How far does a laser pointer shine? Design and principle of operation of laser pointers

You can imagine what it is, but the question often arises: What are they for?

To answer this question, we first need to understand what groups of people could theoretically need laser pointers. After all, the range of uses of these devices is very wide. They are used in presentations by various lecturers and storytellers, DJs, astronomers, rock climbers, travelers, fishermen, miners and just people who want to enjoy and surprise others with the power of this gadget of the future.

Let's look at each of these groups in more detail.

The first and most obvious are various lecturers, storytellers, and tour guides. Imagine what a powerful tool these people have for controlling the attention of their listeners with the acquisition of a green laser pointer. Now you no longer need auxiliary words like “top right,” “center left,” and the like, which distract and relax. Now it is enough to turn on your pointer for a couple of seconds and all listeners, without exception, will look where the narrator is pointing.

Everyone has been on outdoor excursions. How often have you had to mentally lengthen the guide’s hand in order to understand where he is pointing? I think regularly. But if your guide had bought a green laser pointer in advance or been given one as a gift, then how much faster, clearer, more informative and interesting the street tour would have become!

The second and less obvious group, due to the improbability of such an assumption, are astronomers and simply lovers of looking at the starry sky. Why "incredibility"? Because you just can’t believe it (until you try it) that powerful laser pointers can shine for 20, 30 and even 50 kilometers! And this is more than the thickness of our planet’s atmosphere. And, therefore, pointing at the sky at night, you see how the beam of your laser pierces the sky and goes into the distance, to the stars! It's like you're pointing straight at a star! Again no need more words like “To the right” “To the left” “Under the Big Dipper”. How difficult it was for astronomers of the past without such a device.

The proposed design may be useful for protecting non-permanent openings - windows, passage doors - or installed along the perimeter of an open object. The operating principle is triggered when the laser beam is interrupted by an intruder. Despite its simplicity, the system turned out to be quite reliable and economical, and the red laser operating in short pulse mode is practically invisible to the intruder.

Figure 1. Laser security system transmitter diagram

The transmitter, the diagram of which is shown above, consists of a short pulse generator and a current amplifier loaded onto a laser pointer, which is easy to find in almost any stall. The generator is assembled using elements DD1.1, DD1.2 and, with the ratings of the frequency-setting circuit indicated in the diagram, operates at a frequency of about 5 Hz. Next, the signal goes to the differentiating circuit C2R3, which generates short pulses with a duration of about 10 μs. This not only makes the device economical (one six-volt battery type 476 is enough for more than a year of continuous operation of the transmitter), but also invisible to the intruder.

Next, the pulses are equalized in shape and amplitude by elements DD1.3, DD1.4 and are sent to an amplifier assembled on transistor VT1. The amplifier is loaded onto a laser pointer, which is modified - the batteries are removed and the cone-shaped tip is removed. Resistor R7, connected in series with a resistor “imprinted” into the laser flashlight board itself (its nominal value is about 50 Ohms), is current-limiting for the laser LED, toggle switch SA1 turns on the continuous operating mode of the emitter, necessary for adjusting the transmitter-receiver system.

For greater economy and frequency stability, the DD1 microcircuit is powered by a voltage reduced to 3-4 V, the excess is suppressed by resistor R6. The average current consumption by the transmitter does not exceed 10 μA; the LED consumes about 20 mA per pulse, so there is no power switch. The transmitter remains operational (of course, with a decrease in range) when the supply voltage is reduced to 4.5 V.

The receiver, the diagram of which is shown in Figure 2, is assembled on integrated circuit DA1, the sensitive element is the photodiode FD263-01. When replacing it, you need to take into account the length of the illumination pulses - the response time of the LED to illumination should be 5-10 times lower than the laser pulse duration.

In its place, for example, FD320, FD-11K, FD-K-142, KOF122 (A, B) and many others will be able to work. In response to each flash of the transmitter, the receiver generates a pulse at the output high level CMOS amplitude. It can be used for further processing. To exclude external illumination, the photodiode must be installed in an opaque tube that acts as a hood.

Setting up the system comes down to its alignment. This is done visually, aiming the laser beam at the photodetector as accurately as possible. To do this, switch SA1 to switch the transmitter to continuous radiation. After completing the adjustment, both the receiver and the transmitter must be firmly secured. In principle, such a system does not require “micron” adjustment. During the experiments, it worked reliably when the photodetector, spaced 50 m from the transmitter, was located in a circle of radiation scatter with a diameter of 30 cm.

Based on materials from “Radio” No. 7, 2002.

A laser pointer is a useful item whose purpose depends on its power. If it is not very large, then the beam can be aimed at distant objects. In this case, the pointer can play the role of a toy and be used for entertainment. It can also have practical benefits, helping a person point to the object he is talking about. Using improvised objects, you can make a laser yourself.

Briefly about the device

The laser was invented as a result of testing the theoretical assumptions of scientists involved in quantum physics, which was then just beginning to emerge. The principle underlying the laser pointer was predicted by Einstein at the beginning of the 20th century. It’s not for nothing that this device is called a “pointer.”

More powerful lasers are used for burning. A pointer allows you to realize your creative potential, for example, with their help you can engrave a beautiful high-quality pattern on wood or plexiglass. The most powerful lasers can cut metal, which is why they are used in construction and repair work.

Operating principle of a laser pointer

According to the principle of operation, a laser is a photon generator. The essence of the phenomenon that underlies it is that the atom is affected by energy in the form of a photon. As a result, this atom emits another photon, which moves in the same direction as the previous one. These photons have the same phase and polarization. Of course, the emitted light is intensified in this case. This phenomenon can only occur in the absence of thermodynamic equilibrium. To create stimulated emission, use different ways: chemical, electrical, gas and others.

The word “laser” itself did not originate from empty space. It was formed as a result of abbreviation of words describing the essence of the process. In English, the full name of this process is: “light amplification by stimulated emission of radiation,” which is translated into Russian as “light amplification by stimulated emission.” Scientifically speaking, then laser pointer is an optical quantum generator.

Preparation for production

As mentioned above, you can make a laser yourself at home. To do this, you should prepare the following tools, as well as simple items, which are almost always available at home:

These materials are enough to complete all the work on making both a simple and a powerful laser with your own hands.

DIY laser assembly

You will need to find a disk drive. The main thing is that its laser diode is in good working order. Of course, such an item may not exist at home. In this case, it can be purchased from those who have it. People often throw away optical drives, even if their laser diode still works or they sell them.

Choosing a drive for production laser device, you need to pay attention to the company where it was issued. The main thing is that this company is not Samsung: drives from this manufacturer are equipped with diodes that are not protected from external influences. Consequently, such diodes quickly become dirty and are subject to thermal stress. They can be damaged even by a light touch.

Drives from LG are best suited for laser manufacturing: each of their models is equipped with a powerful crystal.

It is important that the drive, when used for its intended purpose, can not only read, but also write information to the disk. Recording printers have an infrared emitter needed to assemble a laser device.

The work consists of the following actions:

A ready-made laser pointer, made with your own hands, can easily cut plastic bags and instantly explode balloons. If you point this homemade device at a wooden surface, the beam will burn through it right away. Care must be taken when using.

Laser pointers initially became widely available to replace conventional wooden pointers. Their main purpose continues to remain the same - indication on wall boards, maps, posters, paintings. However, most commercially sold pointers are not used for their intended purpose. They are bought as toys, which is actively used by marketers and manufacturers. They offer hundreds various models, and their power is hundreds of times greater than the values ​​​​necessary for indicating on the board.

Design and principle of operation of laser pointers

All modern laser pointers, from the lowest power to the most powerful, are semiconductor lasers. Gas lasers are not used. Semiconductor lasers have a simple design and do not require complex power supplies, but they are theoretically impossible to build for high power. It is limited to a few watts. This is more than enough for household pointers. A one-watt laser beam with good collecting optics will be reliably visible at a distance of up to 10 km.

Semiconductor lasers have a very similar design to LEDs. Light is generated in resonant structures. To understand the process, they can be represented as antennas that are assembled into a lattice of many identical elements. This principle is used in TV antennas(many identical elements are installed one after another on a traverse) and in radars. In lasers, the role of “antennas” is played by the crystal structures of semiconductors. When current is applied, electrons are converted into photons and the process of monochrome optical radiation begins.

The wavelength of laser light is very small - from 0.2 to one micrometer, so the emitting cells in the semiconductor crystal are nanoscopic in size. The crystal ensures strictly identical lattice formation at large number cells. This is why the wavelength of the laser is strictly defined and cannot be changed after its production.

Power, drivers, batteries and accumulators

The laser diode can only be powered directly from the battery at very low power. For diodes from 50 milliwatts, a specialized power supply is required. Its main function is voltage stabilization. Even a 0.1 volt change can dramatically reduce the life of a laser diode.

The type of power supply determines the power of the laser pointer. It is always done with a reserve of power. By the way, the power supply is one of the simplest and cheapest elements of the pointer. A typical option is a simple power driver on a round board across the body. Power supplies for LED flashlights or, conversely, boost converters, for example, for compact fluorescent lamps. The batteries used are 18650, 16340, 32650. The batteries are regular AA, AAA, C and D. Hour batteries are often found in keychain pointers.

Typical models, form factors and power

The lower power limit of laser pointers is 1-5 milliwatts. The most powerful laser pointer is 10-20 watts. Laser pointers only come in three colors: red, blue and green. Sometimes there are yellow models, but they are very expensive, these are exotic products. As a middle option, there are also greenish-blue lasers. It is best to use green lasers - green laser. Their wavelength is as close as possible to the peak sensitivity of the human retina.

Based on green laser, there is a popular laser pointer for presentations in the form of a pen. There are models that are built into a regular handle. Great power is not required from such products; on the contrary, it will interfere and harm vision, making the light beam too bright.

Choosing laser pointers: what to look for

• Power is the key criterion. It is indicated in milliwatts and directly affects the price. Higher power means higher price and overall complexity of the product. More powerful laser diodes have a shorter service life. They heat up intensely during operation, and their light output drops faster;
• Nutrition. Replaceable batteries - the best option. Laser pointers powered by watch batteries are completely unsuitable for long-term use. Another good option is unified AA and AAA batteries. They are suitable for infrequent use. If the laser is taken as a rarely used toy, then AA batteries- the best option. Batteries are only justified if used frequently, or if you have another device that runs on the same batteries. Then they can be quickly rearranged;
• Case and heat sink. Die-cast aluminum housing is the best heat sink. Tin and plastic housing is only suitable for low-power models.

If a laser pointer is purchased not for presentations, but as an interesting souvenir or toy, then higher power will be useful. The more power, the more interesting the laser pointer becomes. Its sign will be visible from a greater distance.

Regulated power mode is very important. This will allow laser diode work in a more gentle mode, and it will last longer. Also, adjustable power adds new functions, for example, for a cat you need to set the lowest power mode. Cats respond well to red and green lasers. The precautions here are the same as with people. The cat's eye is just as vulnerable to lasers as the human eye.

What opportunities does a powerful laser offer?

• Long distance alarm. Powerful laser can replace pyrotechnic signaling devices. It is especially effective in mountainous areas with good visibility from populated areas;
• Carrying out measurements over long distances. For example, a 10 W green laser pointer can measure the curvature of the earth's surface;
• Using a high-power laser as a light source for strobes and other entertainment devices. Optical attachments for dividing the beam, highlighting various figures and inscriptions are available in countless varieties. You can always find the most unexpected options in them;
• Laser shooting range with laser burning of balls. The device only works over a short distance;
• Laser fence on long distances. Photo relays, homemade lidars, optical communication stations and other devices.

A powerful laser can illuminate clouds, which is effective means alarms. Under good circumstances, such a signal is even more noticeable than a flare. The devices operate high-power lasers in pulsed mode.

A separate direction is associated with the use of powerful laser decrees for engraving. Only the best are suitable for this powerful models over 10 W. Engraving is possible on soft materials, such as wood.

Precautions when handling a laser pointer

Any, even the lowest-power laser is extremely dangerous for eyesight, so the first and main safety rule when handling a laser pointer is not to point it at your eyes. Green green laser is the most dangerous for vision.

It is prohibited to use signs at airports and on highways. There, a bright light beam (even if it doesn’t blind anyone) can still create an emergency situation. A driver or pilot may be blinded by a laser pointer from a distance. For high-power lasers, this distance exceeds one kilometer. This must be taken into account for safe handling. Powerful laser pointers come with safety glasses. They must be worn according to the instructions.

Promising developments of laser pointers

Semiconductor lasers already have very high efficiency. However, the main direction of further development is to increase efficiency by selecting the composition and production technology. The powerful laser heats up quite intensely, which suggests that its efficiency is far from ideal. The efficiency of lasers increases approximately the same as that of LEDs. The production technology is similar. Both are semiconductor light sources.

Other developments are underway to produce new laser pointer colors. Oddly enough, but this technical problem also not resolved. Green green laser and red have already become too familiar. It would be very interesting to see laser pointers in other colors, but the semiconductors to produce yellow and orange lasers are still very expensive. Developments are underway to reduce their cost.

Hi all!
Today is a review of a very useless, but nevertheless interesting thing for some users.
Laser pointer power 5 mW, green glow.
The seller promises ignition with matches. Let's check if this is true?

I'll start the review as usual, with the packaging.
The laser arrived in a large package with several flashlights. The delivery of this parcel is a completely separate story, not without all sorts of incidents))) But I will tell you about this at the end of the review.
I received a complete gift set. There's a box here.


Inside is the laser itself, battery, charger (universal) and keys.


The battery is the famous blue ultrafire))) Unfortunately, it is not famous for its super quality. Well, okay, there is and there is. Moreover, the laser produces excellent light.

The pointer itself is made of aluminum, like the simplest Chinese lanterns. The size is quite large, the body is larger than the Convoy S2+ flashlight.


Additional parts of the set:

A battery with a stated capacity of 4200 mAh. In fact, there are about 700-800. There is no protection. The length is exactly the same as that of an unprotected Samsung.

Charger with Chinese plug, no adapter included. There is a two-color LED. When charging it lights up red, when it's finished it lights up green. It also lights up green if you just insert the battery and do not plug the plug into the socket.


The simplest cheap charger for almost any lithium battery. The charge is exactly up to 4.2, everything is fair here. But I wouldn’t recommend leaving this one unattended, and even with a complete battery.

The laser has a side button. There is a lock at the back, closing which interrupts the circuit and the laser will not light up. Everything works here without any problems!

Disassembled into several components.

Laser diode:


By the way, with the lens removed, the laser beam will not work. The light spot is quite wide.
It also provides for the use of a small 16340 or 18350 battery. With such a battery, the pointer becomes noticeably more compact. This is achieved by unscrewing the central tube. In addition, my MECO ()16340 batteries have an honest capacity of approximately 700 mAh, which is almost the same as the supplied battery.

This pointer has a focusing ring that allows you to make the beam thinner.


But no matter how I tried to focus the beam, set something on fire, or burst a balloon, I failed. I also shined these lasers directly into the eye of the old webcam. It was not possible to disable it, but after the beam hits, the matrix catches the “bunnies” for a few seconds))) So it won’t be possible to spoil the CCTV cameras either, well, perhaps only temporarily.

And of course, let's see how it shines)))
I had lasers hundreds of times more powerful than this (), still green color is perceived by the eye much better than blue, and this green feels brighter than that blue hyperboloid (as one of the commentators dubbed it). In general, the WOW effect is guaranteed for those unfamiliar with the topic. I guarantee it!








Also, using a long shutter speed on the camera, you can draw letters and all sorts of shapes.

This is such a toy. I don't even know where to use it. You can’t give it to children without accidentally shining it into their eyes.
Oh yes! Cats run after the beam like mad))) But again, there is a danger of getting into the eyes. Be careful!!!

Well, at the end of the review, I will tell the story of how this pointer came to me, and not only that.
Somewhere in the middle of summer, a girl from the TOMTOP store wrote to me on VK and offered products for review. I don’t even remember what she offered, but some kind of crap, and I asked for something else, for example, flashlights. She agreed, saying that I could choose flashlights for 40 bucks. No sooner said than done))) The very next day I provided her with a list. It included two LIXADA flashlights, models X5 and X3, several 16340 batteries, and to get up to 40 bucks I asked for this pointer))) By the way, it also belongs to this brand, as the sticker with the inscription Lixada tells us. Since I'm still looking for inexpensive but high-quality flashlights, I decided to check out this manufacturer. Although Aliexpress is full of such pointers and without stickers. Well, okay, that's not the most interesting thing.
A week later I was given a track. Well, I began to wait. The parcel arrived, but got stuck at customs. A couple of weeks later, I asked that girl if everything was okay, to which she replied that the parcel was turned away at customs at the airport due to the presence of those same 16,340 batteries. China Post by the way.
After some time, she wrote that she had received the parcel back and re-sent it, only by Turkish Post, and also issued a track. And what do you think? This exact situation happened this time too))) All because I am a winner in life)))
It was around August, and I safely gave up on it all. And then two weeks ago they called me from DHL and asked what time would be convenient for me to receive the parcel. I was surprised twice at once, since I had never ordered anything through this company, and that in my muhosransk there is actually an office of theirs))) Well, in general, as you already understood, this package turned out to be from Tomtop, and contained two lanterns and this pointer.

Two central ones, if that.

The lanterns turned out to be very decent, by the way.

But the adventures didn’t end there either.
While the parcel was wandering, these lights disappeared from the site))) Now the old links give me a 404 error. And I don’t know what to do. I’ve been writing to that girl for three days, and there’s still silence. Although the reviews are almost ready, there are no links.
This is the story))) Believe it or not.

Something like this. To summarize, I will say that the toy under review is specific, and many people have it (or have ever had it). Why do I need it? I don't know myself. I wouldn't buy it for money. Only needed for the WOW effect))) There are few applications in everyday life.
But nevertheless, the pointer ended up in my hands and I told about it “from my own bell tower”))) Thank you all for watching the review! Constructive criticism is welcome! If there is anything I haven’t completed, ask, I will answer everyone!
See you soon!

IMPORTANT ADDENDUM!
The laser still burns! Just recorded a video:

Due to my illiteracy in this matter, I did not immediately figure out how to focus the beam so that the match would light.
I furiously upvote the user directly for the advice he provided!
I apologize)))

The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.

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