Flexures in space

Hello all,
I thought it would be of interest to some in those group that the James Webb Space Telescope uses stepper motor driven flexures to precisely position its 18 hexagonal mirror segments. Each actuator is capable of 10 nm position resolution over a range of 20 mm. The image below shows two actuators with the flexure in yellow. The source of this image is from this paper where you can find further information on the design: https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.pdf


Hi There,

you may want to watch BreakingTaps’ video on that matter: The clever engineering of JWST's mirror actuators - YouTube . He reversed engineer and 3D printed the actuator. I was thinking of the eccentric (at 5’03") actuator and thought it might be a mechanism for the x/y movements. This way you periodically move between the boundaries of movement, no switches, no hitting the limits.

Cheers and regards,


The coarse/fine control is very cunning. It does require that the coarse screw does not slip when it is not held though.

Thanks for sharing @JJS that was interesting! I’m now printing the actuator design. Ever since building the openflexure microscope and seeing the mechanism I have pondered designing one for my spectrometer that would allow fine positioning of the diffraction grating depending on the wavelength band of interest but I have no experience in this type of design. Hopefully building the actuator will help me understand how I could use a flexure in the design.