How to make microscopes and astronomical telescopes without telescopes

How do I make a simple astronomical telescope or high-powered microscope?

Equipment】 Yellow cardboard, convex lens.

Production] 1) Choose a convex lens with a focal length of 30 to 50 mm as the eyepiece, which can be replaced by a magnifying glass for repairing clocks. Use a convex lens with a focal length of about 1 meter as an objective, which can be replaced by 100-degree presbyoptic spectacle lenses.

2) Determine the focal length of the convex lens to determine the length of the lens barrel. Place the objective lens and eyepiece facing the sun respectively, put a piece of white cardboard on the other side of the lens, adjust the distance between the paper and the lens, so that the sun is clearly imaged on the white cardboard, and measure the distance between the lens and the paper with a ruler is the focal length of the lens.

3) The lens barrel is made of yellow board paper. The entire tube is divided into two sections: the objective tube and the eyepiece tube.

The diameter of the objective tube is approximately equal to the diameter of the objective lens and the length is approximately equal to the focal length of the objective. The outer diameter of the eyepiece tube is slightly smaller than the inner diameter of the objective tube, allowing the eyepiece barrel to be inserted into the objective tube and the focal length can be adjusted back and forth. The inner diameter of the eyepiece barrel is approximately equal to the diameter of the eyepiece lens and is 100 mm longer than the eyepiece focal length.

The barrel is made by cutting the yellow board paper into strips of paper 70 to 80 mm wide. Find a tube with a diameter equal to the diameter of the lens as the core. Wrap the yellow board paper strip around the core, one by one, without overlapping or gaping, and the two ends of the paper strip and the joint can be connected with glued kraft paper.

After the first layer is rolled, glue is applied to the outside of the yellow cardboard, and then the second layer is wound in the opposite direction to the first layer (Figure 19-3).After rolling, then apply glue and roll the third layer, the direction of winding is opposite to the second layer, generally three layers can be wound, the outermost layer of kraft paper is pasted, the core is removed, and it is placed vertically indoors to dry. After drying, the inner layer of the lens barrel is blackened with black ink to eliminate the influence of stray light on observation.

4) Install the lens inside the lens barrel so that the main optical axis of the objective lens and eyepiece are on the center line of the lens tube. The installation of the lens should be determined according to the size of the lens, the diameter of the lens is smaller than the inner diameter of the lens barrel can be installed according to Figure 19-4a, and the lens diameter is equal to the inner diameter of the lens barrel can be installed according to the way of b in the figure. After the lens is installed, the eyepiece tube can be inserted into the objective lens barrel, aimed at the distant light with the eye, adjust the front and rear positions of the program lens and the objective lens, so that the distant light falls on the field of view seen by the telescope**, which indicates that the main optical axis of the eyepiece falls on the center line of the lens tube, otherwise the position of the eyepiece needs to be adjusted appropriately until it meets the requirements.

5) Install a bracket on the lens tube, which can be a movable tripod or another form, but it must make the lens barrel very stable when rotating. The bracket should be installed at the center of gravity of the telescope tube. There should be enough friction at the place of connection so that the telescope can stay in any position and be stable.

The focal length of a microscope eyepiece is smaller than that of a telescope eyepiece, i.e., the magnification is greater.

Theoretically speaking, it is achievable, and the principle of the two optical tools is the same. But there are several reasons:

The greater the magnification, the less light enters the eye, that is, the light intensity is weaker, and the impression is darker, and the microscope can illuminate objects with a light source, but the telescope cannot.

Telescopes also have high magnification, such as astronomical telescopes, the most basic requirement is that the lens diameter should be large, that is, to allow as much light as possible into the eyeball.

There is also an unavoidable problem that lenses have aberrations, (the basic principle of microscopes and telescopes can be understood as: the first mirror images the object on the surface of the second mirror, and the second mirror magnifies its image) The aberration can only be more required to eliminate a part, and in order to eliminate this part, the rest of the aberration is naturally more serious.

The magnification of a microscope is not fixed (nor is a telescope), and as the distance between the object and the objective changes, the distance between your eyepiece and the objective lens changes accordingly, and the magnification changes accordingly. The so-called magnification of a certain type of microscope is 50 times, which means that when the object is placed at a suitable distance, that is, when the magnification is just 50 times, the image is the clearest. The reason is that the aberration of this multiple is eliminated when the lens is processed, and with the change of the distance between the objects, the multiple changes accordingly, and the clarity becomes worse and worse.

That's the reason you're encountering now, imaging is okay anyway, as long as you reduce the distance between the two lenses at the right time, you can see the image, but the aberration is more serious (mainly coma), so it's blurry.

In general, low-power telescopes, in fact, have not dealt with aberrations, because the method multiplier is small, a little blurry and not felt, or it does not affect the use (but, after a long time, it will be.

Oh), you don't have to deal with it.

<>1. First of all, the objective lens, find a lens with a focal length of 80 cm, be sure to have a plano-convex lens, a suitable lens is generally between the aperture and the focal length ratio of 1:8 or 1:15, such as a lens with a diameter of 5 cm, press 1:

15 to calculate, 5x15 = 75 cm. If it is calculated according to 1:8, that is, 5x8 = 40 cm, which means that a lens with a diameter of 5 cm, the focal length between 40-80 cm is suitable, and the telescope imaging made is still good, and the telescope imaging made by too much is lower or more than this range will be very poor.

2. I use whiteboard paper (thick paper) to roll the outer cylinder of the lens, mainly to facilitate the installation of the objective tube, the thickness of the roll is determined by the inner diameter of the objective lens tube you have, and the diameter of the roll is just the hole in the objective tube. Roll the objective tube directly to the same diameter as the objective finch stalk.

3. Eyepiece, the focal length of about 3 cm can form a composite eyepiece with a focal length of about centimeter, if you want to achieve achromatic, the distance between the two lenses is two-thirds of the focal length of a single piece, and the focal length can be shortened to three-quarters of the original single focal length, and the magnification of the telescope is the focal length of the objective lens divided by the focal length of the eyepiece is equal to the magnification.

<>1. Adjust the optical axis of the primary mirror and the finderscope to be parallel: After the telescope is installed, it is first necessary to select a relatively large building as the observation target, such as a chimney, lead imitation of the outdoor unit of the air conditioner, etc. First, select the eyepiece with the maximum f-number equipped with the telescope and attach it to the primary mirror (usually 20mm or 8mm), and use the primary lens to slowly find the object you are looking at.

The focal length adjustment system makes the image clearer and puts the image in the center of the primary mirror's field of view, and when it is found, lock the tripod completely.

2. Adjust the finderscope: The primary mirror has set the image, and the sleepy imitation is imitated below to adjust the finderscope. Turn the three screws on the finderscope and slowly adjust the image in the center of the main mirror to the center of the crosswire of the finderscope as much as possible.

3. The purpose of the two links is to make the optical axis of the two lens barrels parallel, rather than to observe a certain body, which must be understood.

4. Well, the optical axes of the two mirrors are parallel, and all objects can be observed. Release the locked tripod and slowly move to the approximate position of the object.