Micro and Diffractive Optics Testing by µ-d’Polariscope

Micro and diffractive optical elements are being increasingly developed and used in a variety of applications. With the increase in the level of complexity both in design and fabrication, measurement and inspection of such optics is vital for quality control as well as optimization of the manufacturing process. Also with the emergence of flat optics there is an urgent need for testing and characterizing these new optical elements.

While interferometry appears to be the preferred choice, polariscopes provide an exciting non-coherent, real-time alternative. Here at d’Optron, we have developed and a micro-polariscope system which along with our d’Nanoimager can be coupled to the most microscopes. Since our system has c-mount adapter, it is easy to plug into most microscopes as shown below. This allows to both characterize and test micro-optical components such as lens arrays.

d'Polariscope and d'Nanoimager coupled to microscope


Birefringence & Defects in Micro-optics

For micro lens characterization as with the bulk optics shown earlier, the micropolariscope can provide birefringence measurements as well as defect characterization from the same image. This is shown below for a micro-lens array recorded at 10X magnification. All these results are provided in real-time and hence can be integrated into an inline system.

Diffractive Optic Testing

For diffractive optics, the polariscope provides an alternate new approach to profiling the surface. Since the structure of the optics has features which are of the same order as the substrate, the phase change as shown provides the profile of the structure. While this is still work in progress, based on the simulations and tests that we have done, this approach seems to show much promise as shown below for a typical diffractive optic structure.

Furthermore, polarization effects have also been used to characterize sub-wavelength structures without imaging them. Just like the defects in glass showed characteristic butterfly patterns which can be used to deduced the size of defect, similarly sub-wavelength structures show characteristics differences in polarizations properties which can provide information on the sub-wavelength structures.

Check out Reference 4 to learn more

Bioimaging using polariscope

The micro-polariscope can be provide some interesting clues for bioimaging. Also it has been extensively used in dental applications (see references) for understanding the stress distribution in both the nature of material and shape of structure to optimize its load bearing capability.

Read more in Reference 5