Principle

Optical devices are used to discern objects which are very far away or very small. Essentially, these instruments are designed to enlarge the visual angle. Whether this alone is sufficient to visualize the object depends on various factors, which the students should investigate.
Each ray emitted from an object point (point light source) is diffracted in the tube of the optical instrument. In this experiment, the two slits of a double slit represent the light sources (objects). Two diffraction peaks of 0th order are created, which can just be distinguished from each other when Rayleigh's Criterion is fulfilled. This criterion states that the distance between the diffraction peaks of 0th order may not be smaller than half of the distance between the diffraction troughs of 1st order (comp. Fig. 24).

Benefits

• Multifunctional light box - All-in-one: Can be used for geometric optics on the table, colour mixing and on an optical bench
• Extension with others sets at anytime, no additional light sources needed, recognition value for students

Tasks

On which factors does the resolving power of optical devices depend? In a first experiment the conditions are investigated under which two objects (object points) can just still be perceived individually, i.e. resolved, with the aid of an optical device. Afterwards, the validity of Rayleigh's Criterion d = 1/2 · d1 (comp. Fig. 24) for the resolving power of optical instruments is verified.