Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics Engineering = Taking what you have and making what you need.
Quote: To do interference testing all you need to do is flash polish the concave tool used to grind the convex one and polish it spherical. When the interference fringes are straight then the convex surface is also spherical.
Quote:I have tested the crown only with the flat but also the whole objective assembly.
Quote:To see if it is or has spherical surfaces. Look for turned edges and spherical aberration.
Quote: So..... a simple lens will not be able to be tested via Foucault test even using a single monochromatic wavelength of light .... because..... why is that ?