Frequently Asked Questions
Answers to some of the most often questions that we are asked:
Do I need a licence to use a laser in the UK?
- No, you can use any size laser without the need for any form of licence. The only thing you need is to make sure that the laser projector has all the necessary safety features required present, and it is used responsibly.
What are the regulations I follow now HSG95 has been removed?
- The Control of Artificial Optical Radiation at Work Regulations http://www.legislation.gov.uk/uksi/2010/1140/contents/made
- The British Standards Guidance on Laser Display Safety https://shop.bsigroup.com/ProductDetail?pid=000000000030171733
- PLASA Laser Show Safety Guidance https://www.plasa.org/guidance-for-display-lasers/
What is the HSG95 document and where can I get hold of a copy?
- The HSE document HSG95 was withdrawn, but has been replaced with online details "The Safety of laser lighting displays", which aims to help laser users to procure, install, operate and manage laser lighting displays in the entertainment industry. https://www.hse.gov.uk/pubns/indg224.htm
Do I need to prepare an installation record for every show I perform?
- It is wise to keep, written documentation of any laser installation for any future request.
Can anybody operate a laser?
- Only people with a knowledge of how to competently operate the laser system, and know what safety measures need to be considered should operate a laser display system. When you purchase a system, the company you purchase from needs to advise you on how to install and operate the system, and advise on safety issues. Laser safety training courses are offered by www.lvroptical.com, which are specific courses run for those involved with lasers and the entertainment industry.
Why does a laser system need to have a key?
- The Key Switch is there to prevent unauthorised people from using the laser. It is required under BS EN 60825-1:2014 Safety of laser products. Equipment classification and requirements.
Can the laser be left running unattended?
- The types of lasers used for laser shows should have someone in attendance, monitoring the show, at all times the laser is operational.
What does the term "divergence" mean?
- Divergence is the term used to describe how quickly a laser beam spreads out. The unit of measurement is normally expressed in terms of milli-radians (mr). The smaller the number the less the beam spreads out.
What does the term "wavelength" mean?
- Wavelength is used to describe what frequency(s) of laser radiation is emitted from the laser system. If the wavelengths are in the 400nm to 700nm range, humans can detect different wavelengths as being different colours. Common examples are 532nm for DPSS green lasers, and 630nm for red diodes.
What does irradiance mean?
- Irradiance is the term used to describe the density of laser power per unit area. Basically it is the power of the beam divided by the area that it covers. As the beam extends further from the projector, the cross-sectional area of the beam increases because of the divergence of the beam. The increase in area, causes the irradiance (power density) to decrease. This is why it is safer to view laser beams over a longer distance. The units for irradiance is watts per square meter (wm-²).
What does Maximum Permissible Exposure or MPE mean?
- The Maximum Permissible Exposure level or MPE is the scientifically researched threshold whereby the laser radiation exceeds safe levels, and would cause harm to human tissue. There are two main MPE levels, one for skin and one eyes. As eyes are far more susceptible to damage and require less radiation to cause damage, in light show applications the MPE levels for the eye are the most important values to consider. The Laser Safety Standard BS EN 60825 includes tables which detail the applicable MPE levels for the various situation that can occur in laser light show use.
What harm can a laser cause to the human eye?
- It depends upon the length of the exposure and how intense the laser beam is. In severe circumstances it can cause a complete loss of vision to the central part of your vision, which is used to pick out detail. It's fairly random as to how much and to what extent the damage occurs, which is dependant upon how quickly the eye reacts, and how powerful the beam entering the eye was. If a laser beam is in excess of the MPE the chances of sustaining an injury are increased. The injury may may go unnoticed if it hits part of the eye's peripheral vision. However if a hit is taken in the main part of the eye's vision (the fovea) the person may experience little blind spots in their vision, making it difficult to read text for example. IMPORTANT: Any damage caused to the eye's retina is permanent.
Is there a test I can do to check my eyesight?
- If you are working with lasers regularly you should have your eyesight checked by an ophthalmologist, who will be able to analyse the eye's retina, and check for damage. There is a simple test you can perform to get an idea of if you have any problems with your eyesight, which is the Amsler Grid vision test. Of course, this test should not be used as a substitute to seeing a qualified specialist if you want to have your eyesight tested.
Is is okay to point single beams of light above the audience?
- Yes, as long as it is not reflected back down into the audience, and is terminated correctly. It is safe to project virtually any laser effect 3m above the audience.
Is it okay to point beams of light into the audience?
- No, only if the beam's irradiance is below that of the MPE can it be projected into the audience. Most of the time, with the lasers that are used for laser displays, the energy of a single beam is way in excess of the MPE, and should not be directed into the audience. If more than 1mW can enter the eye then the beam is unsafe.
Are there any dangers from effects scanned above the audience?
- Laser effects projected 3 meters above the audience are eye safe. A survey should be taken to assess the likelihood of any reflective surfaces (such as high windows, chrome bars etc) which could bounce stray beams back down into the audience.
What is a Beam Mask?
- A Beam Mask is a physical barrier that is placed in the exit window of the laser projector to prevent laser beams from straying into unwanted areas, such as the audience, if no audience scanning is permitted.
Can I use electrical or gaffer tape to make a beam mask?
- The beam mask should be made from a solid material such as blackened aluminium, that can absorb the laser radiation without breaking down. The mask should be secured to the projector so that the possibility of any unwanted movement is eliminated. It is not suitable to use tape over the window to create a mask. Laser beams can often melt their way through tape, and there is also the portability that the tape will peel off.
What does the term audience scanning mean?
- It is when a laser effect is directed into the audience, normally to create a tunnel or sheets of light that look like 3D objects that the crowd can touch.
Is it legal to audience scanning?
- There is no law that specifically states that it is illegal to audience scan. But if you do scan laser effects into the audience, you need to be certain that the MPE is not being exceeded. If the MPE is exceeded there is a risk of members of the public sustaining eye injuries caused by the laser - which could lead to all sorts of consequences.
Are some effects more suited to audience scanning than others?
- Yes, effects that include stationary or slow moving beams should be avoided at all times. If you can see the beam moving through the path it is taking, it is almost certainly too dangerous to project into the audience. You should also avoid projecting effects that contain hot spots or dwell points in them. That is where extra points are put into certain parts of the effect to help define a sharp corner etc. The energy present on these types of effect is not evenly dispersed and the hot spots may be hazardous. Smooth flowing effects such as a circular tunnel are safer, because they maintain a more constant speed. Additionally if you keep the whole effect panning over the audience, it helps to reduce the amount of time the laser beam is in any one persons eyes.
Does scanning the effect at a faster speed make things safer?
- Not really, it makes the effect scan past the eye quicker, but it also makes it scan past the eye more frequently, therefore making the dose of laser energy approximately the same.