The interaction between laser beam and metal, and micromachining technology for small-diameter metal tubes by means of a copper vapour laser are considered. The quality and productivity of cutting have been analysed from a point of view of the laser beam intensity distribution in the treatment zone. The divergence of laser beam and its power have been selected to ensure a minimal cut wall roughness with the maximal production rate being preserved. A stent cutting technology for cardio surgery is presented. The technology equipment has been described for precision cutting of products with a cylindrical surface. Tiny devices being cut out from non-metal material
The manuscript presents the results of research of different processes of micro brands (identification marks) manufacturing. Two methods are taken into consideration, namely, the projection method and the method based on making brand by deep laser marking. These manufacturing methods are compared in terms of their accuracy, manufacturing flexibility and efficiency. There are a lot of micro brand manufacturing processes and one of them is laser deep marking. In this paper we consider brand manufacturing by Copper vapor lasers and compare it with well-known Nd:YAG laser. A copper vapor laser has a diffraction-limited divergence, a short pulse, and a high repetition rate. These properties enable an efficient evaporation of any material with a very small heat affected zone and with a minimal amount of the melted material. In the projection method a copper vapor laser cuts a mask of 0.15 mm copper foil. The mask image being projected to a material surface is five times less than the original mask. A pulse solid-state laser illuminating the mask evaporates the exposed material. An impact tool for brand stamping is made of steel by precision deep (0.5 mm) marking using a copper vapor laser. A laser beam 10 mm in diameter is deflected by electromechanical scanners and evaporates material layer by layer at the raster movement. Copper vapor laser marking makes possible the direct manufacturing of brands on gold surfaces at 0.5 mm depth with 10 mm accuracy as well.
This paper presents investigation results of drilling of metal microcomponents by copper vapor laser. The laser consists of master oscillator - spatial filter - amplifier system, electronics switching with digital control of laser pulse repetition rate and quantity of pulses, x-y stage with computer control system. Mass of metal, removed by one laser pulse, is measured and defined by means of diameter and depth of holes. Interaction of next pulses on drilled material is discussed. The difference between light absorption and metal evaporation processes is considered for drilling and cutting. Efficiency of drilling is estimated by ratio of evaporation heat and used laser energy. Maximum efficiency of steel cutting is calculated with experimental data of drilling. Applications of copper vapor laser for manufacturing is illustrated by such microcomponents as pin guide plate for printers, stents for cardio surgery, encoded disks for security systems and multiple slit masks for spectrophotometers.
Results of experimental studies of efficiency of evaporation cutting by copper vapor laser are presented. One- and multi- pass cutting are explored, including cutting with the high instant velocity (with galvanometer-scanner), as well as holes drilling with a changeable repetition rate of pulses. High cutting efficiency and quality are shown in the multi- pass cutting at a high velocity of a focal spot movement.
The copper vapor laser (CVL) can be a very suitable tool for cutting and drilling with minimum roughness and maximum accuracy. Visible range of irradiation, perfect quality of output beam, high pulse power, and pulse repetition frequency favor this application. However, there is no data on productivity of cutting, which defines the economic benefit of using CVL technology. In the present paper, the cutting productivity is estimated on the basis of efficiency of material removal from the processing zone: the ratio of evaporated mass (multiplied by vaporization heat) to laser energy within the processing time. Aluminum specimens with 0.02 (mu) thickness (thin film) and 100 (mu) thickness (foil) are cut with different output power and cutting velocity. Use of specimens with these thicknesses allows the observation of two phenomena which define the cutting efficiency. One of them, evaporation from the free surface, is typical for thin (a few micron or less) materials. The second one, vapor flying and condensation, can only reduce initial efficiency when material thickness becomes more than cutwidth.
Parameters of output diffraction-limited beam from copper vapor laser are investigated for different unstable resonators: self-imaging, self-filtering and modified self-filtering. Three types of intensity distribution (uniform, Gaussian and Bessel) in near-field (output beam) and far-field (focal plane) zones are considered with 20 mm active medium diameter. Divergence of these beams depends on phase and amplitude distortions by active medium gain saturation. Angle beam position dependencies are considered versus position of more curves mirror and field-limiting aperture of unstable resonators.
Copper vapor laser (CVL) was designed on the basis master oscillator (MO) - spatial filter - amplifier (AMP) system which is placed in thermostable volume. Processing material is moved by means of CNC system GPM-AP-400 with +/- 5 micrometers accuracy. Several cutting parameters are considered which define the quality and productivity of vaporization cutting: efficiency, cutwidth, height of upper and lower burr, roughness, laser and heat affected zones. Estimates are made for some metals with thickness 0.02 - 0.3 mm and cutwidth 0.01 - 0.03 mm. The examples of workpieces produced by CVL are presented.
Temporal, spatial and energy characteristics of copper vapor laser with confocal unstable and self-filtering unstable resonators are presented. Conditions for obtaining diffraction-limited divergence of radiation were founded experimentally when light passed only one round-tripp for different magnifications of resonator, diameters of active medium and field-limiting aperture. Comparison is carried out for output characteristics of oscillator-amplifier system with different types of oscillator resonator. Application of this system to laser precise machining is mentioned.
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