The lens is a necessary tool in everyday life. Probably the most indispensable optical device. Telescopes, microscopes, cameras, magnifiers and the like work on lenses. Some people cannot even see properly without them, so they wear glasses, which also consist of lenses. This is the meaning of lenses in our life. There are two types of lenses: diverging lenses and converging lenses. For example, diverging lenses are worn by people with myopia, and converging lenses are worn by people with farsightedness. And these two types are divided into several more types. But let's not talk about theory, let's move on to practice. In this article, I will show you and tell you how to make a converging lens yourself at home from the most improvised materials that every home definitely has. And so, to make a homemade converging lens, we need:
Tools:
1) Sharp clerical knife,
2) Sharp needle,
3) Scissors,
4) Glue gun and hot glue,
5) Medical syringe.
Materials:
1) A transparent plastic bottle from some kind of lemonade or other drink,
2) Water.
The process of making a converging lens with your own hands.
We take any plastic bottle, most importantly, the bottle must be transparent.
Now we need an item round shape, in my case it is a cover from the plastic bottle. She's good because she's big. Other bottles have small caps, so they won’t fit, otherwise the converging lens will be very small. We insert the cap on the bottle and circle it with a sharp needle, it is important that the circle scratched with the needle remains on the bottle. However, this action can be performed with a felt-tip pen and a marker. But you just need to be more careful so that you don’t smear the future lens with the paint of a felt-tip pen or marker. And then the circle should be convex, otherwise you simply won’t be able to make a lens.
You get a circle like this.
With scissors or a clerical knife, cut out this circle along the contour.
With exactly the same actions, we make another exactly the same circle.
Now glue them together with hot glue. But at the same time, you need to leave a small hole in order to pour water into the resulting lens.
Using a syringe, fill the lens with water. In order for life to not appear inside the lens, it must be boiled and salted. However, it is not necessary to do so. After filling the lens with water, close the left hole with hot glue.
That's what my resulting lens is capable of. Enlarges in full decently, but it can be seen blurry.
What if the project calls for a small lens, but there is no suitable size in the bins? Postponing the project and wandering around the flea markets, hoping to find a suitable donor? Not necessary. The lathe allows you to solve this problem:
I take a piece of the correct sheet plexiglass of suitable thickness (in this case, 6 mm). On the front of the chuck jaws, I have a special step machined, which allows me to clamp not cylindrical, but sheet blanks. It is convenient to sharpen bodies such as washers, etc., although of course it must be taken into account that the reliability of fixing the part is not very good. But for the processing of plexiglass, great efforts are not required, and in any case it is necessary to clamp the workpiece gently.
In general, a 6 mm workpiece, clamped in these ledges, is machined just to half the thickness. And then it turns over, and is pierced again. We get a "washer", a flat cylinder of the required diameter.
With a cutter, operating with two feeds at once, I give a convex shape roughly: 
And now I take a trihedral scraper made from a needle file and draw out the shape, removing the risks from the cutter: 
This processing method allows you to literally "shave" plexiglass, removing thin-thin chips with a flat layer. With any other method, ring risks remain.
True, the fingers are in close proximity to the rotating cams, on a large machine I would not dare to do this (800-1000 revolutions).
Now a drop of engine oil on a piece of "zero", and finishing: 
If a biconvex lens is required, then I turn the workpiece over and process the second side.
I take it off the machine and finally polish it with a thread disk with GOI paste. The technique of polishing plexiglass is different from metal. I put more paste on the disc, and the pressure is much less. Light and short-term touches, evenly moving the friction zone over the entire surface of the lens. Otherwise - "burnout", and an incorrigible marriage.
Finished lens: 
And this is the "lens", that is, the mount for this lens: 
Fixation of the lens as in real optical systems, with a thin threaded ring. Although, of course, you can also use an elastic expanding ring-spring, and if it’s quite simple, then put it on glue :-) But the lathe allows you to do everything “in an adult way”, on a fine-pitch thread (in this case, by selecting the gears of a guitar step 0.7 mm is selected). Lens assembly: 
In order not to scratch the lens too quickly, it is useful to make the outer edge of the tube several times. higher than the most convex point of the lens, obviously.
And here is the mechanism from a small women's watch, for which this lens was made: 
As you can see, the optical qualities of the lens are quite satisfactory, despite the fact that the geometry was derived almost “from the bulldozer”. That is, such a lens will certainly not work for a telescope, but for a flash drive it is very suitable :-)
Thank you for your attention.
The simplest electronic digital microscope can be made by hand using an old camera phone, although it is still better to use a smartphone (in our case, iphone) and the screen is larger and the camera is better.
The total magnifying power of the microscope can be up to 375 times, depending on the number and class of lenses used.
By the way, we took the lenses themselves in the manufacture of microscopes from an old laser pointer, but if you do not have one, then you can buy them cheaply in any Chinese online store.
Cost price homemade microscope does not exceed 300 rubles, if we take into account the cost of materials:
Materials for manufacturing
Full list of required materials for the project:
Manufacturing
1) Disassembling the laser pointer and removing the lens.
For this we use the cheapest pointer, so do not buy expensive models for this. A total of 2 lenses are required. (You can skip this step if you buy the lens itself from the store).
To disassemble the pointer, unscrew the back cover and remove the batteries. We extract all the insides with a simple pencil with an eraser. The lens is in the lens, and to get it you need to unscrew a piece of small black plastic.
The lens itself consists of thin translucent glass, about 1 mm thick, you can attach it to the phone's camera to experiment with an enlarged photograph, it is very difficult to take a high-quality photograph, so I decided to make a clamp stand for the microscope.
2) Making the base of the case.
The entrance went to a piece of plywood measuring 7 x 7 cm, in which we drill 3 holes for racks (bolts). Places for drilling holes are shown in the photo with marks.
3) Preparation of plexiglass and lenses.
We cut out 2 pieces of plexiglass with dimensions: 7 x 7 cm and 3 x 7 cm. On the first piece of plexiglass we drill 3 holes according to the plywood template, this will be top part corps. On the 2nd piece we drill 2 holes according to the plywood template, this will be the intermediate shelf of the microscope.
Do not press hard when drilling Plexiglas.
Now you need to drill holes in the plexiglass for the lens and lens, this will require a D = D lens drill or a little less. Finishing the hole is done with round files or rasps.
Lenses must be built into drilled hole in both glasses.
4) Assembly of the case.
When all the details of the microscope are ready, you can proceed to the assembly itself, but there is still 1 point left before that:
- it is necessary to supply a light source from below, for this I drilled a hole in the lower part of the case for mounting a small diode lamp.
We proceed to the final assembly. We twist the bolts tightly to the base.
The intermediate microscope stand with o2 lens must be placed up and down to allow adjustment of the size of the magnification of the optics.
To do this, we tighten the wing nuts, 2 washers on 2 bolts and mount the glass with an already glued lens measuring 3 * 7 cm.
Then we install the top cover, here we already use ordinary nuts, but we put them both on top and bottom.
Congratulations, you just made a cheap digital microscope, here are some pictures taken with it.
Video instructions for making and demonstration of work
(in English)
Hi all!
My name is Sergey.
And in this post, I want to tell you one of the applications of a 3D printer, namely the manufacture of lenses.
The task was the following. There is an RGB LED, but the light source from it is not in the form of a beam, but scattered with a divergence angle of about 38 degrees. I displayed the light source and the divergence of the rays on the sketch, determined the point where the LED crystal should be.
1/f=(n-1)(1/R1+1/R2)................................ ................................................. ....................(1)
Where R1 and R2 are the radii of curvature of the first and second surfaces of the lens, f is the focal length of the lens, n is the refractive index of the lens.
n=n2/n1, where n2 is the refractive index of the lens material (plexiglass 1.5), n1 is the refractive index of the medium surrounding the lens (air, about 1)
For simplicity, I assumed that R1=R2.
I only know f - 20 mm from the formula. We, in fact, have this distance from the LED crystal to the optical center of the lens.
Let's rewrite formula (1), considering that R1=R2=R:
R=f(n-1)2 .......................................... ................................................. ......................(2)
Substituting the data into formula (2) n=1.5 and f=20
we obtain that the radii of curvature of the lens surfaces are 20 mm. See schematic drawing.
Based on these data, we build a 3D model of the lens. It turns out something like this.
I made a lens with a base.
It remains only to print it, which is also not difficult. Result after printing (only printing, no processing).
After the lens, I sanded a little with 1500 sandpaper and polished it with paste. Unfortunately, I did not have a photo of the final result, as well as lenses.
It remains to test the lens in action. This is what the spot from the LED looks like without a lens
And so with the lens.
1. I was not able to achieve a parallel beam, but I think that if I re-manufactured the lens with different parameters, I could do it.
2. The divergence of the rays is reduced by more than 3 times (this suited the customer)
3. The refractive index has most likely been used incorrectly. The lens is made of polymer and its refractive index is unknown.
4. The lens had to be made larger in diameter.
Even with careful handling of glasses, they can be scratched. Damage can be barely noticeable to the eye, but significantly spoil the appearance of the accessory. In this case, the image is distorted, and eye muscles are situated in constant voltage which is not good. How and with what to polish glasses - we will tell in this article.
In this article
How to determine the nature of the defect?
To determine the degree of damage and the nature of its occurrence, carefully inspect your glasses. If there are scuffs and minor scratches on the lenses, you can fix them yourself with the help of tools that are in every home. If the damage is more serious, then to eliminate them you will need special equipment - a grinder.
However, it should be noted that none handy tool cannot completely eliminate defects. If it was not possible to get rid of them on your own, it is better to seek help from professionals.
How to polish glasses lenses? It depends on the material they are made from. Spectacle lenses are made of glass or plastic, some models are also equipped with a polarizing filter. The latter are complex multilayer structures with UV protection.
The condition of each type of lens is corrected in its own way. For example, it is much easier to remove scratches from plastic glasses than from glass ones, and lenses with the effect of polarization cannot be “cured” at all on their own.
How to polish the lenses of polarized glasses?
Glasses that protect the eyes from bright light are quite often covered with scratches that impair the quality of vision. If the glasses are with a polarizing filter, he may also suffer from such defects, and this already entails difficulties in orientation in space for the owner of such glasses.
You can eliminate scratches by polishing and filling irregularities with improvised means. For this you can use toothpaste, baking soda or wax for polishing a car or furniture.
If you are going to polish sunglasses with toothpaste, then you need to choose the most ordinary one, without bleaching additives and abrasive components that can scratch the lens even more.
Also for work you will need soft napkins, cotton pads or a piece of soft cloth.
It is worth noting that all these methods can help get rid of only small defects. If the scratches are large, the lens will need to be replaced or new glasses purchased.
How to polish damaged glass with baking soda?
Baking soda is the most commonly used agent for polishing glasses. It is in any home, and therefore it is widely used to solve various household problems.
How to use baking soda to polish glasses? The procedure is as follows:
- Prepare a slurry of baking soda and water.
- Take a small amount of the paste and apply it to a cotton pad or soft cloth.
- Gently apply the slurry to the lens in a circular motion.
- Rinse the lens with water.
- If necessary, repeat the procedure again, as the composition does not always cope with the task immediately.
Polishing glass with toothpaste
The substances that make up the toothpaste gently polish the outer layer of the lens, eliminating bumps, scratches and other minor defects.
To restore the appearance of glasses, you must perform the following algorithm of actions:
- Apply a small amount of toothpaste to the lens surface.
- Use a soft cloth or cotton pad to rub the paste over the entire surface of the lenses. It is important to do this quickly, preventing the composition from drying out.
- Leave the toothpaste on for a couple of minutes and wipe it off the glass surface with water or glass cleaner.
- At the final stage, wipe the lenses dry. There should be no traces of paste left.
Glass polishing with Goi paste
Goi paste, a technical composition created for polishing optical glasses, will help get rid of scratches on glass lenses. That is why it will not be difficult for him to restore the appearance of ordinary glasses.
- apply the composition to the felt cloth and place the lens on top;
- rotate the glass of the glasses on the felt, thus rubbing the paste and grinding the lens with a cloth;
- after the procedure, remove the remnants of the mixture from the lens with a clean cloth.
If it is impossible to remove the lens from the frame, then it can be processed in the same way as grinding with toothpaste: apply the composition with one-sided in a circular motion by rubbing it into the lens. Act as carefully as possible: the paste should not get on the frame and other elements of the glasses.
This method takes more time than the previous ones, however, the result usually exceeds all expectations: glasses after such processing take on their original appearance.
In addition, Goi paste can be used to process lenses not only by hand. You can rub the composition with a grinder, but this should be done at low speeds so as not to damage the glass. You can also use a shaving machine for these purposes, replacing the knives with a microfiber cloth.
How to polish glasses glasses with vinegar or alcohol?
Vinegar and alcohol do the job just fine when you add baking soda to them. Such a mixture is able to restore the condition of the lenses, saving them from minor damage. The remains of the slurry are removed with running water.
If the damage is very shallow, you can try to get rid of them by wiping the glass with concentrated medical alcohol.
Glass polishing with shampoo or soap
Shampoo, soap, dishwashing detergent, and other similar household cleaners can be used to gently polish lenses. Each of them contains microparticles that grind glass.
To get rid of defects, lubricate the lenses with one of the products and remove its remnants with a soft cloth. It is not necessary to rinse glasses glasses under water: it is worth resorting to this method of eliminating residual funds only if otherwise it cannot be removed without streaks.
Treatment of spectacle lenses by polishing for silver
Silver polish also works well for restoring eyeglass lenses. How to polish lenses with such a tool?
To do this, the glasses of the glasses are sprayed with a composition, which is then rubbed a little. The remains of the product are removed with a soft cloth. If necessary, the procedure can be repeated several times.
Also for these purposes, you can use polish for metal, furniture, car, compositions for processing windshields. Glass processing is carried out in the manner described above.
In the article, we told how and with what you can polish glasses. If none of the above methods gave the desired result, you need to stop trying to restore the glasses yourself and turn to specialists. They will polish the lenses with the help of special equipment and are guaranteed to bring the glasses to their original appearance.