Polarization Adds New Perspectives to Optical Inspection

Cover image: Birefringence distribution from high-precision injection moulded plastic lens.

Polarization is a wave phenomenon of light which until recently had not garnered much notice in metrology apart from some works in photoelasticity. As a tool for modelling-based design, it found industries such as GE and Boeing adopting this technology before the advent of computers and finite element simulations provided better options. The challenge for photoelasticity was that a plastic (epoxy or polycarbonate) model had to be tested which could not be readily translated to different materials in the real structure. The exception was stress concentration factors for which the standards were based on photoelastic results.

The current proliferation of novel advanced manufacturing process used in optical, medical and microfluidics industries. Coupled with advances in polarization components and imaging technologies have brought Polariscopes to the forefront.

We at d'Optron have researched extensively in this area with applications ranging from optical birefringence testing to residual stress in Si-wafers and more recently micro, diffractive and flat optics testing and inspection.

In this newsletter, we showcase our d'Polariscope which can be used for real-time testing and inspection of injection molded components. We also highlight the u d'Polariscope which is used for testing and inspection of micro and diffractive optics structures. Finally our new research idea on a Hue based Polariscope.

Roadmap to Improving Quality of Optics using d'Polariscope

With the growing use of precision moulded components in diverse fields ranging from optics to medical to microfluidics, there is a need to characterize and test them for birefringence or residual stress during processing which would hinder their performance.

Micro & Diffractive Optics Testing using u-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 and optimization of the manufacturing process.

Hue based Polariscope

Hue provides color visualization as seen by human eye. One of the emerging technologies is the use of hue as a means of determining phase difference, birefringence and stress from color photo-elastic fringes. Read more on how we developed an innovative solution using hue as a means of quantifying colors to measure phase difference and birefringence.


1. A. Asundi, Phase Shifting in Photoelasticity, https://doi.org/10.1111/j.1747-1567.1993.tb00269.x

2. Anand Asundi, MATLAB for Photomechanics, Chap.3, Elsevier Science, 2002, https://doi.org/10.1016/B978-008044050-7/50051-3.

3. Wang Pin and Anand Asundi, Residual stress in silicon wafer using IR Polariscope, 2008, https://doi.org/10.1117/12.814538

4. Adhikari, Achyut & Dev, Kapil & Asundi, Anand. Subwavelength metrological characterization by Mueller matrix polarimeter and finite difference time domain method. Optics and Lasers in Engineering, 2016. 10.1016/j.optlaseng.2016.06.014 .

5. Anil Kishen and Anand Asundi, Biophotonics in Dentistry, World Scientific, 2007, https://doi.org/10.1142/9781860948831_0002