Exploring how the variations in the excitation and emission filter spectral profiles, as well as those of the dichromatic mirrors, affect signal levels, overall filter performance, and image contrast in combinations designed for excitation of fluorophores in the blue-violet region.

Explore how the variations in the excitation and emission filter spectral profiles affect signal levels, overall filter performance, and image contrast in combinations designed for dual excitation of fluorophores in the ultraviolet and blue or blue and green regions.

Explore alignment and focusing of the arc lamp in a mercury or xenon burner, which simulates how the lamp is adjusted in a real microscope.

The size of the aperture of a telescope is very important. The aperture is the diameter of the opening on the front of a telescope. The bigger the aperture, the more light can enter the telescope. Your eye has an aperture, too: your pupil. This aperture is only ever a few millimetres large. But optical telescopes rarely have apertures smaller than 8 centimetres. Telescopes in big observatories can have apertures of 10 metres or more!

Who invented theoptical telescope

This is another advantage of reflectors. Refractors bend light down their tube. That means the tube has to be at least as long as the focal length. Since reflectors use mirrors, they can be shorter than their focal length. By reflecting light between multiple mirrors, the light still travels the full focal length. However, the tube itself is not so long.

In a reflector, light enters the telescope at the end opposite the primary mirror. The mirror is a concave mirror. Similar to a convex lens, a concave mirror converges the light at the secondary mirror. The rays of light converge at the focal point. At this point they again begin to diverge. The convex lens in the eyepiece takes the converging light and straightens it back out. As with the refractor, the image is still upside down. It appears as a virtual image beyond the telescope in the direction the person is looking.

Jennifer C. Waters - Nikon Imaging Center, LHRRB Room 113C, Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts, 02115.

A refractor uses lenses within a tube to refract (bend) light. It's the type of long telescope which you might imagine old-time astronomers, like Galileo, using. Reflectors, on the other hand, use mirrors instead of lenses to reflect light.  Most modern observatories use reflectors because their telescopes are so huge. Refractors would not be practical. Their lenses would be very heavy and their tubes would need to be very long.

John D. Griffin, Nathan S. Claxton, Matthew J. Parry-Hill, Thomas J. Fellers, Kimberly M. Vogt, Ian D. Johnson, Shannon H. Neaves, Omar Alvarado, Lionel Parsons, Jr., Michael A. Sodders, Richard L. Ludlow, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.

Remember how we said lenses in a refractor telescope would be heavy? Well, mirrors are less heavy than lenses. That’s why people have been able to build very large reflecting telescopes.

Michael E. Dailey - Department of Biological Sciences and Neuroscience Program, 369 Biology Building, University of Iowa, Iowa City, Iowa, 52242.

The Nikon blue excitation fluorescence filter combinations include bandpass and longpass sets having both broad and narrow excitation bandwidths.

Optical telescopeexamples

In the rapidly expanding fields of cellular and molecular biology, widefield and confocal fluorescence illumination and observation is becoming one of the techniques of choice. These techniques, which are almost universally employed in both the medical and biological sciences, have spurred the development of more sophisticated microscopes and numerous fluorescence accessories.

Galileo did not invent the telescope. But within one year, he had greatly improved on Lippershey’s design. He promoted his own telescopes. He also observed Jupiter’s largest moons. These are the reasons why, when many people hear the words “invention of the telescope,” they think of Galileo!

How doopticaltelescopes utilize the electromagnetic spectrum

Explore how the variations in the excitation and emission filter spectral profiles affect signal levels, overall filter performance, and image contrast in combinations designed for excitation of fluorophores in the green (510-560 nanometers) spectral region.

George H. Patterson and Jennifer Lippincott-Schwartz - Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892.

When you think of telescopes, what do you think of? A long tube that astronomers look through to see the stars on a dark night? That’s true. But it’s only one type of telescope. There are telescopes on the ground, in the sky, and in space. They are watching the planets, stars, and galaxies all the time.

The focal length is also important. The focal length is the length from the aperture to the focal point of the telescope. The longer the focal length, the smaller the patch of sky you're observing. But a longer focal length also gives a higher possible magnification.

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Optical telescopediagram

Abel, P. G. (2015, October). Absolute beginners no. 3: A short introduction to some common types of telescope. British Astronomical Association.

Largestoptical telescopein the world

Secondly, even small-sized telescopes are capable of seeing hundreds of galaxies and nebulae. Some of these galaxies and nebulae are almost a hundred million light-years away! Having a shorter focal length is good for looking at very large objects that don’t need as much magnification. These objects are simply too large to 'zoom in' on. This includes things like constellations or even the Andromeda Galaxy, which is larger than the full Moon in the night sky. Whew! That sounds like a lot of stuff to remember! Luckily, like anything else, the more time you spend around telescopes, the simpler they seem. Find a local astronomy club near you to try a telescope yourself!

A refractor is made up of a long tube containing lenses. The objective lens is the front lens. In other words, it’s the lens at the end where the light comes in. Modern refractors have a second tube that contains the eyepiece or ocular lens. The eyepiece is exactly what it sounds like. It’s a piece you put in the telescope to look through with your eye. In a refractor, the eyepiece may contain several lenses. These lenses can be adjusted to focus the image.

The dimmest objects in the universe don't give us a lot of light to work with. Telescopes have a few ways of making those far away objects look brighter and clearer.

What is a nonoptical telescope

Astronomers used to work really hard to document it all with the naked eye. But the human eye isn't so great at picking out the details of dim and distant objects, even on a clear night. What humans needed was a tool to help make far away things look closer and brighter. Enter the optical telescope.

So should every telescope have the biggest aperture and longest focal length possible? This is not always necessary. First, for anyone studying the solar system, aperture really isn't that important. Most of the planets are visible using even the smallest telescopes. Objects like the Moon are so bright that having a large aperture can actually let in too much light and make it hard to see details, like the craters on the Moon’s surface.

Stephen T. Ross, Anna Scordato, and Stanley Schwartz - Bioscience Department, Nikon Instruments, Inc., 1300 Walt Whitman Road, Melville, New York, 11747.

Alexey Khodjakov and Conly L. Rieder - Wadsworth Center, New York State Department of Health, Albany, New York, 12201, and Marine Biological Laboratory, Woods Hole, Massachusetts, 02543.

How does anoptical telescopework

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Let's consider a basic optical telescope. If you were looking to buy a telescope for yourself, you would learn that there are two basic designs:

Jason R. Swedlow and Paul D. Andrews - Division of Gene Regulation and Expression, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland.

What is anoptical telescopeused for

Explore the light paths in Nikon's SMZ1500 stereomicroscope equipped for fluorescence illumination using an intermediate tube and external lamphouse.

The earliest optical telescopes we know of were made in 1608. They were made in the Netherlands by various optical craftsmen. One of them, Hans Lippershey, publicized his design well enough that news reached Galileo Galilei in Italy in 1609. When Galileo heard of the telescope, he built his own.

Douglas B. Murphy - Department of Cell Biology and Anatomy and Microscope Facility, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 107 WBSB, Baltimore, Maryland 21205.

A classical Newtonian reflector also has a long tube. But instead of an objective lens, it has an objective or primary mirror. Remember, an objective lens is at the end of the tube where the light comes in. In contrast, the mirror is at the opposite end of the tube.  The objective mirror is not a flat mirror. Instead, it’s a curved (concave) mirror. Reflectors have a second mirror called the secondary mirror. The secondary mirror is a flat plane mirror.This mirror is at the opposite end from the primary mirror. It  is at a 45 degree angle to the direction of the light reflected by the primary mirror. In this type of reflector, the eyepiece is on the side of the tube (not the end).

In a refractor, light enters the telescope near the objective lens. The objective lens is a convex lens. This lens converges the light. The rays of light converge at the focal point. At this point they again begin to diverge. A second convex lens in the eyepiece takes the converging light and straightens it back out. This magnifies the image at the focal point and brings it into focus. Because of this, a refractor has to have a long, clear path to allow the light rays to bend. One of the downsides of this type of telescope is that the image appears upside down.