The Study Of Designing Diffractive Axicon With A High Lateral Resolution And A Large Depth Of Focus

Depth of focus means the range of possible position of focal plane or image plane in aspecific optical system. It exists as an essential part among many focusing modulationsystems. In the laser experiment and measure, one crucial factor that determines the accuracyof measurement is dimension and depth of focus. In general, to improve the measurementaccuracy in such as spatial resolution, the focalized beams are often requested to have a smallfocal spot. When we have a tiny focal spot, the large depth of focus is requested at the sametime. In accordance with the formula of Rayleigh condition, there is very close relationshipbetween depth of focus and resolution (also called as focal spot of the plane for observation).Therefore, an optical system with a high depth of focus means to widen the range of depth offocus under the condition of certain resolution; that is to say, the dimension invariableness offocal spot within the range of depth of focus.The distribution of intensity produced by a classical Axicon is not uniform. A diffractiveAxicon is designed to produce the light field with a high lateral resolution (HLR) and a largedepth of focus (LDF). A Gerchberg-Saxton (GS) algorithm of an adjacent sequence iterationmethod optimized by conservation of energy is used to design the phase function of adiffractive Axicon. That algorithm hasn't the disadvantage of GS algorithm. The designedAxicon can produce the light field with a HLR and a LDF.Subsequently, the paper program in matlab, design the diffractive Axicon when there arethree output planes and five output planes. The distribution of light field after the designedAxicon irradiated by Gaussian beam is simulated. The simulated calculation of the designedAxicon indicates that the focusing performance of designed Axicon meets its designrequirements.