Patent Description:
Typically, during the manufacturing of coating compositions, such as automotive OEM or refinish paints, from time to time, an aliquot of such coating compositions being manufactured is taken, applied as a layer of desired thickness over a test substrate, dried and/or cured into a coating and is measured. The process parameters are then adjusted and the described testing procedure is repeated until the adjusted coating composition meets the measurement requirements.

The aforementioned testing procedure is not only time consuming and cumbersome but it also results in frequent interruptions in the manufacturing process. As a result, the batch-to-batch quality of the resulting coating compositions can be affected detrimentally. Several methods have been developed to measure optical properties of a layer from a coating composition in its wet state that correlate to the gloss that can result when such a layer dries and/or cures into a coating.

However, there are issues with the standardization and repeatability of testing of wet layers, as with as with the time required to ensure standardized testing. Accordingly, there is a need for the development of assemblies and methods for performing parameter measurement operations in standardized alignment. Further, there is a need for such assemblies and methods that provide for rapid use. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

<CIT> relates to a process for measuring one or more liquid properties. <CIT> relates to a method for spectrophotometric measurement of the color of liquid paints by means of light reflected from the surface of the paint.

In a first aspect, the present disclosure relates to a method as defined in claim <NUM>.

In a second aspect, the present disclosure relates to an assembly as defined in claim <NUM>.

The present embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:.

The following detailed description is merely exemplary in nature and is not intended to limit the devices and methods as described herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or in the following detailed description.

As used herein, "a," "an," or "the" means one or more unless otherwise specified. The term "or" can be conjunctive or disjunctive. Open terms such as "include," "including," "contain," "containing" and the like mean "comprising. " In certain embodiments, numbers in this description indicating amounts, ratios of materials, physical properties of materials, and/or use are may be understood as being modified by the word "about". The term "about" as used in connection with a numerical value and the claims denotes an interval of accuracy, familiar and acceptable to a person skilled in the art. In general, such interval of accuracy is ±<NUM>%. All numbers in this description indicating amounts, ratios of materials, physical properties of materials, and/or use may be understood as being modified by the word "about" or may be understood as being not modified by the word "about". As used herein, the "%" or "percent" described in the present disclosure refers to the weight percentage unless otherwise indicated.

Embodiments herein are related to methods and assemblies for performing wet color measurements. While embodiments are provided of such measurements performed on liquid coatings formed as a layer on a spinning disk, such embodiments are merely descriptive and are not limiting.

Further, methods and assemblies described herein for measuring optical parameters of liquid coatings are not subject to any limitations as regards the nature of the liquid coating. Exemplary methods can be used for measuring optical, especially colorimetric, parameters on any types of liquid coating. The liquid coating may be, for example, color-giving lacquers pigmented with absorption pigments, so-called plain lacquers, metal-effect lacquers pigmented with metal pigments, for example aluminum pigments, and, optionally, other pigments, or special-effect lacquers pigmented with interference pigments or any other special-effect pigments. The liquid coatings may contain any desired types of pigment in combination with one another. The measurements may be carried out both on solvent-based and on water-based liquid coatings. The further composition of the liquid coatings, for example in respect of binders, additives, and other constituents, is not important. The liquid coatings must simply be such that they can be applied without difficulty to the cylindrical support, and the formation of a homogeneous film is ensured.

Exemplary methods allow measurements, such as wet color measurements, to be carried out on wet liquid coatings rapidly and effectively and with the required accuracy of measurement, irrespective of the color-measuring device used.

Exemplary methods may be used in the coating industry both in the case of quality assurance in coating manufacture and coating standardization, and in the various development stages of coating development. For example, methods may be used in the evaluation of intermediate results in coloring processes in coating manufacture and coating standardization, for example in the production of standardized mixed coatings or standardized pigment pastes. In such processes, intermediate values are determined which are still relatively far removed from the end result, and it is therefore to be possible to determine them rapidly and effectively but with the required accuracy.

Exemplary methods may also be used, for example, in the field of printing inks. Of course, exemplary methods and the devices for carrying out such methods may in principle be used also in any other fields of application in which, in general, optical and, especially, colorimetric measurements on colored, liquid media are required.

Generally, wet color measurement allows for significant time savings as compared to dry measurement, as the user may compare wet batches to ensure proper color position without waiting for drying. Exemplary wet color measurement hardware includes a spectrophotometer, a mechanical carriage to hold the spectrophotometer a fixed distance from the wet paint layer, and a spinning disk that achieves a planar wet paint layer. The distance between the spectrophotometer port and the wet paint layer must be consistent among all spectrophotometers to ensure operation within required testing tolerances.

Currently, the measurement distance is set using an iterative process that requires measurement of a reference wet paint, followed by manual adjustment of carriage relative to the liquid surface. Such a measurement configuration requires a very complex alignment procedure that is time consuming, prone to error, and difficult to repeat without a significant level of training.

Therefore, embodiments herein provide a simplified method and assembly for providing repeatable alignment of devices and testing by those devices. For example, embodiments herein include a removable, temporarily-affixed mechanical alignment fixture placed between the spectrophotometer face and the disk surface that is able ensure that the spectrophotometer port is parallel to the surface of the wet paint surface and held at the proper distance therefrom.

To ensure that the planar surfaces of the spectrophotometer face and the spinning disk are parallel, exemplary assemblies include a mechanical alignment feature providing three points of contact and having uniform critical dimensions, such as three spheres of uniform diameter. The use of three points of contact constrains rotation of along the x, y, and z axes. The uniform diameter of the spheres constrains distance between the spectrophotometer face and the spinning disk in the z direction. Further, translation in the x and y directions of the spectrophotometer is constrained by the mechanical carriage in which the spectrophotometer sits.

In exemplary embodiments, alignment of the spectrophotometer and disk surface is performed by manual mechanical adjustment, such as adjustment of micrometer screws, or similar adjustment devices capable of precise and repeatable geometry modification, interconnecting the carriage and spectrophotometer until all three spheres are in contact with the disk surface. If the plane of the disk is not fully parallel to the plane of the spectrophotometer face due to one side being closer in distance to another, the spheres on the opposing side will no longer contact the disk surface. This method of alignment ensures that the spectrophotometer is directly aligned to the disk surface, mitigating any variability between spectrophotometers, disks, and carriages. Embodiments herein streamline the alignment and ensure less waste by not requiring the use of wet paint. In other words, the alignment process is performed before, and without, the application of any paint on the disk surface. Further, embodiments herein eliminate the variability associated with wet measurement that is endemic to current alignment processes. Specifically, by directly aligning the spectrophotometer face to the wet measurement surface, the main sources of variation are reduced to wet paint and spectrophotometer noise. Also, embodiments provide for rapid alignment and allow for a more robust backup situation where a broken or non-operational instrument can be quickly switched out with a new one to ensure minimal downtime in high volume production facilities.

Referring to <FIG>, a device <NUM> for holding a liquid coating for measurement of a parameter thereof is illustrated. An exemplary device <NUM> is a thin film device for producing a thin film of the liquid coating on a planar surface <NUM>, such as a surface <NUM> of a spinning disk <NUM>.

As shown, the exemplary disk <NUM> is coupled to a rotation shaft <NUM> that is aligned with a rotational axis <NUM> of the disk <NUM> perpendicular to the disk surface <NUM> for providing rotation to the disk <NUM> around the rotational axis <NUM>.

An exemplary device <NUM> further includes a device frame <NUM> that holds the rotation shaft <NUM> and disk <NUM>. An exemplary device <NUM> further includes a motion device <NUM> coupled to the rotation shaft <NUM> for providing rotation to the rotation shaft <NUM>, and a motion control device <NUM> for controlling rotation speed, rotation direction, or a combination thereof, of the motion device <NUM>.

An exemplary device <NUM> further includes a reservoir <NUM> for storing the liquid applied to surface <NUM>. The reservoir <NUM> can be configured so that the liquid, when present in the reservoir <NUM>, is in contact with at least a portion of the planar surface <NUM>. An exemplary device <NUM> may further include a reservoir <NUM> and a retainer <NUM>. The reservoir <NUM> can be positioned to collect overflow of the liquid, when present, retained by the retainer <NUM>. The retainer <NUM> can be affixed to the device frame <NUM>. The device frame <NUM> can have a frame base <NUM> that can have one or more tiers for positioning the reservoirs <NUM> and <NUM>.

The disk <NUM> can be a circular disk and can further comprise a circular retaining barrier <NUM> positioned at the circular edge of the disk <NUM>. The circular retaining barrier <NUM> can be a belt around the edge of the disk <NUM>, a circular grove or a curved edge, a protrusion around the edge of the disk <NUM>, or a combination thereof. A non-circular disk <NUM> can also be suitable when the non-circular disk has at least a circular portion that is rotationally symmetric to the rotational axis <NUM>. The thin film <NUM>[<NUM>] can be formed on such a circular portion.

The disk <NUM> can be so positioned that the liquid, when present, can be moved by the disk, when in rotation, from the reservoir <NUM> to a thin film setting edge (not shown) against gravity. The planar surface <NUM> can be made of stainless steel, polymers, plastics, glass, or a combination thereof. The planar surface <NUM> should be suitable for forming a thin film of the liquid thereon having essentially even thickness for at least a portion of the planar surface <NUM> large enough for measuring properties of the liquid.

Referring now to <FIG>, the liquid surface <NUM> on the device <NUM> from <FIG> is illustrated with respect to an embodiment of an optical device <NUM> for measuring a parameter of a liquid located on surface <NUM>. An exemplary optical device is a spectrophotometer, though other optical devices may be used.

As shown, the optical device <NUM> is received in a mechanical carriage <NUM>. The mechanical carriage <NUM> may be movably mounted to a rail <NUM>. In the illustrated embodiment, the mechanical carriage <NUM> is received and supported by rail <NUM> for movement in direction <NUM> and <NUM>, substantially parallel to surface <NUM>. Other embodiments may be arranged for movement of the mechanical carriage <NUM> perpendicularly to surface <NUM>.

As shown, rail <NUM> is fixed to the device <NUM> by interconnection <NUM>. With this connection, the spatial relationship between the mechanical carriage <NUM> and the surface <NUM> is limited. Specifically, the mechanical carriage <NUM> may be located in an operative configuration, such as is shown in <FIG>, or the mechanical carriage <NUM> may be moved toward the viewer, i.e., in direction <NUM> laterally away from device <NUM> and surface <NUM> to a non-operative configuration.

As shown, optical device <NUM> has a face <NUM> in which a port (not shown in <FIG>) is located for sending an optical beam directed toward surface <NUM> and for receiving a reflected beam from surface <NUM>.

When in the operative configuration, as shown, a distance <NUM> is established between surface <NUM> and the face <NUM> of the optical device <NUM>. Further, when in the operative configuration, as shown, a distance <NUM> is established between surface <NUM> and the mechanical carriage <NUM>. While in <FIG>, the optical device <NUM> protrudes from the mechanical carriage <NUM> such that distance <NUM> is less than distance <NUM>, it is contemplated that the optical device <NUM> be recessed within a frame of the mechanical carriage <NUM> such that distance <NUM> is greater than distance <NUM>.

It is noted that the mechanical carriage <NUM> is configured to return precisely to the operative configuration such that mechanical carriage <NUM> may be moved in direction <NUM> and then moved back in direction <NUM> to return the mechanical carriage <NUM> to distance <NUM> from the surface <NUM>.

In order to adjust distance <NUM> and to adjust the orientation of the face <NUM> of the optical device <NUM>, adjustment features <NUM> are provided. Exemplary adjustment features are micrometers or similar extendible/retractable structures. In an exemplary embodiment, the adjustment features <NUM> interconnect the optical device <NUM> and the mechanical carriage <NUM> and allow for adjustment of the optical device <NUM> with respect to the mechanical carriage <NUM>. Thus, when the mechanical carriage <NUM> is located at a distance <NUM> from surface <NUM>, the distance <NUM> between the surface <NUM> and the face <NUM> of the optical device <NUM> may be adjusted.

In exemplary embodiments, three adjustment features <NUM> are provided and interconnect the optical device <NUM> and the mechanical carriage <NUM>. Each adjustment feature <NUM> is independently able to move the optical device <NUM> in direction <NUM> (toward surface <NUM>) or in direction <NUM> (away from surface <NUM>). Thus, not just distance <NUM>, but the orientation of the face <NUM> of the optical device <NUM> with respect to surface <NUM> may be adjusted. For example, a first adjustment feature <NUM> may be extended to push a first end of the face <NUM> toward the surface <NUM> while a second adjustment feature <NUM> may be withdrawn to pull a second end of the face <NUM> away from the surface <NUM>. In this manner, the face <NUM> may be adjusted to a desired orientation, such as parallel to surface <NUM>.

Referring now to <FIG>, the face <NUM> of optical device <NUM> is shown to include a port <NUM>. As shown, the optical device <NUM> may be surrounded by a frame portion of the mechanical carriage <NUM>.

As shown in <FIG>, a mechanical alignment feature <NUM> may be applied to the face <NUM> of the optical device <NUM>. The exemplary mechanical alignment feature <NUM> includes three protrusions <NUM>. The mechanical alignment feature <NUM> may optionally include a layer <NUM> configured to selectively fix or hold the protrusions <NUM> onto the face <NUM>. For example, the layer <NUM> may be a double-sided adhesive layer that adheres to the face <NUM> and to the protrusions <NUM>. If used, the layer <NUM> may include a void over the port <NUM> as shown.

Other methods of fixing or holding the protrusions <NUM> onto the face <NUM> are contemplated. For example, the protrusions <NUM> may be formed with an adhesive surface or surfaces. Alternatively, the optical face <NUM> may be formed with magnetic/metallic regions for holding metallic/magnetic protrusions <NUM>. It is also contemplated that the face <NUM> be formed with grooves or other features for engagement with the protrusions <NUM>.

Exemplary protrusions <NUM> are spheres, though other shapes are contemplated. For example, protrusions <NUM> may be pyramidal, cubic, cylindrical, or other shapes. Exemplary protrusions <NUM> have an identical critical dimension, such as diameter for spherical protrusions or height for pyramidal or other shaped protrusions <NUM>. As a result, a plane defined by the furthest surface of each protrusion <NUM> from the face <NUM> is parallel to the face <NUM>.

Further, if used, layer <NUM> has a consistent thickness or is compressible to a consistent thickness such that a plane defined by the furthest surface of each protrusion from the face <NUM> is parallel to the face <NUM>.

Cross-referencing <FIG> and <FIG>, use of the mechanical alignment feature <NUM> to align the face <NUM> of the optic device <NUM> with the surface <NUM> is explained. As shown in <FIG>, protrusions <NUM> are held to the face <NUM> of the optical device <NUM> by layer <NUM>. The mechanical carriage <NUM> is brought to the operative configuration such that the mechanical carriage <NUM> is distance <NUM> from surface <NUM>, as shown in <FIG>. Then, adjustment features <NUM> are manipulated to increase or decrease the distance <NUM> between potions of face <NUM> and surface <NUM>. Such adjustment continues until each protrusion <NUM> contacts surface <NUM>. Contact between each protrusion <NUM> and surface <NUM> can be monitored visually. Specifically, when a protrusion <NUM> contacts surface <NUM>, a reflection <NUM> of the protrusion <NUM> in surface <NUM> appears to touch the protrusion <NUM>. In <FIG>, each reflection <NUM> appears to contact the respective protrusion <NUM>. In addition to visual alignment using reflected images of the protrusion surface, alignment using electrical resistivity, pressure sensors, or electronic switches, can also be used.

<FIG> illustrates an exaggerated improper orientation of face <NUM> such that one protrusion <NUM> does not contact surface <NUM>. As shown, the reflection <NUM> of the non-contacted protrusion <NUM> appears to be distanced from the non-contacted protrusion <NUM>.

With this understanding of the structures above, a method <NUM> for measuring a parameter of a liquid coating is described in <FIG>, with reference to <FIG>. In <FIG>, method <NUM> is shown to include, at operation <NUM>, providing a mechanical carriage <NUM> connected to a surface <NUM> configured to receive a layer of the liquid coating. The mechanical carriage <NUM> is configured to move to and from an operative configuration located at a set distance <NUM> and orientation with respect to the surface <NUM>. As indicated in <FIG>, the mechanical carriage <NUM> is indirectly connected to the surface <NUM> through interconnection <NUM>.

Method <NUM> may continue at operation <NUM> with positioning a mechanical alignment feature <NUM> on the face <NUM> of the optical device <NUM>.

Method <NUM> may further continue at operation <NUM> with locating the optical device <NUM> in the mechanical carriage <NUM>. IN exemplary embodiments, the optical device <NUM> is placed into the mechanical carriage <NUM> while the mechanical carriage <NUM> is retracted from the operative configuration.

At operation <NUM>, method <NUM> includes moving the mechanical carriage <NUM> to the operative configuration, such as is shown in <FIG>. In the operative configuration, the mechanical carriage <NUM> is set at distance <NUM> from surface <NUM>.

At operation <NUM>, method <NUM> includes adjusting an orientation of the optical device <NUM> within the mechanical carriage <NUM> to an aligned orientation based on a relationship between the surface <NUM> and the mechanical alignment feature <NUM> on the optical device <NUM>. For example, adjustment features <NUM> may be manipulated to extend and retract ends of the face <NUM> such that each protrusion <NUM> of the mechanical alignment feature <NUM> contacts the surface <NUM>. In exemplary embodiments, the adjustment features <NUM> are micrometers that interconnect the optical device <NUM> to the mechanical carriage <NUM>, and adjusting the orientation of the optical device <NUM> within the mechanical carriage <NUM> includes independently adjusting the micrometers.

Operation <NUM> of method <NUM> includes checking the orientation of the optical device <NUM>. Specifically, operation <NUM> may include visually checking the interface between the surface <NUM> and the mechanical alignment feature <NUM> to visually observe that the reflection <NUM> of each protrusion <NUM> appears to contact each respective protrusion <NUM>. If the optical device <NUM> is not at the proper orientation, i.e., if face <NUM> is not parallel to surface <NUM>, then the method <NUM> returns to operation <NUM>.

When the optical device <NUM> is at the proper orientation, i.e., when face <NUM> is parallel to surface <NUM>, then the method <NUM> continues with operation <NUM>, which includes retracting the mechanical carriage <NUM> from the operative configuration. For example, in <FIG>, the mechanical carriage <NUM> may be moved in direction <NUM> along rail <NUM>. Such operation allows for a user access to the face <NUM> and the mechanical alignment feature <NUM>.

At operation <NUM>, method <NUM> includes removing the mechanical alignment feature <NUM> from the face <NUM> of the optical device <NUM>. In embodiments in which a layer <NUM> and protrusions are used, both the layer <NUM> and the protrusions <NUM> may be removed. Alternatively, only the protrusions <NUM> may be removed. Typically, removal of the mechanical alignment feature <NUM> may be performed simply by grasping and pulling the protrusions <NUM> and/or the layer <NUM> from the face <NUM>.

After removing the mechanical alignment feature <NUM> from the face <NUM> of the optical device <NUM>, method <NUM> includes, at operation <NUM>, moving the mechanical carriage <NUM> back to the operative configuration, i.e., to distance <NUM> from the surface <NUM>. As shown in <FIG>, the mechanical carriage <NUM> is moved in direction <NUM> when returned to the operative configuration.

When the mechanical carriage <NUM> returns to the operative configuration, the face <NUM> of the optical device <NUM> returns to the aligned orientation achieved in operation <NUM>.

Method <NUM> then continues, at operation <NUM>, with performing, with the optical device in the aligned orientation, the parameter measurement. For example, gloss, multi-angle color, multi-angle reflection, highspeed video, layer uniformity, layer opacity, pigment concentration, coating appearance, and/or sparkle information may be measured. In exemplary embodiments, the optical device is a spectrophotometer, and the measurement process performed with the spectrophotometer obtains a wet color measurement.

Referring now to <FIG>, an exemplary method <NUM> for method for aligning an optical device with a surface configured to receive a liquid coating is described in relation to <FIG>. Method <NUM> includes, at operation <NUM>, locating a removable mechanical alignment feature between a face <NUM> of the optical device <NUM> and the surface <NUM>. In certain embodiments, locating the removable mechanical alignment feature between a face <NUM> of the optical device <NUM> and the surface <NUM> includes applying the removable mechanical alignment feature to the face <NUM> of the optical device <NUM>. In other embodiments, locating the removable mechanical alignment feature between a face <NUM> of the optical device <NUM> and the surface <NUM> may include applying the removable mechanical alignment feature to the surface <NUM>. In either case, applying the mechanical alignment feature to a selected location may include retaining three projections on the selected location. For example, applying the mechanical alignment feature to a selected location may include adhering a substrate having opposite adhesive surfaces to the selected location and adhering the three projections to the substrate. Alternatively, the three projections have adhesive surfaces, and applying the mechanical alignment feature to a selected location may include adhering the three projections directly to the selected location. In exemplary embodiments, the optical device has a port on the face, and retaining three projections on the selected location includes positioning the port inside of a triangle defined by the three projections.

At operation <NUM>, method <NUM> includes moving the optical device and/or the surface to establish a selected distance therebetween. For example, the optical device <NUM>, seated within mechanical carriage <NUM>, and/or the surface <NUM> may be moved to an operative configuration in which distance <NUM> is establish between the mechanical carriage <NUM> and the surface <NUM>.

Method <NUM> may continue at operation <NUM> with adjusting the orientation of the optical device <NUM> to an aligned orientation based on a relationship between the mechanical alignment feature <NUM>, the optical device <NUM>, and the surface <NUM>. In exemplary embodiments, adjusting the orientation of the optical device <NUM> to an aligned orientation based on a relationship between the mechanical alignment feature <NUM>, the optical device <NUM>, and the surface <NUM> includes contacting the mechanical alignment feature <NUM> with the surface <NUM> and the face <NUM>.

At operation <NUM>, method <NUM> includes increasing the distance between the optical device <NUM> and the surface <NUM>. For example, the optical device <NUM>, seated in the mechanical carriage <NUM> can be moved in the direction <NUM>. Alternatively, or additionally, the surface <NUM> can be moved away from the optical device <NUM>.

As shown, method <NUM> further includes, at operation <NUM>, removing the mechanical feature <NUM> from the selected location, whether the face <NUM> or the surface <NUM>.

Then, method <NUM> includes, at operation <NUM>, moving back the optical device <NUM> and/or the surface <NUM> to re-establish the selected distance <NUM> therebetween. For example, the optical device <NUM>, seated in the mechanical carriage <NUM> can be moved in the direction <NUM>. Alternatively, or additionally, the surface <NUM> can be moved back to the operative configuration.

The method <NUM> for aligning an optical device <NUM> with a surface <NUM> configured to receive a liquid coating may further proceed with performing a parameter measurement of a liquid coating received on the surface <NUM> with the optical device <NUM>, at operation <NUM>.

Further, method <NUM> may include, at operation <NUM>, replacing the optical device <NUM> with another optical device <NUM>, such as a second optical device <NUM>. As shown, operations <NUM>-<NUM> may then be repeated for the most recently installed optical device <NUM>. In this manner, testing across different optical devices <NUM> is performed with a standardized distance <NUM>.

Cross-referencing <FIG>, a low-cost assembly <NUM> for performing standardized parameter measurements is described. An exemplary assembly <NUM> includes a plurality of optical devices <NUM>, each having a face <NUM>. Further, the exemplary assembly <NUM> includes a mechanical carriage <NUM> connected to a surface <NUM> configured to receive a layer of a liquid coating. Anh exemplary mechanical carriage <NUM> is configured to move to and from an operative configuration located at a set distance <NUM> and orientation with respect to the surface <NUM>. Further, the mechanical carriage <NUM> is configured to receive and hold each optical device <NUM>, one at a time.

An exemplary assembly <NUM> further includes a removable mechanical alignment feature <NUM> that is configured to be temporarily retained on the face <NUM> of each optical device <NUM>. Also, an exemplary assembly <NUM> includes an adjustment feature <NUM> configured to adjust an orientation of each optical device <NUM> within the mechanical carriage <NUM> to an aligned orientation based on a relationship between the surface <NUM> and the mechanical alignment feature <NUM>.

With the structure of assembly <NUM>, testing of liquid coatings on surface <NUM> may be performed at a standardized distance <NUM> from the optical device face <NUM> to the surface <NUM>, and to the layer of liquid coating thereon. Further, assembly <NUM> provides for such standardization through a quick and easy process of temporarily holding the mechanical alignment feature <NUM> between the optical device face <NUM> and the surface <NUM>, such as on the optical device face <NUM>. Therefore, the assembly <NUM> is an inexpensive solution to the issue of non-standardization of testing performed by different optical devices by different users.

Claim 1:
A method for measuring a parameter of a liquid coating, the method comprising:
providing a mechanical carriage (<NUM>) connected to a device (<NUM>) comprising a surface (<NUM>) configured to receive a layer of the liquid coating, wherein the mechanical carriage (<NUM>) is configured to move to and from an operative configuration located at a set distance (<NUM>) and orientation with respect to the surface (<NUM>);
locating an optical device (<NUM>) in the mechanical carriage (<NUM>);
adjusting an orientation of the optical device (<NUM>) within the mechanical carriage (<NUM>) to an aligned orientation based on a relationship between the surface (<NUM>) and a mechanical alignment feature (<NUM>) on the optical device (<NUM>); and
performing a parameter measurement operation with the optical device (<NUM>) in the aligned orientation,
characterized in that:
adjusting the orientation of the optical device (<NUM>) within the mechanical carriage (<NUM>) to an aligned orientation comprises contacting the mechanical alignment feature (<NUM>) with the surface (<NUM>) when the mechanical carriage (<NUM>) is in the operative configuration; and/or
adjusting the orientation of the optical device (<NUM>) within the mechanical carriage (<NUM>) to an aligned orientation based on a relationship between a mechanical alignment feature (<NUM>) on the optical device (<NUM>) and the surface (<NUM>) comprises visually observing the mechanical alignment feature (<NUM>) and a reflection (<NUM>) of the mechanical alignment feature (<NUM>) in the surface (<NUM>).