Optical System Modeling

Vladimir Krylov, Opto-Mechanical Engineering Manager

Cogmedix provides comprehensive product development and commercialization services with extensive knowledge and expertise in the area of optical and laser-based medical devices. Many of these products are based on a laser or imaging optical system which provide the primary function and thus are the most critical system component.

The design of optical systems starts with the review of product requirements from which the proposed solution is derived. This is followed by performance estimates and detailed optical system modeling using raytracing software, such as Zemax. Cogmedix has extensive experience with both imaging and laser delivery optical systems, and understands how their modeling relates to the physical system performance.

In imaging optical systems, it is important to go beyond the raytracing of a basic prescription and analyze the effect of tolerances as well as perform a stray light analysis. Tolerance analysis ensures that the modeled system can be built and better predicts the real, rather than theoretical, performance of the imaging system. Stray light can significantly degrade performance, especially in reflective designs; the stray light analysis provides the input to the optical system packaging effort with the location of baffles, surface finish requirements, and similar considerations.

When modeling laser beam delivery systems, it is critical to understand the impact of the laser radiation coherence on the performance requirements. Diffraction and interference effects can degrade the intensity uniformity of the spot on target, which is often critical in medical applications. We can analyze these effects using physical optics modeling and have an accurate prediction of the laser radiation intensity distribution on target. Another important aspect of designing laser beam delivery systems is back reflection analysis. Even with the high-performance anti-reflection coatings, there is enough reflected energy or power to damage optical components when focused. As we perform the back reflection analysis, we ensure that when the optical design requires having surfaces which focus the back-reflected light, the location of such spots are away from susceptible surfaces.

Considering that optical elements are often among the most expensive and longest lead components of the system, thorough optical system modeling provides us with a close approximation of the real-life performance and allows us to minimize the development cost and schedule impact of optical design oversights and mistakes.

Cogmedix is dedicated to providing a wide range of medical device engineering services under our Design for Compliance and eXcellence™ (DFcx™) approach, always keeping safety and compliance at the forefront!