The AIAA Hampton Roads Section (HRS) Young Professionals Committee is proud to host a lecture series to highlight the significant technical contributions of AIAA HRS Young Professionals. The Spring 2022 lecture will take place in a virtual lunch & learn format featuring the work of the 2022 Laurence Bement Paper Competition winner, Dr. Joshua Weisberger. Attendance is encouraged and open to all!
Single Source/Cutoff Grid, Self-Aligned Focusing Schlieren System
By Dr. Joshua Weisberger
BIO: Dr. Joshua Weisberger is a research engineer in the Advanced Measurements and Data Systems Branch at the NASA Langley Research Center. He received his B.S., M.S., and Ph.D. degrees from the University of Buffalo. His research area of interest is non-intrusive optical diagnostic development, including absorption spectroscopy, interferometry, and flow visualization schlieren and shadowgraph techniques.
ABSTRACT: A compact focusing schlieren system is presented that eliminates the need for a separate source and cutoff grid. Light is projected through a grid ruling and onto a background, where it forms an image of the ruling. The light from this projected image is then reflected back onto the original grid ruling, with a polarizing prism imparting a small offset between the two. Translation of this prism along the instrument axis provides an adjustment of sensitivity of the resulting schlieren images, equivalent to the knife-edge insertion percentage of a conventional schlieren system. The manipulation of the polarization state of the light through the system allows the projected and reflected light to be coincident, maintaining a small footprint for the system, which can effectively be mounted to the front of an imaging camera. Both small-scale and large-scale systems are demonstrated, with fields-of-view ranging from tens of millimeters to approximately 500 mm-square. Because retroreflective material is used, the system is ideal for wind tunnel facilities without optical through-access, and it is demonstrated that windows have little effect on the resulting images, with only a slight reduction in image contrast observed when imaging at normal incidence to a window. The ease of construction and alignment of the system, as well as its conventional-schlieren-comparable image quality, indicates that the system could be used as a replacement of conventional systems where a focusing ability is desired.
DATE: Thursday, May 26, 2022
TIME: 11:30 AM – 12:00 PM (EST)
PLACE: Online via AIAA Zoom Meeting
For webinar access, please register for the meeting at: https://tinyurl.com/AIAA-2022SpringTEL
Flyer link: https://tinyurl.com/YP-TEL-Spring2022
Contacts:
Brett Hiller
brett.hiller@nasa.gov
Michelle Lynde
michelle.n.lynde@nasa.gov
Morgan Walker
morgan.a.walker@nasa.gov