The earliest excavator was powered by manpower or animal power. It was used to dig deep mud river bottoms. The bucket capacity generally did not exceed 0.2-0.3 meters. 31833-1836. American Otis designed and manufactured the first A steam engine driven, iron-wood hybrid structure, semi-rotary, rail-type single bucket excavator with a productivity of 35 meters, but not used due to poor economy. The improved steam shovel was officially produced in the 1970s and applied to open pit mining. In 1880, the first semi-rotary steam shovel with a tractor as the chassis appeared.
From the early 20th century to the end of the 1940s, excavators entered the diversified stage of power and walking gear. In 1910, the first motor-driven single-hopper excavator appeared; in 1912, a gasoline-powered and kerosene-driven full-rotation single-excavator appeared; in 1916, a diesel-driven single-excavator was produced; 1924 The direct drive of the diesel engine was started on the single bucket excavator; the crawler type travel device was adopted in 1910. Tire type walkers are widely used in small excavators as the automotive industry develops. In the 1930s, pedestrian walking devices appeared; in the mid-1950s, Germany and France developed a full-slewing hydraulic excavator, and the development of the excavator entered a new stage.
Dudou excavators also have a history of more than 100 years. In 1860, France produced the world's first and more mature multi-dump excavator for the excavation of the Suez Canal. In 1889, the multi-dump trencher produced in the United States was able to dig trenches with a width of 0.29 meters and a depth of 1.4 meters. At the end of the 19th century, bucket wheel excavators were widely used in lignite mining in Germany. By 1958, each bucket had reached 3,600 liters. In 1977, the Federal Republic of Germany built the world's largest bucket wheel excavator with a productivity of 240,000 meters.
Wedge prism is an optical element having plane-inclined surfaces, usually the faces are inclined toward one another at very small angles. Wedges divert light toward their thicker portions.
Wedge prism is commonly used in laser system for eliminating the reflections from the second surface or for beam steering.circle wedge,square wedge,irregular wedge...Every materials,sizes,wedges and coatings may be available by custom orders. Standard and broadband antireflection coatings are available upon request.
optical wedges
Specification of our wedge prism as follow:
*Material: HK9L Grade A optical glass,Fused Silica JGS1,JGS2,JGS3, or other optical glass materials.
*Dimension Tolerance:+/-0.20mm to +0.01/-0.01mm
*Thickness Tolerance:+/-0.20mm to +/-0.005mm
*Surface Quality:80-50 to 10-5 Scratch/Dig
*Surface Flatness: at 632.8nm lambda to lambda /20 per 25mm
*Clear Aperture:80% -- 100%
*Angle Tolerance:3-5 minutes to 3 second
*Chamfer:0.3+/-0.20mm *45degree
*No Chamfer
*Coating Optional
Wedge Prism,Fused Silica Wedge Prism,Jgs1 Wedge Prisms,N-Bk7 Wedge Prism
China Star Optics Technology Co.,Ltd. , https://www.realpoooptics.com