An optical waveguide comprising: a front surface; a rear surface; a first end; a second end; and a first optical element configured to: allow light from a coherent light source to enter the optical waveguide through the front surface, wherein the light source is associated with a coherence length; and cause the light to traverse in a first direction towards the first end; and a second optical element configured to: receive the light traversing in the first direction from the first optical element; and allow a first portion of the light traversing in the first direction to exit the optical waveguide through the rear surface with a first optical path length; and a third optical element configured to: receive a second portion of the light traversing in the first direction from the second optical element; and cause a third portion of the light to traverse in a second direction towards the second end, wherein the second optical element is further configured to: receive the third portion of the light traversing in the second direction from the third optical element; and allow a fourth portion of the light traversing in the second direction to exit out of the optical waveguide, wherein the fourth portion of the light has a second optical path length, and further wherein a difference between the first optical path length and the second optical path length is greater than the coherence length. a front surface; a rear surface; a first end; a second end; and a first optical element configured to: allow light from a coherent light source to enter the optical waveguide through the front surface, wherein the light source is associated with a coherence length; and cause the light to traverse in a first direction towards the first end; and allow light from a coherent light source to enter the optical waveguide through the front surface, wherein the light source is associated with a coherence length; and cause the light to traverse in a first direction towards the first end; and a second optical element configured to: receive the light traversing in the first direction from the first optical element; and allow a first portion of the light traversing in the first direction to exit the optical waveguide through the rear surface with a first optical path length; and receive the light traversing in the first direction from the first optical element; and allow a first portion of the light traversing in the first direction to exit the optical waveguide through the rear surface with a first optical path length; and a third optical element configured to: receive a second portion of the light traversing in the first direction from the second optical element; and cause a third portion of the light to traverse in a second direction towards the second end, wherein the second optical element is further configured to: receive the third portion of the light traversing in the second direction from the third optical element; and allow a fourth portion of the light traversing in the second direction to exit out of the optical waveguide, wherein the fourth portion of the light has a second optical path length, and further wherein a difference between the first optical path length and the second optical path length is greater than the coherence length. receive a second portion of the light traversing in the first direction from the second optical element; and cause a third portion of the light to traverse in a second direction towards the second end, wherein the second optical element is further configured to: receive the third portion of the light traversing in the second direction from the third optical element; and allow a fourth portion of the light traversing in the second direction to exit out of the optical waveguide, wherein the fourth portion of the light has a second optical path length, and further wherein a difference between the first optical path length and the second optical path length is greater than the coherence length. receive the third portion of the light traversing in the second direction from the third optical element; and allow a fourth portion of the light traversing in the second direction to exit out of the optical waveguide, wherein the fourth portion of the light has a second optical path length, and further wherein a difference between the first optical path length and the second optical path length is greater than the coherence length.