• Power scaling

    Keith • 08/31/2026 at 00:46 • 0 comments

    The prototype lasers are about 1 milliwatt. This is a class 1 laser (see https://en.wikipedia.org/wiki/Laser_safety).

    Military systems use about 2 to 150 kW to knock out small targets like drones. That is 2 to 150 million times larger.

    Blowing up Alderaan (assuming it is like Earth) takes about 2.49×1032 J. At these energies, you will need some good quality PPE (Personal Protection Equipment) so don't buy it from the people who supplied the UK government. 

  • Health and Safety Regulatory paperwork

    Keith • 08/30/2026 at 16:21 • 0 comments

    The bane of my life. If you are a baddie, you won't mind losing a few henchmen. Its their career choice, if you work for evil people, grisly deaths are just an occupational hazard. Deal with it. Besides, some companies have death-in-service benefits that are just to die for. 

    If you are a goodie, like Q in the Bond movies, then you have to fill in things like risk assessment forms, and the government has examples:

    https://www.hse.gov.uk/simple-health-safety/risk/risk-assessment-template-and-examples.htm

    Ironically, it is easier to do this for dangerous things than safe ones. I had to do a risk assessment for a vacuum sealing box. It was safe enough for a junior kitchen hand to use. It was a struggle to come up with possible hazards. It was heavy, so get two people to lift and move it. But what else? Don't get liquids in the electrics? Don't put pressurised aerosol sprays in there? Don't slam the lid shut on body parts?

    Fortunately, sharks with laser beams are inherently dangerous, which is their whole point, and you should have no trouble finding risks to put in the forms.

    You then have to create safety measures to avoid accidents. Or as we really know, to avoid being sued. Guard rails around shark pools, poolside areas kept dry to avoid slips, and no nameless henchmen wandering around it for no reason. No explaining evil plans to victims being lowered into their elaborate demise then leaving without making sure the job is done.

  • Ingress Protection rating

    Keith • 09/03/2022 at 22:41 • 0 comments

    Where there is electrical equipment, dust and water, there are various ratings: 

    https://en.wikipedia.org/wiki/IP_code

    IP65 is a common rating, meaning no dust gets in and protected against water jets. The IP ratings cover immersion between 1 and 3 metres, but sharks can dive as deep as 2000 m. The Great White dives down about 1200 metres. The record for human submarines is 1000 m.

    The prototype shark used is rated as hand washable at 30°C. Kitchen sink depth is -1 metre, so I believe the system is safe so long as the laser is removed while the shark is immersed.

  • Safety warning signs

    Keith • 08/28/2022 at 23:27 • 0 comments

    The lasers use AAA alkaline cells, but if a nuclear battery was used then you would need this sign:

  • Second, find your lasers

    Keith • 08/28/2022 at 23:02 • 0 comments

    Easily done, I bought a pack of three different colours for £9 with free postage from eBay.

    Image 1 - PACK OF 3 Laser Pointer Blue Green Red 1MW Powerful Cat Toy Beam Powerful Pen

    2022-09-03

    Laser arrived. 650 nm red laser very bright, 405 nm blue laser rather dim, 532 nm green laser dead. Not even a faint glow.

    This was with NiMH cells, 1.2 volts each, 2.4V total. Maybe the non-red lasers need alkaline cells of 1.5 volts each, 3V total. This had the same results.

    Swapping the battery barrel was not possible, as the green laser has a different thread. But it was possible to hold a different barrel in place long enough to verify the laser actually worked.

    Poking a screwdriver down the middle of the barrel, I managed to measure the resistance between it and the barrel as open circuit. The barrel is metal-coated plastic, maybe the coating was missing at the end. Maybe a bit of scrunched-up aluminium foil would help? Pressing this in with the batteries pushed the end of the battery barrel out, allowing a good look at the coating. My guess was right, very poor coating. Reassembled, the green laser was much brighter than the red. 

    This is a bit worrying. You might think it is cool to have a brighter laser than you paid for, but you REALLY DO NOT WANT anything more powerful than five milliwatts. One milliwatt is fairly safe, five is borderline and anything above is well dodgy. One 9-year old boy was blinded playing with a laser his mum bought from a toy shop:

    https://metro.co.uk/2018/09/05/boy-blinded-himself-after-shining-laser-in-his-eye-after-his-mum-told-him-not-to-7915033/

    It is clear that there is little or no control on the sales of lasers. The technology that makes them cheap enough to be used in consumer electronics also makes them cheap enough to be sold as toys. There are lasers for sale on eBay in the 500 or even 2000 mW range. They really ought to be made highly illegal to own without a damn good reason and strict safety measures in place. 

    DO NOT dick around with lasers. Stupid people regularly get arrested for shining lasers at people or aircraft. They are not toys for playing with cats either.

    https://www.gov.uk/government/publications/laser-radiation-safety-advice/laser-radiation-safety-advice

    Another reason for the relative brightness of the green laser is that the human eye is more sensitive to green:

    LEDs Are Still Popular (and Improving) after All These Years - Tutorial ...This graph shows green appears about ten times brighter than red. The 'blue' laser of 405 nm is in the very insensitive zone, and looks more like purple.

  • First, find your sharks

    Keith • 08/28/2022 at 22:50 • 0 comments

    A full size shark presents a storage problem, being up to 6 metres and 2 tonnes. My bath is less than 2 meters long, and I need it for washing myself in. My loved ones will go chimpy no matter how reasonable my explanation is. I live in a small flat, not a hollowed-out volcano with plenty of space.

    All the sources available to me supply fish dead and filleted. I said "I want a whole live shark, and make it snappy!". All I got was funny looks. They said "We're gonna need a bigger fish van..."

    Famous Lines in Movies that were Actually Improvised - "You're Gonna ...

    So I looked for a scaled-down shark. The first alternative I found had forward-facing eyes which is good in a predator. $30 Canadian dollars from https://snugasabug.com/shark-puppet/ but will take time to get to the UK.

    The second alternative was available locally, https://www.hobbycraft.co.uk/fiesta-crafts-shark-hand-puppet/6393911000.html, so I bought one.

    My neighbour's cat, Gimli, didn't find this menacing at all.

    Disappointing, but it is only a prototype.