Tuesday, April 23, 2013

Pros and Cons of Laser Grids

The use of Laser Grids became popular with ghost hunters in America after a popular ghost show highlighted them on several episodes. 

When using them the basic concept is to set them up in a room or hallway with a video camera pointed in the same direction in order to capture any shadow, movement, shape etc. that passes by. If this grid of dotted lights is broken or blocked out it might mean that something paranormal has been captured.

The best-case scenario is that the lights that are not blocked out in this light grid will outline some kind of human form. 

More often than not the evidence that is captured does block out some of the lights within the grid but I have never seen anything that looks like a “human form”. 

This does not mean something was not captured. Many believe paranormal activity does not take on the standard stereotyped human form. For instance, it could be a thick mist etc. that is blocking out part of the laser lights.

Having said the above let me note that the “kind” of evidence these grids may capture is not valid evidence from my perspective. The images that are captured on video have too many factors that make them questionable. 

In a darkened room with this grid displayed-- the play of light and shadow alone can trick the observers’ eye. There are also too many iffy factors when this play of light is filmed.

Whether you agree with me or not these grids present several basic drawbacks to the investigator. The cheapest version of these laser grids is the "Laser Pen" which has become a popular choice.

This option has some pros but more cons. They are small and lightweight so they are easy to transport but I feel the cons outweigh these positive features.

These pens where not developed for continuous use. This is why the button on them only can be pushed down for brief periods of time there is no on/off switch. 

Laser pens basically are a “diode pumped solid state frequency doubled”. The laser runs through a series of diode crystals and dielectric mirrors that pass through a resonant cavity. There is a filter placed behind the mirror in order to block IR radiation that eventually passes through a collimator lens.

These pens diode crystals overheat after ten minutes of continuous use. So the pen needs to be shut down for three to five minutes in order to let it cool down. 

When overheated these pens begin to fail which causes parts of the grid to start to fade--which can result in a false positive. This last factor reinforces my belief that laser grids cannot be used as valid evidence. 

If you disagree, here are some basic tips to follow when using a Laser Pen on an investigation.

Of course, you never direct the beam into someone’s eyes for this can cause damage. 

When placed on a table make sure the surface is flat so it will not roll. Place the tip out over the edge of the table so an insect cannot land in front of the beam causing a false positive. 

Never direct the beam at a mirror or other reflective or shiny surfaces. 

You should buy a pen with at least 30mW. If your pen didn’t come with a rubber ring to hold the button down you can tape the button to keep the laser on--remember to shut the pen off after each ten minutes of continuous use.

If you really love your laser keep this option in mind, there are plug in lasers on the market that have internal cooling systems so they don’t overheat. But these models are larger and much more expensive. 

1 comment:

Unknown said...

In my experience the biggest problems could be a) Movement of the laser pen that causes distortion of the grid. b) Dust particles floating into the laser beam causing fluctuations c) animals like birds etc might get harmed by the laser beam.