What are performance expectations?
It is the limitation of the optical centering device.
When we move the focal plane to a different level, the very frustrating phenomenon is the “roaming” of the optical center. Two different reasons are determined by our experience:
First, the first reason is the inherent rebound in mechanical focusing mechanisms of these ranges. If you want to move the lens, you need a microscope to use the inner line. There are two cases of this thread, the first one is molded, but if it is not molded, it is machined. Although, to some extent, a thread can be processed to lower roaming the severity of the problem is, but after our test show that there are still some wandering, this makes it impossible will focus on the dial to return to the same location will happen, to refocus on the same focal plane is unable to do it. Although high-end camera technology can be used to solve this problem, it is not realistic to add thousands of dollars in cost.
The second one is more subtle, but also very interesting. For accurate scanning, there is no need for the absolute alignment of the light axis of the microscope, but the influence of optical alignment is still real. As we all know, this calibration does not mean that the optical axis is parallel to the main axis. After the alignment, the optical axis and the main axis overlap in the focal plane is what we know. Very unrealistic is combining scope and main shaft axis, the typical consumer electronics fpc6 sensor also be offset, the offset position is on the optical axis, makes the third pile errors were caused, and cannot be easily overcome the difficulties. It is very impractical to correct these problems and produce a cost to align the system, which is, of course, the cost of the fpc2 scanner system.
The contents of figure 12 are shown below. The ability of the variable focal length to maintain the center on different focal planes is shown by these two graphs. In this example, we can see that the scope is aligned to the center of the hole in 200x (top image). When the working distance is increased, the image is refocused on the 60x (bottom image), and the center wanderings occur.
What is figure 13? What is the optical and the centering axis? We can see that they are 50 x zoom in on the focal plane of the joint event, but if amplified to 20 x change, will make a center error, unless the camera to aim at, they can overlap again.