I did not find any explanation for the origin of the bright lines l' and l". The line l' is visible in relation to the laser beam at an angle >30°, while the line l" is visible up to 180°. This can be seen if a circular screen is placed instead of a flat screen.
In this regard, I am interested in the following questions:
How is the origin of bright lines l' and l” interpreted?
Are they just a continuation of the diffraction pattern f or is l' created by diffraction and l" by the reflection of the incident light beam?
How is it that the line l" stretches (bends) at such a wide angle (180°)? Maybe partly diffraction and partly reflection?
What is their usual name? Can it be said that these are diffraction lines?