數(shù)字圖像相關(guān)技術(shù)（DIC）的測(cè)量依賴于制備在試件表面的隨機(jī)的高對(duì)比度散斑，以獲取最準(zhǔn)確的測(cè)量結(jié)果。在實(shí)踐中，如果散斑太稀疏、太密集、或者散斑點(diǎn)過大，都將使測(cè)量的空間分辨率受損。相反，如果散斑點(diǎn)太小、混疊，則可能會(huì)導(dǎo)致數(shù)據(jù)嘈雜。為了減少測(cè)量噪音和降低不確定度，需要制備符合視場（FOV）尺度和相機(jī)分辨率的理想散斑圖案。VIC散斑制備套件的作用即是幫助用戶能夠輕松將理想散斑制備于試件表面，而無需對(duì)試件區(qū)域有精確的了解。該套件易用、靈活，適用于各種VIC-2D或VIC-3D系統(tǒng)的應(yīng)用場景。 該套件實(shí)際上消除了由于試件制備不當(dāng)而導(dǎo)致的潛在測(cè)量偏差。

Digital Image Correlation (DIC) relies on a high-contrast random pattern applied to the specimen’s surface to produce the most accurate results. In practice, if the pattern is too sparse, too dense, or the speckles are too large, spatial resolution of the measurement will suffer. Conversely, if the speckles are too small, aliasing may result causing noisy data. To reduce noise and lower uncertainty, the ideal speckle pattern for the desired field of view (FOV) and camera resolution must be applied.  The VIC Speckle Pattern Application Kit enables the user to easily apply the ideal pattern to the surface of the specimen without any precise knowledge of sample area.  The kit is easy-to-use, flexible, and available for a wide range of applications suitable with your VIC-2D or VIC-3D system.  The kit virtually eliminates the potential bias that would result from poor sample preparation.

CSI公司提供的散斑制備套件包含一系列工具，以供新老DIC用戶使用，來快速創(chuàng)建理想的散斑圖案。針對(duì)不同視場和圖像采集器分辨率組合，還提供散斑點(diǎn)尺寸建議表。 以下列出了套件中所包含的物品。

The speckle application kit from Correlated Solutions provides an array of tools which can be used by new and experienced DIC users alike to quickly create the ideal speckle pattern. Speckle size suggestion tables for multiple fields-of-view and sensor resolution combinations are also provided. The items included in the kit are shown and listed below.

六個(gè)帶自動(dòng)上墨器的壓印輥 六個(gè)可互換的膠質(zhì)轉(zhuǎn)印片與一個(gè)壓克力手柄 一個(gè)墨水墊盒與一瓶額外補(bǔ)充裝的墨水 硬件可根據(jù)用戶需求定制創(chuàng)建更大的散斑點(diǎn)   Six stamp rollers with self-inking inserts Six interchangeable stamps with one acrylic rocker One ink pad with an extra bottle of ink Hardware to create larger dots available upon request

雖然市面已有很多散斑圖案制備技術(shù)，但是其中很多提供的都是不一致或不規(guī)范的散斑點(diǎn)尺寸，這將導(dǎo)致不一致的結(jié)果。當(dāng)執(zhí)行重復(fù)測(cè)試時(shí)，這可能尤其令人失望。而使用CSI公司的VIC散斑制備套件生成的散斑點(diǎn)尺寸是可重復(fù)且一致的，能夠快速創(chuàng)建精度可以預(yù)測(cè)和控制的散斑圖案，從而實(shí)現(xiàn)的一致且準(zhǔn)確的結(jié)果

There is a wide range of speckle pattern application techniques, but many provide inconsistent dot sizes from sample to sample, which also yield inconsistent results. This can be especially frustrating when recurring tests are performed. Producing repeatable dot sizes with the VIC Speckle Pattern Application Kit from Correlated Solutions provides the ability to quickly create predictable and controlled speckle patterns, which allows for the highest level of accurate and consistent results.

為什么散斑圖案質(zhì)量對(duì)我們的測(cè)量很重要 Why Is Your Speckle Pattern Important?

理想的散斑圖案是高對(duì)比度的、散斑點(diǎn)分布是隨機(jī)的、散斑點(diǎn)尺寸大小是一致的、且試件表面上的黑白分布密度是等量的。如果滿足所有這些條件，則我們的測(cè)量關(guān)注區(qū)可將噪音控制在很低的水平，并且能夠以非常高的誤差確定度進(jìn)行跟蹤測(cè)量。

The ideal speckle pattern is high contrast, contains random speckles, consistent dot sizes, and equal amounts of black and white on the sample’s surface. If all of these conditions are met, the area of interest will produce low levels of noise and may be tracked with very high levels of certainty.

以下是各種散斑圖案如何影響測(cè)量噪聲的例子。中間區(qū)域的圖案是使用VIC散斑制備套件中的滾筒創(chuàng)建的，而另外兩外側(cè)區(qū)域上的圖案均使用噴漆創(chuàng)建。正如您所看到的那樣，來自散斑制備套件的滾筒產(chǎn)生了高對(duì)比度圖案，黑色和白色覆蓋率約為50％，而噴漆創(chuàng)建的圖案只具有較低的對(duì)比度以及尺寸不一致的散斑點(diǎn)。

Below is an example of how various speckle patterns can effect measurement noise.  The middle pattern was created using a roller from the VIC Speckle Pattern Application Kit, while the patterns on either side were created using spray paint.  As you can see, the roller from the speckle pattern kit produces a high contrast pattern with approximately 50% black and white coverage, while the painted pattern produces a lower contrast pattern with inconsistent dot sizes.

圖示1: 具有三種不同散斑圖案的平板的Z值置信度分析

Figure 1:A relatively flat plate with three different speckle patterns analyzed to show the variable Sigma_Z

圖1顯示了變量Sigma_Z的二維數(shù)據(jù)疊加，它是在Z方向上進(jìn)行測(cè)量（離面形狀測(cè)量）的可置信度。 Sigma值越接近零，所顯示的數(shù)值就越可能是正確的值。左側(cè)區(qū)域圖案的對(duì)比度低，而且過度細(xì)膩，導(dǎo)致Sigma_Z值較大，表明置信度較低。 中間區(qū)域顯示了較低的Sigma_Z值，這表明對(duì)測(cè)量具有高置信度。 圖中其結(jié)果顯而易見。

Figure 1 shows a 2D data overlay of the variable Sigma_Z, which is the confidence margin of the measurements taken in the Z direction (out-of-plane shape measurement).  The closer Sigma is to zero, the more statistically likely the value shown is indeed the correct value.  The outside patterns are low in contrast and overly fine which result in larger Sigma_Z values, which indicates less confidence.  The middle pattern shows lower Sigma_Z values, which indicates high confidence in the measurement.  The results speak for themselves.

圖示2: Sigma_Z的3D圖顯示了差的散斑導(dǎo)致產(chǎn)生了低置信區(qū)間和嘈雜的形狀測(cè)量結(jié)果

Figure 2:The 3D plot of Sigma_Z displays how poor patterns create low confidence margins and noisy shape measurements.

為什么置信度Sigma值很重要 Why Is Sigma Important?

VIC-2D和VIC-3D中的高Sigma值表明較高的測(cè)量不確定度，這可能導(dǎo)致形狀、位移和應(yīng)變數(shù)據(jù)中的測(cè)量噪聲增加。如圖2所示，兩側(cè)區(qū)域顯示比平整的樣本的Z值范圍較大，而中心區(qū)域顯示的偏差較小。

High Sigma values in VIC-2D and VIC-3D indicate higher measurement uncertainty, which can result in an increase in measurement noise in the shape, displacement, and strain data.  As Figure 2 shows, the outside patterns show a larger range of Z values of a relatively flat sample, while the center pattern shows much smaller bias.

在下面的圖示3中，顯示了在剛體轉(zhuǎn)動(dòng)后變量exx的數(shù)據(jù)（在X方向上的橫向應(yīng)變），其結(jié)果應(yīng)該是0應(yīng)變。而應(yīng)變?cè)茍D中顯示的應(yīng)變值范圍在兩側(cè)外部區(qū)域的結(jié)果比中心區(qū)域高得多，表明兩側(cè)局部區(qū)域的測(cè)量產(chǎn)生了不該存在的應(yīng)變?cè)胍艚Y(jié)果，這會(huì)導(dǎo)致不準(zhǔn)確的數(shù)據(jù)。這可以很好地說明差的散斑圖案如何導(dǎo)致噪聲影響測(cè)量，而好的散斑圖案（應(yīng)用散斑套件）則會(huì)產(chǎn)生更好的結(jié)果。

In Figure 3 below data for the variable exx (transverse strain in the X direction) is shown for the same plate after a rigid body translation, where there should be zero strain.  The range of strain values shown in the contour plot are much higher on the outside patterns than the center pattern.  The result shows that the local strain measurements on the outside patterns are more noisy and will produce data that is less accurate.  This is a good illustration of how poor speckle patterns can result in noisy measurements, while favorable patterns (applied with the speckle kit) will produce much better results.

通過使用VIC散斑制備套件可幫助用戶獲得散斑圖案，使您的結(jié)果噪聲更少，數(shù)據(jù)更準(zhǔn)確。

By applying the optimal speckle pattern using the VIC Speckle Pattern Application Kit your results will be less noisy and more accurate.

圖示3:在剛體偏轉(zhuǎn)后顯示的橫向應(yīng)變信息。 由于外側(cè)的散斑質(zhì)量不佳，板的外側(cè)顯示出比板中部高得多的噪聲。

Figure 3: Transverse strain is shown after a rigid body translation. The outsides of the plate display a much higher level of noise than the middle of the plate due to the poor speckle patterns.

VIC散斑制備套件將提升您的測(cè)量結(jié)果 The VIC Speckle Pattern Application Kit Will Improve Your Results:

Correlated Solutions，Inc.公司的VIC散斑制備套件可以幫助測(cè)量結(jié)果保持非常低的噪聲和非常高的DIC測(cè)量結(jié)果的置信度。 散斑制備套件給予新用戶和有經(jīng)驗(yàn)的DIC用戶同等的能力，可以為幾乎任何鏡頭和圖像采集器組合的不同尺寸視場創(chuàng)建理想的、可重復(fù)的散斑圖案。 擁有此功能可以簡化試件制備過程，確保重復(fù)測(cè)試結(jié)果的一致性，并配合VIC-2D或VIC-3D系統(tǒng)為所有測(cè)量獲得始終如一的低應(yīng)變?cè)肼?span style="background-color: initial;">結(jié)果。

The VIC Speckle Pattern Application Kit from Correlated Solutions, Inc. can help produce very low noise and very high confidence results for DIC measurements.  The speckle kit allows both new and experienced DIC users to create ideal and repeatable patterns for many fields of view for nearly any lens and sensor size combination.  Having this capability can streamline the sample preparation process, ensure consistent patterns for recurring tests, and provide a means to obtain a consistently low strain noise floor for all measurements acquired with your VIC-2D or VIC-3D system.

VIC散斑工具套件參數(shù) The VIC Speckle Pattern Specifications: