The 13th Southern Star Party. The first to be held at Leeuwenboschfontein: Wednesday 22nd of February to Monday 27th February 2017.

The first Southern Star party held at Leeuwenboschfontein was a success. So, any suspicions about unlucky 13 were neatly sidestepped or perhaps the jinx only applies to people who suffer from triskaidekaphobia.

TOP: The barn with the display tables on the left, the lecture area in the centre and the kitchen on the right. 2nd FROM TOP: Our pull-up banners and some of the posters. 2nd FROM BOTTOM: This banner is always a showstopper. BOTTOM: The group at the opening.
TOP: The barn with the display tables on the left, the lecture area in the centre and the kitchen on the right. 2nd FROM TOP: Our pull-up banners and some of the posters. 2nd FROM BOTTOM: This banner is always a showstopper. BOTTOM: The group at the opening.

Lynnette, Snorre and I arrived on Wednesday the 22nd, downloaded our stuff at Dalzicht and set about getting the shed converted into a lecture area with a display section. Fortunately, their spacious kitchen made organising the coffee area very easy.

And here we all are. You can figure out who’s who on your own. I gave up putting in the names because we are not standing in nice neat rows and I could not make my list of names match the people in the photograph.
And here we all are. You can figure out who’s who on your own. I gave up putting in the names because we are not standing in nice neat rows and I could not make my list of names match the people in the photograph. Six people could not make it for the group photo.

Who attended:

Jim Adams (speaker), Jonathan Balladon, Deon Begeman, Ronelle Begeman, Steyn Botha, Samuel Botha, Dominique Brink, Johan Brink, Nellie Brink, Anja Bruton, Alan Cassells, Rose Cassells, Pamela Cooper, Chris de Coning, Micah de Villiers, Pierre de Villiers, Barry Dumas, Miemie Dumas, Clair Engelbrecht, Dwayne Engelbrecht, Arné Esterhuizen, Iain Finlay, Edward Foster, Lynnette Foster, Louis Fourie, Maureen Helman, Cheyenne Kersting, Christine Kersting, Harald Kersting, Jamie Kersting, Evan Knox-Davies, Dianne Nxumalo-Kohler, Robin Kohler, Bennie Kotze, Paul Kruger, Lia Labuschagne, Eddy Nijeboer, Jannie Nijeboer, Lorenzo Raynard (speaker), Kim Reitz, Marius Reitz, John Richards, Rogan Roth, Johan Roux (Jnr), (Johan Jnr’s wife), (Johan Jnr’s eldest son), (Johan Jnr’s 2nd son), Alecia Roux, Henda Scott, Barry Shipman, Auke Slotegraaf, Corne van Dyk, and Chris Vermeulen, Alex Wright.

Some of the keen people pitched on Thursday and among them were Deon and Ronelle Begeman. Deon had, as promised at the previous SSP in Bonnievale, constructed two magnificent binocular viewing tripods for Auke and myself.  This is really quite an ingenious device with many improvements over what is currently on the market and it is very reasonably priced too when compared to its competitors. I will do a separate post with pictures about it at a later stage.

What a super way to advertise the Star Party against the backdrop of the busy telescope area and Leeuwenbosch’s starry skies.
What a super way to advertise the Star Party against the backdrop of the busy telescope area and Leeuwenbosch’s starry skies.

On Thursday evening Paul and I went up Swartberg in his 4×4.  It was a whole lot easier than walking up but also considerably more taxing on one’s nerves and I am not implying that Paul drove recklessly; quite the contrary. It is just that the vehicle adopts a wide variety of very unusual angles during both the ascent and descent and one has to trust the driver a whole lot more than when driving down a normal road.

TOP: I cannot recommend a visit to the hut on top of Swartberg strongly enough. This shot shows the hut in the first rays of the rising sun. CENTRE: looking east down the Nouga Valley in the early morning with smoke from the extensive veldt fires packed in the valleys. BOTTOM: Early morning looking south-west from the hut. The Langeberg lies on the far horizon and the tiny white spike of a microwave tower is just visible at the top of Rooiberg Pass.
TOP: I cannot recommend a visit to the hut on top of Swartberg strongly enough. This shot shows the hut in the first rays of the rising sun. CENTRE: looking east down the Nouga Valley in the early morning with smoke from the extensive veldt fires packed in the valleys. BOTTOM: Early morning looking south-west from the hut. The Langeberg lies on the far horizon and the tiny white spike of a microwave tower is just visible at the top of Rooiberg Pass.
Christine took this from the lawn in front of De Oude Opstal just to prove that Paul and I had been on top of Swartberg. Thanks Christine for sharing.
Christine took this from the lawn in front of De Oude Opstal just to prove that Paul and I had been on top of Swartberg. Thanks Christine for sharing.

TOP LEFT: We had some magnificent thunderclouds on Thursday. TOP RIGHT: Paul snapped his first lightning bolt from the top of Swartberg. BOTTOM LEFT: Paul’s night shot of the Leeuwenbosch complex from the top of Swartberg. BOTTOM RIGHT: Paul’s early morning shot of the hut and his pickup.

TOP LEFT: We had some magnificent thunderclouds on Thursday. TOP RIGHT: Paul snapped his first lightning bolt from the top of Swartberg. BOTTOM LEFT: Paul’s night shot of the Leeuwenbosch complex from the top of Swartberg. BOTTOM RIGHT: Paul’s early morning shot of the hut and his pickup.

Arne and Alex had their vehicle expire on the R318 while on the way to the SSP, but they were picked up by Evan and brought to Leeuwenboschfontein. The two seemed pretty laid back about leaving the car at the side of the road until Monday when they would set about sorting it out from Cape Town.

TOP: The group attending Deon’s presentation. BOTTOM: Deon and his very good representation of the Milky Way.
TOP: The group attending Deon’s presentation. BOTTOM: Deon and his very good representation of the Milky Way.

The beginner’s session at the telescopes was quite successful on Friday as was the beginners talk on Saturday morning.

TOP LEFT: How much traffic is there in the telescope area during a star party. This tangle of lights against the star trails in the background, as captured by Auke, should give you a good indication. TOP RIGHT: Taken from a different perspective by Auke and showing the south celestial pole very nicely is a second view of the telescope area. BOTTOM LEFT: A less cluttered short exposure of the telescope area showing Leo rising in the east. BOTTOM RIGHT: There are some very rare beings prowling the telescope area at night, as this shot would seem to prove. In real life, Eddy is not nearly as daunting I assure you.
TOP LEFT: How much traffic is there in the telescope area during a star party. This tangle of lights against the star trails in the background, as captured by Auke, should give you a good indication. TOP RIGHT: Taken from a different perspective by Auke and showing the south celestial pole very nicely is a second view of the telescope area. BOTTOM LEFT: A less cluttered short exposure of the telescope area showing Leo rising in the east. BOTTOM RIGHT: There are some very rare beings prowling the telescope area at night, as this shot would seem to prove. In real life, Eddy is not nearly as daunting I assure you.

Jonathan had to leave suddenly on Saturday morning as he was needed to fly a plane somewhere.  He promised he would flash his landing lights if his route took him over Leeuwenboschfontein which it apparently didn’t.

TOP LEFT: Part of the smallish group. TOP RIGHT: Me demonstrating the Southern Star Wheel. BOTTOM LEFT: Samuel and Steyn. BOTTOM RIGHT: Steyn on the left, John in the background on the right and Henda up front.
TOP LEFT: Part of the smallish group. TOP RIGHT: Me demonstrating the Southern Star Wheel. BOTTOM LEFT: Samuel and Steyn. BOTTOM RIGHT: Steyn on the left, John in the background on the right and Henda up front.

During my beginners’ session on Saturday morning, Jim Adams, retired Deputy Chief Technologist at NASA and Anja Bruton Science Engagement Coordinator at the SKA arrived. The problem was that Lorenzo Raynard Communications Manager at the SKA, who was due to give the first talk had not pitched and all efforts to contact him were unsuccessful. Jim, hearing of our predicament, very kindly agreed to give the talk he was scheduled to give that afternoon in Lorenzo’s slot. So we started off with “Spinoff: How investing in astronomy and space science changes life on Earth”. Jim proved to be every bit as good a speaker as Anja had said he was; relaxed, knowledgeable and very good at fielding questions too.

In the meantime, Lynnette and Anja were frantically trying to trace Lorenzo.

Martin Lyons and his wife Pat flew in (literally) especially for the social braai in the lapa at the campsite during lunchtime on Saturday.  They stayed until after lunch and then flew home again. According to Paul and Louis, the takeoff was actually quite tense but Martin, during subsequent discussions, downplayed any suggestion of problems.

Just before the braai the Vito was attacked by a vicious tree and lost its back window.

The Vito was the victim of an unfortunate incident just before the braai on Saturday when it was attacked by one of the vicious trees at Leeuwenboschfontein.
The Vito was the victim of an unfortunate incident just before the braai on Saturday when it was attacked by one of the vicious trees at Leeuwenboschfontein.
TOP LEFT: Eddy and Jannie. TOP CENTRE: Louis and Deon. TOP RIGHT: Cheyenne Kersting CENTRE LEFT: Alex and Arne BOTTOM LEFT: Chris de Coning RIGHT: Micah and Auke.
TOP LEFT: Eddy and Jannie. TOP CENTRE: Louis and Deon. TOP RIGHT: Cheyenne Kersting CENTRE LEFT: Alex and Arne BOTTOM LEFT: Chris de Coning RIGHT: Micah and Auke.
TOP: Corné hard at work. CENTRE: A relaxed group outside with Alan and Rose who drove through to visit for the day. Thanks, guys! BOTTOM: Is Louis explaining where to find the stars? We will have to ask Bennie.
TOP: Corné hard at work. CENTRE: A relaxed group outside with Alan and Rose who drove through to visit for the day. Thanks, guys! BOTTOM: Is Louis explaining where to find the stars? We will have to ask Bennie.
TOP LEFT: Claire and Dwayne relaxing. TOP 2nd FROM LEFT: Barry and Miemie. TOP 2nd FROM RIGHT: A Cape Centre group tucking in. CENTRE LEFT: Alan’s version of the Polynesian fire poi possibly needs some practice. CENTRE: Myself, Lynnette and Jim. CENTRE RIGHT: Kim and Marius. BOTTOM LEFT: The Kerstings. BOTTOM RIGHT: Micah and Chris.
TOP LEFT: Claire and Dwayne relaxing. TOP 2nd FROM LEFT: Barry and Miemie. TOP 2nd FROM RIGHT: A Cape Centre group tucking in. CENTRE LEFT: Alan’s version of the Polynesian fire poi possibly needs some practice. CENTRE: Edward, Lynnette and Jim. CENTRE RIGHT: Kim and Marius. BOTTOM LEFT: The Kerstings. BOTTOM RIGHT: Micah and Chris.
TOP LEFT: Chris. TOP CENTRE: Jannie and Eddy. TOP RIGHT: Henda. CENTRE: Lia and Paul. BOTTOM LEFT: Lia. BOTTOM CENTRE: Evan and Jim. BOTTOM RIGHT: Alan and Rose.
TOP LEFT: Chris. TOP CENTRE: Jannie and Eddy. TOP RIGHT: Henda. CENTRE: Lia and Paul. BOTTOM LEFT: Lia. BOTTOM CENTRE: Evan and Jim. BOTTOM RIGHT: Alan and Rose.

By now Lorenzo had been traced and was on his way but would not make it in time for his time slot. We, or at least Anja, talked Jim into giving a second talk in Lorenzo’s slot. This talk “Robots in Space and Space Exploration; Past, Present and Future” went down very well with the audience.  Lorenzo finally pitched later on Saturday afternoon. As his talk would cut into observing time we decided to rather have him give his talk on Sunday morning.

After Jim’s talk and the lively question session we took the usual group photograph and, as is usual, some people did not pitch up. People who were absent were Jonathan Balladon, Steyn & Samuel Botha, Dominique & Nellie Brink and Lorenzo Raynard.

The group photograph was followed by the Pub Quiz which, this year, was orchestrated the usual degree of malevolence and cunning by Auke.  After several gruelling rounds the overall winner, by a very large margin was Alex.  Well done Alex, you left several past winners staggering around in your slipstream’s dust.

TOP LEFT: Jim Adams and during his first presentation. CENTRE LEFT: Handing over Jim’s speaker prize. BOTTOM LEFT: Lynnette, Anja and Lorenzo in conversation on Sunday morning. TOP RIGHT: Alex, the overall winner of the Pub Quiz, receiving his prize from Lynnette. BOTTOM RIGHT: Snorre surveying the proceedings.
TOP LEFT: Jim Adams during his first presentation. CENTRE LEFT: Handing over Jim’s speaker prize. BOTTOM LEFT: Lynnette, Anja and Lorenzo in conversation on Sunday morning. TOP RIGHT: Alex, the overall winner of the Pub Quiz, receiving his prize from Lynnette. BOTTOM RIGHT: Snorre surveying the proceedings.

The number of beginners at the telescopes on Saturday evening was disappointing but I am hoping it was the sudden drop in temperature that convinced them to stay indoors.

Paul’s star trails arch over the telescope area.
Paul’s star trails arch over the telescope area.

Lorenzo’s talk on Sunday morning. “The public face of SKA in South Africa” was reasonably well attended and, after some discussion, the great dispersal began and the site emptied fairly rapidly. This year, though, more people stayed on to observe the partial solar eclipse on Sunday afternoon.

TOP: My series of photographs following the solar eclipse with a late afternoon shot of Leeuwenboschfontein from the top of Swartberg. BOTTOM LEFT: Auke’s very artistic shot of the shadows cast by the people around the telescope. BOTTOM RIGHT: A picture of the sun through one of Chris’s filters.
TOP: My series of photographs following the solar eclipse with a late afternoon shot of Leeuwenboschfontein from the top of Swartberg. BOTTOM LEFT: Auke’s very artistic shot of the shadows cast by the people around the telescope. BOTTOM RIGHT: A picture of the sun through one of Chris’s filters.

Dwayne and Claire, who got engaged during the 11th SSP at Night Sky Caravan Farm, missed the 12th SSP because they were getting married. Now, while attending the 13th SSP, Mr and Mrs Engelbrecht announced they were expecting their first child. I suppose it will be too much to expect them to call the baby SSP, but it would be nice if they would.

On Monday morning we packed up and after Calla had very professionally helped close of and dust proof the gaping hole where the Vito’s rear window had been, Lynnette, Snorre and I also left for home.

Green Lasers in the Astronomy context

Green Lasers in the Astronomy context.

The use of green lasers by amateur astronomers has become increasingly popular since their appearance in the marketplace around 2000. Even a low-powered green laser (<5 mW) is visible at night through Rayleigh scattering from air molecules, making this type of pointer a popular tool to easily point out stars and constellations at star parties and similar astronomy related events.  There is a reasonable Wikipedia article here for anyone who wants to know more about Rayleigh scattering.

The use of these devices has been brought into the public eye and placed under the scrutiny of Law Enforcement Agencies as a result of a number of incidents here and abroad.  In other countries strong action has been taken against persons who have violated the local laws governing the use of these instruments.  It is perhaps timeous to say something about green lasers in general and the issues involved in their use, and especially their abuse.

Green laser pointers come in various classes.

Class I (1) Lasers: These are low-powered and do not emit hazardous radiation under normal operating conditions because they are completely enclosed.
Class II (2) Lasers: These are lasers that emit accessible visible laser light with power levels less than 1 mW (< 1 mW) and should not constitute a hazard if viewed briefly with the unaided eye.
Class IIIa (3A) Lasers: These are systems with power levels of 1 to 5 mW (1 mW – 5 mW) that do not normally constitute a hazard if viewed for only very brief periods with the unaided eye.
Class IIIb (3B) Lasers: These are systems with power levels of 5 mW to 500 mW (5 mW – 100 mW) for continuous wave lasers or less than 10 J/cm² for a 0.25 s pulsed laser. These lasers constitute a definite eye hazard if viewed directly even for brief periods.
Class IV (4) Lasers: These are systems with power levels greater than 500 mW (> 500 mW) for continuous wave lasers or greater than 10 J/cm² for a 0.25 s pulsed laser. These lasers constitute definite eye, skin and fire hazards.

Laws

First and foremost, pointing a laser at a vehicle, plane, boat, another person, animal and otherwise dangerous actions involving a laser are illegal and punishable in most countries.  Let’s take a look at what other requirements there are in a few countries.

Australia
Victoria, New South Wales, and the Australian Capital Territory:  Any laser pointer with an accessible emission limit greater than 1 mW is classified as a prohibited weapon and any sale of such items must be recorded.  You can read the New South Wales Police regulations covering lasers here

Western Australia: Laser pointers are classified as controlled weapons and demonstration of a lawful reason for possession is required. The State Government has, as of 2000, banned the manufacture, sale and possession of laser pointers higher than Class 2.

Canada
New regulations were introduced in 2011 to control the importation and sale of laser pointers (portable, battery powered).  These regulations prohibit the sale of Class 3B (IEC) or higher power lasers to “consumers” as defined in the Canadian Consumer Protection Act.

Netherlands
As of 1998 it has been illegal to trade Class 2 laser pointers that are “gadgets” (e.g. ball pens, key chains, business gifts, or any devices that will end up in childrens’ hands.). Trading Class 2 (< 1 mW) laser pointers is allowed, provided they meet the requirements regarding warnings and instructions for safe use to be displayed in the manual. Trading of Class 3 and higher laser pointers is provided.

Sweden
The use of pointers with a output power > 5 mW is regulated in public areas and school yards.  As of the 1st of January 2014 a special permit is required to own a laser pointer with an output of over 1 mW.

United Kingdom
The UK and Europe have now agreed on the use of Class 2 (<1 mW) laser pointers or laser pens for use in general presentations. Health and Safety regulations insist on the use of no higher than a Class 2 pointer anywhere the public can come in contact with the laser light. The Department of Trade & Industry has urged Trading Standards authorities to use their existing powers under the General Product Safety Regulations 2005 to remove lasers above Class 2 from the general market. For a general overview of the official point of view in the UK go here

Europe in general
Most countries already ban or will in the near future ban Class 3A and higher rated pointers.

South Korea
Only Class II or lower powered lasers are permitted and no lasers are allowed for children

United States
Laser pointers are defined as devices in Class II or Class IIIa producing an output beam with power less than <5 mW. U.S. Food and Drug Administration  regulations prohibit the sale or promotion of more powerful lasers, as laser pointers. All lasers in a Class higher than IIIa (> 5 mW), requires a key-switch interlock and other safety features.  Take note that the laws differ from state to state.

South Africa
Any Class 3B or Class 4 laser system must be licensed for use.

Incidents
In the recent past the number of incidents involving the improper or illegal use of lasers has increased and contributed to passing of more stringent laws and regulations.  Here are some examples to illustrate the problem

Sport
In 2008 laser pointers were aimed at players’ eyes in a number of sport matches worldwide. Olympique Lyonnais was fined by UEFA because of a laser pointer beam aimed by a Lyon fan at Cristiano Ronaldo.

In a World Cup final qualifier match held in Riyadh, Saudi Arabia between the home team and the South Korean team, South Korean goalkeeper Lee Woon-Jae was hit in the eye with a green laser beam.

In February 2009 South African cricketer Wayne Parnell had a laser pointer directed at his eyes when attempting to take a catch, which he dropped.

Aviation and law enforcement
In Canada, as of July 2011, three people had been charged under the federal Aeronautics Act, which carries a maximum penalty of $100,000 (that is ZAR963 000 on 14/03/2014) and five years in prison, for attempting to dazzle a pilot with a laser.

In 2014 in the UK, a man was convicted of recklessly endangering the lives of a police search helicopter crew with a laser, and awarded a five month suspended sentence.

In the US, according to an MSNBC (Microsoft and the National Broadcasting Corporation) report, there were, in 2010 alone, over 2 836 incidents logged by the Federal Aviation Authority (FAA).
On April 30, 2010, an Arizona resident was found guilty on two counts of endangerment which involved shining a handheld laser pointer at an Arizona Department of Public Safety helicopter. He was given a sentence of two years in prison for each count, to run concurrently.
On November 2, 2009, a Southern California resident was sentenced to 2.5 years in a federal prison after being found guilty of shining a hand-held laser light into the eyes of two pilots landing at John Wayne Airport.
In January 2005 a New Jersey man was arrested for pointing a green laser pointer at a small jet flying overhead.
If you are interested in reading a quite comprehensive summary of similar sentences in the US and elsewhere go here. 

Hazards
The question in the minds of most users of these devices is why do they have to be regulated and what dangers can they possibly pose?  Let me run you through some of the problems around green lasers.

Erroneous power rating
The classification system should mean that we can go out and buy a laser and comply with legal requirements, based on the power rating given on the laser’s label, but this is not so.  The National Institute of Standards and Technology in the US conducted tests on a selection of laser pointers labelled as Class IIIa in 2013.  Around 50% of those tested emitted power at twice the Class limit, in other words, they were Class IIIb and significantly more hazardous.  The highest measured power output was 10 times the Class IIIa limit; a staggering 66.5 mW. Furthermore, green laser light is generated from an infrared laser beam, which should always be confined within the laser housing but, in more than 75% of the pointers tested, infrared light in excess of the safety limit was emitted. You can go here to read a more comprehensive report on the testing. 

Eye injury
Laser pointers are able, over a very long range, to distract or dazzle people. Green lasers are particularly effective, as the wavelength (532 nm) is near peak sensitivity of the dark-adapted eye and may appear to be 35 times brighter than a red laser of identical power output.  Go here to read a report by the Federal Aviation Authority on this particular aspect. 

Studies have found that a low-power laser beam not > 5 mW has the potential to cause permanent retinal damage if gazed at for several seconds; however, the eye’s blink reflex makes this highly unlikely. Such laser pointers have reportedly caused afterimages, flash blindness and glare, but not permanent damage, and are generally safe when used as intended.

In 2010 a high-powered green laser pointer, bought over the Internet, reportedly caused a decrease of visual acuity from 20/20 to 20/40. Two months later the acuity had recovered to 20/20, but some retinal damage remained. The US Federal Drug Administration has issued a warning after receiving two other anecdotal reports of eye injury resulting from laser pointers.  A report from Princeton University about these and other incidents can be viewed here.

Laser pointers available for purchase online often have a significantly higher power output than the pointers typically available in stores. Sometimes referred to as “Burning Lasers”, they can burn through light plastics and paper.  The problem is that they often (deliberately) look no different from their low-power counterparts and this can be disastrous.

Studies undertaken thus far indicate that the risk to the human eye from accidental exposure to light from commercially available Class IIIa laser pointers (< 5 mW) seems small; however, intentional prolonged viewing for 10 seconds or longer, will probably cause damage.

In the UK the Health Protection Agency has warned specifically against these higher-powered green laser pointers which are readily available over the Internet.  They consider these lasers to be “extremely dangerous and not suitable for sale to the public.  You can go here to read the full text of their recommendations.

Most references to potential eye damage, when using a green laser pointer, focus on the visible light produced by the device, i.e. the green beam. This is also the widely prevalent perception amongst users of laser pointers and, although the visible beam certainly poses a threat, there is another “unseen” potential danger in the form of infrared radiation and to explain that we have to branch off into the technicalities of how the laser functions.  Infrared radiation in the wavelength range between 700nm and 1400nm is known to cause both retinal and corneal damage of a permanent nature.

How do green laser pointers work?
Most laser pointers are technically referred to as DPSSFD lasers or “Diode Pumped Solid State Frequency-Doubled lasers if you want their full title. The green light for a green laser is generated in an indirect process because laser diodes are not generally available to do so in the required wavelength range. The process is started by a high-power infrared AlGaAs (Aluminium gallium arsenide) laser diode operating at 808 nm. The 808 nm light excites a crystal of neodymium-doped yttrium aluminium vanadate (other combinations of elements are also used), which producers a laser emission deeper in the infrared at 1064 nm.

The neodymium-doped crystal is coated on the diode side with a dielectric mirror that reflects at 808 nm and transmits at 1064 nm. The crystal is mounted on a copper block heat sink; its 1064 nm output is fed into a crystal of potassium titanyl phosphate (KTP), also mounted on a heat sink, in the laser cavity resonator. The orientation of these crystals must be carefully matched, as they are both anisotropic (directionally dependent) and the neodymium-doped crystal outputs polarized light.   Go here if you want to know what polarized light is.

The KTP unit acts as a frequency doubler and, in the process, halves the wavelength to the required 532 nm (green). The final element in the resonant cavity is a dielectric mirror that reflects at 1064 nm and transmits at 532 nm. An infrared (IR) filter behind the mirror removes any stray IR radiation (808 & 1064 nm) from the output beam and the assembly ends in a collimator lens (a lens that effectively causes all the light rays to exit the instrument parallel to each other – go here to read about collimation.

The use of inadequate filters or their omission, in less-expensive “pointer-style” green lasers causes the “invisible” problem, i.e. emission of IR radiation.  The problem is especially prevalent in the high powered laser pointers available over the internet, as these lasers often originate from sources that do not follow laser safety regulations for laser manufacture, packaging or labelling.  The products are often presented in housings similar to regular laser pointers but, due to the cost and additional effort required, they have IR problems. Below is a diagram of a frequency doubled laser pointer by Chris Chen that I took from a Wikipedia article.  I am hoping it might make the explanation above a little clearer.

Green-laser-pointer-dpss-diagrams
A frequency-doubled green laser pointer, showing internal construction. Diagram credits to Chris Chen & Wikipedia

Although the infrared output in these pointers is not collimated it does actually produce a beam of IR light, predominantly at 808 nm.  This poses a relatively low risk in green laser pointers with outputs < 5mW, because its intensity is low and the brightness of the visible (green) component will normally cause the eye to blink involuntarily before any damage can be done.

However, higher-powered (> 5 mW) green laser pointers, with inadequate or totally absent IR filters, are another matter entirely because, in these higher powered units, the IR laser output can be quite significant.  Ironically this unfiltered IR output is especially hazardous when laser safety goggles are worn, because they block only the visible output of the laser (the green). The IR light will pass right through and, because the pupils are probably completely dilated, the invisible IR light becomes an even greater risk factor. Dual-frequency YAG (Yttrium aluminium garnet) laser eye-wear is significantly more expensive than single frequency laser eye-wear.  It is doubtful if this type of eye protection will be supplied with unfiltered, pointer style, green lasers which output 1064 nm as well 808 nm IR laser light.  For those readers interested in more information about potential IR damage to the eyes please go to this article from the Intersil Corporation.

Star People & ELF Astronomy policy on the use of green lasers.
After all that, what position does ELF Astronomy and Star People take on the question of lasers used at events that we organize.  Our position is that there is a law and we have, we think, given adequate reasons here why that law should be adhered to.

Policy statement
Any Class 3B or Class 4 laser system at the event must be licensed for use.  Attendees at events organized by either Star People or ELF Astronomy are encouraged to register their unregistered laser products.  It is currently free to do so.

Details on why you need to register your green laser are explained by the following two references:

  1. Green lasers – responsible use and registration is discussed in detail on Auke Slotegraaf’s excellent site and you can go here to read all about the issue
  2. The issue was also discussed in detail at a laser workshop during the 2011 ASSA Symposium and is summarised here on the website of the Pretoria Centre of ASSA.

Note that

  1. At any and all events organised by either Star People or ELF Astronomy, the organisers will be liable, in accordance with the Occupational Health and Safety Act (Act 85 of 1993), for any incident during the event.  Star People and ELF Astronomy, therefore have to define the “laser rules” for these events and act accordingly.
  2. Star People and ELF Astronomy have the right to confiscate (store in a ‘safe” position) any non-compliant laser pointer used at all events organised by us.

Additional essential information

To apply for a license download the  form here.  Once you have filled it in you should e-mail it to Johan Uys, at UysJ@health.gov.za.  Johan is employed by the Department of Health and can also be contacted at 021 957 7450 during office hours.

The Department of Health’s Directorate of Radiation Control has made available a comprehensive document entitled “Requirements for the Safe Use of Class 3B and Class 4 Lasers or Laser Systems”  can be downloaded here.