Application Group

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Test Results

Laser Engraving Resolution Chart

31/3/2015

General

The following report describes the measurements results obtained when scanning a metal sheet

that a resolution chart was engraved on its surface.

The intent of this test was to ascertain the capabilities of Optimet sensors in measuring the micron

size (width and depth) chart on the metal sheet.

The measurements were performed using Conopint-10 sensor with 25mm and 16mm lens. The

scanner used was the Conoscan 3000 at the application group laboratory.

In order to confirm our measurements results we have measured the samples depth using a high

power microscope and by using its adjustable focusing scale by focusing first on the top surface

and then focus at the bottom of the groove. By reading the scale change we were able to estimate

the depth of the engraved area within ±5µm.

Sample Numbering

Sample numbering

1 2 3 4 5 6 7

ConoPoint-10 with 16mm lens

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Main Conclusions

1. The sample with the 7 different engravings as described above is scannable with Optimet

sensor.

2. The lack of distinction at the 1 or 3um level engraving depth is mainly associated with the

sample itself. The sensor with 16mm lens has a resolution in Z of around 0.3-0.5um with

lateral resolution of <1um.

3. It is noticeable that the walls of the engraving are not 90° but more closer to 60 - 70°. This

implies that there is a tradeoff between the depth and the width attainable using this

particular laser.

4. It is also clear that the engraving is not accurate in depth within ±5um, and especially

engraving under 10um depth.

5. The conclusion above (4) can clearly being observed when scanning a slope as than in

sample #2. In the beginning of a slopes, first 10-15um, there is a different slope angle.

6. It is also observed that at the bottom of the narrow grooves the surface is not flat probably

because of the laser engraving beam spot configuration. It is clear that samples engravings

are not uniform within ±5um.

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Sample #1

The results of sample #1 are shown in the figure below. The lateral distance between the

centers of the grooves is 1.939mm.

Sample #2

The sample 3D scan is shown below. All the detailed structure is clear.

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The angle of the two slopes can be calculated:

Angle = (180-177.278) = -2.722° angle = 2.6002

It can be seen that in the beginning of the slopes there is a short slope with a different angle of

around 8 degrees. It is also observed that at the bottom of the narrow groove the surface is not

flat probably because of the laser engraving beam spot configuration.

Sample #3

The sample microscopic picture is shown below:

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The 3D scan results are shown in the following picture for which the length is 2.039mm depending

were the points are taken. (The walls are not 90° and not uniform with in ±5um)

The depth of the engraved box is as shown:

The height difference from the surface to the bottom is different between the two sides by 6.5um

Left height: a-b = 105.3um

Right height: c-b = 111.8um

The Roughness on the bottom Rq= 1.618um

As can be clearly seen the bottom surface is not uniform, this is also very clear in the picture taken

using a microscope (first picture above, in sample #3)

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Sample # 4

The microscopic picture of sample # 4 is depicted below:

When scanning the top portion of the sample ( X- axis) the 3D results are shown:

10

9

8

7

6

5

4

3

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The Sensor has a depth resolution of sub microns (0.5um) and According to the above results it is

demonstrated that the engraving shows clear results only from #5 and above while below that we

see the grooves but engraving depth is not as expected probably due to the laser engraving

system.

Target # Points on

figure

Height

difference (um)

10 a-b 20.8

9 c-d 18.4

8 e-f 15.4

7 g-h 11.4

6 i-j 6.9

5 k-l 4.6

4 m-n 4.4

3 o-p 3.3

When scanning the bottom area of target #4 (Y-axis resolution grid) we were able to get clear

results all the way down to #2 and even #1 as shown in the picture below. It must be noted that #1

engraving is not very clear along the whole line. Meaning the depth of the engraving is not

uniform.

7 4 5 6 3

2

1

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Sample # 5

The microscopic picture of sample #5 is depicted below:

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Since each groove has a nominal depth listed we compare the height difference between what

was measured and the nominal:

NOTE: take into consideration that the grooves depth are not 100% uniform and there might be a

few microns (sometimes even 5um) difference within the grooves them self. The values listed below

are the average depth of the groove

taken in one cross section.

Nominal

(um)

Measured

(um)

Delta

(um)

10 18.2 8.2

20 28.4 8.4

30 38.3 8.3

40 47.5 7.5

50 54.8 4.8

60 61.9 1.9

70 75.7 5.7

80 83.8 3.8

90 97.7 7.7

100 107.6 7.6

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Sample # 6

We skipped #6 since it's the same idea as #7.

Sample # 7

The microscopic picture of sample #7 is shown below:

According to the nominal written, the depth and width of the grooves should change by 10um.

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Let's focus on the 10um groove which is on the bottom left side of the picture above:

If we look at the height between the bottom of the groove and the top surface, it moves from

14.5um to 15.5um. (Nominal is 10um)

But if we take the difference between the bottom of the groove and the top of the separating hill

top between the grooves, the height is 9.5-10um.(see below)