How to implement the laser pointer physics experiment?

In physics teaching, light interference and diffraction are not only the key but also the difficulty of teaching, and the best way to break through this difficulty is to do the relevant physical experiments. Laser pointer light source is the best light source for these experiments. However, current teaching uses laser light sources composed of helium-neon lasers. The interference and diffraction of light are verified by experiments with a common laser pointer. The front side of the laser pointer is aluminum foil, which is perforated with a needle. This kind of aluminum foil is thicker than supermarket ones. The diameter of a needle is about a fraction of a millimeter, which is much larger than the wavelength of light. Fringes are interference fringes and diffraction fringes. I found some information, but unfortunately I don't understand it. If I could understand that, that would be great. I probably understood Huygens' principle, mainly because math was so bad that high school was about to be forgotten. The diffraction calculations in the book assume that the wavelength is much larger than the aperture, and in my experiment the aperture is much larger than the wavelength. How do you calculate that? Concentric circles have relatively weak light, so watch carefully.