Optical Instruments – Lens, Camera, Microscope & Telescope
Optical instruments are an essential companion of modern life.
History of Optical Instruments:
The first lenses were made from polished quartz in 750 BC. Reading stones were invented in the medieval period by priests to function as reading glasses, as they magnified objects kept close. A number of great European inventors were then involved in developing the science of optics and building lens systems. Hans Lippershey in the Netherlands is credited with inventing the first telescope.
Galileo improved the design, and Isaac Newton invented the first ever reflecting telescope. While reflecting stones were simple microscopes, compound microscopes with multiple lenses were made in Europe around 1620. Again, Galileo invented a much better design of the compound microscope soon after.
The first lenses were made from polished quartz in 750 BC.
The earliest cameras were the pinhole variety. Lenses for photography were discovered rapidly in the late 1800s in Europe.
The antistigmat Protar lens was the first modern photographic lens invented in 1890.
The anastigmat Protar lens was the first modern photographic lens invented in 1890. They were invented by Ernst Abbe and Otto Schott.
Definition of Photographic Lens
Photographic lenses are an array of lenses that focus the image on a camera plane. They are accompanied by a camera body that holds the lens and the photo film. It’s also called camera lens. In principle, a photographic lens is not different from a telescope or a microscope. A converging lens, which is convex, should focus the image on a plane.
Photographic lens or Camera Lens are an array of lenses that focus the image on a camera plane.
However, an array of lenses is used to correct out the various aberrations that are associated with single lenses. Also, multiple lenses provide more flexibility in terms of the power of focus.
Functions of Microscope and Types of Microscope:
Microscopes are used to see objects that are too small to make out with the naked eye.
Definition of Simple and Compound Microscope:
Simple Microscope is simple lenses that magnify objects viewed through them, like magnifying glasses. They are usually spherical convex lenses and form erect images behind the lens.
These are usually made of two lenses. The objective lens is towards the object being viewed. Its function is to collect as much light as possible and form a real image inside the microscope. The eyepiece lens then enlarges the image formed for the viewer. Often, the eyepiece lens can be varied in distance and power to provide for higher and lower magnification and focusing power. Compound microscopes provide a much higher magnification than simple ones.
Other variants of microscopes such as the traveling microscope and the confocal microscope have also been invented. The most modern microscope is the electron microscope. These are based on quantum principles and use electron waves in place of light. Because electron waves have a much smaller wavelength than visible light, they can see much smaller objects. DNA molecules and the smallest viruses have been seen in much detail using electron microscopes.
Types of Telescope-Refracting & Reflecting Telescope:
Telescopes are used to see objects that are too far away to make out with the unaided eye. Historically, the development of telescopes was carried out to aid astronomical investigations.
Definition of Refracting telescopes
These work on the same principle as compound microscopes, using two convex lenses. By changing the distance between the objective and eyepiece, objects that are far away can be brought into focus. The images formed for the viewer at the eyepiece are inverted, which is a feature of telescopes.
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In telescopes, the aperture of the objective lens is also critical. The aperture dictates the light gathering power of the telescope, which is critical when viewing very dim celestial objects. These exist mostly for use by amateur astronomers.
Definition of Reflecting telescopes:
A reflecting telescope uses a concave mirror in place of a convex lens for the role of an objective. The advantage is that wide aperture mirrors can be more easily made that are free of defects. Reflecting telescopes were invented by Isaac Newton. Reflecting telescopes are used for research purposes.
A reflecting telescope uses a concave mirror in place of a convex lens for the role of objective.
Modern telescopes work in wavelengths besides visible light. Big arrays of telescopes that capture radio waves from galaxies far away have been built in India(GMRT Pune) and in other places. The world’s largest space telescope is the. It will be launched to replace the Hubble Space Telescope.
Reflecting telescopes were invented by Isaac Newton.