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Frequently asked questions about lasers

What a type of laser is to choose?

The answer to this question is not always as simple as the customer wishes. On deciding what a laser to select we must take into account a few of fundamental practical items.

1) What a distance is to be alighted?
2) What light conditions are to be expected on the place of work?
3) What sort of material is to be lit up?
4) Climatic effects on workplace.
5) Available sources of supply voltage and their distance from laser.
6) The needed quality of laser beam, e.g. angle or thickness of line.
7) Laser operating mode and laser working life.
8) Shape of the laser beam.
9) Safety at work.

1) What a distance is to be alighted?

The most important thing, on selection the laser, is to know the length of max. needed decay of laser beam.
If there is a few of centimetres or decimetres enough there will be 5mW laser in any colour design adequate. It is practically the same whether wood, stone or normal piece of iron are lit up. The beam can be seen also by daylight. If the same laser and the same material are situated in a workshop, hall or a similar area where is no direct sunlight incident on the material, the line will be visible even from a 5m distance.

2) What light conditions are to be expected on the workplace?

As already mentioned in point 1), the localized lighting is a very important factor speaking about visibility distance. This visibility is a very subjective and variable matter. Hardly anybody is going to run about the workplace with an illuminometer eliciting illumination level on the place of work.  We can say by experience that for prevailing workshop lighting without sunlight can be applied a laser up to the output of 5mW usable for distances up to 5m.


Everything depends on the current weather and quality of operator´s eyesight. We meet with cases and customers, especially during winter season by cloudy sky, the customers say a weaker laser would be also enough. On the contrary in summer even the double output seems to be deficient. The only constant background is the area without any exterior lighting, depending on artificial light sources only. 

There is no reason for fear. It doesn´t mean you are making the decision between the situation “it can be seen” or “it can´t be seen”. The line is always visible in such a workplace. Only sometime better, sometime worse, it fluctuates only depending on the weather. This problem gets especially conspicuous at the end of the 5m line in case of longitudinal material enlightenment by laser. It means from the one end to the other end. It is to be considered how often you need perfect visibility at the end of 5m distance.

3) Sort of material to be lit up

Material sort for exposure plays also a significant role speaking about beam visibility. Smooth pine-wood deals, white paper and dull smooth materials are the best choice for floodlighting. Materials such as “hairy” deals, cloth tissue, black metal sheets, rubber and materials with low light reflections are worse for this purpose. There is necessary to add about 25% - 50% of power. The worst for the floodlighting are the glossy surfaces, e.g. chromium-plated surfaces or burnished stainless steel. It is necessary to add till 100% power for the same distance as mentioned for materials in the first group. It is recommended with these materials to use a green laser for the lighting distances over 1m. Human eye distinguishes a line on such a material better than in case of red laser.  

4) Climatic effects on workplace - operational temperatures

Laser diode belongs among the semiconductor devices very temperature sensitive. The common cheap diodes can stand the temperatures from -10°C up to + 35°C. The better ones survive the temperature from -15°C up to +45°C. Very high quality and expensive diodes are able to resist even -20°C up to +80°C. The “rather better” diodes, in range of -15°C up to +45°C, are most suitable for our climatic Conditions.

Placement of a laser is very important for its working life. It means its situating in the open air or in a bounded space protected from freeze in winter and from extreme high temperatures in summer. The best is the so-called room temperature within 18°C - 22°C for the laser.

Indicated temperatures, given on all technical sheets (unless otherwise agreed) in this country and all over the world too, is relevant to diode-temperature. It means, e.g. in this country, that with the laser with persistence of +45°C is a real, by customer measurable, temperature on the laser outside about +42°C. This temperature means already emergency conditions! Reaching of such a temperature results in rapid degradation of the laser diode and its weakening. It is therefore advisable to prevent this state using cooler or another acceptable regulation influencing outside temperature. See section 7 as well as Chart of service life.

With our red lasers, class up to 5mW (applies to versions for 12V up to 24V AC/DC, at versions with convertor for 6V up to 30V AC/DC the problem is practically avoided) is installed emergency reverse thermal fuse which cuts down the laser performance until the laser gets colder to an acceptable temperature. We call attention to the fact that we describe the Emergency conditions and multiple repeating of this stadium results, out of doubt, to the damage of the laser diode. Likewise the laser running under these conditions of the “poor beam” and at the same time laser being very hot for a period of tens of minutes results also to the destruction of the laser diode. For damage like this no guarantee is granted all over the world.

The similar situation occurs with the laser which is overcooled under the temperature of
-15 °C. It can, owing to the short circuit, immediately blow out. 

All our industry lasers are resistant against water, snow, dust, wind, shocks and minor vibrations. Lasers meet requirements of minimum IP code of IP65 and more.

5) Available sources of supply voltage and their distance from laser

Prior to your purchase order, will you please make certain what possibilities for laser power supply are there on your workplace. We produce our lasers up to 10mW output on 3VDC=; 5VDC= (also for USB); 12V AC/DC; 24V AC/DC; as well as Universal with DC/DC converter for 6-30V AC/DC. Sophisticated lasers over 16mW can be supplied within the voltage from 9V up to 24V DC or from 9V up o 17V AC.

Will you please also make sure about the cable length, needed from the laser to the feeding point. Normally we have been producing the cable length of 3m, 6m and 10m. Nevertheless we can make for the cable of any length up to 100m for a very friendly price.

We always recommend models with internal stabilization, protection against reversing of polarity and overheating for the applications in industry. Fit for 12V or 24V AC/DC, preferably however with DC/DC convertor fit for 6-30V AC/DC.

We are able to provide you also with a suitable feeding adapters fit for concrete models. We can directly connect, or enclose by request, for you the needed link connectors. Where it is impossible to make use of net energy sources we shall help you using our battery source with waterproof switch.

6) The needed quality of laser beam, e.g. angle or thickness of line

We are able to focus the laser beam variously according to your wish. It is possible for us to focus the laser in that way that line or point is in the desired distance narrow or small to the most. The most of with us produced lasers operates with output angle of 70°. Reason for it is plain enough, the relation between angle and the amount of on line creating surface incident light is most optimal. This system suits to majority of application required by our customers. We shall adjust you free of charge the output angle from usual 70° to 35°, 45°, 85°, 110° or to extreme 130°. We can offer you also various unconventional light shapes such as cross-lines, disc, various screens and others.

Why don´t run after a big laser beam fan angle.

It is always better to find a proper place for laser fixation with smaller fan angle, than to want at any price a laser with a large beam fan angle.
The reason is the arrangement of laser light output along the Gaussian curve. The line is most distinct in the middle because outwards it becomes more and more feeble. The bigger the beam fan angle the less it is visible at the periphery. See figure Arrangement of laser output with different beam fan angles.

Here you can find a simple guidance instrument to determination of laser flaring angle you need. Reference to a detailed table you can find at the end of this chapter.

Angle Alfa - height – line-length a
45° - 1m - 82cm
70° - 1m - 140cm
80° - 1m - 167cm
110° - 1m - 285cm
115° - 1m - 313cm

When lightening lengthways it is possible to comprehend with a smaller angle a longer distance (line-length a).
Angle Alfa - height v – line-length a
45°  - 1m - 100cm
50°  - 1m - 119cm
60°  - 1m - 173cm
70°  - 1m - 274cm
80°  - 1m - 567cm

When lightening lengthways it is also possible, on condition that the laser is placed only a very small distance in front of the surface you need to lighten (Z=20cm), with a smaller angle to achieve even a longer distance (line-length a).

Angle Alfa - height v – line-length a
45°  - 1m - 129cm
50°  - 1m - 162cm
60°  - 1m - 273cm
70°  - 1m - 623cm

If you are lazy to calculate all of that, here is a synoptic table for you:

tables of exposure triangletables of exposure triangle

7) Laser operating mode and laser service life.

7) Laser operating mode and laser service life.

There is schematically imaged dependence of life-time on diode temperature in the enclosed diagram. Will you please take it as informative only. It not a mere laboratory output but there is also our practical experience in it. 

Almost all of red industrial lasers are for non-stop operation designed. The most suitable however are lasers with DC/DC converter fit for 6-30V AC/DC, because they heat up very little of self-operation. At the models, where this is not the case, it is noted in technical specifications. 


Nevertheless every laser has its number of hours it should endure to operate prior the moment the laser diode is totally burnt out. It is usually more than 5000 life-hours, considering running temperature of about 20°C.  There is no problem with switching the laser often off and on - it plays no role in its life-time. These lasers are able to manage more than 20 000 cycles. So we recommend to you switching them off, unless you need them to be lighting. In this way you will enjoy a significant life-span extension of your laser by reason that it wears not so much. Laser can be compared to a candle. The candle can also get flamed up thousand times but with the life-time of candle at burning happens nothing.  

8) Shape of the laser beam

8) Shape of the laser beam

Most frequent shape is a point or a line. Someone requires cross and it is also possible to design by use of diffraction optics a number of other shapes. Grid density or various sizes and dot-numbers can be chosen from various shapes and numbers of lines. We shall make for you the special lasers like these after having consulted your needs and ideas with you. They can´t be ordered from day to day, the delivery time is 14 days as a minimum. It is also necessary to take into account that the price of one piece of optic can be the same as the price of two or three Standard industrial lasers. These optical items pay to be bought only with bigger series, more than 10 pieces. 

Beam shapes possible to be done as custom-made

9) Safety at work

9) Safety at work

The lasers are sub-classified in light of labour protection. Each of classes has its own laser emission limits as well as well-defined risks when working with each concrete laser class. There are firstly following classes to be found in our offer: 1M, 2, 2M, 3R, 3B.

It is necessary to have in mind that the risks in Standard IEC 60825-1 are specified exactly for spot lasers. With dot pitch 1mm2 (the diameter makes then 1,128 mm with circular beam section). In case of using optic e.g. for a line, there is perceptible decreasing output incident on surface with accruing distance. Herewith, there is also decreasing the risk of retina damage.
 
Simplified safeness example:
Class 3R is max 5mW in visible spectrum at spot-laser (with the spot-surface of 1mm2) . There is no need to use protective aids there is a natural eye-wink reflex enough for us to get protected. This reflex disallows limit violation of incident terminal energy of 0,25mJ/mm2 in 0,25s on eye-retina. A simple head distract out of the laser beam is also enough.

We however need to make use of a stronger laser of 100mW, which belongs to the class 3B if it is a spot-laser, but we are going to work with a line-laser. Considering theoretically that the line is 1 mm thick we can, by means of simply division of line length and output, find out an approximate(*) effective power impinging on the surface 1mm2. Then, providing the line is 100mm long and 1mm thick, on 1mm2 surface impinging value amounts approximately 1mW only  (100mm / 100mW = 1mW/mm2). For safety reasons we multiple 2x see (*). Well, the result is 2mW/mm2 provided the line is 10cm long! It is ca. in distance of 5cm from the laser optical system and emissive angle 90°. We are therefore “with our hazard” deep in the class 3R, not too far from the class 2M (class 2M= max 1mW). Dangerous hazard threatens therefore at very close view only, namely at the distance of few centimetres only between laser and eye.

In spite of that I recommend in any case not to depreciate the risk. I want only to call your attention to the fact that the risk is restricted and it occurs under certain circumstances only. Much greater danger is presenting by children and intoxicated as well as impaired persons. They are even able to compete for that “who outstay it…”.

(*) – it is approximate therefore because the output is distributed unequal, according to Gausov-curva (see art. 6). Therefore on the margin of the line there is less light than in the centre. It is desirable for this reason to multiply at least two-time to obtain the brightest point and a safe reserve. 

You can find detailed specification for the single classes in the appended table.

ES declaration of conformity

ES declaration of conformityThere is made out CE declaration of conformity for each of our lasers. Receipt of its delivery creates a part of each laser-manual. We shall make out a copy of this declaration for each of our customers, if required

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