Optical element with 3D gradient refractive index

An optical element, comprising:

• a first gradient-index element to transmit light from a scene in one direction;
• a second gradient-index element attached to the first gradient-index element and having an off-axis focus point and a refractive index that changes in a direction from a center of the gradient-index element to adjust an angle of incident light that is incident from a second direction and reflected across an irradiance profile of the incident light to collimate the reflected light;
• and
• a dichroic coating between the first gradient-index element and the second gradient-index element to reflect the incident light and transmit the light from the scene, wherein
• the second gradient-index element reduces an optical power of the first gradient-index element.

An optical element, comprising:

• an optic to transmit light from a scene in one direction;
• a first freeform element attached to the optic and having an off-axis focus point and a first freeform surface to collimate light reflected from incident light that is incident from a second direction;
• and
• a dichroic coating between the optic and the first freeform element to reflect the incident light and transmit the light from the scene, wherein
• the optic reduces an optical power of the first freeform element.