25 ft = 4.5 ft.
Depending on how big they are, reflector lamps can either have a spot beam or a flood beam.
Having both types gives you more ways to light your property.
When choosing a bulb for your space, think about what kind of atmosphere you want to create.
Spot lights are usually bulbs with a narrow beam, like 12°.
Flood or wash lights are bulbs with a wider beam, like 60° or so.
Beam Shaping and Steering
Beam shaping and steering is a key part of many modern technologies, like optical tweezers and camera lenses.
Optical elements like lenses, mirrors, and gratings are used to change the shape of the beam and direct it in a certain direction or focus it on a target.
This method is also used to control beams with different refractive indices, periods, incident angles, and cross-sectional shapes in dielectric metasurfaces.
Reducing Beam Spread
In ultrasound technology, you can make the beam spread smaller by using a transducer with a high frequency or by making the diameter of the transducer bigger.
By moving an optically trapped micro-sphere through a light beam, it is possible to control how a beam moves in an optofluidic device.
Particle accelerators have many ways to control or change beam spread, such as injection and extraction methods, beam cooling, spin transport, polarization, first turn analysis, closest tune approach, compensating the sum resonance, and emittance near coupling resonance.
There are also the following ways to narrow the beam:
Using a beam expander: Beam expanders can be used to reduce beam divergence and make sure the beam diameter doesn't go over a certain limit when the output beam is far away.
By making the beam bigger inside the system, the input diameter grows, which makes the divergence smaller.
- Using a collimator: A collimator can be used to reduce the spread of the laser beam and make it more collimated.
- Using a smaller aperture: The size of the hole that the laser beam goes through can affect how far apart the beam is.
Most of the time, a smaller aperture will make the beam spread less.
- Using a lens with a longer focal length: A lens with a longer focal length can be used to focus the laser beam into a smaller spot, which can reduce beam spread.
It is important to keep in mind that these techniques can help reduce beam spread, but they can only do so much.
Also, some techniques can cause other optical aberrations, like spherical aberration, which can lower the quality of the beam.
It is important to think carefully about the needs of the system and choose the right way to reduce beam spread.
Sound Beam Spread in the Far Field
Several things affect how a sound beam spreads in the far field.
These include the size and shape of the ultrasound source, the frequency of the beam, how the beam is focused, and the size or aperture of the transducer.
The Far Field
The far field is the area where the beam diameter grows farther away from the source than one near zone length.
Transducer Diameter and Frequency of Ultrasound
How much a sound beam spreads out in the far field depends on the size of the transducer, called the aperture, and the frequency of the sound waves.
Larger diameter crystals producing higher frequency sound produce beams that diverge less in the far field.
Crystals with a smaller diameter and a lower frequency make beams that are very spread out in the far field.
Size and Shape of Ultrasound Source
The beam width, length of the Fresnel zone, and angle of divergence beyond the near field are all affected by the size of the ultrasound source.
For a transducer in which no focusing is applied, the length of the Fresnel zone is determined by the diameter of the transducer and wavelength.
Beam Focusing
The way the beam is focused also changes how it looks in the far field.
Focusing the beam can make the beam spread less in the far field.
Using a transducer that doesn't focus the beam, on the other hand, makes the beam spread more.
In short, the diameter or aperture of the transducer, the frequency of the ultrasound, the size and shape of the ultrasound source, and the way the beam is focused all affect how much a sound beam spreads out in its far field.
By knowing about these factors, engineers and researchers can make ultrasound systems that work best for their needs.
Wavelength, Nearfield, Beam Spread Calculations
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Conclusion
As we conclude this discussion on beam spread, it's worth taking a moment to consider the profound impact that this concept has on the engineering world.
Beam spread is a very important concept to understand if you want to design lighting systems for a stadium, improve sonar imaging for submarines, or make laser technology for medical uses.
Engineers can do work that is more precise and efficient than ever before by carefully controlling and changing the way waves behave as they move through different materials.
So, the next time you are working on an engineering project, keep in mind the power of beam spread and how it can help you reach your goals.
With a little imagination and creativity, there are really no limits to what you can do.
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