Power supply circuit for a laser diode for an engraver. Laser diode from magneto-optical drive. Connecting a laser diode: diagram, features of operation. Focusing the light flux into a beam

In this post I will describe how I assembled a purple laser pointer from junk I had on hand. For this I needed: a violet laser diode, a collimator to converge the light beam, driver parts, a housing for the laser, a power supply, a good soldering iron, straight hands, and the desire to create.

If you are interested and want to dig deeper into electronics, please refer to cat.

I came across a dead Blu-ray cutter. It was a shame to throw it away, but I didn’t know what could be made of it. Six months later I came across a video that showed such a homemade “toy”. This is where Blu-ray comes in handy!

The drive's read-write system uses a laser diode. In most cases it looks like this:

Or like this.

To power the “red” diode, 3-3.05 volts are needed, and from 10-15 to 1500-2500 milliamps, depending on its power.
But the “purple” diode requires as much as 4.5-4.9 volts, so powering it through a resistor from a lithium battery will not work. We'll have to make a driver.

Since I had a positive experience with the ZXSC400 chip, I chose it without hesitation. This chip is a driver for high-power LEDs. Datasheet. I didn’t bother with the wiring in the form of a transistor, diode and inductance - everything is from the datasheet.

I made a printed circuit board for the laser driver, known to many radio amateurs as LUT (Laser Ironing Technology). For this you need a laser printer. The diagram was drawn in the SprintLayout5 program and printed on film for further transfer of the drawing to textolite. You can use almost any film, as long as it doesn’t get stuck in the printer and it prints well. Film from plastic envelope folders is quite suitable.

If there is no film, no need to be upset! We borrow a women's glossy magazine from a friend or wife, cut out the most uninteresting page from it and adjust it to A4 size. Then we print.

In the photo below you can see a film with applied toner in the form of a circuit layout, and a piece of PCB prepared for transferring the toner. The next step will be preparing the PCB. It is best to take a piece twice as large as our diagram, so that it is more convenient to press it to the surface during the next step. The copper surface must be sanded and degreased.
Now you need to transfer the “drawing”. We find an iron in the closet and turn it on. While it is warming up, we place a piece of paper with the circuit on the PCB.

As soon as the iron heats up, you need to carefully iron the film through the paper.

This video shows the process very clearly.

When it “sticks” to the PCB, you can turn off the iron and move on to the next step.

After transferring the toner using a regular iron, it looks like this:

If some tracks were not transferred, or were not transferred very well, they can be corrected with a CD marker and a sharp needle. It is advisable to use a magnifying glass, the tracks are quite small, only 0.4 mm. The board is ready for etching.

We will poison with ferric chloride. 150 rubles per jar, lasts a long time.

We dilute the solution, throw our workpiece there, “stir” the board and wait for the result.

Don't forget to control the process. Carefully pull out the board with tweezers (it’s also better to buy one, this way we will save ourselves from excess mat and “snot” of solder on the future board when soldering).

Well, the board is etched!

Carefully clean it with fine sandpaper, apply flux, and tin it. This is what happens after servicing.

You can apply a little more solder to the contact pads than everywhere else, to make soldering the parts more convenient, and without applying additional solder.

We will assemble the driver according to this scheme. Please note: R1 - 18 milliOhm, but not megaohm!

When soldering, it is best to use a soldering iron with a thin tip; for convenience, you can use a magnifying glass, because the parts are quite small. For this soldering, flux LTI-120 is used.

So, the board is practically soldered.

The wire is soldered in place of the 0.028 Ohm resistor, since we are unlikely to find such a resistor. You can solder 3-4 SMD jumpers in parallel (they look like resistors, but labeled 0), they have about 0.1 ohm of real resistance.

But there weren’t any, so I used regular copper wire of similar resistance. I didn’t measure it exactly - just some calculations from some online calculator.

We are testing.

The voltage is set to only 4.5 volts, so the light is not very bright.

Of course, the board looks a bit dirty before the flux is washed off. You can wash it off with simple alcohol.

Now it’s worth writing about the collimator. The fact is that the laser diode itself does not shine with a thin beam. If you turn it on without optics, it will shine like a regular LED with a divergence of 50-70 degrees. In order to create a beam, you need optics and a collimator itself.

The collimator was ordered from China. It also contains a weak red diode, but I didn’t need it. The old diode can be knocked out with a regular M6 bolt.

We unscrew the collimator, unscrew the lens and the back part, and unsolder the driver from the diode. We clamp the remaining fastener in a vice. You can knock out the diode by hitting it.
The diode is knocked out.

Now you need to press in the new purple diode.
But you can’t press the legs of the diode, and it’s inconvenient to press it in any other way.
What to do?
The back of the collimator is great for this.
We insert the new diode with its legs into the hole in the back of the cylinder, and clamp it in a vice.
Smoothly tighten the vice until the diode is completely pressed into the collimator.

So, the driver and collimator are assembled.
Now we attach the collimator to the “head” of our laser, and solder the diode to the driver outputs using wires, or directly to the driver board.

As a body, I decided to use a simple flashlight from a hardware store for a hundred rubles.
It looks like this:

All hardware for the laser and collimator.

A magnet is attached to the clothespin for easy attachment.
All that remains is to insert the laser device into the housing and tighten it.

Sprint layout 5, PCB layout files in

Laser diodes - Previously, manufacturing lasers was associated with great difficulties, since it requires a small crystal and the development of a circuit for its operation. For a simple radio amateur, such a task was impossible.

With the development of new technologies, the possibility of obtaining a laser beam in everyday conditions has become a reality. The electronics industry today produces miniature semiconductors that can generate a laser beam. Laser diodes became these semiconductors.

The increased optical power and excellent functional parameters of the semiconductor make it possible to use it in high-precision measuring devices both in production, in medicine, and in everyday life. They are the basis for writing and reading computer disks, school laser pointers, level gauges, distance meters and many other useful devices for humans.

The emergence of such a new electronic component is a revolution in the creation of electronic devices of varying complexity. High-power diodes form a beam, which is used in medicine to perform various surgical operations, in particular to restore vision. The laser beam is able to quickly correct the lens of the eye.

Laser diodes are used in measuring instruments in everyday life and industry. The devices are manufactured with different power levels. A power of 8 W is enough to assemble a portable level gauge at home. This device is reliable in operation and is capable of creating a laser beam of very long length. Getting a laser beam into the eyes is very dangerous, since at a short distance the beam is capable of damaging soft tissues.

Design and principle of operation

In a simple diode, a positive voltage is applied to the anode, then we are talking about biasing the diode in the forward direction. Holes from the “p” region are injected into the “n” region of the p-n junction, and from the “n” region into the “p” region of the semiconductor. When a hole and an electron are located next to each other, they recombine and release photon energy with a certain wavelength and phonon. This process is called spontaneous emission. In LEDs it is the main source.

But under certain conditions, a hole and an electron are capable of remaining in one place for a long time (several microseconds) before recombination. If a photon with a resonance frequency passes through this area at this time, it will cause forced recombination, and a second photon will be released. Its direction, phase and polarization vector will absolutely coincide with the first photon.

The semiconductor crystal is made in the form of a thin rectangular plate. In fact, this plate plays the role of an optical waveguide in which radiation acts in a limited volume. The surface layer of the crystal is modified to form the “n” region. The bottom layer serves to create the “p” area.

The end result is a flat p-n junction of significant area. The two side ends of the crystal are polished to create parallel smooth planes that form an optical resonator. A random photon perpendicular to the planes of spontaneous emission will travel along the entire optical waveguide. In this case, before leaving outside, the photon will be reflected several times from the ends and, passing along the resonators, will create forced recombination, forming new photons with the same parameters, which will cause an increase in radiation. When the gain exceeds the loss, the creation of a laser beam will begin.

There are different types of laser diodes. The main ones are made on particularly thin layers. Their structure is capable of creating radiation only in parallel. But if the waveguide is made wide in comparison with the wavelength, then it will function in various transverse modes. Such laser diodes are called multi-house laser diodes.

The use of such lasers is justified to create increased radiation power without high-quality beam convergence. Some dispersion is allowed. This effect is used to pump other lasers, in chemical production, and laser printers. However, if a certain focusing of the beam is necessary, the waveguide must be made with a width comparable to the wavelength.

In this case, the beam width depends on the boundaries that are imposed by diffraction. Such devices are used in optical storage devices, fiber optic technology, and laser pointers. It should be noted that these lasers are not capable of supporting multiple longitudinal modes and emitting a laser beam at different wavelengths at the same time. The band gap between the energy levels of the “p” and “n” regions of the diode affects the wavelength of the beam.

The laser beam immediately diverges at the output, since the emitting component is very thin. To compensate for this phenomenon and create a thin beam, converging lenses are used. For wide multi-house lasers, cylindrical lenses are used. In the case of single-house lasers, when symmetrical lenses are used, the laser beam will have an elliptical cross-section, since the vertical divergence exceeds the beam size in the horizontal plane. A good example of this is the laser pointer.

In the considered elementary device, it is impossible to distinguish a specific wavelength, except for the wave of the optical resonator. In devices that have a material capable of amplifying the beam over a wide range of frequencies, and with several modes, action at different waves is possible.

Typically, laser diodes operate at a single wavelength, which, however, has significant instability and depends on various factors.

Varieties

The design of the diodes discussed above has an n-p structure. Such diodes have low efficiency, require significant input power, and operate only in pulse mode. They cannot work any other way, as they will quickly overheat, so they are not widely used in practice.

Double heterostructure lasers have a layer of substance with a narrow band gap. This layer is located between layers of material that has a wide bandgap. Typically, aluminum gallium arsenide and gallium arsenide are used to make a double heterostructure laser. Each of these connections with two different semiconductors is called a heterostructure.

The advantage of lasers with this special structure is that the region of holes and electrons, called the active region, is located in the middle thin layer. Consequently, many more pairs of holes and electrons will create amplification. In the region with low gain there will be few such pairs left. In addition, light will be reflected from the heterojunctions. In other words, the radiation will be completely located in the region of greatest effective gain.

Quantum well diode

By making the middle layer of the diode thinner, it begins to function as a quantum well. Therefore, electronic energy will be quantized vertically. The difference between the energy levels of quantum wells is used to produce radiation instead of a future barrier.

This is effective in controlling the beam waveform depending on the thickness of the middle layer. This type of laser is much more efficient, unlike a single-layer laser, since the density of holes and electrons is distributed more evenly.

Heterostructure laser diodes

The main feature of thin-layer lasers is that they are not able to effectively contain a beam of light. To solve this problem, two additional layers are applied on both sides of the crystal, which have a lower refractive index, unlike the central layers. This structure is similar to a light guide. It holds the beam much better. These are heterostructures with separate confinement. Most lasers were produced using this technology in the 90s.

Lasers with feedback Mainly used for fiber optic communications. To stabilize the wave at the pn junction, a transverse notch is made to create a diffraction grating. Because of this, only one wavelength is returned to the resonator and amplified. Such lasers have a constant wavelength. It is determined by the grating notch pitch. The notch changes under the influence of temperature. This laser model is the basis of telecommunication optical systems.

There are also laser diodes VСSEL and VECSEL, which are surface-emitting models with a vertical resonator. Their difference is that the model VESSEL The resonator is external, and its design is available with optical and current pumping.

Connection features

Laser diodes are used in many applications where a directed light beam is needed. The main process in assembling a device using a laser with your own hands is the correct connection.

Laser diodes differ from LED diodes in that they have a miniature crystal. Therefore, a large amount of power is concentrated in it, and consequently the amount of current, which can lead to its failure. To facilitate the operation of the laser, there are special device circuits called drivers.

Lasers require a stable power supply. However, there are models of them that have a red glow of the beam and operate normally even with an unstable network. If there is a driver, then the diode still cannot be connected directly. To do this, you additionally need a current sensor, the role of which is often played by a resistor connected between these elements.

This connection has the disadvantage that the negative pole of the power supply is not connected to the minus of the circuit. Another disadvantage is the power drop across the resistor. Therefore, before connecting the laser, you must carefully select the driver.

Types of drivers

There are two main types of drivers that can ensure normal operation of laser diodes.

Pulse driver made by analogy with a pulse voltage converter capable of increasing and decreasing this parameter. The output and input powers of such a driver are approximately equal. However, there is some heat generation, which consumes a small amount of energy.

Line driver operates according to a circuit that most often supplies more voltage to the diode than required. To reduce it, a transistor is needed to convert excess energy into heat. The driver has low efficiency, so it is not widely used.

When using linear microcircuits as stabilizers, as the input voltage decreases, the diode current will decrease.

Since lasers are powered by two types of drivers, the connection diagrams are different.

The circuit may also include a power source in the form of a battery or accumulator.

The batteries must produce 9 volts. The circuit must also have a current-limiting resistor and a laser module. Laser diodes can be found in a faulty computer disk drive.

The laser diode has 3 outputs. The middle pin is connected to the minus (plus) of the power supply. The plus connects to the right or left leg, depending on the manufacturer. To determine the correct pin to connect to, power must be applied. To do this, you can take two 1.5 V batteries and a resistance of 5 Ohms. The minus of the source is connected to the middle leg of the diode, and the plus first to the left, then to the right leg. Through such an experiment, you can see which of these legs is the “working” one. Using the same method, the diode is connected to the microcontroller.

Laser diodes can be powered by AA batteries or a cell phone battery. However, we must not forget that an additional limiting resistor of 20 ohms is required.

Connecting to a home network

To do this, it is necessary to provide auxiliary protection against high frequency surges.

The stabilizer and resistor create a block that prevents current surges. A zener diode is used to equalize the voltage. The capacitance prevents high frequency voltage surges. Proper assembly ensures stable operation of the laser.

Connection procedure

The most convenient for operation will be a red diode with a power of about 200 mW. Such laser diodes are installed on computer disk drives.

Before connecting using a battery, check the operation of the laser diode.
You need to choose the brightest semiconductor. If the diode is taken from a computer disk drive, then it emits infrared light. The laser beam must not be pointed at the eyes, as this will cause eye damage.
The diode is mounted on a radiator for cooling, in the form of an aluminum plate. To do this, pre-drill a hole.
Apply thermal paste between the diode and the radiator.
Connect a 20 Ohm and 5 watt resistor according to the circuit with batteries and a laser.
Bypass the diode with a ceramic capacitor of any capacity.
Turn the diode away from you and check its operation by connecting the power. A red beam should appear.

When connecting, be aware of safety. All connections must be of high quality.

To install on homemade laser module or laser pointer, the printer carriage needs to be modified. And I discovered that the pad from the computer case is perfect for these purposes, and one of them happened to be at hand. Poor guy.

I somehow miraculously managed to bend, trim, drill and finally screw it to the carriage. You just need to be creative and precise. She during this brain assemblies is your faithful companion, but can also be your worst enemy if you neglect her!

The carriage was not at right angles to the scanner table, but luckily for me, a small nut saved the day.

Even before this, I found a small pulley from a cassette player, I installed it on the carriage, but then I realized that it was colliding with the X-axis guide, and I had to remove it. But it's definitely worth keeping it in case of future modifications.

Step 11: Etching the PCB

After successfully testing my prototype, assembled on a breadboard and correctly executing some G-code commands, I began creating a printed circuit board. I have never done such things before, but I am an assistant in a chemical laboratory, so working with chemicals does not cause me any fear.

And used it again for this brainstorming Groover, taking from there the layout of the laser board, which is in the EagleCAD format file.

I mirror-printed this layout on plain paper, glued it onto a photosensitive copper-plated board, and drilled the necessary holes with a Dremel. I don't have a newfangled automatic exposure meter, so I just took some alcohol and removed the protective varnish. Using a contour projector pen and a ruler, I drew the paths by hand. This brain pen leaves a very beautiful shiny mark. I also tried using a German fine permanent marker (acid-resistant), but it produced thick, unsightly lines. And with a contour pen you only had to draw a line once, and not several, and you got a good protective layer.

Etched the board crafts I use ferric chloride (III), I don’t like other available remedies. Some steam, others have a strong smell, and others contain peroxide and can explode if kept in a closed container. Therefore, ferric chloride is the best option for both storage and disposal.

However, DO NOT POUR it down the drain! It will corrode your sewer pipes if they are made of copper and kill all the beneficial bacteria in your septic tank.

Step 12: Laser Shield

I don't know how the pins (that connect to the Arduino pins) are soldered on the back side, so I installed them on the top side of the board and pushed them through.

Just in case, I drew drivers on the board brainlaser where which electrical components should be located. Note: test runs without a laser can be carried out without this board.

List of electrical parts

I have attached a list from my order from an electronics supplier, which with all the descriptions looks a little scary.

Note 1:
The supplier made a mistake with the relay in the order, so I had to disassemble the old PC power supply, which I found in my supplies. I am immensely happy with my “stash” of old equipment; most of the electronics are still functioning, and I keep them instead of giving them to a collection point. They sell it to Africa as "second hand", although this is not the case. I built this one brain engraver, to show that “old technology” is not trash. In skillful hands, it is as valuable as money.

Note 2 (important):
When connecting an Arduino with the board installed, make sure to connect the external power supply first. I noticed that when connecting the Arduino to USB, without a connected power source, the steppers start to “scream”, which is not at all cool.

Step 13: Alternative Laser Shield (Easylaser Shield)

Groover's laser shield is great, but there are a few things that don't work with the way I control the laser:
- it cannot switch to the microstepping mode of stepper motors.
The steppers in the DVD he used didn't require this, but if you're using different motors from different units, this option can help you control the motors more accurately.
— I was also not happy with the relay that controls turning the laser on/off.
— and finally, the wires going from the laser shield to the laser were too long, I think it would be more correct to place the shield closer to the laser.
So, to summarize:

I modified the driver from Groover
— moved the driver board, placed it on the terminal clamp for the laser module,
— added jumpers to Easydrivers, thereby activating the microstepping mode.

Upgrade: do-it-yourselfer jduffy54 was kind enough to fix the easylaser board. I updated the layout brain boards, the microstepping jumpers should now work as expected.

Step 14: Laser Diode

The laser diode I used is very powerful. This is a targeted 300mW red class 3 laser, which means you MUST use safety glasses. Otherwise, you can get conjunctivitis and cataracts. It's not like smoking, which can possibly lead to cancer. No, if the beam hits your eyes, then you are guaranteed to get cataracts. And even the beam reflected from the walls is much more dangerous than if you look at the sun. You don't want to risk your vision. Pause…

BE CAREFUL!!

Safety glasses should not transmit radiation with a wavelength of 600-670 nm (optical density 4+). These glasses are not cheap, but the eyes are priceless!

An optical density of 4+ means 10^-4 of incoming (red) light is filtered.
Eg:
300 mW * 10^-4 = 0.03 mW.

Laser diode pinout:

Having removed a laser diode from an old DVD burner or purchased it on the Internet, the first thing you need to do is determine its polarity. I took two for this brain batteries AA in the case, which are “+” and “-”, respectively, and tried to connect them to the laser diode until it lit up.

The housings of laser diodes such as aixiz contain a heatsink. They often come with a focusing plastic lens. Glass lenses are of course better, as they provide 10-20% more usable power.

Laser diode power setting:

Before you connect the laser to the circuit, you need to adjust the “power” it will receive. This is easy to do using the blue potentiometer.
The red laser from the DVD writer can withstand 300mV (under load - accordingly 300mA), but I don’t know how long it will last.
This means that if you want to increase its service life, you can reduce the power supplied to it to 200 mV (under load - 200 mA).
And I advise you, if possible, to find an old DVD writer, because you don’t want to adjust the power of the laser diode on the laser module used in the craft.

It sounds strange, but for this setup we will use the equivalent of a load that needs to be placed in the circuit instead of an actual laser diode. In this case, you can gradually increase the power, while measuring the voltage, and without the risk of damaging the “precious” diode.
In the photo you can see this very equivalent load, it simulates a red laser. And if you have a blue laser, then you need to use 6 1N4001 diodes.

The equivalent load for a red laser is 4 1N4001 diodes and one 1 Ohm resistor.
for a blue laser - 6 1N4001 diodes and one 1 Ohm resistor.

Again, we take a breadboard and connect diodes and a resistor in series, on which the voltage is measured. It doesn’t matter which side of the diodes you place it on. Set the multimeter to 2000mV and apply the probes to the terminals brain resistor. Next, we connect the wires from the laser driver contacts to the breadboard. Load gcodesender, or the terminal you are using, and connect to the microcontroller. Next, we send the command “M3” (turn on the spindle/laser) and readings should appear on the multimeter.
Then turn the potentiometer clockwise until you get the value you need, for example 300mV. This will correspond to what will be supplied to the laser diode.

CW = boost voltage
CCW = reduce voltage
After this, we send the command “M5” to turn off the laser.

Laser Focus:

To focus the laser, I turned the lens until it became a point on the wall, and then tried to light a match.
To “roughly” adjust the focus, I pasted a ruler on the table and installed a laser next to it, so that the edge of its body was at the 0mm mark. Next, I placed a sheet of black paper in front of the laser and moved it until it lit up. Perhaps you also need to “play” with the lens and the distance of the sheet.

I did the final adjustment of the focal length in a similar way, but this time I calculated how long it would take to burn a hole in the paper. This is how I got the focal length closest to ideal.

Step 15: Soft

Determination of working area:

In the Inkscape editor you need to set the dimensions of the working area. To do this, go to “File” - “Document Properties” and change the page to your size.

One thing you need to know before you start engraving is how to get the gcode for your designs. My choice is Inkscape with a modified Groover Gcodetools (Metalevel 8), which is available on its page.

Before creating a gcode pattern, you need to mirror it. If you just want to select everything and reflect it, this can give strange results in Inkscape.
Therefore, before mirroring, select everything (key combination Ctrl + a), combine it into a group (Ctrl + g) and only then reflect it (‘h’). After mirroring, ungroup (Ctrl + Shift + g) and transform it into a path (Ctrl + Shift + c).

gcodetools needs to be copied to “…\Inkscape\share\extensions”.

But now to get gcode you need to do the following:

1. Ungroup all objects (possibly twice)
2. Ctrl + a (select all) - Path - Object to path
3. Selected all - Extensions - Laserengraver - Laser
4. In the "Preferences" section, select the output folder.
5. Important! Switch to the "Laser" tab
6. Enter the desired speed. It can be overwritten later using Gcodesender.
7. Enter the file name + .nc Next, click “Apply” and you’re done!
8. Launch Gcodesender, connect to Arduino and load the .nc file. If desired, change the speed.
9. !!WEAR SAFETY GOGGLES!!
10. Click “Print”

Inkscape cheat sheet

Action Keyboard shortcut

Select all Ctrl + A
Group (group) Ctrl + G
Ungroup Shift + Ctrl + G
Mirror (horizontal) reflect horizontally H
vertical V
Convert object to path (convert to path) Shift + Ctrl + C
Align dialog Shift + Ctrl + A
Fill / Stroke dialog Shift + Ctrl + F

Step 16: He came to life!!!

Some of their carved or engraved works.

Today, many household and other devices use laser diodes (semiconductors) to create a targeted beam. And the most important point in assembling a laser system yourself is connecting the diode.

Laser diode

From this article you will learn about everything you need for a high-quality connection of a laser diode.

Features of the semiconductor and its connection

The laser model differs from the LED diode in its very small crystal area. In this connection, a significant concentration of power is observed, which leads to a short-term excess of the current value in the junction. Because of this, such a diode can easily burn out. Therefore, in order for the laser diode to last as long as possible, a special circuit is needed - a driver.

Note! Any laser type diode must be powered with a stabilized current. Although some varieties that give red light behave quite stably, even if they have unstable nutrition.

Red laser diode

But, even if a driver is used, a diode cannot be connected to it. A “current sensor” is also needed here. Its role is often played by the common wire of a low-resistance resistor, which is connected to the gap between these parts. As a result, the circuit has one significant drawback - the power minus is “severed” from the minus present in the circuit’s power supply. In addition, this circuit has one more disadvantage - power loss occurs at the current-measuring resistor.
When planning to connect a laser diode, you need to understand which driver it should be connected to.

Driver classification

At the moment, there are two main types of drivers that can be connected to our semiconductor:

pulse driver. It is a special case of a pulse voltage converter. It can be either downward or upward. Their input power is approximately equal to the output power. In this case, there is a slight conversion of energy into heat. A simplified pulse driver circuit looks like this;

Simplified switching driver circuit

linear driver. The circuit typically supplies more voltage to such a driver than the semiconductor requires. To extinguish it, a transistor is needed, which will release excess energy with heat. Such a driver has low efficiency, and therefore is used extremely rarely.

Note! When using linear integrated circuit stabilizer chips, the current will decrease as the input voltage across the diode drops.

Line Driver Circuit

Due to the fact that any laser diode can be powered through two different types of drivers, the connection diagram will be different.

Connection Features

The circuit that will be used to power the laser diode may contain not only a driver and a “current sensor”, but also a power source - a battery or battery.

Connection diagram option

Typically, the battery/battery in this case must have a voltage of 9 V. In addition to them, the circuit must include a laser module and a current-limiting resistor.

Note! In order not to spend money on a diode, you can remove it from the DVD drive. Moreover, it must be a computer device, and not a standard player.

Computer DVD drive

The laser semiconductor has three terminals (legs), two of which are located on the sides and one in the middle. The middle output should be connected to the negative terminal of the selected power source. The positive terminal must be connected to the left or right “leg”. The choice of left or right side depends on the semiconductor manufacturer. Therefore, you need to determine which output will be: “+” and “-”. To do this, power must be applied to the semiconductor. Two batteries, each 1.5 volts, as well as a 5 ohm resistor will do the job perfectly here.
The negative terminal at the power supply should be connected to the central negative terminal defined at the diode. In this case, the positive side must be connected to each of the two remaining terminals of the semiconductor in turn. Thus, it can also be connected to a microcontroller.
Power for the laser diode can be provided using 2-3 AA batteries. But if you wish, you can also include a battery from a mobile phone in the circuit. In this case, you must remember that you will need an additional 20 Ohm limiting resistor.

Connection to 220 V network

The semiconductor can be powered from 220 V. But here it is necessary to create additional protection against high-frequency voltage surges.

Option for powering a diode from a 220 V network

Such a scheme should include the following elements:

Voltage regulator;
current limiting resistor
capacitor;
laser diode.

The resistance and stabilizer will form a block that can prevent current surges. To prevent voltage surges, a zener diode is needed. The capacitor will prevent the appearance of high-frequency bursts. If such a circuit was assembled correctly, then stable operation of the semiconductor will be guaranteed.

Step-by-step connection instructions

The most convenient way to create a laser installation with your own hands will be a red semiconductor, which has an output power of approximately 200 milliwatts.

Note! This is the semiconductor that any computer DVD player is equipped with. This greatly simplifies the search for a light source.

The connection looks like this:

One semiconductor must be used for connection. They must be checked for functionality (just connect to a battery);
choose a brighter model. When testing the IR LED (taking it from the computer player), it will glow a faint red glow. Remember that it

DO NOT aim at the eyes, otherwise you may completely lose your vision;

Diode check

Next, we install the laser on a homemade radiator. To do this, you need to drill a hole in an aluminum plate (about 4 mm thick) with such a diameter that the diode fits into it quite tightly;
It is necessary to apply a small layer of thermoplastic between the laser and the radiator;
Next, we take a wire-wound ceramic resistor with a resistance of 20 Ohms with a power of 5 W and, observing the polarity, connect it to the circuit. Through it you need to connect the laser and a power source (mobile battery or battery);
the laser itself should be bypassed using a ceramic capacitor having any capacitance;
Then, turning the device away from you, you should connect it to the power supply. As a result, the red beam should turn on.

Red beam from a homemade device

It can then be focused using a biconvex lens. Focus it for a few seconds on one point on the paper that absorbs the red spectrum. The laser will leave a red light on it.
As you can see, we have a working device that is connected to a 220 V network. Using various circuits and connection options, you can create different devices, even a pocket laser pointer.

Conclusion

When connecting a laser diode, you need to remember about safe handling and also know the nuances that are present in its operation. After this, all that remains is to choose the circuit you like and connect the semiconductor. The main thing to remember is that all contacts must be well sealed, otherwise the part may burn out during operation.

Calculation of lumens per square meter for different rooms

It's no secret that each of us as a child wanted to have a device like a laser machine that could cut metal seals and burn through walls. In the modern world, this dream can easily come true, since it is now possible to build a laser with the ability to cut various materials.

Of course, at home it is impossible to make a laser system so powerful that it will cut through iron or wood. But with a homemade device you can cut paper, polyethylene sealing or thin plastic.

Using a laser device, you can burn various patterns on sheets of plywood or wood. It can be used to illuminate objects located in remote areas. The scope of its application can be both entertaining and useful in construction and installation work, not to mention the realization of creative potential in the field of engraving on wood or plexiglass.

Cutting laser

Tools and accessories you will need to make your own laser:

Figure 1. Laser LED circuit diagram.

faulty DVD-RW drive with a working laser diode;
laser pointer or portable collimator;
soldering iron and small wires;
1 Ohm resistor (2 pcs.);
capacitors 0.1 µF and 100 µF;
AAA batteries (3 pcs.);
small tools such as a screwdriver, knife and file.

These materials will be quite sufficient for the upcoming work.

So, for a laser device, first of all, you need to select a DVD-RW drive with a mechanical breakdown, since the optical diodes must be in good condition. If you do not have a worn-out drive, you will have to purchase it from people who sell it for spare parts.

When purchasing, keep in mind that most drives from the manufacturer Samsung are unsuitable for the manufacture of cutting lasers. The fact is that this company produces DVD drives with diodes that are not protected from external influences. The lack of a special housing means that the laser diode is subject to thermal stress and contamination. It can be damaged with a light touch of your hand.

Figure 2. Laser from a DVD-RW drive.

The best option for a laser would be a drive from the manufacturer LG. Each model is equipped with a crystal with varying degrees of power. This indicator is determined by the writing speed of dual-layer DVDs. It is extremely important that the drive is a recording drive, since it contains an infrared emitter, which is needed to make a laser.

A regular one will not work, since it is intended only for reading information.

DVD-RW with a 16X recording speed is equipped with a red crystal with a power of 180-200 mW. The 20X speed drive contains a 250-270 mW diode. High-speed recording devices of the 22X type are equipped with laser optics, the power of which reaches 300 mW.

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Disassembling the DVD-RW drive

This process must be done with great care, since the internal parts are fragile and can be easily damaged. Having dismantled the case, you will immediately notice the necessary part; it looks like a small piece of glass located inside the mobile carriage. Its base needs to be removed; it is shown in Fig. 1. This element contains an optical lens and two diodes.

At this stage, you should immediately warn that the laser beam is extremely dangerous to human vision.

If it hits the lens directly, it damages the nerve endings and the person may remain blind.

The laser beam is blinding even at a distance of 100 m, so it is important to watch where you point it. Remember that you are responsible for the health of others while such a device is in your hands!

Figure 3. LM-317 chip.

Before you begin, you need to know that the laser diode can be damaged not only by careless handling, but also by voltage surges. This can happen in a matter of seconds, which is why diodes operate based on a constant source of electricity. When the voltage increases, the LED in the device exceeds its brightness standard, as a result of which the resonator is destroyed. Thus, the diode loses its ability to heat, it becomes an ordinary flashlight.

After removing the crystal, you must immediately tie up its ends with exposed wires. This is necessary to create a connection between its voltage outputs. To these outputs you need to solder a small capacitor of 0.1 µF with negative polarity and 100 µF with positive polarity. After this procedure, you can remove the wound wires. This will help protect the laser diode from transients and static electricity.

Nutrition

Before creating a battery for the diode, it is necessary to take into account that it must be powered from 3V and consumes up to 200-400 mA, depending on the speed of the recording device. You should avoid connecting the crystal directly to batteries as this is not a simple lamp. It can deteriorate even when exposed to regular batteries. The laser diode is a self-contained element that is supplied with electricity through a regulating resistor.

The power supply system can be configured in three ways with varying degrees of complexity. Each of them requires recharge from a constant voltage source (batteries).

The first method involves electrical regulation using a resistor. The internal resistance of a device is measured by detecting the voltage as it passes through the diode. For drives with a 16X write speed, 200 mA will be sufficient. If this indicator increases, there is a possibility of damaging the crystal, so you should stick to the maximum value of 300 mA. It is recommended to use a telephone battery or AAA batteries as a power source.

The advantages of this power supply are simplicity and reliability. Among the disadvantages are the discomfort when regularly recharging the battery from the phone and the difficulty of placing batteries in the device. In addition, it is difficult to determine the right moment to recharge the power source.

Figure 4. LM-2621 chip.

If you use three AA batteries, this circuit can be easily installed in a Chinese-made laser pointer. The finished design is shown in Fig. 2, two 1 Ohm resistors in sequence and two capacitors.

For the second method, the LM-317 chip is used. This method of arranging a power system is much more complicated than the previous one; it is more suitable for stationary type laser installations. The scheme is based on the manufacture of a special driver, which is a small board. It is designed to limit the electric current and create the necessary power.

The connection circuit of the LM-317 microcircuit is shown in Fig. 3. It will require elements such as a 100 ohm variable resistor, 2 10 ohm resistors, a 1N4001 series diode and a 100 μF capacitor.

A driver based on this circuit maintains electrical power (7V) regardless of the power source and ambient temperature. Despite the complexity of the device, this circuit is considered the simplest for assembly at home.

The third method is the most portable, making it the most preferred of all. It provides power from two AAA batteries, maintaining a constant voltage level supplied to the laser diode. The system maintains power even when the battery level is low.

When the battery is completely discharged, the circuit will stop functioning, and a small voltage will pass through the diode, which will be characterized by a weak glow of the laser beam. This type of power supply is the most economical, its efficiency factor is 90%.

To implement such a power system, you will need an LM-2621 microcircuit, which is housed in a 3x3 mm package. Therefore, you may encounter certain difficulties during the period of soldering parts. The final size of the board depends on your skills and dexterity, since the parts can be placed even on a 2x2 cm board. The finished board is shown in Fig. 4.

The choke can be taken from a regular power supply for a desktop computer. A wire with a cross-section of 0.5 mm is wound onto it with a number of turns of up to 15 turns, as shown in the figure. The throttle diameter from the inside will be 2.5 mm.

Any Schottky diode with a value of 3 A is suitable for the board. For example, 1N5821, SB360, SR360 and MBRS340T3. The power supplied to the diode is adjusted by a resistor. During the setup process, it is recommended to connect it to a 100 Ohm variable resistor. When testing functionality, it is best to use a worn or unwanted laser diode. The current power indicator remains the same as in the previous diagram.

Once you find the most suitable method, you can upgrade it if you have the necessary skills for this. The laser diode must be placed on a miniature heatsink so that it does not overheat when the voltage increases. After completing the assembly of the power system, you need to take care of installing the optical glass.