Contribution: There are many on-line resources available to learn about optics and photonics, but no assessment tools exist to evaluate the learning achievements. This paper presents an assessment framework whose validity has been proven on a course with over 70 engineering students. Background: There is evidence that on-line resources complement the learning experience in many engineering fields. In the context of optics and photonics, it may be worthwhile to assess the learning experience of engineering students taking a virtual lab as a complement to on-site, traditional lab. The assessment should use empiric, measurable results that demonstrates the effectiveness of the didactic innovation proposed, based on the Technology Acceptance Model. Intended Outcomes: Students using OPTILAB software are expected to be able to demonstrate their learning of optics and photonics by having a good score in the specific question about optical diffraction included in the final exam. Application Design: OPTILAB software, simulating the optical diffraction produced by different apertures, was developed. Students use OPTILAB to check, in advance, the experimental results they will obtain in the on-site lab, with various optical apertures and settings. This is expected to make the on-site lab session more efficient, minimize errors that inevitably occur when students are confronted with a new physical phenomenon, and ultimately increase the students learning experience. Findings: The marks obtained in the exercise about optics in the final exam by the experimental set (~67.3%) and control set (~49.2%) demonstrate that OPTILAB can improve students' learning experience in optics. The findings from the survey based on the Technology Acceptance Model are also discussed.