The Influence of the Wavelength of Laser Light on the Non-Contact Measurement of the Roughness of Shiny Cut Surfaces on Stainless Steel A304 Material

Abstract

The article is focused on the study of the effect of laser light with three wavelengths used in a laser profilometer for the measurement of selected roughness parameters of the shiny surface of stainless steel A304 material. The measured results were compared with the results we achieved with the reference contact roughness meter (SJ-400). The findings presented are relevant to the parameters of the experiment outlined within the article. In general, the obtained results make it possible to state that when measuring the roughness of shiny cut surfaces using non-contact laser profilometry, reflections of laser light occur. The relatively best results of measuring the parameters of the roughness of a shiny cut surface on the evaluated material (A304) were achieved by laser light with a wavelength of λ = 445 nm. In contrast, as the surface roughness of the cutting surface of the used material increased, the reflection of laser light decreased. Furthermore, we can state that the values of the roughness parameters Ra and Rz of the shiny surface measured by laser profilometry were several times higher than the values measured by the reference method. In contrast, the non-contact method of laser profilometry is not suitable for accurate measurements of the roughness parameters of shiny surfaces.

1. Introduction

There are many experiments and much research aimed at creating 3D models that serve to evaluate the quality of a cutting surface. These models are used to analyze and characterize various factors affecting the cut quality, such as tool geometry, the cutting process’s parameters, the material, the cutting speed, and many others. Evaluation of cut quality is important because industrial processes often require precise and high-quality cut surfaces. The quality of the cutting process depends on many factors, such as the accuracy of the tool, the material, the cutting parameters, and the cutting conditions. The overall quality of the product is influenced by these factors and is conditioned by three types of accuracy, namely shape, size, and area measurement, which are characterized by the roughness parameters [1].

The spatial characteristics of the surface provide new possibilities for the expression and presentation of the structure of the surface. By including an additional dimension and a significantly larger amount of data, they enable a more objective assessment of the surface and potentially predict its functionality and evolution during operation. Spatial analyses of the structure of the measured surface provide us with a graphical representation of the profile from different points of view, such as a topographic map or a record of the coordinates’ intensity. These measurement methods provide a large amount of information that can be used by an experienced observer [2].

Spatial methods are measurement techniques that serve to obtain information about topographical deviations of the surface of objects. These deviations are referred to as z (x,y) and represent the distance of the point (x,y) from the reference plane [3].

The reference plane can be defined either through physical calibration, where a known reference surface is used to adjust the measurement system, or by the principle of the method used, which can have its own internal reference plane [4].

The field of spatial methods has undergone significant development in recent decades. This progress was made possible mainly due to the development of computing technology, optical detectors, and light sources [5].

Enhancing the longevity and operational dependability of components hinges on the superior quality of their functional surfaces, encompassing dimensional precision, the shape’s fidelity, and the surface texture. As progressive construction materials with constrained machinability become more prevalent, alongside advancements in cutting materials and machine tools, there is a growing imperative for the evolution of measurement techniques and assessment methods to ensure the quality of the components’ surfaces [6].

An important factor in the evaluation of the quality of the surfaces of the components is the roughness of the surface, which is an important indicator of the technology and processes used to create it [7].

In contemporary machining technologies such as AWJ (abrasive water jet), laser, or additive methods, it is commonplace for the surface roughness to be different between the entry point into the material and the exit point [8].

Scoring itself harms the quality of machined surfaces, as it can cause unevenness, increased roughness, and undesirable shape deviations. Therefore, it is important to divide the machined surface into several zones to better characterize the quality of the surface and allow possible correction or optimization of the processes. Zones can be defined on the basis of various criteria, such as the depth of grooving, roughness, shape deviation, or other factors affecting the surface’s quality. In this way, it is possible to identify areas with high roughness, undesirable shape deviations, or other problems and focus on their optimization and improvement [9,10].

Surface roughness analysis is an important tool in the evaluation and control of machining technology and surface treatment processes. Through the evaluation of the surface roughness of the components, it is possible to obtain information about the current state of the surface and to identify any deficiencies or discrepancies from the required specifications [11].

The trend of automation of production processes is also reflected in the automation of controlling surface structures. In fully automated production, the optimal scenario involves acquiring data regarding the deviation of the resultant surface from a predefined standard. Subsequently, the production process can be adjusted by modifying the machining corrections or other parameters to attain the desired quality of the surface structure [12].

Research dedicated to measuring surface roughness is progressing swiftly, with the ongoing development of new methods and technologies aimed at precisely assessing even the most nuanced deviations in the profiles of diverse surfaces. These technologies are essential in many industries and applications where high accuracy and detailed analyses of surface properties are required. It also provides important information for the design, manufacture, quality control, and development of new materials and products. The use of modern technologies, such as laser profilometry, opens new horizons in the investigation of materials’ surfaces. These technologies provide detailed information on the three-dimensional shape of the surface, which is crucial for the research, development, and quality control of materials in many industries and applications [13].

When transitioning to smaller measurements, choosing the right metrology tool becomes crucial due to the diverse methods available, each with its own set of advantages and limitations. The selection depends on factors such as the sample being measured, and the specific properties needed. Understanding how these techniques can influence the measured parameters is essential for accurate results [14].

The use of optical techniques to study surfaces has been very popular for a long time and there have been many developments over the years to improve the accuracy of the metrology. In recent years, the use of interferometry and confocal microscopy has become more and more widespread, and much is now known about the pros and cons of the techniques [15].

The surface roughness can be measured using many techniques, including optical and scanning electron microscopy, contact and noncontact profilometry, and atomic force microscopy (AFM) [16].

Profilometers utilize a variety of optical concepts, including interferometry, focus detection, and light scattering, to analyze the surface profile of an object. The data generated by the profilometer can be used to create two-dimensional (2D) and three-dimensional (3D) surface profile graphs of the object [17].

These instruments offer a broad measuring range of amplitude and are consequently widely used to test the surface of materials. However, it may not provide a good visual description of the surface with 2D and 3D measurements [18].

Two of the primary characteristics utilized for assessing surface roughness are Ra, which represents the mean arithmetic deviation of the profile, and Rz, which indicates the height of irregularities in the profile. These parameters offer insights into the distribution of surface irregularities and can be measured with either non-contact or contact profilometers. In addition to Ra and Rz, there are many other surface roughness characteristics such as Rq (the root mean square deviation of the assessed profile), Rt (the total height of the profile), Rmax (the maximum depth of roughness), and many others. Each of these characteristics provides different information about the surface roughness and may be suitable for different applications and evaluations [19].

Laser Profilometry (LPM)

Laser profilometry plays an important role in the evaluation of surface roughness parameters. It is capable of accurately and reliably measuring the dimensional accuracy, the shape accuracy, and the surface roughness of components. Laser profilometry makes it possible to obtain detailed information about surface deviations, curvatures, the thickness of coatings, geometric shapes, and other critical parameters that are important for the functional reliability and service life of components [20].

Laser profilometry, applying the triangulation principle, involves projecting a linear laser beam onto the surface of the object being measured at a specific angle. Subsequently, a camera positioned perpendicular to the object’s surface detects the deformed image (profile) of the laser’s track on the surface (Figure 1). After that, the surface of the object to be measured, or the sensing device itself, is moved by a small distance with the help of a programmable displacement, and another profile is captured by the camera. This procedure is repeated, obtaining a series of profiles from the surface of the measured object. After obtaining several profiles, their images are combined and aligned into one overall image, resulting in an actual 3D profile of the measured object, which provides a large amount of information about the surface structure, such as differences in height, the roughness, geometric characteristics, and other parameters. This information is important in assessing the quality of the surface and its functional properties, as well as in identifying possible problems or changes during operation. This process of the composition and subsequent evaluation of individual profiles is implemented using specialized software equipment for laser profilometry itself [21].

In the past, laser profilometers and scanning technologies used (red) lasers with a wavelength of around 650 nm, or infrared lasers. This color of light was common for historical reasons and was considered suitable for the given applications [22].

In recent decades, the rapid development of microelectronics and material physics has resulted in a wide spectrum of light sources being available for experimental 3D measurement setups [23].

Traditional lasers are gradually being replaced by laser diodes, which provide a sufficient coherence length necessary for use in coherent topographic methods and are also more affordable [24].

Currently, however, with the expansion of modern technologies and their implementation in various areas, alternative laser devices with different wavelengths of radiation than the red spectrum are beginning to appear. The reason is the need to look for new possibilities and to adapt to specific requirements and properties of materials and applications [25].

There are several reasons why alternative colors of laser light are being explored. For example, some materials may have better visibility or contrast with other colors of light, which can lead to more accurate and reliable roughness measurements. The use of other wavelengths may bring advantages for certain applications, such as improved resolution when measuring finer structures or a better ability to penetrate the surface [26].

Laser profilometry is widely used in all branches of industry, where quality control of the surface properties and the shape of objects is important. This technology enables fast and accurate measurements in real-time, which contribute to the higher quality, efficiency, and productivity of production processes [27].

Introducing the spatial control of surface quality into metrological practice is a challenge that requires us to solve technical, economic, and processing problems. Not only the surface measurement itself but also the processing of the results and the effective use of the obtained information are important aspects. The effective use of this method will depend on the ability to solve these challenges and provide relevant and reliable surface information for various applications in industry and metrology [28].

The development and use of spatial assessments of the surface structure are inextricably linked to the growing demands for accuracy, quality, and complexity in production technologies. As new materials and technologies such as nanotechnology emerge, there is anticipated to be a surge in demand for methods such as laser profilometry. With their inherent advantages, spatial evaluation of surface structures is viewed as a promising metrological method for the future [29].

Laser profilometry has its advantages and disadvantages, which must be considered when considering the use of this method. Laser profilometry offers several advantages, including non-contact measurement, the ability to detect cracks and micro-irregularities, the repeatability of the measurements, its suitability for curved surfaces, comprehensive surface evaluation, and the capacity to measure the entire sample’s surface. However, there are also notable drawbacks to consider. These include challenges with measuring shiny surfaces, difficulties with multi-layered surfaces, higher equipment costs, and the need for an experienced operator to properly configure and interpret the results [30].

The results presented in the article apply to the creation of 3D models that predict the relationship between surface quality and technological parameters. The study of parameters in this combination and range is considered unique, where quality control and the evaluation of surfaces are important. The main novelty in this article is the unique combination of the effects of the color of the light (wavelength) of the laser in the laser profilometer on the reflection and the correct evaluation of the measurement of the roughness of the surface parameters, especially for materials with a shiny surface. Our work focused on supplementing the results on the influence of the colors of the laser light on measuring the roughness of shiny surfaces, whether the color of the laser light reduces the reflection of light from the surface and whether it can affect the accuracy and reliability of surface roughness measurements, especially for specific shiny surfaces. We hope that these data will be beneficial from a research and practical point of view for choosing the right colored laser lights for specific materials and surfaces, which can lead to improved measurement processes, a better understanding of the effect of the light’s colors on reflection, and a more accurate assessment of the roughness of surface parameters.

2. Materials and Methods

The experiment was designed to investigate the impact of the color of the laser light (wavelength) emitted by a laser profilometer on the light reflected from the sample’s surface. This effect was then compared with reference results obtained using the Surftest SJ-400 contact roughness meter. The tested sample was made of stainless steel. When measuring with a laser profilometer, we used three colors (wavelengths) of laser light. Samples were measured and evaluated using two systems: a reference Mitutoyo contact roughness meter (Surftest SJ-400, Tokyo, Japan) and a newly available non-contact laser profilometer (KVANT, Bratislava, Slovakia). Both measurement methods were applied to the same sample and measured a cross-sectional area.

During the evaluation of surface roughness, we closely monitored the parameters Ra and Rz, which typically offer adequate information about the roughness of the surface under examination [19].

The measured roughness values were plotted on a graph, comparing them with the reference values for the qualitative roughness parameters Ra and Rz.

2.1. Description of the Tested Material and Preparation of the Sample

The choice of material was based on several basic requirements, such as high usability and availability in industry, and various material properties, including a high gloss. To achieve a shiny surface on the test sample, we used laser technology to divide the material. The cutting machine TruLaser 3040 from the company TRUMPF (Farmington, CT, USA) was used to divide the material, while the speed of cutting the material with the laser was 2.1 m/min. This technology enables the creation of cutting surfaces with a very shiny surface, which is an important factor in measuring surface roughness, as it can affect the reflection of light and thus also the measurement results. Thanks to the use of laser technology in cutting the material, we achieved the desired effect of a gleaming surface on the test sample. The chosen material separation approach and the selection of a sample with a very shiny surface are important for the accuracy and reliability of the measurement of surface roughness. These aspects are crucial for assessing the suitability of laser profilometry and the influence of the color of the laser light on the measurement.

The test sample was made of material designated as stainless steel A304 (Source 21, Inc., Sound Beach, NY, USA) with dimensions of 50 × 50 mm and a material thickness of 5 mm (Figure 2).

2.2. Description of the Non-Contact Measuring Device

For non-contact measurement of roughness, we used a laser profilometer (Figure 3), which consisted of basic and additional parts. The basic parts included a massive aluminum support structure made of components with vertical positioning of the measuring tube (z axis), a work plate that was fixed to stepper motors with movement in the x and y axes, a laser beam source, a backlight, and a detector, which was a CMOS camera (STMicroelectronics, Geneve, Switzerland) (complementary metal oxide semiconductor). The camera was chosen as it had sufficient camera features and due to its immediate availability, as it is part of the laboratory equipment. Additional parts included a computer with LPM View control and evaluation software, and an image splitter.

Placing the experimental sample in an anti-vibration material and eliminating vibrations from the surrounding environment is of great importance when measuring with a non-contact system. These measures can ensure the stability of the sample and minimize the possible effects of vibrations on the measured data. In this way, it is possible to achieve higher accuracy and reliability in the measurements of surface roughness.

In our experiment, the light source was an exchangeable laser light (red with a wavelength of 635 nm, green with a wavelength of 520 nm, and blue with a wavelength of 445 nm) (Figure 4).

Laser profilometry enables the measurement and evaluation of the surface roughness parameters of samples in line with ISO 4287 standards [31] (including Rq, Rv, Rz, Ra, and Rp). The obtained roughness data can be exported in CSV format, facilitating further processing of the experiments as raw data. In our analysis, we focused on evaluating the surface roughness parameters Ra and Rz using laser profilometry.

When measured by non-contact laser profilometry, the surface of the sample was scanned in 45 lines (count of scan lines) with a step size of 110 µm on the length of the scan line in the x-axis, which measured 4000 µm.

2.3. Measurement of the Surface via Direct Contact

As outlined in the introduction, to validate the accuracy of measurements obtained through non-contact laser profilometry and to compare them with those obtained through contact methods, the samples were also assessed using the Mitutoyo Surftest SJ-400 roughness meter (Metrology Parts LLC., Walker, MN, USA).

The parameters Ra and Rz of the sample’s surface roughness were measured using this device, which incorporates a contact tip and applies the differential induction detection method to measure surface profiles. The device then evaluates the surface’s quality parameters according to established standards. The length of the measuring needle’s path in the roughness measuring device is 13.3 mm. Figure 5 illustrates a close-up of the measuring device used for assessing the surface roughness of the sample section.

Both measurement methods focused on the identical section of the surface being assessed.

2.4. Measurement of the Experimental Sample

The roughness parameters Ra and Rz of the cut surface were measured at three distinct levels across the cut surface: the smooth, medium, and coarse zones. At the same time, the individual measurement lines characterized the individual areas of the cross-section of the cutting surface, which were created after using cutting technology; in our case, the material was cut with a laser. Measuring Line 1 characterized the smooth area, Measuring Line 2 characterized the middle area, and Measuring Line 3 characterized the rough area of the cutting surface. We set the individual measurement lines in such a way that it was possible to identify different cross-sectional areas of the cutting surface created after the use of laser material cutting technology. At the same time, they served to characterize the differences in the area profile of the surface in different areas of the divided material.

Furthermore, the measured surface was divided transversally into sections labeled A, B, and C (as illustrated in Figure 6). Individual measurement lines (1, 2, and 3) were established at intervals of 1, 2.5, and 4 mm, respectively, commencing from the smooth zone of the sample.

The measurements were conducted at various measurement lines, specifically within the smooth zone at 1 mm, the medium zone at 2.5 mm, and the rough zone at 4 mm. Each measurement line was subdivided into sections denoted A, B, and C. Three repetitions of the roughness measurements were executed on each of these sections.

3. Results and Discussion

The non-contact method (LPM) for measuring surface roughness used laser light to capture and analyze the surface profiles, unlike the contact method (SJ-400), which required physical contact.

Our experiment analyzed how the color (wavelength) of the laser light in laser profilometry affected the accuracy and reliability of measuring the roughness parameters (Ra, Rz) on glossy surfaces created using laser cutting to aid in selecting the most suitable measurement method for specific finishes.

Data from experimental measurements were processed into graphical dependencies enabling a visual analysis and a comparison of the results between reference measurement data and the individual colors of laser light in individual measured sections.

A graphic comparison of the measured values of the parameter Ra on individual measuring lines (1, 2, and 3) and sections (A, B, and C) by the non-contact method (LPM) using laser light with different wavelengths versus the reference contact method (SJ-400) is shown in Figure 7.

When using light with a wavelength of λ = 445 nm, we found that the values of the Ra parameter measured by the non-contact method were 7.5 to 9.6 times higher on Measuring Line 1, 5.7 to 7.8 times higher on Measuring Line 2, and 3.9 to 4.3 times higher on Measuring Line 3 compared with the reference values from the contact roughness gauge. We also observed similar trends for lights with a wavelength of λ = 520 nm and λ = 635 nm, where the values of the parameter Ra were also significantly higher compared with the reference values. These differences in the character of the individual areas of the cross-section of the cutting surface were a consequence of the laser cutting technology itself. Laser cutting can have different effects on the material’s surface depending on the cutting parameters, the material’s properties, and other factors.

Based on the comparison of the Ra parameter values, a significant negative difference between non-contact laser profilometry and the reference contact method was shown.

From the findings above, we can conclude that the high negative difference in the measured Ra values was caused by the fact that the non-contact laser profilometer evaluated the reflections of laser light from the surface of the sample, which were captured by the CMOS camera and subsequently evaluated by the LPM software (http://testsite.kvant.sk/solutions/lpm/, accessed on 11 March 2024) as increased surface roughness, i.e., a measurement error that can be explained as the unwanted glare in the camera sensor.

These findings indicate that the non-contact method of measuring the roughness of glossy surfaces is inappropriate and not reliable for measuring the Ra parameter. The contact method using the SJ-400 roughness meter is more objective and provides more realistic results for the Ra parameter.

Studies by Stojanovic et al. [30] and Mitala et al. [6] reported that a non-contact laser profilometer can evaluate reflections as increased surface roughness. On the basis of our measurements, we found that the value of the Ra parameter was, however, several times higher than the reference value. Therefore, we do not agree with the statement that it is only an increased value of Ra. It is important to emphasize that our research was conducted on a different material sample and therefore may have led to possible different results.

A graphic comparison of the measured values of the Rz parameter on individual measuring lines (1, 2, and 3) and sections (A, B, and C) by the non-contact method (LPM) using laser light with different wavelengths versus the reference contact method (SJ-400) is shown in Figure 8.

Our measurements using different laser lights in comparison with the Surftest SJ-400 contact roughness meter also showed differences in the values of the Rz parameter. The measurements indicated that even the Rz parameter values obtained by the non-contact method using different laser wavelengths (445 nm, 520 nm, and 635 nm) were higher compared with the reference values from the contact roughness meter. When using light with a wavelength of λ = 445 nm, we noted a 1.3- to 1.5-fold increase for Measurement Line 1, a 1.0- to 1.5-fold increase for Measurement Line 2, and a 1.2- to 1.4-fold increase for Measurement Line 3 compared with the reference values from the contact roughness gauge. We also observed similar trends for lights with a wavelength of λ = 520 nm and λ = 635 nm, where the values of the parameter Rz were also significantly higher compared with the reference values.

When comparing the measured values of the parameter Rz obtained using a non-contact laser profilometer and the reference values from the contact roughness meter Surftest SJ-400, we also found a significant negative difference, as was the case with the parameter Ra. Although this difference in the Rz values was several times lower than the difference in the Ra parameters, we can also state that the non-contact laser profilometer method provided negative results for the Rz parameter compared with the contact roughness meter.

The measured Rz values for the individual measuring lines were not evenly distributed compared with the Ra value. The differences in the values of the parameter Rz from the individual measuring lines in the cross-sectional areas of the cutting surface were caused by the laser cutting technology itself.

Measuring Line 1 was characterized as a smooth area of the cutting surface, where the surface showed relatively little roughness. We also measured the highest multiple of the Rz parameter, which also resulted in the highest level of light reflection from the surface. The C1 region performed relatively better for Rz compared with the B1 region for all three laser lights.

Measuring Line 2 characterized the middle area of the cutting surface, where the surface may show a slight increase in roughness compared with the smooth area, where, at the same time, the reflection of the laser light was also milder compared with that of Measuring Line 1. We can explain the reduced reflection of laser light in Part A2 as the effect of increased scoring, which was caused by the onset of the laser beam during splitting of the material. At the same time, in the given area, we also recorded an increased value of the parameter Rz during the reference measurement.

Measurement Line 3 characterized a rough area of the cutting surface, which was associated with more pronounced surface unevenness and a coarser texture compared with the previous two areas, and here, the measured value of the Rz parameter was closest to the reference values too.

For the Ra parameter, the best results were achieved using light with a wavelength of λ = 445 nm. On the other hand, in the areas C2, B3, and C3, the measured values of the Rz parameter when using light with a wavelength of λ = 445 nm showed relatively worse results than light with a wavelength of λ = 520 nm. We hypothesize that these differences were due to an increase in scoring, which was created by the interaction between the tool (for example, a laser) and the material. This interaction led to the removal of material and the formation of grooves and rough surfaces, which negatively affected the quality of the machined surfaces. These irregularities, the increased roughness, and the undesirable shape deviations had the effect of reducing the reflection of the laser light from the surface of the sample, which was captured by the CMOS camera.

The high measured values of the Rz parameters compared with the reference contact method indicated that the non-contact method of measuring the roughness of shiny surfaces is unsuitable and is not reliable even when measuring the Rz parameter. The contact method using a roughness gauge is more reliable and provides more accurate results.

According to the studies of Ružbarský [21] and Mital’ et al. [23], the problem is the shiny surfaces, which are problematic to measure by laser profilometry due to reflections of the laser light from the surface of the sample, which were captured by the scanning camera and subsequently evaluated by the laser profilometry software as increased surface roughness. These authors proposed a solution in the form of using laser light with a different wavelength to minimize the light reflected from the surface. Our results indicated that laser light with a wavelength of λ = 445 nm achieved the best results. However, when comparing these results with the reference measurement, we found that the values of the roughness parameters Ra and Rz were significantly higher, which was very undesirable. The achieved results disqualify the non-contact method for measuring shiny surfaces.

In the case of shiny surfaces, it is necessary to choose methods and treatments of the measured surfaces that reduce or eliminate the reflection of laser light. One of these ways can be the use of a special transparent coating on the surface of the sample. Such a coating can be designed to absorb reflected laser light and minimize the unwanted effects of reflection and glare. It is also possible to prevent glare by staining the surface and thus matting it. This would reduce the interference between the laser light and the surface, which would allow a more accurate measurement of roughness by the non-contact method.

4. Conclusions

By investigating and comparing the effects of different laser light wavelengths on measurements of roughness, particularly on glossy surfaces, we gained valuable insights. This knowledge has the potential to drive the development of novel techniques and methodologies for accurately measuring surface roughness on glossy surfaces, tailored to specific materials and diverse application requirements. Furthermore, it contributes to a deeper understanding of this area, paving the way for enhanced surface analysis techniques.

• In the zone with the greatest roughness of the cutting surface, the reflection of the laser light was the least. Conversely, in zones with a lower surface roughness at the cutting surface, the reflection of laser light was higher.
• Of the three laser light wavelengths used, the laser light with a wavelength of λ = 445 nm achieved the best results for measuring the roughness parameters of the shiny surface.
• When we compared the percentages of the measured values of the roughness parameters Ra and Rz of the shiny surface between those obtained by laser profilometry and those of the reference contact roughness meter SJ-400, we found that the values measured by laser profilometry were several times higher than the reference values.
• When measuring the roughness of shiny surfaces using non-contact laser profilometry, reflections of laser light occur, which cause distortion or interference with the measured results, with the consequence of affecting the accuracy of the measurement. One way to partially limit this phenomenon is to use a special transparent coating on the surface of the sample, which absorbs some of the reflections. There is also the possibility of preventing glare by making the surface cloudy and therefore matt.
• The non-contact method of laser profilometry is not suitable for accurate measurements of the roughness parameters of shiny surfaces. This conclusion is important from the point of view of choosing a suitable measurement method if precise values of the roughness of shiny surfaces are essential. In that case, we recommend using a contact roughness meter.

An experiment that analyzes the effect of the color of laser light in a laser profilometer on the reflection of light from a surface can also have several practical benefits:

• Experiments that involve using different colored spectral laser lights to measure surface roughness can help identify the optimal light color for a particular type of surface.
• Different colors of light have different abilities to penetrate the material and reflect from the surface. In this way, it may be possible to highlight certain surface features and improve the visibility of details that might otherwise be less obvious or hidden.
• Experiments with different colored spectral lights can provide important information about these surface properties and may help in evaluating and comparing the quality of different surfaces.

Measuring surface roughness using non-contact methods such as laser profilometry is a technically challenging task. Achieving accurate measurements at such a fine level is at the limit of physical possibilities and requires careful calibration and proper setup of the measurement system. These experiments can provide valuable insights into the possibilities and limitations of these methods and contribute to the development of better techniques and procedures in the field of the measurement of surface roughness. These experiments can help push the boundaries and bring innovations in the field of measuring surface roughness and creating reliable and accurate surface profiles.

It is important to keep in mind that the results of this experiment may vary depending on the specific material type, the surface texture, and the measurement device’s settings. Therefore, it is necessary to carry out enough repeated measurements and a thorough analysis of the results achieved.