Imperial College London Speeds Up Microscopy Design by Automating Stock Lens selection for Remote Refocusing Projects

“With the solution we built using the ZOS-API in Ansys Zemax OpticStudio, optical design teams and researchers can now ‘try out’ thousands of doublet combinations in just a few seconds per combination, and then only buy the ones that they know will deliver the best performance — there’s no need to resort to guesswork or spending time on laborious manual modelling of different lens pairs to find what works.”

— Christopher Dunsby
Research Professor in Photonics / Department of Physics, Royal College of London

Challenges

3D imaging typically requires optical scientists to follow one of two common tactics: scanning the sample you’re imaging with respect to its objective, or else moving the objective back and forth with respect to the sample, either manually or with a mechanical actuator. These methods work for some types of optical systems, but they fall short in the development of some types of fluorescent microscope, where movement can produce vibrations or can require outsized actuators in order to achieve the required image acquisition speed.

Remote refocusing in microscopy refers to an optical system where an optical relay is used to produce a true 3D image of a specimen (as opposed to simply a magnified image) with equal lateral and axial magnification. Achieving this fidelity requires adherence to a precise formula: the overall magnification of your system must equal to the ratio of the sample medium’s refractive index to the refractive index in which you’re forming the image.

“For example, if your sample is in water and you’re trying to make a remote image in air, then you need the optical system magnification to be equal to the refractive index of water, or 1.33,” said Chris Dunsby, Professor in the Photonics Group, Department of Physics at Imperial College London. “Not a very big magnification in this case, but it will yield a true 3D image, where say a spherical object results in a matching spherical image.”

Dunsby has worked in the area of biomedical optics for his whole career, and his research team at Imperial College London focuses on developing novel technologies to address real-world applications of photonics. In the course of their work, the team uses Ansys Zemax OpticStudio in a variety of capacities. Recently, he and Wenzhi Hong, a graduate research fellow in Dunsby’s department and a PhD candidate in the Photonics Group, examined ways of leveraging OpticStudio’s capabilities to make the design of remote refocusing system more feasible and accessible to optical scientists. Their results provide a new method for overcoming the practical limitations of lens selection for remote refocusing projects.

Engineering Solution

• Dynamic catalog of stock manufactured lenses.
• Ansys Zemax application programming interface (ZOS-API).
• Built-in, seamless programming interface with MATLAB.

Benefits

• Built easy-to-use applications for rapidly identifying lens doublets to use with remote refocusing systems in 3D fluorescent microscopes.
• Reduced the time-intensive process of identifying available stock lenses for a project to only a few seconds per lens combination using automated cataloging, specification checking, and lens pairing.
• Optimized performance without resorting to costly custom lens development.

For more information, please download the full case study.