Patent ID: 6974236

Claim:
An illuminating apparatus comprising: a light source comprised of a light emitting tube; and an optical unit disposed forwardly on the object side of the light source; the optical unit being provided with an incidence surface on which light from the light source is incident, a light emergence surface provided with a Fresnel lens, and a side reflecting surface for totally reflecting the light incident on the incidence surface toward the Fresnel lens, said side reflecting surface being one of the side reflecting surfaces formed on both sides of the of the lengthwise direction of the light emitting tube and making an angle ranging between 85 degrees to 95 degrees to a lengthwise direction of the light emitting tube; wherein the light totally reflected by the side reflecting surface is refracted by the edge surface of the Fresnel lens and emerges toward the object side thereof and wherein and the vertical angle of the Fresnel lens is formed along a direction perpendicular to the lengthwise direction of the light emitting tube.