Lensacon

Abstract

A diffractive optical element has been synthesized with laser phototechnology. It can transform a point source into a bright caustic (a light line) stretched along the optical axis. The element transforms a spherical wave into a conic and a point source in the object space to a ring structure in the image space. We investigated how the parameters of the light line (the length and the effective diameter) depend on the wavelength of the light source and the movement of the source along the optical axis. Also the interference field outside the caustic (Fresnel and Poisson fringes) was investigated. For an explanation of experimental data the geometrical theory of interferometers was used. The conditions for the appearance of fringes in white light are given. A device for rectilinear control of large tool beds and for centering machine components was manufactured. Experiments on determining the macroshape and the microshape of objects were performed.

Diffractive optical elements and quasioptical schemes for experiments on a high-power terahertz free-electron laser

“…Characteristic sizes of the DOE structure should correspond, in order of magnitude, to the radiation wavelength. Therefore, as a rule, photolitography is used for the creation of DOEs in the optical band [25]. In the microwave band, the structures have macroscopic sizes and are easily manufactured.…”

<title>Application of diffractive optical elements in laser metrology</title>

“…2a). The diffractive element "lensacon" 2 [12] converts a spherical wavefront from a point source 1 (for example a laser diode) in a conical one. Lensacon combines functions of a collimating lens and axicon.…”

“…Fig. 3 shows the image [12] of trajectories of scanning the laser beam formed by lensacon when measuring the shape of the object (plate) and the result of computer reconstruction of the object cross-section. In a number of fields of science and engineering, there is a problem of the optical visualization of the relative position of microimages disposed in two different plains.…”

Optical coherence tomography (Review)

“…The relative change of axial intensity is reduced to ~18% [54]. An optical element, a lensacon, was fabricated using laser phototechnology [55]. The lensacon refers to a type of round diffraction lattices that can focus radiation in caustic surfaces expanding along the optical axis.…”

“…In the general case, an extended light field formed after the lensacon. The dependence of the field parameters (length and effective diameter) on the radiation source wavelength and its shift along the optical axis of the scheme was studied in detail [55]. It was shown experimentally that the lensacon was capable of transforming a spherical wave into a conic one; a point light source, into a circular structure.…”