reflection of rays on connected flat reflectors and parametric curved mirrors

‎in this paper‎, ‎reflections of two distinct rays and also of families of orthotomic rays‎, ‎either on connected flat reflectors (as a nonsmooth surface) or on a parametric curved mirror‎, ‎are investigated in 2d cartesian plane‎. ‎in this way‎, ‎both situations either when the source point is at a finite distance or at infinity are considered‎.  although we used the usual methods in differential geometry but interestingly‎, ‎in our calculations‎, ‎the differential equations have not been used‎. ‎in fact‎, ‎at first‎, ‎for two distinct rays‎, ‎the intersection point of the reflected rays (which under some conditions is the interference point of simultaneous pulses) is geometrically described‎. ‎moreover‎, ‎for two joint flat reflectors‎, ‎conditions by which the intersection point (or image) will be in front of the reflector‎, ‎are computed‎, ‎such that they give us an interval for the place of incident point on the second reflector‎. ‎in the continuation‎, ‎considering orthotomic families of rays‎, ‎the locus of interference points of reflected rays on two joint flat walls is obtained‎. ‎then‎, ‎by the obtained results of two distinct rays (as a movement from discrete to continuous family)‎, ‎it is shown that the caustics of a family of reflected rays on a parametric curved mirror can be obtained‎. finally‎, ‎finding the caustic for a curved reflector which has self-intersection‎, ‎and a theoretical idea to find the shape of an unknown mirror‎, ‎for a given source and image curve‎, ‎are described‎.