Contact lenses articles

October 31, 2007

Vin de Savoie AOC are made by Vistakon

Filed under: Uncategorized — admin @ 4:23 pm

Vin de Savoie is a wine AOC in the Savoie departement of France, on the lower slopes of the Alps.

The wines are mostly white, made from Chasselas, Jacquère, Altesse and Roussanne grapes, although there are also some (relatively light) reds made from Mondeuse, Gamay Noir and occasionally Pinot Noir, and rosés made from Gamay, and some sparkling wines.


See also

  • French wine

Crazy Prices of Ireland.

Filed under: Uncategorized — admin @ 2:32 pm

Crazy Prices was a supermarket chain operating in the Republic of Ireland and Northern Ireland formerly owned by Associated British Foods. When Associated British Foods sold its Irish operation in the late 1990s to Tesco, the stores were rebranded to Tesco (in Northern Ireland) and Tesco Ireland (in the Republic).

Crazy Prices were noted for concentration on price reductions at the expense of presentation, including the Yellow Pack brand and presenting goods to shoppers still in warehouse packaging (not unlike LIDL). They were among the first supermarkets in Ireland to regularly offer late-night opening - further detailled in the Tesco Ireland article.

October 30, 2007

John Ireland Ireland.

Filed under: Uncategorized — admin @ 5:07 pm

John Ireland may refer to:

  • John Ireland (theologian) (1440–1495), Scottish theologian and Rector of the Sorbonne
  • John Ireland (martyr), (d. 1544), martyr
  • John Ireland (biographer) (d. 1808), biographer of William Hogarth
  • John Ireland (politician) (1827–1896), Governor of Texas
  • John Ireland (archbishop) (1838–1918), of St Paul, Minnesota, university founder
  • John Ireland (composer) (1879–1962), English composer
  • John Ireland (actor) (1914–1992)
  • John Ireland (scientist) (1918–2001), Manhattan Project and World War II veteran
  • John Ireland (barrister) (1950–present), Australian barrister

Florida State Road 139 headquartered in Jacksonville Florida.

Filed under: Uncategorized — admin @ 10:44 am

State Road 139 (SR 139) is an unsigned state highway in Jacksonville, Florida, United States. Most of it is signed as U.S. Highway 23.


Exit list

Mile Destinations Notes
State Road 115 south - Jacksonville Beaches southbound exit and northbound entrance
U.S. Highway 1 Alternate north; Martin Luther King Jr. Parkway; Sports Complex (State Road 115 north; State Road 115A south)
Coliseum; A. Philip Randolph Boulevard
Union Street eastbound exit and westbound entrance


References

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4Pi STED microscopy lenses

Filed under: Uncategorized — admin @ 10:04 am

The 4Pi-STED-microscope is the result of combining the two unrelated concepts of STED- and 4Pi-microscopy. Here, the fluorescent sample is placed in the common focus of two opposing lenses, but excitation and detection are performed through a single lens (4Pi mode A). The green excitation pulse is immediately followed by a red STED-pulse, which enters the focal region through both lenses inducing stimulated emission of the excited fluorescent molecules to the ground state. To permit fluorescence emission from the center but suppress it from neighbouring regions it is useful to phaseshift the STED beam to have a minimum at the center.


External links

Technical details

Agglomeration community of Lens - Liévin Contact Lens

Filed under: Uncategorized — admin @ 3:08 am

The Communauté d’agglomération de Lens - Liévin (French for “Community of Agglomeration of Lens - Liévin”) was created on January 1, 2000. It adopted the name Communaupole on June 25, 2004

It covers 36 communes, with a total population of 250,000:

Ablain-Saint-Nazaire, Acheville, Aix-Noulette, Angres, Annay-sous-Lens, Avion, Bénifontaine, Billy-Montigny, Bouvigny-Boyeffles, Bully-les-Mines, Carency, Éleu-dit-Leauwette, Estevelles, Fouquières-lès-Lens, Givenchy-en-Gohelle, Gouy-Servins, Grenay, Harnes, Hulluch, Lens, Liévin, Loison-sous-Lens, Loos-en-Gohelle, Mazingarbe, Méricourt, Meurchin, Noyelles-sous-Lens, Pont-à-Vendin, Sains-en-Gohelle, Sallaumines, Servins, Souchez, Vendin-le-Vieil, Villers-au-Bois, Vimy, Wingles.


External links

October 27, 2007

Boot Key Florida.

Filed under: Uncategorized — admin @ 11:28 pm

Boot Key is an island in the middle Florida Keys located adjacent to Key Vaca. Boot Key is within the city limits of Marathon, Florida, USA. The island is largely undeveloped despite having a bridge to Key Vaca. The only significant operation on the island is Radio Marti which broadcasts U.S. government news and cultural information to Cuba.

A hawkwatch is conducted every fall on Boot Key.

Normal lens Lens

Filed under: Uncategorized — admin @ 9:11 pm

In photography and cinematography a normal lens is a lens that generates images that are generally held to have a “natural” perspective similar to human eyesight, compared with lenses with longer or shorter focal lengths.

Lenses of shorter focal length are called wide-angle lenses, while longer focal length lenses are called telephoto lenses.

In still photography, a normal lens is a lens whose focal length is roughly equivalent to the diagonal of the image projected within the camera.

  • Standard normal lenses for various film formats for photography are:
Film format Image dimensions Image diagonal Normal lens focal length
9.5 mm Minox 8 × 11 mm 13.6 mm 15 mm
APS C 16.7 × 25.1 mm 30.15 mm 28 mm, 35 mm
135 24 × 36 mm 43.27 mm 50 mm, 45 mm
120/220, 6 × 4.5 (645) 56 × 45 mm 71.84 mm 75 mm
120/220, 6 × 6 56 × 56 mm 79.20 mm 80 mm
120/220, 6 × 7 56 × 68 mm 88.09 mm 90 mm
120/220, 6 × 9 56 × 84 mm 100.96 mm 105 mm
large format 4 × 5 sheet film 96 × 120 mm (image area) 153.67 mm 150 mm
large format 8 × 10 sheet film 194 × 245 mm (image area) 312.51 mm 300 mm

For a 35 mm camera with a diagonal of 43 mm, the most commonly used normal lens is 50 mm, but focal lengths between about 40 and 58 mm are also considered normal.

The 50 mm focal length was chosen by Oskar Barnack, the creator of the Leica camera, as a compromise between the theoretical value and good sharpness, as lens technology at the time was such that slightly longer focal lengths were able to achieve optimum sharpness.

  • In Digital photography the situation is more complex. The sensor type diameter is not the sensor diameter:
(*) refers to tv-tube diameters that were standards in the 50’s. The normal lens focal length is roughly 2/3 of the TV tube diameter.
(**) this is a mathematical calculation because most of the cameras are equipped with zoom lenses.
Sensor type TV-tube diameter * Image dimensions Image diagonal Normal lens focal length **
1/3.6″ 7.1 mm 4.00 x 3.00 mm 5.00 mm 5 mm
1/3.2″ 7.9 mm 4.54 x 3.42 mm 5.68 mm 5.7 mm
1/3″ 8.5 mm 4.80 x 3.60 mm 6.00 mm 6 mm
1/2.7″ 9.4 mm 5.37 x 4.04 mm 6.72 mm 6.7 mm
1/2.5″ 10.2 mm 5.76 x 4.29 mm 7.2 mm 7 mm
1/2″ 12.7 mm 6.40 x 4.80 mm 8.00 mm 8 mm
1/1.8″ 14.1 mm 7.18 x 5.32 mm 8.93 mm 9 mm
1/1.7″ 14.9 mm 7.60 x 5.70 mm 9.50 mm 9.5 mm
1/1.6″ 15.9 mm 10.5 mm
2/3″ 16.9 mm 8.80 x 6.60 mm 11.00 mm 11 mm
1″ 25.4 mm 12.80 x 9.60 mm 16.00 mm 16 mm
4/3″ 33.9 mm 18.00 x 13.50 mm 22.50 mm 23 mm
(APS-C) 1/8″ 45.7 mm 22.70 x 15.10 mm 27.3 mm 27 mm
DX n/a 23.7 x 15.8 28.40 mm 28 mm
FF (35 mm film) n/a 36 x 24 mm 43.30 mm 50 mm
(4 x 5 cm) n/a 49.0 x 36.7 mm 61.22 mm
  • In cinematography a focal length roughly equivalent to twice the diagonal of the image projected within the camera is considered normal.
Film format Image dimensions Image diagonal Normal lens focal length
N-8 3.68 x 4.88 mm 6.11 mm 12 - 15 mm
Single - 8 (FUJI) 4.22 x 6.24 mm 7.53 mm 15 - 17 mm
Super - 8 4.22 x 6.24 mm 7.53 mm 15 - 17 mm
9.5 mm 6.5 x 8.5 mm 10.70 mm 20 mm
16 mm, magnetical sound 7.49 x 10.26 mm 12.70 mm 25 mm
16 mm, optical sound
35 mm 18.00 x 24.00 mm 30.00 mm 60 mm
35 mm, sound 16.03 x 22.05 mm 40.53 mm
65 mm
70 mm 52.6 x 23.0 mm 57.41 mm


See also

  • angle of view
  • photographic lens

First contact (astronomy) contact

Filed under: Uncategorized — admin @ 6:03 pm

In astronomy, during a transit or eclipse, first contact is the moment when the apparent positions of the two bodies first touch. Historically, measuring the precise time of each point of contact during a transit, was one of the most accurate ways to determine the positions of astronomical bodies.

October 26, 2007

Water contact contact

Filed under: Uncategorized — admin @ 4:16 pm

Water contact is a term used in the hydrocarbon industry to describe the elevation above which fluids other than water can be found in the pores of a rock.

For example, in a traditional hand-excavated water well, the level at which the water stabilizes represents the water table, or the elevation in the rock where air starts to occupy the rock pores.

In most situations in the hydrocarbon industry the term is qualified as being an oil-water contact (abbreviated to “OWC”) or a gas-water contact (”GWC”). Often there is also a gas-oil contact (”GOC”).

In an oil or gas field, hydrocarbons migrate into rocks and can be trapped if there is a permeability barrier to prevent upward escape. Gas and oil are lighter than water, so they will form a bubble at the high end of the “trap” formed by the impermeable barriers. A simple physical model of this would be a coffee cup held upside down underwater with an air bubble occupying the highest portion of the cup’s interior. The base of the bubble is the water contact.

Capillary action can obscure the true water contact in permeable media like sandstone. Capillary pressure prevents the hydrocarbons from expelling all of the water in the pores, which creates a transition zone between the fully saturated hydrocarbon levels and the fully saturated water levels.

In poorly porous intervals, the oil-water, gas-water or gas-oil contacts can similarly be obscured, which makes estimation of hydrocarbon reserves difficult. Descriptions of the well’s petrophysics will then often further qualify to delineate a gas-down-to, oil-up-to, oil-down-to and water-up-to line, clearly showing the uncertainties involved.

October 24, 2007

James Ayscough contact lenses

Filed under: Uncategorized — admin @ 12:24 pm

James Ayscough (?-1759) was an English designer and maker of scientific instruments.
He was apprenticed to an optician named James Mann from 1743 to 1747.

James Ayscough became known for his microscopes. His shop was in London between 1740 and 1759.

Around the year 1752, James Ayscough introduced spectacles with double-hinged side pieces. Although he made clear lenses, he recommended lenses tinted blue or green to treat some vision problems. These spectacles with tinted lenses were not intended for use as sunglasses, which were invented much later.

Optical power Lens

Filed under: Uncategorized — admin @ 9:05 am

Optical power (dioptric power or refractive power) is the degree to which a lens or mirror converges or diverges light. It is equal to the reciprocal of the focal length of the device. The dioptre is the most common unit of measurement of optical power. The SI unit for optical power is the inverse metre (m-1).

For two or more thin lenses in contact, the optical power of the combined lenses is very well approximated by the sum of the individual optical powers of each lens. Optical powers are commonly used to characterize lenses used in ophthalmology and for geometric ray tracing.

An eye that has too much or too little refractive power to focus light onto the retina has a refractive error. A myopic eye has too much power so light is focused in front of the retina (e.g. the focal length of the lens is too short). Conversely, a hyperopic eye has too little power so when the eye is relaxed, light is focused behind the retina (e.g. the lens’ focal length is too long). An eye with a refractive power in one meridian that is different from the refractive power of the other meridians has astigmatism. Anisometropia is the condition in which one eye has a different refractive power than the other eye.


See also

  • Vergence
  • Consumer Guide to Contact Lenses Learn about types of contact lenses, best places to buy, 30-day wear, special effects, colors, bifocals, contacts for astigmatism and solving comfort
  • Movie Lens MovieLens is a movie recommendation website. It uses your ratings to generate personalized recommendations for other movies you will like and dislike,
  • Lensbabies >>> Selective Focus SLR camera lenses Lensbabies are selective focus SLR camera lenses that bring one area of your photo into sharp focus with that sharp area surrounded by graduated blur.
  • Lens - Wikipedia, the free encyclopedia The word lens originally comes from the Latin for a lentil; the first, biconvex, optical lens was given its name because it was lentil-shaped.
  • Free printable cardboard lens hoods This site offers free printable cardboard lens hood for Canon, Nikon, Olympus, Minolta and Sigma camera lenses.
  • Squidoo : Explore Lenses Why have a lens? Roll over the images below to find out. For starters, a lens makes it easy for you to: Set up a signpost online.
  • Tamron; Digital Camera Lens (DSLR), Security CCTV Lenses Visit Tamron USA to learn more about our Photographic DSLR Digital Camera Lenses and our Security CCTV Camera Lens offerings. Digital, telephoto and more!
  • The MLI Project The Magic Lens Interface project is one of the efforts of the Graphics and Interaction Research Area. This page updated September 16, 1998.

Saturn Curve curve

Filed under: Uncategorized — admin @ 6:48 am

The Saturn Curve was a roadster concept by Saturn (even if designed by the, at the time, SAAB head of design Michael Mauer) that was shown at the 2005 North American International Auto Show along with the concept of Saturn Sky.

This project would also evolve to a new “SAAB Sonett”, with a different front styling, but ultimately SAAB’s intencions to make it an AWD car didn’t come true, and Saturn opted to go with the Opel project, giving birth to the Sky.


External links

  • Photo of the Saturn Curve

October 22, 2007

Munster Vistakon

Filed under: Uncategorized — admin @ 2:22 am
For other places with the same or similar names, and other uses of the word, see Munster (disambiguation).

Munster (Irish: An Mhumhain, , Cúige Mumhan or Mumha) is the southernmost of the four provinces of Ireland. It comprises the counties of:

  • Clare (110,800)
  • Cork, (480,909)
  • Kerry, (139,616)
  • Limerick, (183,863)
  • Tipperary (149,050)
  • Waterford. (107,942)

The largest city in Munster is Cork.

The name is derived from the Celtic goddess, Muma. The province was once divided into six regions: Tuadh Mhuman (North Munster), Deas Mhuman (South Munster), Urh Mumhan (East Munster), Iar mumhan (West Munster), Ernaibh Muman (the Ernai tribe’s portion of Munster), and Deisi Muman (the Deisi tribe’s portion of Munster). Ultimately, these were all subsumed into the kingdoms of Thomond (North Munster), Desmond (South Munster), and Ormond (East Munster), all of which were eventually subsumed by surrender and regrant as Earldoms in the Peerage of Ireland.
The names exist only indirectly today, particularly in the case of Thomond. The three crowns represent these three kingdoms. This flag can easily be confused with the flag of Dublin which has three castles in a similar pattern on a blue background; it also resembles the lesser coat-of-arms of Sweden, the Three Crowns.

In 1841 before the Great Famine, there were just under 3 million people living in the province of Munster, but the population had dropped devastatingly low due to mass emigration in the 1840s and continued emigration up until the 1980s.

For 30 days during the Irish Civil War, the province of Munster broke away from the Irish Free State and established the Munster Republic in opposition to the acceptance of the Anglo-Irish Treaty. The Munster Republic was short lived and subsequently crushed by heavily-armed Irish Free State forces.

Munster is also an Irish Rugby Football Union representative side which competes in the Celtic League and for the Heineken Cup, winning in 2006.

Contents


Cities

Cork is the largest city conurbation, which has a population of 190,384 (2006) and 380,000 within the Greater Cork Area. (See Cork Co. Council population report below)

Other important cities are Limerick 90,757 (2006) which also has over 100,000 people in the greater Limerick area and Waterford 49,213 (2006).


Large towns

In order of size of population
  • Ennis (24,253)
  • Tralee (22,190)
  • Killarney (16,931)
  • Clonmel (16,910)
  • Carrigaline (16,664)*
  • Ballincollig (16,339)*
  • Cobh (12,887)*
  • Mallow (11,195)
  • Midleton (10,336)*
  • Shannon/Clenagh (9,774)
  • Dungarvan (9,254)
  • Nenagh (9,219)
  • Thurles (8,987)
  • Tramore (8,799)
  • Youghal (7,195)
  • Newcastle West (5,915)

(* towns in Metropolitan Cork area)

  • (All figures - 2002 Census)


Economy

The province of Munster contributes 40 billion euro (US$52.57bn) to Irish GDP (25% of total Irish GDP) (2004) (greater than the GDP of Northern Ireland) (See “GDP stats” below). Munster is the home to many modern capital intensive, highly productive private sector enterprises.

Historically, much of the province of Munster has focussed heavily on food processing. Munster is Ireland’s main dairying region, and the chief source of Ireland’s butter and cheese exports. Munster has a favourable climate, a tradition of expertise in dairy processing going back to the 1600s, and a strong history of successful involvement in co-operative movement. In the mid 1980s the Dairy sector was the largest single sector of the Irish economy, and routinely accounted for 18-23% of national GDP, generating much needed foreign currency at a time of continual trade deficit in the general economy. There is also a small scale speciality food sector in Munster, which is of greater relative importance than in the other regions of Ireland. The produce from this sector is available in numerous farmer’s markets in Ireland (of which Munster has the highest concentration).

The Cork harbour area was the centre of Ireland’s heavy industry manufacturing sector. Cork had a steel mill, a shipyard, a car assembly plant, a tyre plant, a deep harbour, and a thriving textile sector in the mid twentieth century. (Cork people are proud point out that this was greater than any other Irish city including Belfast, which did not figure in the automotive industry). However heavy taxes, excessive regulation, competition from larger centres of economic activity, and the sudden removal of protective tarifs upon membership of the European Economic Community caused a decline in the 1970s. Cork was Ireland’s rust belt city in the 1980s, as heavy industry moved out, and newer sectors tried to get established in as unemployment peaked.

Waterford was the location of the high end Waterford Crystal plant, which at time paid the highest manufacturing wages in Ireland. However a recession in the 1980s resulted in redundancies, that paradoxically increased competition as workers went to found their own workshops.
Since then Waterford Crystal has struggled to regain its full former glory.

Ireland’s only oil refinery and oil storage facility is still located at Whiddy Island.

Munster was the home of ‘The Munster and Leinster Bank’, which is parent of Ireland’s richest and largest bank Allied Irish Bank. Cork, in Munster, is also home of the two largest Irish owned retailing organizations, Dunnes Stores, and the Musgrave Group. Cork is also home to two of the three Irish Stout brands; Murphy’s Irish stout, and Beamish, as well as the ‘Paddy’ brand of Irish whiskey.

Shannon airport, a rich music tradition, the best food from land and sea, and landscapes of international renown, have all been influential in the development of the tourist sector in Munster.

Munster has developed into the centre of Ireland’s Pharmaceutical industry. The province plays an ever greater role in the bio-pharmaceutical industry and is successful in fighting off stiff competition from Switzerland and Singapore for inward investments in the bio-pharmaceutical area in companies such as Amgen and Pfizer.
Munster is one of Ireland’s most important I.T. hubs with such multinationals as Apple, Intel, Amazon and Dell locating in the province. Fexco Financial Services in Killorgan one of many organizations to locate in the South-West, to avail of a long tradition of astute financial management.

The following are some of the more important employers in the region: AOL, Bausch & Lomb, Dairygold, Dell, Amazon, Motorola, Amgen, Pfizer, Analog Devices, Fexco Financial Services, Vistakon, Waterford Crystal, Apple Computer, Intel, Novartis, O2, Lufthansa Technik, Kerry Group, Teva Pharmaceuticals, Siemens, Sony. The largest employment hub in Munster is Metropolitan Cork, with many large multinational firms located in the area. The second most important is the Shannon Free Zone with over 120 international firms based there employing over 7,500 people.


International airports

  • Cork Airport
  • Kerry Airport
  • Shannon Airport
  • Waterford Airport


Irish language

The Irish language is spoken as a first language in Gaeltachtaí (Irish speaking areas);

  • in West Kerry (Corca Dhuibhne)
  • in South Kerry (Uíbh Ráthach). Here, the language died out in the 1950s.
  • in West Cork (Múscraí)
  • in south-west Cork (Oileán Cléire)
  • in south-west Waterford (Gaeltacht na Rinne or Gaeltacht na nDeise)

The number of Gaelscoileanna (Irish language schools) has increased sharply in the last ten years. Children learn Irish and speak Irish in the Gaelscoileanna.


Munster media


Television

  • RTÉ Cork - Cork based television broadcasting studios for RTÉ
  • South Coast TV - Cork based television company


Newspapers

  • The Irish Examiner - Cork based National Newspaper
  • The Avondhu - covers North East Cork, West Waterford, South Limerick and South Tipperary.
  • The Munster Express - covers the South East.
  • Nationalist & Munster Advertiser

The Limerick Leader (covers the Mid West)


Clare

  • Clare Champion
  • Clare People
  • Clare Courier


Cork

  • The Imokilly People (East Cork)
  • The Carrigdhoun
  • The Corkman
  • The Mallow Star
  • The Southern Star
  • The Vale Star
  • The Avondhu[1]
  • Evening Echo


Kerry

  • The Kerryman
  • The Kingdom
  • The Kerry’s Eye


Limerick

  • Limerick Leader
  • Limerick Post
  • Limerick Independent
  • The Vale Star (South & East Limerick)
  • The Weekly Observer (West Limerick)


Tipperary

  • The Guardian, Nenagh
  • The Tipperary Star
  • The Nationalist, Clonmel


Waterford

  • The Waterford News and Star
  • The Munster Express, Dungarvan


Radio

  • Red FM - Cork Youth-driven service.
  • Clare FM - County Clare
  • Tipp FM - County Tipprary
  • Radio Kerry - County Kerry
  • WLR FM - Waterford City and County
  • 96FM and 103FM County Sound (dual franchise) - General service for Cork
  • Live 95FM - Limerick City and County
  • West Limerick 102 - Limerick city and County
  • Spin SW
  • Beat 102-103 - Youth-driven service. Counties Carlow, Kilkenny, Waterford, Wexford and South Tipperary.
  • RTÉ Ráidió na Gaeltachta “Camchuairt” - Tralee, County Kerry


Munster stadia

In order of capacity
  • Tipperary County Thurles Semple Stadium 55,000
  • Limerick County Limerick Gaelic Grounds 50,000
  • Kerry County Killarney Fitzgerald Stadium 48,000
  • Cork County Cork Pairc Ui Chaoimh 45 000
  • Clare County Ennis Cusack Park 28 000
  • Waterford County Waterford Walsh Park 17 000
  • GAA-use Waterford Fraher Field 15 000
  • Munster Rugby Limerick Thomond Park Stadium 13 300
  • Cork City Cork Turners Cross Stadium 11 500
  • Cobh Ramblers Cobh St.Colman’s Park 10 000
  • Waterford United Waterford Regional Sports Centre 8 200
  • Limerick 37 Limerick Jackman Park 8 000
  • Munster Rugby Cork Musgrave Park 7 000


External links

  • 2006 Prelim Census Report
  • Cork County Council population report
  • Census 2006 Preliminary Report
  • [1]
  • Munster Stadia
  • Munster cycling clubs (Lakeland Cycle Club)
  • The Kerryman newspaper
  • Kerry’s Eye weekly newspaper
  • The Corkman newspaper


See also

  • Provinces of Ireland
  • Kings of Munster
  • Thomond
  • Munster Gaelic Athletic Association
  • Munster Rugby
  • Munster Senior Club Football Championship

Calif Vistakon a subsidiary of

Filed under: Uncategorized — admin @ 12:32 am

Calif may refer to:

  • Caliph
  • Abbreviation of California
  • Calif, A subsidiary company of French bank Société Générale

Barlow lens Lens Prescriptions

Filed under: Uncategorized — admin @ 12:16 am

The Barlow lens, named for its creator, the English engineer Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, effectively increases the focal ratio of an optical system as perceived by all components after it in the system.

In its astronomical use, a Barlow lens may be placed immediately before an eyepiece to effectively decrease the eyepiece’s focal length by the amount of the Barlow’s divergence. Since the magnification provided by a telescope and eyepiece is equal to the telescope’s focal length divided by the eyepiece’s focal length, this has the effect of increasing the magnification of the image.

Astronomical Barlow lenses are rated for the amount of magnification they induce. Most commonly, Barlow lenses are 2x, but 3x Barlows and adjustable Barlows are available. The power of even ordinary Barlow lens is “adjustable”: adding an extention tube between the Barlow and the eyepiece increases magnification. The magnification is one more than the number of Barlow focal lengths between the Barlow lens and the eyepiece. If the length of a standard 2x Barlow lens’ tube is doubled, it becomes a 3x Barlow, if the tube length is tripled, it becomes a 4x Barlow, and so on.

In microscopy the Barlow lens is used to increase working distance and decrease magnification. The lens are “objective lenses” that are mounted in front of the microscope’s last objective element. Standard lenses are 2x which decreased the working distance by half and increases the magnification, .75x which increases the working distance proportionally to the .75 and decreases the magnification similarly. A .5x would double the working distance and half the magnification.

Barlow lenses have an unfortunate reputation in some quarters due to poor results given by the Barlows included with some department-store telescopes. These results, however, are perhaps better attributed to poor optics and shaky mounts permitting less practical magnification in these telescopes than to an inherent failing of Barlow lenses.

October 21, 2007

Teleconverter Contact Lens

Filed under: Uncategorized — admin @ 10:42 pm

A teleconverter is a secondary lens which is mounted between the camera and a photographic lens. Its job is to enlarge the central part of an image obtained by the objective lens. For example a 2× teleconverter enlarges the central 12×18 mm part of an image to the size of 24×36 mm. Teleconverters are typically made in 1.4×, 2× and 3× models.

The use of a 2× teleconverter (or doubler) gives the effect of using lens with twice the focal length. It also decreases the intensity of the light reaching the film by the factor of 4 (an equivalent of doubling the focal ratio) as well as the resolution (by the factor of 2).

Teleconverter works similarly to a telephoto group of a proper telephoto lens. It consists of a group of lenses which together act as a single diverging lens. The location of a teleconverter is such that the image produced by the objective is located behind the teleconverter in a distance smaller than its focal length. This image is a virtual object of the teleconverter which is then focused further away and thus enlarged. For example when a single negative lens is placed so that the image formed by the objective is located in the midpoint between the lens and its focal point the lens produces the image in its focal point enlarging it two times thus acting as a 2× teleconverter.

Dedicated teleconverters only work with a limited number of lenses, usually telephoto lenses made by the same manufacturer.

The use of objective with teleconverter is less expensive than telephoto lens but also introduces some aberrations.

A Leica R series doubler, with the female part of in bayonet mount…

…and the male part.

Kimchi bokkeumbap made by Vistakon a

Filed under: Uncategorized — admin @ 10:25 pm

Kimchi bokkeumbap is a popular Korean dish, made with kimchi and rice among other ingredients such as fried egg, ham, seaweed, and vegetables. Its name literally translates as “stir-fried rice made with kimchi”.

Another popular version of kimchi bokkeumbap is made with spam.


See also

  • Korean cuisine

Circular cause and consequence exception

Filed under: Uncategorized — admin @ 6:11 pm

Circular cause and consequence is a logical fallacy where the consequence of the phenomenon is claimed to be its root cause. It is exemplified in the question, “Which came first, the chicken or the egg?”


Examples

There are many real world examples of circular cause-and-effect, in which the chicken-or-egg question helps identify the analytical problem:

  • Fear of economic downturn cause people to spend less, which reduces demand, causing economic downturn
  • Fear of violence/war can make people more defensive/violent, the resulting tension/violence will cause more fear.
  • More jobs cause more consumption, which requires more production, and thus more jobs.


Contradictions

Circular cause and consequence is often confused with mutually contradictory statements, such as the famous ‘catch 22′, in which two mutually exclusive statements seem to send the reader back and forth in a cycle. Circular reasoning however is a problem of finding the ‘root cause’ however (e.g. which came first) which is not the basis of the ‘catch 22′ or any of the following examples of contradictions.

For example, Lewis Carroll in Through the Looking-Glass, where the White Queen states “Jam yesterday and jam tomorrow, but never jam today”. Since every tomorrow becomes eventually today as the future turns into present, and past is gone forever, the result is that poor Alice will never have jam.

A real-life mutual contradiction is that one cannot get a job without experience, but one cannot get experience without a job. In this respect, the initial move to the job market can be very challenging.

Mutual contradiction is much akin to No true Scotsman fallacy, but where “No true Scotsman” fallacy assumes the premise wrong in an exception, the circular cause and consequence implies an impossible outcome in an exception. This implication makes circular cause and consequence similar to a Catch-22, where two mutually exclusive premises are required to reach the conclusion, hence the conclusion is impossible.

Profilometer contact

Filed under: Uncategorized — admin @ 3:42 am

A profilometer is a measuring instrument used to measure a feature’s length or depth, usually in the micrometre or nanometre level.

While the historical notion of a profilometer was a device similar to a phonograph that measures a surface as the surface is moved relative to the contact profilometer’s stylus, this notion is changing along with the emergence of numerous non-contact profilometery techniques.


Contact profilometers:

A diamond stylus is moved vertically in contact with a sample and then moved laterally across the sample for a specified distance and specified contact force. A profilometer can measure small surface variations in vertical stylus displacement as a function of position. A typical profilometer can measure small vertical features ranging in height from 10 to 65,000 nanometres. The height position of the diamond stylus generates an analog signal which is converted into a digital signal stored, analyzed and displayed. The radius of diamond stylus ranges from 5 μm to about 25 μm, and the horizontal resolution is controlled by the scan speed and scan length. There is a horizontal broadening factor which is a function of stylus radius and of step height. This broadening factor is added to the horizontal dimensions of the steps. The stylus tracking force is factory-set to an equivalent of 50 milligrams (~500 mN).
Advantages of contact profilometers:

  • Acceptance: Most of the world’s surface finish standards are written for contact profilometers. To follow the prescribed methodology, this type of profilometer is often required.
  • Surface Independence: Due to the fact that the stylus is in contact with the surface, this method is not sensitive to surface reflectance or color. Also, contacting the surface is often an advantage in dirty environments where non-contact methods can end up measuring surface contaminants instead of the surface itself.


Non-contact profilometers:

An optical profilometer is a non-contact method for providing much of the same information as a stylus based profilometer. There are many different techniques which are currently being employed, such as laser triangulation (triangulation sensor), confocal microscopy and digital holography.
Advantages of optical profilometers:

  • Speed: Because the non-contact profilometer does not touch the surface the scan speeds are dictated by the light reflected from the surface and the speed of the acquisition electronics.
  • Reliability: Optical profilometers do not touch the surface and therefore cannot be damaged by surface wear or careless operators. Many non-contact profilometers are solid-state which tends to reduce the required maintenance significantly.
  • Spot size: The spot size, or lateral resolution, of optical methods ranges from a few micrometres down to sub micrometre. On the small end, this is roughly an order of magnitude smaller than typical stylus tips.

One special application is road pavement profilometers. These are of non-contact type, most of them use laser triangulation in combination with an inertial unit that establishes a large reference plane to which the laser readings are related. The inertial compensation makes the profile data more or less independent of what speed the profilometer vehicle had during the measurements.

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