Autocollimation自动测量

                                                   北京正科科技有限公司测量仪器部

自动测量：

It is the system used by all preset manufacturers to measure in a very quick way.

自动测量是所有的制造商用来快速测量的方式。

Unfortunately it is the less precise either for accuracy, for repeatability and for reproducibility.

然而，自动测量对于精度、可重复测量精度来说并不是最好的方式。

As the sharp shadow enters the vision camera sensor (and it is possible to see it on the screen), immediately the software estimates the limit between the black Pixel and the white one and gives the distance compared to a memorized fixed point (for instance: rotation axis).

当刀具轮廓进入CMOS显示系统时，软件会立即跟踪到刀具轮廓黑白相间的这部分，并且给出此点的相对值（例如：旋转主轴）。

In every point you'll find the shadow , the software always estimates the distance. It is a very quick method and of big effect, however it brings some errors in. The errors depend on the lens bending, on the sensor central Pixel distance to the one interested in measure, on the analogical/digital signals processing.

对于任何一个点，你都能在屏幕上找到阴影，软件总是能够计算出这个点的相对距离。这是一种快速的测量方法，然而它有着很多的缺点和误差。误差主要由：透镜的曲率、以及传感器对于距离的测量又经过一次模拟量到数字量的转换引起的。

CCD→Analogical signal→Analogical/digital converter →Digital signal→Electronics

CCD→模拟量信号→模数转换器→数字信号→电子信息

C-MOS→Digital signal→Electronics

C-MOS→数字信号→电子信息

The analogical/digital signal converter brings errors in.

模数转换器带来了转换误差。

In conclusion, in the automatic measuring method a 3÷6µm repeatability is normal. Always when the exact focus choice is precise and steady.

我们的结论是，在自动测量模式下，3-6µm的可重复测量精度是正常的。（当我们选择的聚焦点是准确的）

Collimation on fixed reticle

Just to avoid autocollimation  errors, only Elbo Controlli gives a second working method. In this case the Pixel that calculate, the measure will be always the same and will have a central position.

为了避免测量误差，全球对刀仪制造商只有ELBO Controlli提出了另外一种新的工作方法。总是把图象显示在屏幕中心位置，从而我们得到的测量结果有着很好的稳定性。

So no lens bending error. The sensor Pixel is always the same and it is in the centre.

如果不存在透镜的曲率误差，那么图象总是显示的屏幕中心的同一个位置。

Furthermore the C-MOS sensor doesn’t need a converter.

另外，C-MOS传感器不需要一个模-数转换器。

In order to have the best repeatability /reproducibility and also accuracy you need to pay the utmost attention to the focus bar. X axis has often a different focus from Z axis one (tools rake).

为了获得最好的可重复性测量精度以及精度标准，必须引起对聚焦条足够的重视。X轴和Z 轴分别有一个聚焦条显示。

You always have to check the repeatability one axis every time and focus with the bar only one axis at a time.

必须检测可重复测量的精度，每次都必须使图象聚焦度最大。

Every focus bar segment is 2÷3µm.

聚焦条一个小格为2/3µm。

If the bar doesn’ t remain steady but swings, lighting and switching only one segment off, you can have 1÷3µm of difference.

如果聚焦条不稳定，一直在闪烁，光学和电源配置系统只能引起一个聚焦条小格的偏移，这样就有1-3µm的偏差。

The kind of environment light , the shadows we simply have when the operator moves, the sharp metals reflection can cause light changes and therefore the focus bar instability.

外界环境下的光源系统，不可避免出现光源的一个影子，当操作者移动时，金属的反射会引起光的变化，因此聚焦条会闪烁。

Then you have to check also the X and Z axes digital comparators.

然后你必须检查X轴和Z 轴的数字比较器。

 In the repeatability tests the zero reference is basic. Only a little swing of the red indicator is enough to determinate differences of 1÷3µm. You have to do the measurings only when both the digital comparator and the axis in measure focus bar are perfectly steady  and exactly in the same points.

零点的测量对于可重复性测量是最基本的。仅仅一点点儿的震动，红色指示器足够确定出1/3µm。你不得不做测量，当数字比较器和轴的聚焦条在同一点是确定的、稳定的。

You have also to pay the utmost attention not to create a counting inversion error, measuring always in the same direction.

测量时必须引起足够的重视：为了避免一个倒置方向性的错误，轴的移动必须始终向着同一个方向。

 If you measure form right to left , please remember that if you get over the digital comparator zero, you have to go back and repeat. If you get over the zero, you have never to go back on the zero from left to right

( about the counting inversion error there are many treatises, it is not a problem that concerns Elbo Controlli itself  but all the measuring systems).

如果你的测量方向是从右至左的，那么你得注意你是否把光标移动过了零点。如果过了零点，那么你不得不返回重新移动测量。（关于这个倒置后产生误差有很多的论述，这不是ELBO本身的问题，而且是整个测量界面临的问题）。

The correct procedure explained in the training to do repeatability and reproducibility tests is the following:

正确的程序是我们在做可重复性测量测试时：

-          set(position-plan) the measuring function out on the fixed reticle.

-          对于“十”字刻线设置正确的测量函数。

-          move  the axes till the sharp shadow enters the screen and bring it near the axis measure reference (for instance the digital comparator lights up).

-          移动轴直到其轮廓进入屏幕，逼近轴，直至出现数字比较器。

-          Turn the sharp till the focus bar lights all up.

-          移动，直至尖端的逼近出现聚焦条。

-          In this position do sharp microrotations clockwise and counterclockwise. The focus bar has always to remain at most, while the digital comparator red reference does very small swings.

-          在这个位置对主轴做一下顺时针和逆时针移动。聚焦条总是存在，当数字比较器的显示红色，存在一些小的震动时。

-          With the focus bar at most, go on the most left point of the digital comparator and now stop the spindle rotation; the focus bar has to be completely lightened and has not to switch on or off segments.

-          当聚焦条出现了绝大部分时，继续向左移动数字比较器显示值停止，停止主轴的旋转；聚焦条完全的点亮并显示在屏幕，并且中间没有分割点。

-          Move with the X axis micrometric movement the sharp shadow, till the digital comparator red light is on the zero right position.

-          微调移动X轴接近“十”字比较尺，直到数字比较器的指示灯在零点右边变亮。

-          Always with the X axis micrometric adjusting, bring the indicator on the digital comparator to zero.

-          微调X轴，使数字比较器逐渐到零点。

-          If you get over the zero, repeat the reading, going back to the right position with the indicator.

-          如果移动过程中越过了零点位置，必须返回“十”字刻线右边。

-          With the bar at most and the red indicator on zero, in total absence of movements: read the quote.

-          聚焦条大多在红色指示器在零点时，停止移动轴，读出数值。

-          Repeat and see the differences.

-          重复测量找出每次测量的不同。

In the workshop 1÷2µm are usual, with great attention and a little practise and experience.

在车间环境下，1÷2µm的测量误差是正常的，测量时操作人员必须有足够的耐心。

For what said in the introduction the zero value is improbable.

实际上，零点也不是完全真实存在的。

During the training, this practical test is made many times on all the machines and 2/3µm values are always considered very good在实际测量中，经过多次测量，所有的机器得到2÷3µm的误差值是非常棒的结果！

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