Wednesday, May 28, 2008

Small Hole Technologies

Hole Definition

In effect, a round hole is a cylindrical surface that extends between the front and back surfaces of a substrate sheet. Recent advances in laser hole drilling techniques have provided the means to produce precision holes in the one micron diameter region that are of a higher quality than that produced by the micro drill bit.

Mechanical Drilling

For centuries, people have made holes for many applications using the mechanical drill bit. The micro machining industry has been able to serve the market for small holes of a diameter greater than 25 microns (0.00098"). The industry, however, has found it difficult and challenging to economically produce precision small holes in the range less than 25 microns in diameter. In machining, the harder materials are more difficult to work and the very hard materials are impossible to work.

Laser Drilled Holes

Laser drilling is a non-contact procedure that yields a precision, clean, round and burr-free hole with sharp edges that may be easily reproduced for mass production. In, addition, harder materials are easier to drill and control than softer materials. Materials that are impossible to machine drill, such as diamond, sapphire, ruby, and alumina, are easily worked by the laser beam. The laser drilled small hole industry is now able to economically serve the market for small holes of a diameter less than 25 microns.

This does not imply that the laser is only useful for drilling microscopic sized holes. A hole of almost any size may be laser drilled. The drilling diameter is a function of the focused beam spot size. Larger diameter laser rods yield a larger focused spot. This new industry is a separate technology field. Lenox Laser, Inc. a leader in small hole technology has through use of recent advancements in laser drilling techniques, provides precision holes as small as one micron and below that may be reliably and quickly produced in a wide variety of materials. Small holes are drilled in discs in the range of 0.002" thickness, which are then mounted in a more massive holder for retention in the end use mechanical system.

Small Hole Features









Every physical object is three-dimensional. A hole is a void in a three-dimensional object and may be of any size or shape. A perfect round hole is a cylindrical surface that extends between and is normal to the front and back surface of a substrate sheet. Further, a round hole generates a circular void in the front surface and a circular void in the back surface of the substrate sheet. There are many parameters to consider when specifying or describing a hole.

For the sake of discussion, let us reflect upon the characteristics of a round hole, as described above. In the micro-dimensional real world, the absolutely perfect round hole is difficult to achieve. Thus, we must consider how the round hole may deviate from perfection. The ends of a cylinder describe flat surfaces that are a circular, parallel to each other and normal to the axis. The hole entrance and exit apertures may not be circular, they might be oval or irregular in shape.
  • If the front and back surfaces of the substrate sheet are not parallel to each other, the cross section of the hole cylinder is trapezoidal in shape.
  • If the hole is not drilled at the normal to the surface of a parallel surface substrate sheet, the cross-section of the hole cylinder describes a parallelogram.
  • If the hole entrance circle diameter is different than the hole exit circle diameter, the surface extending between them (the hole wall) is a section of a cone.
Also, the surface extending between the entrance and exit aperture may be totally irregular and may contain particles. The edges of the circular entrance and exit aperture may be beveled or rounded and may contain particles or burrs known as ablation. The descriptive geometrics of dimensioning and tolerances of a round hole include roundness or circularity, cylindrically or deviation from a perfect cylinder, perpendicularity or how much the cylindrical axis deviates from the normal to the substrate sheet surface.

Monday, May 19, 2008

Pinhole Sieves















Lenox Laser Pinhole Sieves can be drilled in varying shapes, sizes, patterns, and materials. Customers can submit drawings and details for a quote. Some examples can be seen at Lenox Laser Services.

Description:

Our pinhole sieve is an array of holes with diameters of 100 micrometers. The illumination of the detector will increase with the number of holes reducing the exposure time correspondingly. The separation between holes brings more spatial frequencies causing increase in the sharpness of the image. The specific arrangement of the pinholes causes the diffraction interference and makes the filter orientation sensitive. This property can be utilized for special effects if used with combination with polarization filter.

Applications:

These pinhole sieves can be used in synchrotron's for controlling and focusing soft x-rays, pinhole sieve photography,
high-resolution X-ray microscopy and spectroscopy, Fresnel zone plate applications, telescope space based surveillance, and advanced apodization.