Lasers drilling

Drilling diamonds using a focused laser beam to bum out dark inclusions or make the inclusions accessible to a chemical treatment is a frequent enhancement. In a potential deception, a cubic zirconia diamond imitation was laser drilled to make it more convincing (15). 

Osmotic Pressure Controlled Oral Tablets. Alza Corp. has developed a system that is dependent on osmotic pressure developed within a tablet. The core of the tablet is the water-soluble dmg encapsulated in a hydrophobic, semipermeable membrane. Water enters the tablet through the membrane and dissolves the dmg creating a greater osmotic pressure within the tablet. The dmg solution exits at a zero-order rate through a laser drilled hole in the membrane. Should the dmg itself be unable to provide sufficient osmotic pressure to create the necessary pressure gradient, other water-soluble salts or a layer of polymer can be added to the dmg layer. The polymer swells and pushes the dmg solution through the orifice in what is known as a push-pull system (Fig. 3). The exhausted dmg unit then passes out of the body in fecal matter. 

Osmotic Control. Several oral osmotic systems (OROS) have been developed by the Alza Corporation to allow controUed deHvery of highly water-soluble dmgs. The elementary osmotic pump (94) consists of an osmotic core containing dmg surrounded by a semi-permeable membrane having a laser-drilled deHvery orifice. The system looks like a conventional tablet, yet the outer layer allows only the diffusion of water into the core of the unit. The rate of water diffusion into the system is controUed by the membrane s permeabUity to water and by the osmotic activity of the core. Because the membrane does not expand as water is absorbed, the dmg solution must leave the interior of the tablet through the smaU orifice at the same rate that water enters by osmosis. The osmotic driving force is constant until aU of the dmg is dissolved thus, the osmotic system maintains a constant deHvery rate of dmg until the time of complete dissolution of the dmg. 

Micro-jet arrays are usually associated with lower energy consumption rates than sprays generated by the special (HAGO) nozzle for the same flow rate. The liquid was pushed through a 0.5 mm stainless steel orifice plate to form the jets. The holes in the plate were laser drilled and were arranged in a circular pattern giving a radial... 

The manufacture of this system utilizes essentially the same process as the one inherent in the manufacture of OROS. The complicating factors are that a bilayer tablet press is required and the tablet must be oriented during the laser drilling operation to ensure that the drug-containing layer is directed toward the laser beam. 

See also Planar cavity surface-emitting laser (PCSEL) diodes Vertical cavity surface-emitting laser (VCSEL) diodes compound semiconductor-based, 22 179 Laser Doppler velocimetry (LDV), 11 784 Laser Doppler velocimeters, 11 675 Laser-drilled surgical needles, 24 206 Laser dye energy levels, 14 702-703 Laser fabrication techniques, titanium, 24 857... 

Pills can operate as osmotic "pumps" if they have miniscule laser-drilled holes in them. The pill coating is selective in that water from the body is allowed to enter to displace the drug at a constant rate. 

Laser Drilling None Identified Convergent Energies... 

The active substance is mechanically ejected from a blister through laser-drilled nozzles with a diameter of a few pm and integrated into the blisters by means of punch, to produce a mist consisting of drops measuring 1-6 pm. The blister is inserted into an electronically controlled dosing unit that measures the airstream and induces aerosolization in synchrony with inspiration. The bioavailability of morphine sulphate (total dose 8.8 mg) blistered in portions of 1.2 mg was 75% of that on intravenous administration (dose 4 mg), which is much higher than conventional aerosol formulations (Gonda et al., 1999 Otulana etal., 1999). 

The solute is solubilized in supercritical fluid at high pressure in an autoclave, and later the solution is decompressed through the nozzle. One key component of the apparatus is the nozzle, of which two types are used - a capillary of suitable diameter (< 100 qm) or laser-drilled nozzles of 20-60 qm diameter. 

Material removal - This type of operation involves material removal using machining operations, stamping, laser, drilling, etc. 

HF etching (4 min, 1 mm dia., 145 um deep) C02 laser drilling Ultrasonic abrasion Electrochemical discharge machining Powder blasting... 

In order to provide access holes on fused quartz cover chips, laser drilling [151,152,828,1006] or ultrasonic drilling [349,1041] have been used. In order to remove particulates caused by drilling, the drilled quartz plate was rinsed in 0.5% HF for 5-10 min in an ultrasonic bath [153,658]. However, in some cases no drilling was performed, with the end of the channel protruding out of the coverslip [148],... 

The hybrid circuit 10 comprises a buffer structure 16 which is comprised of a material which accommodates the difference in thermal expansion coefficients of the HgCdTe detector array 12 and the silicon read-out chip 14. The buffer layer is made of sapphire which also has good thermal conductivity properties. The buffer structure has laser drilled vias 18 which are formed in registration with unit cells of the detector array and the read-out circuit. Each of the vias is provided with indium bumps 20 at opposing ends thereof. The buffer structure is interposed between the detector array and the read-out chip. Cold weld indium bump technology is employed to couple the bumps 20 to the buffer structure. The buffer structure is further... 

A (100) silicon wafer 10 is anisotropically etched to form hollows 11 having sloped sides 15. A plurality of via holes are etched or laser drilled through the floor 17 of each hollow. Next, the wafer is oxidized to coat its surfaces with a first insulator of SiC>2. A refractory conductor is deposited within the vias to form conductive conduits. A perspective view of a single hollow is shown below. 

The laser drilling based marking system is commercially feasible and could be fully automated for a production procedure. It could also be used to tag individual items. If desired, the holes could be fully hidden by a treatment of the surface after drilling. Further work is in progress to evaluate the potential... 

Figure 4. A photograph of a pattern of laser drilled holes in steel representing the number 5383158068. Abo shown is a Va" stamped digit for the purpose of size comparison.

Compared with conventional photolithography, laser drilling is a dry process and keeps the surface of polyimide gate dielectric layer away from water, etching solution, or other solvent, which often degrade the polyimide surface. We have confirmed that the electronic performance of transistors with laser via holes is identical with that without laser via holes. 

Both films with organic FETs and photodiodes are transferred to the vacuum chamber without exposure to air after the manufacturing process and uniformly coated with a 2 pm poly(monochloro-para-xylylene) (parylene) passivation layer. Spots of parylene on electrodes are removed by a CO2-laser drilling machine for... 

This push-pull system has been applied to a system containing a liquid formulation (called L-OROS ). A liquid drug layer and an osmotic engine, or push layer, are encased in a hard gelatin capsule surrounded by a semipermeable membrane. However, there is a barrier layer separating the drug layer from the push layer in order to prevent any interaction between the two. A laser-drilled orifice is set in the top of the drug layer. 

Laser cutting is a fast growing process. The laser can act as a materials eliminator. Concentrating its energy on a small spot, it literally vaporizes the material in its path. If the workpiece is held stationary, the laser drills a hole. If the piece is moved, it slits the material. The induced heat is so intense and the action of the laser is so fast that only little heating of the adjacent areas of the piece takes place. 

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