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"Lighting a path to the future with nano-optics."

Diffractive Optics

Diffractive optics are an entire class of optic that work on the principles of diffraction and interference.  Diffraction refers to a whole range of phenomena that occurs when a light wave either bends around obstacles or spreads out through small openings and diffractive optics take advantage of these phenomena.  The most common example of the results of diffraction occur when you look at a CD or a DVD and see the rainbow effect as light bounces off the disc.  This occurs because a CD or a DVD has millions of tiny "pits" arranged in a spherical pattern around the disc and these pits function like a diffraction grating, breaking up the light into it's individual wavelengths.  

However, there is more to diffractive optics than just pretty rainbows.  Diffractive optics can peform a whole range of functions.  Diffractive optics can be used for beamsplitters, a kind of optic that takes a single beam and splits it up into two, three, or a hundred copies all fanning out at some angle from the beamsplitter.  

Diffractive optics can also be used to make beam shapers.  If you measure the intensity of the spot of light made by the average laser beam, you would see that it has what is known as a Gaussian profile, meaning that it is hottest at the center and it's intensity decreases as you get closer to the outside diameter of the beam.  Sometimes, this isn't a problem.  At other times, such as when industry uses a laser to burn a via hole in a circuit board, you want the entire diameter of the hole to burn through at the same rate and this is where diffractive optics come to the rescue.  With a Gaussian profile laser, since the center of the laser is hotter than the outside edges, the center burns through quickly but the outer edges take forever.  To solve this problem, you can send the Gaussian beam through a kind of diffractive optics known as a beam shaper.  The diffractive optics beam shaper sends some of that central energy to the outer edges creating what is often referred to as a "top hat" profile which is just another way of saying that the intensity of the beam is the same no matter how far any portion is from the center.  

Diffractive optics can be used to make holograms which can project any kind of a pattern.  If you look at the pictures above, the picture on the far right shows the Nalux logo created by shining a beam through a hologram made using diffractive optics that was correctly shaped to create the Nalux logo.  This type of diffractive optics is not a mask.  In other words, diffractive optics are not like a blank sheet of paper with the word Nalux cut out of the paper so that the light shines through the letters.  If you looked at the diffractive optics that create these patterns under an electron microscope, to the untrained eye their surface would look very jumbled and cratered, like the surface of the moon, and it would be a sea of chaotic looking structures.  However, if these diffractive optics are made correctly and you shine a light through them, you can project a logo, the pointing hand you see on some laser pointers, and even pictures of people.  

Designing the structure of diffractive optics is a very complex business and requires some very advanced software, but fortunately it is actually a well developed technology that improves our lives.  Nalux has both the engineering expertise and the software tools to make diffractive optics out of all kinds of glasses, metals, and plastics.  Give us a call and see how diffractive optics and Nalux can improve your business and quality of life.