Police Study of tactical use of Strobe

[Grizzlyb]

Sorry for the other readers in this thread. You all had good info back and we learned a lot new insides.
I tried to answer all Your questions to my best knowledge.
We did a long term research and never claimed anything.
We just wrote down what we did and found.
Apparently not all can read it the way we intended it to be.

NLI,
I don't think you misunderstand what I write on purpose.
Maybe You honestly think that everyone is wrong and You are the only one that sees the truth in all.
If You think that You are the Professional that needs to uncover the truth and that we are just some Laymen with anecdotal evidence, so be it.
I can tell You that there are no conspiracy and no secret complots here that have to be drawn out.

Any inconsistencies You think You have to find, are probably due to translation or just misreading on Your side.
I really did my best to translate it in words You could understand.
Being a teacher,I am sorry I failed in that.

I won't react on NLI's claims and statements anymore.
I hope that others will do the same and not react on NLI anymore, otherwise he will effectively kill this thread.

Scottyhazzard,
Lets talk on this by pm.

 

[ledmitter_nli]

If I'm going to reequip a department with new lights I'd wish to field test a few things beforehand, so our personnel could see for ourselves.

It's only prudent to ask questions.

Grizz it was an interesting discussion none the less.

 

[scottyhazzard]

Grizz, that's it! Just what I have been looking for. That is a huge boost forward for my project. I can't thank you enough.

 

[Grizzlyb]

Glad to be of help Scotty.

 

[Slazmo]

Just noticed that the Nitecore EA4 has a constantly fluctuating defense strobe function - a "WHOLE" lot more disorientating / vomit inducing than the strobe in the LL MT7!!!!

 

[Grizzlyb]

Hi Slazmo,

Personally, I find the EA4 a real nice light. Small but sturdy fellow fits smoothly in my hand.
The strobe indeed is a "puker" to me too, variable somewhere between the 9Hz and 19Hz I think.
The nice thing with the EA4 is, that it never becomes to slow (below about 9/10Hz) or to fast (above 25Hz).
Effects every brain just enough to keep from concentrating/focusing.

Fast changing frequencies possibly have some advantages on a medical level to.
The frequency where a photosensitive (epileptic) person can be triggered is different for every other individual. (many between the range of 10 and 20Hz, but some on a specific frequency)

It takes a reasonable long time for susceptible people to get triggered (even up to 90 seconds), so when the strobe is not to long on 1 frequency, that could help prefent epileptic seizures.
There still is a lot to learn on that subject.

To keep it on the highest tactical level, it is best to not let it drop to slow.
We prefer a strobe in 1 frequency, but as long as it is in the right range, it will work perfectly

We haven't done it yet, but talking about it and reading all your experiences,
I think we will also try some higher variable strobes, between 15Hz and 23Hz. Scaling up and down every 3 seconds. Maybe that still has all the pro's and even less con's.
From a tactical point of view, what we have now, works 100%, but....we are very keen on prefenting even the smallest chance of medical problems.

 

[nativecajun]

Very informative

 

[Tachion]

Hi Grizzly

Thanks for a great writeup and an interesting thread.

I'm studying to become a LEO in Sweden and I thought I'd give the TDL 20 a try. There are two holsters for it. One open loop and one closed loop. Which one do you recommend? I want to keep the back of my belt free from tools. The front is pretty much taken with a baton, pepper-spray, handcuffs and gloves. So I'm thinking I'll have to try to squeeze the flashlight in on the left side of the belt. (My gun-holster is on the right side)

 

[Grizzlyb]

Hi Tachion.

We have the best results with the ESP model that is open on the front and closed on the back.
This model:

For safety reasons we have a small spiral cord between the light and holster.
This way we can let go of the light when we need handcuffs.

We also squeeze the light between the stuff on the left side of our belts.
Some day I'll take a picture for You to show how we do it. (remember me on PM when I forget )

This model is to wide on the belt.

Be adviced, that the closed loop model (picture below) is not made for 1 handed quick draw operations.
AND it is wrong side up.

Good luck with the study mate,

Stay safe.

Hi Kestrel,
Sorry if I did something wrong?
I cropped them a little to get the text off?
They are on my own smugmug account.

 

[Tachion]

I meant the loop on the back just like the top three pictures. I haven't seen the bottom one before, but I'd like to try the quick draw option so I'll skip that one. I will go for the top one with a closed back loop then, space on the belt is to precious to waste.

That spiral cord sounds like a really good idea. Especially when you use the light as a distraction before grabbing someone (no time to put away the flashlight).

 

[Grizzlyb]

Especially when you use the light as a distraction before grabbing someone (no time to put away the flashlight).

Yep, You got the right idea

 

[Nachtwacht]

Hello Grizzlyb,

Thank you for sharing your test results. Very interesting information.

Two questions:

1) I took a look at the specs of the Eden tdl light and noticed that the user interface activates the momentary strobe by pressing the switch half-way. A full press seems to activate constant-on strobe. Is this correct? If so, have you encountered problems with students activating constant-on strobe by 'accident', on the firing range or while conducting scenarios?

2) Have you conducted similar tests with dedicated weapon lights, using 18-20 hertz strobe? If so, what is your preferred user interface? (e.g. Surefire X300, Insight Technology WX150 / Procyon, Streamlight TLR, Blackhawk Xiphos,...)

Thanks again,

Greetings,

Nachtwacht

 

[Grizzlyb]

Hello Grizzlyb,

Two questions:

1) I took a look at the specs of the Eden tdl light and noticed that the user interface activates the momentary strobe by pressing the switch half-way. A full press seems to activate constant-on strobe. Is this correct? If so, have you encountered problems with students activating constant-on strobe by 'accident', on the firing range or while conducting scenarios?
2) Have you conducted similar tests with dedicated weapon lights, using 18-20 hertz strobe? If so, what is your preferred user interface?

Thanks again,
Greetings,
Nachtwacht

Hi Nachtwacht,

About 1mm pressing is momentary on, soundless and real smooth. Constant on by pressing the full length about 4mm to 5mm and You notice a mecanical switch. No chance of accidents here.
It is always possible though, that under very high levels of stress the switch is pushed all the way down, but once you are used to the light, very unlikely.

If you have read the thread you should know that this is not meant to be a weapon light.
It is build for tactical advantage in hand to hand combat.

But, It CAN ofcoarse be used together with a handgun, but not as a mounted light.
We did work with it on the shooting range many times, and found that strobes on this higher frequency do not hinder the shooter, but it still greatly hinders the one on the receiving end.

There are many other good lights that are built for that weapon mounting perpose. We didn't go in that direction, many specialist done that already. It was not our field of research.

There can only be 1 user interface for a light designed for the perpose of the TDL20. That is why the TDL20 has this user interface.
Sorry, I can't advice you on a user interface for weapon mounted lights.

 

[AnAppleSnail]

It has been interesting to read this thread. Perceptually speaking, there are some things to consider.



"What is strobe?"
Purely speaking, I would call a strobe light then dark. So the parameters of interest are light period length, dark period length. This is often presented only as the cycles per second, which skips the ratio there. I believe (But do NOT know) that this ratio is important. If the dark periods are too long, unobserved actions can happen. If they are too short, the 'strobe' is too similar to a normal flashlight. What is optimum to reduce a subject's vision in many lighting conditions, while allowing an officer to see? I do not know, and it would be difficult to study this. I have played with some toy-type smart phone programs that allow an (uncalibrated) strobe of varying duration on/off. The most disorienting-to-me effects are around half light cycles at near 10-20 Hz. But I can't clock that strobe, and I have not tested it on as many others as you have. With LED (As opposed to arc-lamp strobe) the electronics can create almost any ratio of bright to dark desired.


"Why can an officer see a strobed subject easily?" When you watch a movie in a theater, it was (Until recently) shown at about 24 FPS. Standing in front of that projector and trying to see even a bright scene behind the light would be difficult - The things you want to see are overwhelemed 24 times per second.

"What does a strobe do?"
I wouldn't expect a strobe to stun most people, but your experiences seem to indicate an important advantage that can be acted on.

Scotty, I hope that your nurse recovers quickly, and that you guys find a way forwards to keep everyone safe.

 

[selfbuilt]

Interesting thread. I'm glad to see the issues around "tactical" strobe frequencies are getting a full airing here. It certainly seems like you and your compatriots have done a lot of work on this, Grizzlyb.

Purely speaking, I would call a strobe light then dark. So the parameters of interest are light period length, dark period length. This is often presented only as the cycles per second, which skips the ratio there. I believe (But do NOT know) that this ratio is important. If the dark periods are too long, unobserved actions can happen. If they are too short, the 'strobe' is too similar to a normal flashlight. What is optimum to reduce a subject's vision in many lighting conditions, while allowing an officer to see? I do not know, and it would be difficult to study this.

I have exactly the same thought. Strobe pulse duration (i.e., how long the light is "on" per pulse) is indeed another variable that may change, indepedendent of strobe frequency. In any study comparing the effects of different strobe frequencies, it would be important to ensure that strobe pulse duration remained constant (otherwise you have a potential confound).

I have measured the strobe characteristics on a large number lights over the years. Until recently, most manufacturers opted for a single constant frequency (usually somewhere in the 10-15 Hz range), and a single constant pulse duration (typically in the ~40-60% "On" range per pulse). However, I have come across strobes in that frequency range that have unusually long or short "on" pulses (i.e., I've seen ones that are "on" <10% of the pulse time, or >90%). The visual appearance of these is quite different than the typical ~50% "on" pulses - even for lights that are all using the same frequency. This is just an empirical observation that they appear different - I don't how that affects functional use, but it stands to reason it could be important (as AnAppleSnail points out above).

Note that the above is a more general issue about regular strobes (i.e., I'm not even thinking about the multiple-frequency strobes). Although I have of course seen many of those in the last couple of years - I typically consider these oscillating strobes (i.e., switching between two - or more - specific frequencies). These are often done as one frequency for a defined time, followed by the other, in repeating fashion (e.g. 2 secs of one freq, then the other, in an alternating fashion). But I've also seen literal alternation between each pulse (i.e., freq1 flash, freq2 flash, freq1 flash, etc), or a random alternation between two - or more - frequencies.

More recently, I have been seeing some truly variable strobe pulse frequencies. Nitecore in particular has been experimenting with a lot of different kinds. Note that most (but not all) of these Nitecore strobes are not only variable-frequency but ALSO variable-pulse-duration. Again, in some cases it seems truly variable (on one or both measures), and on others I can detect specific multiple reoccuring pulse widths or frequencies (depends on the model).

A third variable that I haven't seen mentioned here that may also affect relative perception is strobe pulse intensity (i.e. output level). Initially, almost all strobes I measured were full 100% max output. But in some cases, I've seen lower output, usually at a constant level (e.g.,a ~30% output strobe mode, likely to conserve battery life). In most of these lower output strobe cases, the frequencies are also lower (i.e., they are probably meant for emergency signalling purposes, not disorientation). But I've also noticed variable-intensities on some high-frequency strobe lights, often in combination with variable-frequency and/or variable pulse-duration (i.e., some of these Nitecores referenced above).

I'm not trying to depress anybody with level of complexity presented above - just pointing out there are two other pulse characteristics you need to consider, along with frequency. Different manufacturers have taken - and continue to take - various approaches at modulating all three. My general take-home message would be that in any study of one variable, it would be important to ensure the other variables remain constant (i.e., measure the pulse characteristics to ensure that you can ascribe the effect to a single variable change).

 

[Grizzlyb]

Thanks Selfbuilt,

Much appreciated contribution to the thread.
You have a lot of experience in testing strobes (probably more the we do :thumbsup and echo some of my thoughts on the subject. There are lots of variables to take in account.
Strobe has probably more uses than I can come up with, but our main use was disorientation.

On that part alone there are already a lot of angles to think about.
For starters, how is it effecting the opponent, on what level, how long, why is one person more effected then the other and of coarse why are people effected at all. (there is nowadays enough medical research to know why it is effecting us the way it does.) Not that much effect for most, but enough to get the desired advantage.

When that is more or less sorted out, you have to look at IF, WHEN and HOW it is effecting the user.
The wanted result for us was the lowest possible effect for the user and of coarse the highest possible effect to the opponent, without doing any form of real physical harm.

At lower frequencies, (50/50 on/off at 5 to 10 Hz) the strobe was effective on the disorienting part for the opponent, but there was overall to much unwanted "out" time, and the users where also effected enough to get lower scores on the shooting range. Telling us that they indeed had a little trouble with focusing.
The 50/50 strobe from 18Hz to 23Hz had considerable less effect on the users and still the disorienting effect we looked for, on the opponent.
We haven't made any changes on the 50/50 on/off time. But it is an interesting concept we have not thought about fiddling with.
As long as the "off" time is not to long. . . .?
With enough "out/dark" time, the opponent could make small movements without detection, and also, when looking into the strobe for a few seconds, when there is a little back light, and enough "out"/dark time, you can slowly start to see the silhouette of the user.
There for we had to look for much "on" time and little "off" time. (as long as the disorienting is still good enough.)

The intensity is indeed the third variable.
As far as we know now, when the strobe is working in an effective frequency, the intensity is enough as long as the lux level of a steady beam on that distance (4th variable ) is enough to blind a person completely from his surroundings. The higher the better, as long as the user is not effected (and no back light by rebounce) and there is no physical harm to the opponent.

 

[Grizzlyb]

double post

 

[bluemax_1]

Hmmm... good points about pulse duration. Now it makes me wonder about strobes in the 10Hz range (+/- 0.5Hz). Although this is the threshold where Grizzlyb's testing indicates that slower than this might provide too much dark/off time allowing the subject to make small movements undetected, what about a 10Hz strobe where the On pulse accounts for 80% of the cycle as opposed to 50/50? Would that provide the greater disorientation that some have noted at these slower rates, while still minimizing the dark/off time eliminating the possibility of undetected movements?

I'm definitely curious to see the newer Nitecore constantly variable strobe implementation as documented in Selfbuilt's EA4/EA8 reviews. As Grizzlyb noted, 2 offset strobes with very slight frequency variances can be VERY disorienting. I experimented with this using the P25 and M22 simultaneously. The effective strobe rate constantly changing as the 2 lights go in and out of sync makes for a very disorienting effect. I wonder if the Nitecore implementation can simulate this with a single LED/light?


Max

 

[Bullzeyebill]

I have removed some obviously trolling posts and responses to them.

Bill

 

[Bullzeyebill]

Ledmitter_nli, I've removed several of your obviously trolling posts. You are, in effect, flaming the OP, and contributing little to this thread. Please read CPF Rule 4. When you are posting a rebuttal to a post, please be respectful. Attack the post, not the poster.

Bill