So while handheld laser out of the initial phase are the same, but encountered reflective objects (here after the wall, diffuse. The surface of the mirror and smooth with dust), reflecting to a certain point after some photons go, some photons walk less some reflection, so to meet again when they phase is different, so there will be some local bright dark flecks of some places this pattern, known as speckle.
According to the Huygens Finel principle, diffuse surfaces in tiny points of light. Due to the strong coherence of handheld laser, emitted by the point light sources of coherent light beam coherent wavelet. Different phase coherent light beam, the formation of bright spots, dark spots in space, or in bright spots and dark spots between the. The diffuse phase difference between wavelet coherent beam is randomly distributed, and the coherent light beam in space wavelet formed bright spots and dark spots of countless random distribution, known as speckle.
After the presence of speckle often affect the resolution of optical instrument.Handheld laser for holographic lighting, also found that the effect of laser speckle on the holography resolution. It was believed that the speckle is a special noise with useless information, a lot of methods to weaken or even eliminate the speckle. Until 1969, people through research gradually found some useful information carried by the speckle, and gradually developed into a laser speckle measurement techniques.
Diffuse surface handheld laser lighting solid beam spread, and thus the diffuse reflection surface after laser speckle formed in space, in a certain space to determine the location of the observed
The individually made corrective lenses handheld laser eliminate the inevitable defects of the stack, almost entirely from X ray to 3/4 light field, the formation of 250 nm (millionth mm) diameter of the light field, close to the theoretical limit. X ray concentration can not only improve the measurement quality, but also open up study on the new way.
Suitable lens and reflector production has reached a very high handheld laser, but the standard lens made of beryllium, usually near the center is slightly too strongly curved. “Beryllium by molding precision mold lens. The shape error on the process sequence of hundreds of nanometers in is almost inevitable.” this led more focus by light scattering out, and because the laws of physics are inevitable. More importantly, the light distribution in a large area.
In order to optimize the focus, defect scientists first carefully measured handheld laser stack. Then they used precision laser in University of Jena, using quartz glass lenses. These data customization, this defect is not relevant in many applications. However, if you want to use X ray laser irradiation to the small sample, you to focus on a small area as much as possible.
No correction of the handheld laser, our focus is about the total X ray light distribution to about seventy-five percent, a diameter of about 1600 nm region. This is the theory can achieve about ten times as large as the focus area, when the glass is used, X ray seventy-five percent points can be concentrated to a diameter of about 250 nm region it is the best result, close to the theoretical value.
Spot speed “is a very unusual moment produced a number of definitions of.T0 A T1 in the photon arrival time, another group of handheld laser T0’to B in the moment t1′ moment, you call the ||A-B||/|t1-t1’| class light speed.
Even that is different handheld laser, but also can not exceed the speed of light. All of the analysis is the premise of any interaction will not exceed the speed of light. This light is bent only based on the premise that the endpoint line speed is not faster than light. I don’t know, measuring the speed of light concrete now. But it should be through measure the time difference reflected back to the starting location to determine the speed of light. Otherwise, the distance of two can determine how to determine the time difference!
Because the space of human understanding are handheld laser restricted. The rules in this light how good time occurs beyond the speed of light? Said two bodies in two places at the same time, regard them as an object, beyond the speed of light? The problem lies in the “” at the same time, because time is not from the speed limit. Two objects in different locations is different in different time. The place is different, the time difference is the speed of light!
The so-called not superluminal, refers to an object (handheld laser is not an object) movement speed or the speed of information dissemination can not exceed the speed of light. The wave group velocity wave (i.e. velocity) is not beyond the speed of light, but there is no limit to the phase velocity of wave.