Advanced OCT system using cascaded interferometers for precise, non-contact measurement of complex freeform optical surfaces
Institute Reference: 2-18049
High-precision optical metrology is essential for ensuring surface accuracy, particularly in advanced optics manufacturing, where tolerances can reach sub-nanometer scales. Modern optical components feature increasingly complex, freeform surfaces with rotational asymmetries, which present significant challenges for traditional interferometry. Conventional methods struggle with such surface complexities and can involve lengthy processing times. Therefore, there is a need for a versatile, fast, and accurate measurement solution to handle intricate freeform surfaces and transmissive components.
This technology introduces a cascade Fourier domain optical coherence tomography (OCT) system which integrates two interferometers arranged in series. The first interferometer generates an interference signal between the test sample and a reference surface using a broadband source. The second interferometer further splits and varies the optical path lengths of the signal, performing a hardware-based Fourier transform. This eliminates the need for software-based signal linearization and reduces data processing time.
The cascaded architecture enables precise 3D imaging and nanometer-scale measurement of surface topographies, even for complex, rotationally variant surfaces. The system also supports simultaneous measurements of multiple surfaces and subsurface features, making it ideal for non-contact optical metrology across various manufacturing stages.
This technology allows for high precision non-contact measurement with nanometer-scale uncertainty, making it ideal for applications requiring extreme accuracy. Its hardware-based Fourier transform significantly accelerates data processing compared to conventional software-based methods. The system is versatile, capable of measuring reflective, transmissive, and subsurface features. It also provides adaptability through interchangeable reference surfaces and supports null configurations to accommodate complex geometries. With the ability to handle both figure-level and mid-spatial frequency measurements, it covers a broad spatial frequency range. Additionally, the compact design eliminates the need for large-scale mechanical actuation, making it more efficient for measuring smaller optical components.
This technology offers diverse applications across multiple industries. In optics manufacturing, it can improve quality control by providing precise measurements for freeform optics and lenses. In medical imaging, it enables high-resolution OCT scanning, supporting advancements in fields such as ophthalmology and dermatology. For material science, it facilitates the inspection of advanced materials during production, with the added capability to detect subsurface features. In aerospace and defense, the system ensures accurate metrology for precision optics used in sensors and targeting equipment. Additionally, it supports consumer electronics by delivering reliable measurements for compact optical components, including camera lenses and AR/VR devices.
The University of Rochester is open to exploring funded research collaborations, licensing agreements, and other partnership opportunities.