Overview of SAFS Technology
NASA engineers are addressing the challenge of visualizing airflow around aerospace vehicles to improve aircraft design and safety. Understanding invisible air movement is crucial for developing safer and more efficient aircraft. For eight decades, "focused schlieren imaging" was used by researchers; this camera system detects subtle changes in air density to visualize airflow.
The Self-Aligned Focusing Schlieren (SAFS) system offers a compact, cost-effective, and user-friendly visualization tool, reducing complexity compared to prior schlieren systems.
NASA engineers Brett Bathel and Joshua Weisberger, inventors of SAFS at Langley Research Center, state that improved airflow visualization facilitates advancements in aircraft design and flight safety.
Operational Principles and Applications
The SAFS system employs cameras and light polarization to visualize flow structures, such as complex shock structures along rocket booster models at various angles of attack.
Implementation of SAFS in wind tunnels and research facilities enables aerospace engineers to acquire high-speed flow visualization data more efficiently, reducing downtime and costs. This technology could influence the design of commercial aircraft and spacecraft.
NASA uses SAFS to support its aviation and space mission goals. Researchers apply SAFS to study flow separation on the High Lift Common Research Model for aircraft performance prediction and to investigate shock cell structures in Space Launch System model exhaust plumes.
Global Adoption and Recognition
The SAFS technology has been adopted globally by over 50 institutions across more than 8 countries. Commercial versions are becoming available through licensed companies.
The SAFS system has received multiple accolades, including a 2025 R&D 100 Award from R&D World and NASA's 2025 Government Invention of the Year award.
Advantages Over Previous Systems
Prior focused schlieren imaging systems necessitated access to both sides of a test object, requiring precise alignment of separate light source grids on each side. Setup for these older systems could take weeks, with minor disturbances often requiring the process to be restarted.
In 2020, NASA researchers developed SAFS by utilizing light polarization. Unlike previous systems, SAFS requires access to only one side of the test object and employs a single grid, simplifying the setup significantly.
The SAFS system reduces setup time from weeks to minutes and allows for on-the-fly adjustments to sensitivity, field of view, and focus. Its compact design also provides immunity to vibrations.
This innovation addresses long-standing challenges in scientific visualization through a simplified approach, impacting global research.
Development Support
Support for SAFS development came from NASA's Aerosciences Evaluation and Test Capabilities portfolio office and the Transformational Tools and Technologies project, part of the Aeronautics Research Mission Directorate's Transformative Aeronautics Concepts Program.