AstroworX Aperture/Seeing Mask – DIMM (Differential Image Motion Monitor)
At AstroworX Engineering, innovation combines with precision. Our latest development — a custom-designed Aperture/Seeing Mask based on the DIMM (Differential Image Motion Monitor) principle — is now in testing.
What is a DIMM?
The Differential Image Motion Monitor (DIMM) is a proven technique used by observatories worldwide to measure atmospheric seeing — the effect of turbulence in Earth’s atmosphere on astronomical image quality.
The DIMM method works by measuring wavefront slope differences over two small, spaced apertures known as Hartmann holes in the telescope’s entrance pupil. As starlight passes through each aperture, two distinct star images form in the focal plane. By analysing the relative motion between these two images, astronomers can determine the local wavefront tilts caused by atmospheric turbulence.
Since the DIMM is a differential measurement, it is not affected by telescope tracking errors, making it a reliable and widely used tool for characterising site seeing conditions.
AstroworX Innovation
Our team at AstroworX Engineering has designed and manufactured a custom DIMM-style aperture mask built for precision, durability, and compatibility with a variety of telescope configurations. The design remains compact while maintaining high sensitivity to wavefront variations — making it ideal for both research-grade observatories and educational institutions.
The AstroworX DIMM Mask is also fully compatible with Starguage software, allowing users to easily analyse seeing data, monitor atmospheric stability, and record performance metrics directly from their imaging sessions.
Testing Underway
We are proud to report that our prototype is currently undergoing field testing, with early results showing promising performance in accurately measuring atmospheric seeing.
This development is another step in our mission to deliver high-quality, Australian-made astronomical instruments that help observers and institutions explore the universe with clarity and confidence.