US Patent 11085609 Illumination device

An illumination device including a light source array and a microlens array is provided. The light source array includes a plurality of light sources arranged in an array. The microlens array includes a plurality of microlenses arranged in an array. The illumination device satisfies the following conditional expressions so as to produce structured light: z=z0+dz and z0=(m/2)*(P2/λ), where z is a distance between the light source array and the microlens array along a central axis of the microlens array, P is a lens pitch of the microlens array, λ is a wavelength of the light sources, m is an integer and m′ is a non-integer number. The illumination device satisfies 1%≤dz/z0≤5% or −5%≤dz/z0≤−1%.