Why do lasers look grainy

The main reason for its granular appearance is what we call the speckle pattern. When you point a laser in one direction, it produces a beam of light with varying wave nature called the interference. As the beam of light touches a rough surface, it will produce wavelets and bounce off.

This occurrence will then cause a diffuse reflection, which is commonly visible in rough surfaces, paper, and anything similar. The reflecting of light will cause the wavelets to overlap, which in turn causes the granular pattern when we look at it. Although many other factors create the speckle pattern — one factor that significantly influences the appearance of this pattern is our eyes.

Depending on our eyes, and how we look at it, we may see a different design or structure of the laser beam. Its appearance varies from near-sighted to far-sighted people as well as when we look at it with our head slightly tilted or not.

With all these said, we can say that the laser pointer is not just a simple device, but it holds a whole lot of science by simply pointing its laser. Now that we know the reason for the grainy pattern of lasers, let us take a more in-depth look into the different facts of lasers. As mentioned earlier, lasers have been around for many years. I cleaned the lens both inside and out with alcohol and a swab But I'm afraid to clean the lens directly on the diode I'm afraid of alcohol getting down in the works I added a picture of the lens I'm afraid of cleaning.

HitShane Active member. Joined Nov 30, Messages Points Get it to touch the window, and use circles to clean it Going from hot to cold or vis versa will cause fog on the glass Dust or smoke can fog the glass also.

Try to keep smoke from hitting your laser and its lens Its prob just your crystals coming out of place though or setting in Last edited: Feb 28, I have some camera lens cleaning wipes somewhere I'll try cleaning the lens and will let you know how it turns out.

I cleaned all the lenses Still fuzzy. Jdjd96 New member. Joined Jan 9, Messages 1 Points 0. Yea my laser was introduced to smoke. My personal observations agree with this. What the others have already told you is that the pattern forming is a speckle pattern: each bump in the surface acts as a source for a spherical wave, these waves then interfere to produce this pattern.

The black dots and circles in the image below. In the wikipedia-article there is also mentioned the concept of "objective speckle pattern": when the reflected laserlight falls on another smooth surface after being shined on a rough surface, then the pattern on the smooth surface is, as wikipedia puts it, "the same regardless of how it is imaged, just as if it were a painted pattern". Now you can imagine that your eyes are in the plane of a imaginary smooth surface where the light reflected from the rough wall is hit on.

On this "wall" the pattern the green dots stays the same. When you move your eyes parallel to this plane, a part of the pattern disappears on the one end while a new one appears on the other end.

I suspect you are referring to the speckle pattern of a laser which is a diffraction effect associated with the microscopic roughness of a surface. The phenomenon you are describing is an intensity pattern know as speckle pattern. Speckle patterns are very prominent in patterns produced by coherent single frequency light such as laser beams.

The speckle effect is a result of the many photons in a beam having different phases and amplitudes, which add together to give a resultant amplitude interference pattern that varies randomly with the position in the beam.

As others have said, this is called a laser speckle pattern which is due to the laser being an almost coherent source with a narrow wavelength spread. What others have not made clear is that the surface roughness causes that pure wavelength to undergo constructive and destructive interference - causing bright spots at your retina where waves interfere constructively and dark spots where waves interfere destructively.

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