The crystal detector was developed into a practical device for wireless telegraphy by Greenleaf Whittier Pickard, who invented a silicon crystal detector in 1903 and received a patent for it on November 20, 1906.

This troublesome device was superseded by thermionic diodes by the 1920s, but after high purity semiconductor materials became available, the crystal detector returned to dominant use with the advent of inexpensive fixed-germanium diodes in the 1950s.

Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector.

The point-contact crystal detector became vital for microwave radio systems, since available vacuum tube devices could not serve as detectors above about 4000 MHz ; advanced radar systems relied on the fast response of crystal detectors.

When they land on a piece of film or other detector, these beams make a diffraction pattern of spots ; the strengths and angles of these beams are recorded as the crystal is gradually rotated.

The detector ( red box ) can be slid closer or further away from the crystal, allowing higher resolution data to be taken ( if closer ) or better discernment of the Bragg peaks ( if further away ).

Early radio receivers, called crystal radios, used a " cat's whisker " of fine wire pressing on a crystal of galena ( lead sulfide ) to serve as a point-contact rectifier or " crystal detector ".

* Acoustic detector ( crystal transducer and solid-state amplifier ) to detect micrometeorite ( cosmic dust ) impacts.

*" Simultaneous " spectrometers have a number of " channels " dedicated to analysis of a single element, each consisting of a fixed-geometry crystal monochromator, a detector, and processing electronics.

The instrument is programmed to move through a sequence of wavelengths, in each case selecting the appropriate X-ray tube power, the appropriate crystal, and the appropriate detector arrangement.

The common feature of monochromators is the maintenance of a symmetrical geometry between the sample, the crystal and the detector.

The earliest crystal radio receivers used a crystal diode detector with no amplification.

The PDS was a crystal ( sodium iodide / caesium iodide ) scintillator detector capable of absorbing photons up to 300 keV ( 48, 000 aJ ).

It gets its name from its most important component, known as a crystal detector, originally made with a piece of crystalline mineral such as galena.

Crystal radios are the simplest type of radio receiver and can be handmade with a few inexpensive parts, like an antenna wire, tuning coil of copper wire, crystal detector and earphones.

The frequency used for these experiments is 15 mc. and the transducer is a specially cut crystal with an epoxy lens capable of providing beam diameters smaller than one millimeter.

Af appeared to be well suited for the study of these matters, since it is a normal paramagnet, with three unpaired electrons on the chromium, its crystal structure is very simple, and the unknown position of the hydrogen in the strong Af bond provides structural interest.

Therefore these parts of the crystal grow out very quickly ( yellow arrows ).

Therefore, the flat surfaces tend to grow larger and smoother, until the whole crystal surface consists of these plane surfaces.

The short wavelength of these matter waves makes them ideally suited to study the atomic crystal structure of solids and large molecules like proteins.

Mineralogists have been able to use the pressure and temperature data from the seismic and modelling studies alongside knowledge of the elemental composition of the Earth at depth to reproduce these conditions in experimental settings and measure changes in crystal structure.

Gabbro may be extremely coarse grained to pegmatitic, and some pyroxene-plagioclase cumulates are essentially coarse grained gabbro, although these may exhibit acicular crystal habits.

One inevitable ambiguity about these structures relates to the strong evidence that channels change conformation as they operate ( they open and close, for example ), such that the structure in the crystal could represent any one of these operational states.

Differences in chemical composition and crystal structure distinguish various species, and these properties in turn are influenced by the mineral's geological environment of formation.

According to these new rules, " mineral species can be grouped in a number of different ways, on the basis of chemistry, crystal structure, occurrence, association, genetic history, or resource, for example, depending on the purpose to be served by the classification.

:* Crystallography – the study of regular arrangement of atoms and ions in a solid, the defects associated with crystal structures such as grain boundaries and dislocations, and the characterization of these structures and their relation to physical properties.

Of the thirty-two crystal classes, twenty-one are non-centrosymmetric ( not having a centre of symmetry ), and of these, twenty exhibit direct piezoelectricity ( the 21st is the cubic class 432 ).

Ten of these represent the polar crystal classes, which show a spontaneous polarization without mechanical stress due to a non-vanishing electric dipole moment associated with their unit cell, and which exhibit pyroelectricity.

Natural sources of radiation in the environment knock loose electrons in, say, a piece of pottery, and these electrons accumulate in defects in the material's crystal lattice structure.

One of the properties of the crystal structure of oxide superconductors is an alternating multi-layer of CuO < sub > 2 </ sub > planes with superconductivity taking place between these layers.

From the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal.

In general, single-crystal X-ray diffraction offers more structural information than these other techniques ; however, it requires a sufficiently large and regular crystal, which is not always available.

In the third step, these data are combined computationally with complementary chemical information to produce and refine a model of the arrangement of atoms within the crystal.

The relative intensities of these spots provide the information to determine the arrangement of molecules within the crystal in atomic detail.

In the early 20th century it was recognized that other cases such as carbon were due to differences in crystal structure.

In the early 1970s liquid crystal displays ( LCDs ) were in their infancy and there was a great deal of concern that they only had a short operating lifetime.

They also enabled tunable oscillators in early discrete tuning of radios, where a cheap and stable, but fixed-frequency, crystal oscillator provided the reference frequency for a voltage-controlled oscillator.

The origins and the complex history of liquid crystal displays from the perspective of an insider during the early days were described by Joseph A. Castellano in Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry.

The earliest known lenses were made from polished crystal, often quartz, and have been dated as early as 700 BC for Assyrian lenses such as the Layard / Nimrud lens.

This greatly improved the crystal set which rectified the radio signal using an early solid-state diode based on a crystal and a so-called cat's whisker.

Other early innovators in quartz crystal oscillators include G. W. Pierce and Louis Essen.

During the early 1900s it was a manufacturer of lead crystal but after almost three decades ownership shifted and it became a major foundry.

If a signal is strong enough, not even a power source is needed ; building an unpowered crystal radio receiver was a common childhood project in the early decades of AM broadcasting.

The remarkable mace or sceptre of the Lord Mayor of the City of London comprises crystal and gold set with pearls ; the head dates from the 15th century, while the mounts of the shaft are from the early medieval period.

Those used with early wireless radio had to be more sensitive and were made with more turns of finer wire ; impedance of 1, 000 to 2, 000 ohms was common, which suited both crystal sets and triode receivers.

Before the Siamese seized it in the early nineteenth century, this crystal image was the palladium of the Lao kingdom of Champassack.

A crystal radio receiver, also called a crystal set or cat's whisker receiver, is a very simple radio receiver, popular in the early days of radio.

The earliest practical use of crystal radio was to receive Morse code radio signals transmitted by early amateur radio experimenters using very powerful spark-gap transmitters.

Many early crystal sets did not have a tuning capacitor, and relied instead on the capacitance inherent in the wire antenna ( in addition to significant parasitic capacitance in the coil itself ) to form the tuned circuit with the coil.

In early sets, this was a cat's whisker detector, a fine metal wire on an adjustable arm that touched the surface of a crystal of a semiconducting mineral.

To improve the sensitivity of some of the early crystal detectors, such as silicon carbide, a small forward bias voltage was applied across the detector by a battery and potentiometer.

The early earphones used with wireless-era crystal sets had moving iron drivers that worked similarly to loudspeakers.

* A website with lots of information on early radio and crystal sets

Other medium sized family companies specialized in textiles ( for instance those located in the city of Covilhã and the northwest ), ceramics, porcelain, glass and crystal ( like those of Alcobaça, Caldas da Raínha and Marinha Grande ), engineered wood ( like SONAE near Porto ), canned fish ( like those of Algarve and the northwest ), fishing, food and beverages ( alcoholic beverages, from liqueurs like Licor Beirão and Ginjinha, to beer like Sagres, were produced across the entire country, but Port Wine was one of its most reputed and exported alcoholic beverages ), tourism ( well established in Estoril / Cascais / Sintra and growing as an international attraction in the Algarve since the 1960s ) and in agriculture ( like the ones scattered around the Alentejo-known as the breadbasket of Portugal ) completed the panorama of the national economy by the early 1970s.