This paper presents a method for determining the degree of misalignment between a LED and its epoxy encapsulation in a simulated environment. The misalignment is determined by analyzing the light emitted by the optoelectronic component and transmitted through a grid of holes. The results obtained are compared with simulated and experimental registers wherein there is no misalignment between the LED and the epoxy but a displacement of the whole optoelectronic component perpendicularly to the observation axis. We prove that the method used allows us to distinguish between the existence of misalignment inside the optoelectronic component and a simple displacement between the optoelectronic component and the observation axis.
This work presents the validation study of a method developed to measure contact angles with a confocal device in a set of hydrophobic samples. The use of this device allows the evaluation of the roughness of the surface and the determination of the contact angle in the same area of the sample. Furthermore, a theoretical evaluation of the impact of the roughness of a nonsmooth surface in the calculation of the contact angle when it is not taken into account according to Wenzel’s model is also presented.
This work presents the first results obtained in the validation study of an innovative technique to calculate the contact
angle of a solid surface by means of a confocal device, which confirms the reliability and the accuracy of the presented
A measurement technique has been developed to measure the contact angle with of a confocal device. This technique has
the unique advantage of allowing to perform both topography and contact angle measurements in the same location,
therefore avoiding any shift in the sample positioning between the two measurements and ensuring the proper location of
both measurements in the same area of the sample, thus enhancing the evaluation of the surface energy of the surface.
Specifically, this technique uses the confocal device to measure some parameters of the drop, such as the height (ℎ) and
the apparent diameter (), in a top-view configuration. The drop volume is already known and small enough to discard
gravity effects, so the shape of the drop can be approximated by a truncated sphere. Several purely geometric
calculations are available to calculate the radius de of the drop and subsequently, the contact angle.
This work reports the first results of the ongoing validation study of this technique and the several mathematical
calculations employed to extract the contact angle value. These initial measurements were performed for a hydrophobic
surface with water as a measurement liquid. The contact angles for different set of drops for this sample were also
measured by a commercial contact angle meter in side-view configuration, with the same liquid and drop dimensions, in
order to verify the validity and the accuracy of the presented technique. This validation of the calculation of the contact
angle is the first step for the further validation of the developed measurement method for the surface energy
Due to their manufacturing process, plastic injection molded lenses do not achieve a constant density throughout their volume. This change of density introduces tensions in the material, inducing local birefringence, which in turn is translated into a variation of the ordinary and extraordinary refractive indices that can be expressed as a retardation phase plane using the Jones matrix notation. The detection and measurement of the value of the retardation of the phase plane are therefore very useful ways to evaluate the quality of plastic lenses. We introduce a polariscopic device to obtain two-dimensional maps of the tension distribution in the bulk of a lens, based on detection of the local birefringence. In addition to a description of the device and the mathematical approach used, a set of initial measurements is presented that confirms the validity of the developed system for the testing of the uniformity of plastic lenses.