Optical arrangement for collimated light beam

A lamp for producing a collimated light beam, comprising:

• at least one light source disposed on a casing,
• a retaining plated having at least one opening for accommodating an optical assembly,
• the optical assembly comprising an upper portion having a convex shaped lens, and
• a bottom portion having an upper wall configured as a concave shaped lens and having an aperture wherein the aperture is located on a top of the light source;
• wherein the optical assembly further comprises an inverted dome shaped shell defined by lateral walls and a refractive wall and comprises a domed portion having the convex shaped lens extending outwardly from the lamp, and
• a curvature radius ratio (r1/r2) between a curvature radius (r1) of the convex shaped lens and a curvature radius (r2) of the concave shaped lens is a value in a range of 1.7 to 1.9.