Photon Engineering - FRED

Biomedical Systems

From non-invasive procedures to ultra-sensitive diagnostic instrumentation, photonic devices play an indispensable role in today’s bio-medical industry. For the last quarter century, timely design and delivery to market of these new technologies has been possible only with the aid of sophisticated software tools and experienced optical engineers. Photon Engineering firmly believes that its optical engineering product FRED can help accelerate the pace of innovation in the biomedical community by enabling its members to participate more fully in the process. FRED combines a GUI interface, where geometry creation and visualization are intuitive, with a powerful computational engine capable of satisfying the most demanding requirements. The relevance of FRED to the bio-medical industry can best be expressed by presenting several familiar yet innovative applications such as a gonioscope, laser-induced fluorescence in a capillary, and a human skin model.

Human skin models are valuable aids in the design of non-invasive diagnostic devices such as the oximeter as well as in the development of modern dermatological instruments. With the release of version 6.20, FRED now offers the Henyey-Greenstein volume scatter model recognized by the biomedical community as being representative of scattering in human tissue. There are numerous sources for the parameters associated with this model, namely an anisotropy factor g and the scattering and absorption coefficients m_s and m_a. In FRED, this volume scatter model is applied through a material definition using dialog boxes to input the parameters for both the Henyey-Greenstein phase function and to define volume absorption. A catalog of over 50 different human tissue definitions are included for the users convenience. Once such materials are defined or selected, they can be assigned to various interfaces in a geometric model by the drag&drop method.

The physical process of fluorescence involves conversion of light at one wavelength to that of a longer wavelength. An intrinsic feature of FRED essential to modeling fluorescence is that wavelengths are assigned to rays on an individual basis. When coupled with the flexibility of FRED ’s scripted scatter model feature, the path to a practical simulation of fluorescence becomes evident. Given a particular emission spectra, a scripted scatter model can be constructed that reassigns ray wavelengths by interpreting the emission curve in terms of probability.

For more information on how FRED simulates biomedical applications download the application note in pdf format here.

FRED model of Human Tissue

Shack-Hartmann wavefront sensing system with eye model

FRED fluorescence detection system

FRED modeled handheld tissue scanner with built-in spectrometer. Green rays at the detector indicate the presence of fluorescing material under the skin.