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Is a laser flashlight a "laser" in California?

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In December 2021, a defense lawyer in California contacted LaserPointerSafety.com. Their client was a person with no criminal history who was charged with a felony for pointing the light from a Weltool W4 LEP flashlight (shown above) at a police helicopter. Such a flashlight has a "laser excited phosphor." In an LEP, the emitted light comes from the glowing phosphor material and not directly from the laser.

The lawyer asked whether the Weltool W4 was a "laser" under California law; specifically,
Penal Code section 247.5.

Below is a screenshot from the
Weltool W4 product page, and then our response to the query.

W4 product page screenshot

Screenshot captured January 11, 2022

Our response

The short answer is that whether the Weltool W4 LEP flashlight is a laser depends on the exact definition of "laser". In the W4, the original light is from a laser. This is then aimed at a glowing surface ("emitting phosphor") to create the light that actually exits the flashlight lens. The light coming from the phosphor -- and thus the light "discharged" towards an object such as an aircraft -- is not what most scientists would call "laser light".

Specifically, the light emitted from the W4 device is not spatially or temporally coherent, either or both of which would be required to be laser light.

Here are some details.

Scientific background

"LEP" refers to a "laser excited phosphor". One definition is "the process of emitting a blue laser through a focused lens onto a phosphor element backed by a metal substrate. The laser is then reflected (bounced) off the phosphor and converted to broad-spectrum light. In a flashlight, the resulting white light is directed out the end via a series of lenses." The linked page has a diagram which shows the light production process:

LEP laser excited phosphor diagram

Identical or similar processes are also used in many other laser-generated lighting devices other than LEP flashlights, such as:

  • Laser illuminated video projectors (LIPs), which range in price from office models at about $800 to many tens or hundreds of thousands of dollars for cinema-quality laser movie projectors.
  • Laser pumped lamps (LPLs) including laser headlights on vehicles.
  • Laser illuminated lighting instruments (LILIs) used at concerts such as the 2020 Super Bowl halftime show with Shakira and Jennifer Lopez.
In all of these devices, a laser starts the process but what emerges from the working end (lens, headlight, flashlight, concert light) is non-laser light. While the light is very bright, the emitted light would not be considered laser light.

The California definition of "discharge"

California Penal Code Section 247.5 starts out "Any person who willfully and maliciously discharges a laser at an aircraft..."

So one question is whether the "discharge" is from a laser.

The W4 "discharge" beam is not a laser beam. The W4 beam has high light intensity. But intensity alone does not make it a "laser beam".

The W4 beam does not have other laser characteristics such as monochromaticity (being one very specific wavelength [color]). It is not spatially coherent since the beam is much more divergent than a laser beam, spreading out roughly 20 times wider and faster. The W4 light does not have the shimmering, sparkling "speckle" which is a distinguishing characteristic of coherent laser light.

One photo at the W4 webpage shows a white beam being emitted. That indicates the beam is not laser output since a laser emits only one color, or a few very specific colors. (It is possible to mix multiple lasers to get white light, or to use special processes, but the W4 info states it is a blue laser. The white comes from shining the blue laser onto the phosphor, which stimulates or "excites" it into emitting a wider range of wavelengths.)

It is possible to purchase the W4 with a yellow beam, as shown in another picture on the webpage. This does not indicate the output is as temporally coherent (monochromatic) as a yellow laser's output would be. The W4 could just be from using a different type of phosphor.

The California definition of "laser"

The last paragraph of Section 247.5 defines the word laser thusly: "As used in this section, 'laser' means a device that utilizes the natural oscillations of atoms or molecules between energy levels for generating coherent electromagnetic radiation in the ultraviolet, visible, or infrared region of the spectrum, and when discharged exceeds one milliwatt continuous wave."

In that sense, the W4 device definitely meets the first part of the definition. There is a laser diode inside which does utilize "the natural oscillations of atoms or molecules between energy levels for generating coherent electromagnetic radiation in the ultraviolet, visible, or infrared region of the spectrum...."

The second part is trickier. The incoherent, non-laser light coming out of ("discharged") from the W4 exceeds "one milliwatt continuous wave." It is certainly brighter than a 1 mW small, bullet-shaped, pet store laser pointer costing a few dollars. It is not clear whether the term "one milliwatt continuous wave" can be meaningfully applied to laser-generated incoherent light which is not generally characterized by the term "continuous wave," or whether "continuous wave" only applies to actual laser beams.

To summarize, the last paragraph of Section 247.5 seems to define the a key part of the device as a "laser". However, the beam that is emitted is not laser light as discussed earlier.

W4 product info and marketing

The W4 product information and documentation at their webpage indicates that Weltool is treating the W4 ONLY as a laser device. The Product Owners Manual shows only a standard laser safety warning label, with the laser danger triangle, Class 3B indication, and "avoid exposure to beam" text and graphic.

Similarly, when the box is opened as described in the review here, there is the same laser safety warning label.

There is no indication of the W4 being assigned an IEC 62471 lamp device safety standard "Risk Group" which is used for high-powered lamps as well as LIPs, LPLs and LILIs. If the W4 did state a Risk Group, that would indicate the manufacturer considers this as a "laser product designed to function as a conventional lamp" as per the IEC 60825.1 laser device safety standard.

Instead, the manufacturer seems to be considering it, and marketing it, only as a laser device.

Bright light use and misuse

The W4 is intended for use as a flashlight, not as a laser. It cannot do some things lasers can such as having a very narrow beam, or being a single color, or having a distinctive coherent "speckle" when the light is viewed on a surface.

On the other hand, a person aimed it at an aircraft, which is a Bad Idea. The light is bright and can distract, disrupt and temporarily flashblind a pilot. That is the general idea behind Section 247.5, and is certainly the idea behind the "light and other bright device" language in Section 248.

(Incidentally, the W4 could not cause serious or permanent damage to a pilot's eyes at the ground-to-aircraft range seen in laser/aircraft illumination scenarios. Without going into detail, it is extremely difficult for even a high-powered handheld laser device to cause injury. After more than 100,000 reported laser/aircraft incidents worldwide since 2004, there have been no confirmed or proven cases of actual injury to a pilot's eyes from a laser — much less from a LEP — as of December 2021. Therefore, the issue of potentially harming a pilot's eyes should not be a consideration in this legal case.)

Suggestions for the defense

If the defense is primarily concerned with the charge being a felony vs. a misdemeanor, they may have some leverage with the prosecution by pointing out that the "discharge" is not laser light. While there are some negative factors such as the last paragraph of Section 247.5, a defense lawyer could raise enough questions in the mind of a judge or jury ("why are they sending someone to jail over a flashlight?") that the prosecution might settle for some type of deal.

Going to trial under Section 248 is a problem for the prosecution because then they have to prove intent to interfere with the operation of an aircraft. In contrast, under Section 247.5 they only have to prove that the "laser" in 247.5 is discharged at the aircraft -- an easier case for them to make.

So perhaps the deal could be to drop the Section 247.5 charge to a misdemeanor in return for a guilty plea. (This assumes that the client did aim the W4 at the aircraft and is not otherwise a criminal or anti-social etc.)

There may be some problem with the last paragraph of 247.5. But the defense can argue to the judge or jury that despite how the light is first generated, what is 'discharged' is not laser light.

There is also a slight problem with the manufacturer calling this a laser via the labeling on the device and marketing material. But regardless of how they choose to have it be regulated and marketed, the defense can argue that what is coming out ("discharged") from the device is key to determining the device's legal status.

Comparing white light and laser light effects on aircraft

The defense could also bring up a February 2009 study which showed that conventional light from searchlights and handheld bright flashlights had "no concern" for pilots at distances from 200 to 500 meters, while even a low-powered 3.5 mW laser pointer caused unacceptable glare. The full study is here.

The study gives some indication that a white light non-laser source is less visually objectionable than an actual laser. However, on the other hand, this test did not use LEPs such as the W4; it used a high-powered flashlight circa 2009 before LEPs were available in flashlights. (The study does not state the exact light source or bulb inside the tested flashlight.)

Test the LEP effect vs. a laser

If the defense wants to compare LEPs to lasers, have someone aim first a W4 and then a low-powered laser pointer of less than 5 milliwatts (Class 2, II, 3R or IIIa) at a person, as they sit behind the windshield of a car located at a distance approximately the same as the ground-to-aircraft distance in this case. As long as the person is more than 52 feet from the <5mW laser their eyes will be safe for a brief exposure. Of course, the viewer should not stare into the laser beam. Such a test will compare a direct hit from the laser, to see if it is much more disruptive than light from the W4 at the same distance.

It may also help to video this comparison. The video may be useful both in any negotiations with the prosecution and if the case should go to trial.

Two important caveats

Note that LaserPointerSafety.com is not taking a side on this or other issues. When we are asked for technical advice in legal cases, we provide the facts, pro and con, as we know them for either or both sides in a case. We do not appear as expert witnesses. We wish to remain impartial and to provide information for whomever is interested — prosecution, defense, media, etc.

Also, the above analysis does not mean that aiming a LEP flashlight at an aircraft is OK.

Whether it is a laser, LEP or a strong conventional flashlight, deliberate aiming of a bright light source at an aircraft is a distraction, disruption and temporary flashblindness hazard and thus is wrong. There should be some penalty for a person who knowingly aims a laser or bright light at an aircraft. The severity of the penalty should be based on the egregiousness of the aiming (e.g., a brief glance vs.deliberate tracking) and the person's maturity and knowledge level (children vs. adults).