As mentioned not only Ronchi gratings can be manufactured that way. Knife edge as well as wire tester patterns are easily doable as well.
Here my tester setup with a small digital camera to take the Ronchi
The light source is a bright white LED with a flattened front surface behind a ground piece of glass.
Here a close-up of the optical head of the tester with a Foucault pattern
Here is a Foucault image using the above setup.
Here the same with a Ronchi grating. The tester is in slitless mode
The light source is behind the same grating as the observer.
The last batch of film seems to show a higher amount of light scattering
This needs to be investigated with the film provider.
Copyright images and processing Gert Gottschalk.
Copyright Bilder und Verarbeitung Gert Gottschalk.
Email : firstname.lastname@example.org
Back to my astronomy home page
Zurueck zur Astronomie Startseite