Lighting apparatus

1. A lighting apparatus comprising:

a plurality of LED structures having a plurality of LEDs arranged in a row;

a wiring board having an elongated shape, on which the LEDs are mounted; and

an optical lens that covers the LED structures, and controls distribution of light emitted from each of the LEDs, wherein

each of the plurality of LED structures includes a plurality of LED types that each emit light of a different color from each other and are mounted on the wiring board in a row, and

the light emitted from each LED has an optical axis orthogonal to the wiring board,

the optical lens is a converging lens which has an elongated shape that covers all of the LEDs included in at least one of the LED structures, and includes a light incident surface on which the light emitted from the LED is incident, a medium that guides the light incident from the light incident surface, a light emitting surface that emits the light guided through the medium, and a diffuser that contains diffusing particles for causing the light incident from the LED to diffuse, and

the concentration of the diffusing particles in the diffuser is high in the vicinity of the optical axis of the light emitted from the LED and gradually decreases as a distance from the optical axis increases,

wherein the medium contains the diffusing particles to provide the diffuser.

2. The lighting apparatus according to claim 1 , wherein

the optical lens is configured to have a Fresnel structure at the light emitting surface.

3. The lighting apparatus according to claim 1 , wherein

the optical lens is configured to have a Fresnel structure at the light incident surface.

4. The lighting apparatus according to claim 2 , wherein

the optical lens further includes a translucent coating that coats the light emitting surface, and

the translucent coating has a refractive index higher than a refractive index of the medium.