Optical head and optical etching apparatus

The invention discloses an optical head and a photoetching device. The minitype optical head can provide secondary wavelength focal lightspots and super great depth of field. The minitype optical head comprises a transparent base material, a lighttight film and at least one secondary wavelength annular ring. As synchronous light penetrates the transparent base material supporting the optical head and passes through the secondary wavelength annular ring properly designed, the photoetching device can overwhelm the limit that light diverges due to diffraction, and effectively improves the penetrated energy. The penetrated light becomes the light of the size equal to secondary wavelength after a distance, and keeps unchanged for a long distance without divergence.