A plate
Van Leeuwenhoek's microscopes consisted of a small, single converging lens mounted on a brass plate, with a screw mechanism to hold the sample or specimen to be examined.
The stage usually has arms to hold slides (rectangular glass plates with typical dimensions of 25×75 mm, on which the specimen is mounted).
2. Глаголы трудные для перевода
To allow
The arm angle may be adjustable to allow the viewing angle to be adjusted.
To be due to
Compound microscopes are heavier, larger and more expensive than simple microscopes due to the increased number of lenses used in construction.
It took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes, due to difficulties in configuring multiple lenses.
Due to the difficulty in preparing specimens and mounting them on slides, for children it's best to begin with prepared slides that are centered and focus easily regardless of the focus level used.
To produce
The Huygens ocular is still being produced to this day, but suffers from a small field size, and other minor problems.
Anton van Leeuwenhoek (1632–1723) is credited with bringing the microscope to the attention of biologists, even though simple magnifying lenses were already being produced in the 16th century.
To give
In some high performance microscopes, the optical configuration of the objective lens and eyepiece are matched to give the best possible optical performance.
Galileo's microscope was celebrated in the Accademia dei Lincei in 1624 and was the first such device to be given the name "microscope" a year later by fellow Lincean Giovanni Faber.
To provide
It took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes, due to difficulties in configuring multiple lenses.
The whole of the optical assembly is traditionally attached to a rigid arm which in turn is attached to a robust U shaped foot to provide the necessary rigidity.
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Actual
The actual power or magnification of a compound optical microscope is the product of the powers of the ocular (eyepiece) and the objective lens.
Actually
The date is unlikely, as it has been shown that Zacharias Janssen actually was born around 1590.
Commercial
The vast majority of modern research microscopes are compound microscopes while some cheaper commercial digital microscopes are simple single lens microscopes.
Instruments
Demonstrations by British microscopist have images from such basic instruments.
Van Leeuwenhoek's home-made microscopes were very small simple instruments, with a single, yet strong lens.
Material
These are used with index-matching material such as immersion oil or water and a matched cover slip between the objective lens and the sample.
The refractive index of the index-matching material is higher than air allowing the objective lens to have a larger numerical aperture (greater than 1) so that the light is transmitted from the specimen to the outer face of the objective lens with minimal refraction.
Objective
Some high performance objective lenses may require matched eyepieces to deliver the best optical performance.
Oil immersion objective
Some microscopes make use of oil-immersion objectives or water-immersion objectives for greater resolution at high magnification.
Originally
If a microscope did not originally have a mechanical stage it may be possible to add one.
Originally images were captured by photographic film but modern developments in CMOS and charge-coupled device (CCD) cameras allow the capture of digital images.
Specific
Modern biological microscopy depends heavily on the development of fluorescent probes for specific structures within a cell.
Since the mid 20th century chemical fluorescent stains, such as DAPI which binds to DNA, have been used to label specific structures within the cell.
Techniques
While basic microscope technology and optics have been available for over 400 years it is much more recently that techniques in sample illumination were developed to generate the high quality images seen today.
This method of sample illumination gives rise to extremely even lighting and overcomes many limitations of older techniques of sample illumination.
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To be unlikely
The date is unlikely, as it has been shown that Zacharias Janssen actually was born around 1590.
5. Слова, близкие по написанию, но разные по значению
About, above
It took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes, due to difficulties in configuring multiple lenses. Still, despite widespread claims, van Leeuwenhoek is not the inventor of the microscope.
The former typically ranges from 5× to 100× while the latter ranges from 0.14 to 0.7, corresponding to focal lengths of about 40 to 2 mm, respectively.
To attack, to attach
The whole of the optical assembly is traditionally attached to a rigid arm which in turn is attached to a robust U shaped foot to provide the necessary rigidity.
To because, because of
Historically optical microscopes were easy to develop and are popular because they use visible light so the sample can be directly observed by eye.
Coarse, course, of course
Focus wheel to move the stage (4 – coarse adjustment, 5 – fine adjustment)
Adjustment wheels move the stage up and down with separate adjustment for coarse and fine focussing.
Normally this will include controls for focusing, typically a large knurled wheel to adjust coarse focus, together with a smaller knurled wheel to control fine focus.