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.

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.

PhotoSieve 011

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

New Family of High-Power Aperture Mounts

thumbnail_aperturemount

* Aluminum/Anodized Standard Mount
* Stainless Steel for Vacuum Applications
* Copper/Gold Electroplated for High-Power Heat Sink

Overview

This 1″ square aperture holder allows interchanging pinholes drilled in 9.5mm metal foil discs. It is ideal for use in the environments where no outgassing is permitted. The combination of the materials with different thermal conductivities extends the pinhole life under the fluencies close to the ablation threshold sometimes from minutes to days. The geometrical design is robust to the large temperature range. The threaded 8-32 mounting hole is centered on a side and can be interfaced with optical posts and stages.

Meet Thomas Young

THOMAS YOUNG
Thomas Young was an English polymath (a person with encyclopedic or varied knowledge or learning) who contributed to the scientific understanding of vision, light, solid mechanics, energy, physiology and Egyptology.. So great was his knowledge that he was called “Phenomena Young” by his fellow students at Cambridge.
Young was born in 1773, the eldest of 10 children. By the age of fourteen, he had learned Greek and Latin and was acquainted with French, Italian, Hebrew, Chaldean, Syriac, Samaritan, Arabic, Persian, Turkish and Amharic, a Semitic language spoken in North Central Ethiopia.
Thomas_Young

In 1792, Young began to study medicine in London. He later moved to Gottingen, where he obtained his doctorate in physics in 1796. A year later, in 1797, Young entered Emmanuel College at Cambridge. By 1799, Young had established himself as a physician in London where he published many of his first academic articles anonymously to protect his reputation at a physician. It is to be noted that while studying medicine in London, he explained the mode by which the eye accommodates itself to vision at different distances as depending on change of the curvature of the crystalline lens. This was to prove valuable to him being the first to describe astigmatism.

In 1801, Thomas Young was appointed professor of natural philosophy (mainly physics) at the Royal Institution in Cambridge. His initial interest in light and vision carried over to this new academic endeavor. Here, Young presented the hypothesis, later developed by Hermann von Helmholtz, that color perception depends upon the presence in the retina of three kinds of nerve fibers which respond respectively to red, green and violet light. This theory was experimentally proven in 1959, one hundred fifty eight years later!

While at Cambridge, Young performed his now famous double slit experiment where he passed a beam of light through two parallel slits in an opaque screen, forming a pattern of alternating light and dark bands on a white surface beyond which established that light was a transverse wave motion whose wavelength determined color (see wave interference). His findings were strongly opposed by contemporary scientists who believed that Newton, who had proposed that light was corpuscular in nature, would not possibly be wrong. However, Young’s work was soon confirmed by the French scientists, Fresnel and Arago.

In 1804, Young’s essay, “Cohesion of Fluids”, founded the theory of capillary phenomena on the principle of surface tension. He also observed the constancy of the angle of contact of a liquid surface with a solid, and showed how from these two principles to deduce the phenomena of capillary action (see Young-Laplace Equation and the Young-Dupre Equation). He went on to describe the characterization of elasticity that came to be known as Young’s Modulus.

After holding positions at St. George’s Hospital and on various scientific boards and committees, Thomas Young died in 1829 after a relatively short but distinguished career. His contemporary, Sir John Herschel, called him a “truly original genius”. Young being the first to define the term “energy” in the modern sense, was praised by Albert Einstein in his 1931 forward to an edition of Newton’s Opticks. Other admirers include physicist Lord Rayleigh and Nobel laureate Philip Anderson.

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Lenox Laser Helps Uncover Archimedes Palimpsest.

A spatial filter is an optical device which uses the principles of Fourier Optics to alter the structure of a beam of coherent light. Spatial filtering is commonly used to remove aberrations in the beam due to imperfect, dirty or damaged optics, or due to variations in the laser gain medium itself. This can be used to produce a laser beam containing only a single transverse mode of the laser’s optical resonator.

In spatial filtering, a lens is used to focus the beam. A beam that is not a perfect plane wave will not focus to a single spot, but rather will produce a pattern of light and dark regions in the focal plane. It can be shown that this two-dimensional pattern is the two-dimensional Fourier transform of the initial beam’s transverse intensity distribution. Light in the very center of the transform pattern corresponds to a perfect, wide plane wave. Other light corresponds to “structure” in the beam, with light further from the central spot corresponding to structure with higher spatial frequency. A pattern with very fine details will produce light very far from the transform plane’s central spot. This pattern is called an Airy pattern.

By altering the distribution of light in the transform plane and using another lens to reform the collimated beam, the structure of the beam can be altered. The most common way of doing this is to place an aperture in the beam that allows the desired light to pass, while blocking light that corresponds to undesired structure in the beam. In particular, a small circular aperture or “pinhole” that passes only the central bright spot can remove nearly all fine structure from the beam, producing a smooth transverse intensity profile. With good optics and precisely measured pinhole, one could even approximate a plane wave.

The diameter of an aperture is chosen based on the focal length of the lens, the diameter and quality of the input beam, and its wavelength. If the hole is too small, the beam quality is greatly improved but the power is greatly reduced. If the hole is too large, the beam quality may not be improved as much as desired.

The size of the aperture that can be used also depends on the size and quality of the optics. To use a very small pinhole, one must use a focusing lens with a low f-number, and ideally the lens should not add significant aberrations to the beam.

A commonly used spatial filter configuration is to use a microscope objective lens for focusing the beam, and an aperture made preferably by laser drilling a small, precise, hole in a piece of metal foil. Such apertures made in a variety of sizes and materials are readily available commercially from companies, such as, Lenox Laser, Inc., the leader in microhole technology.

Nasa Stereo Mission

NASA’s recent STEREO (Solar TErrestrial RElations Observatory) project is a mission to capture the sun in three dimensions. The two-year long project involves having two near-identical telescopes (one ahead of earths’ orbit and one behind) to record the behavior of the sun, studying phenomena like coronal mass ejections.

Lenox Laser fabricated custom parts for the Government and provided consulting services in support of testing the focus setting of one of the STEREO instruments during satellite integration at NASA/Goddard Space Flight Center.

Lenox Laser’s role was critical to a successful test. As a result, Lenox Laser was awarded the NASA/Goddard Space Flight Center Instrument Systems and Technology Division 2006 Contractor Team Spirit Award.

NASA’s STEREO Mission

A close up of loops in a magnetic active region, observed by STEREO's SECCHI/EUVI telescope. This powerful active region, observed here on Dec. 4, 2006 produced a series of intense flares over the next few days. Credit: NASA
A close up of loops in a magnetic active region, observed by STEREO’s SECCHI/EUVI telescope. This powerful active region, observed here on Dec. 4, 2006 produced a series of intense flares over the next few days. Credit: NASA

 

NASA’s recent STEREO (Solar TErrestrial RElations Observatory) project is a mission to capture the sun in three dimensions. The two-year long project involves having two near-identical telescopes (one ahead of earths’ orbit and one behind) to record the behavior of the sun, studying phenomena like coronal mass ejections.
Lenox Laser fabricated custom parts for the government and provided consulting services in support of testing the focus setting of one of the STEREO instruments during satellite integration at NASA/Goddard Space Flight Center.

Lenox Laser’s role was critical to a successful test. As a result, Lenox Laser was awarded the NASA/Goddard Space Flight Center Instrument Systems and Technology Division 2006 Contractor Team Spirit Award.

Lenox Laser Helps Uncover Archimedes Palimpsest.

Intensive efforts are underway to uncover centuries-old hidden writings of Greek mathematician Archimedes. Researches at the Stanford Linear Accelerator Center (SLAC) are utilizing advanced X-ray technology to uncover writings of Archimedes once completely unknown. Discovered in 1906 by then-Professor J.L. Heiberg of the University of Copenhagen, Denmark, the hidden text appeared within historical monastic prayer documents. The ancient practice of washing text away to make reuse material is called “Palimpsesting”.

The Archimedes Palimpsest writings lingered unseen for centuries, seemingly purged from the documents forever, until Professor Heiburg began to review small scrawls beneath the visible text. At SLAC, a revolutionary modern analysis of the writing medium has been made – revealing they do contain historically important information left behind by Archimedes, Hidden from the naked eye.

When confronted with an engineering challenge involving their Synchrotron X-Ray source, SLAC issued a request to Lenox Laser to produce microscopic laser-drilled holes in thin Tungsten film. These small apertures would prove critical to the team’s success in uncovering the Palimpsest’s “hidden treasure”.

Using a new X-Ray Fluorescence (XRF) technique, the team at SLAC, along with other collaborations, revealed writings involving mathematics and science once hidden for more than 1000 years. Conservation scientists are referencing this experiment to encourage similar new endeavors. Could many more documents in historical collections today hold hidden texts currently unknown? Time and Technology will tell.

The SLAC experiment has proven successful, and the story was featured on several prominent news and documentary programs. The Archimedes Palimpsest rests at the Walter’s Art Gallery in Baltimore, MD – continuously monitored by preservation professionals, and studied regularly by scholars from around the world.

Introduction to Young’s Double-slit Experiment

Youngs_Double_slit
The double slit experiment, thought to have been first performed by English scientist Thomas Young circa 1800, generally refers to an experiment in which light is allowed to diffract through slits which produces fringes, or wave-like interference patterns on an opposing screen.

A similar experiment was performed by Claus Jonsson of the University of Tubingen where beams of electrons showed similar interference patterns. The results of this experiment are often taken as evidence of the “wave-particle duality” predicted by quantum physics. (a.k.a. Englert-Greenberger duality)

In the case two pinholes are used instead of slits, as in the original Young’s experiment, hyperbolic fringes are observed. This is because the difference in paths traveled by the light from the two sources is a constant for a fringe which is the property of a hyperbola. If the two sources are placed on a line perpendicular to the screen, the shape of the interference fringes is circular as the individual paths traveled by light from the two sources are always equal for a given fringe.

It is little wonder that the experiment performed by Dr. Jonsson (Young’s Double Slit applied to the interference of single electrons) ranks first in the list of the top ten most beautiful experiments as chosen by the readers of Physics World magazine.

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