Perfect pinhole diffraction pattern with sharp fringes using a 632nm laser I'm trying to produce a diffraction pattern with pinhole using a laser of 632nm wavelength .The pinholes' diameter are ranging from 10um , 25um , 50 um , 0.1mm and so on .
I also have good lenses for collimation and focusing.
What is of importance to me is to generate distinguishable bands in a way that I can make sure there exist no photons in dark band and the fringes are perfect borders between light and dark bands.
At the moment what I can observe is such a pattern .
http://www.pictureshoster.com/files/ihyxqb9relj0tv9mbab6.png
You can also have a look at setup which I used .
http://www.pictureshoster.com/files/y0iqmqttzzc4y8n2y6mq.jpg
As you see there aren't perfect circles over there and borders have some aberrations!
Is there any way to produce sharp fringes of diffraction pattern ? 
 A: This image is the Fraunhofer (farfield) diffraction pattern from a circular aperture. I have labeled the main problems I see in it below.

In the middle, the image is saturating, i.e. the camera's gain is too high. I suggest the first thing you need to do if you haven't already is to find a freeware software to convert the camera image into a 2D field of intensities. Many cameras are quite linear, so that the greylevel brightness for each pixel is pretty much proportional to the light's intensity. Once you have the image intensities, you can readily see saturation (peaks crashing into the maximum intensity) and other nonideal effects and use this knowledge to tune your measurement. 
I would suggest the high frequency ripples you are seeing are extremely small and you're unlikely to get rid of them. I take it that these ripples are what you mean by "aberration". When you lower the camera's gain so that the central peak is not saturating, these ripples will be very tiny indeed. Although they may seem worrying, try taking a cross-section through them with your image analysis software and you'll see that their amplitude is very small compared to the main lobe intensity. The human eye and site system is exquisitely sensitive to patterns like this, so interference like this is wont to seem much worse than it really is. These ripples I believe are coming from a point scatterer somewhere near a system Fourier plane, i.e. at or near the pinhole itself or it could be some dirt near the aperture stop of your imaging system. 
Once you've got the camera's gain properly set, you should be looking for the Airy function intensity distribution discussed in section 8.5.2 of Born and Wolf "Principles of Optics". The section is called "the circular aperture". Take a cross-section through the peak and you should be looking for the following intensity distribution:
$I(r) = \left(\frac{2\,D\,J_1\left(k\,a\,\frac{r}{D}\right)}{k\,a\,r}\right)^2$
where $D$ is the distance between the pinhole and imaging plane, $r$ the radial coordinate on the imaging plane, $a$ the pinhole's radius, $k$ the freespace wavenumber of the light question and $J_1$ the first order Bessel function of the first kind. See below for symbol definition.

I have plotted below what you should theoretically be seeing; as you can see the side lobes are of very small intensity compared with the central peak. The Mathematica command I used to plot this was DensityPlot[(2 BesselJ[1, Sqrt[x^2 + y^2]]/ Sqrt[x^2 + y^2])^2, {x, -10, 10}, {y, -10, 10}, PlotRange -> All, PlotPoints -> 200]. The argument on each axis was the variable $k\,a\,\frac{r}{D}$.

A: Apart from the overdrive (saturation), the imperfections you see are laser speckles. It is an interference effect produced by imperfections inside your laser, possibly involving some dust or back-reflections. If you use cheap diode lasers, you will almost always get some of these, even from just the bare laser chip.
There is a trick to clean up your beam: Focus it into a small spot and use an appropriately sized pinhole to only use the bit that corresponds to the TEM$_{00}$ mode. All the (small) imperfections will be spatially separated in the focal plane. The setup is a bit more complicated than what you have because, to be effective, you will need to use not just a suitable lens (or, more likely, multiple lenses) and one of your smaller pinholes. Because the position of the pinhole is so critical, you will need a translation stage, ideally in three axes. But the result is worth it; holographers use this trick to rid their art from similar artifacts.
