Project "Hellmeet" (Headlamp)

[Barbarin]

The purpose of this thread is to have your input for the development of a headlamp, and at the same time to keep you informed of the steps taken.

Let's imagine you have an appointment in hell, and of course there is no daylight at all. You are going to need a headlamp reliable, waterproof, capable of working under extreme temperatures (-30 ºC to +90º C), designed to stand every impact and bright enough to illuminate all that darkness and dangers in front of you. Can you imagine a worse place to be left in the dark?

The name of the headlamp is "Hellmeet", a kind of word game as this headlamp will be used very often on a helmet.
I have been making my own headlamps during years, and thanks to that I have some conclusions I would like to share:

1. Cables are to be avoided. You always have time enough to change a battery so I prefer to take care 1 minute each three hours to replace the batteries than being all the time taken care of the cable.

2. One single LuxIII (80 lm) fitted with the proper reflector was more than enough to beat the performance of carbide lamps. While resting, cooking or whatever, 5 lm is more than enough for most of the tasks.

3. The desirable corona is 120º. More than that will put light in places in which you in fact can't see it, so wasting light and energy.

Those graphics are on Spanish, but I think you can understand them easily. If not I will translate.

4. The desirable spot is around 10º. A diffuse spot is important as long as we need more light in our central vision field. This central vision is much more accurate than peripheral, but in exchange it needs more light. That is the reason I don't like "pure flood" lights as personal lights, exception made of photography/video or very close tasks.

5. 2 XCR123/ 1x Li-ION 18650 is the perfect combination. The performance of lithium chemistries is superior to any other. While Li-ION is the rechargeable-constant use option, CR123's are perfect as back-ups, or the option for remote places. At the end, if you take your time and money to plan a caving expedition in Africa or a expedition in Antarctica you will take care of having enough batteries with you, and you won't trust on the remote hypothetical gas station to supply you. The cost of the batteries is like 0,5% of the expenses… cutting it to the third by using AA's won't mean more than 0,33% in the total. And you will be paying poor performances.

6. Output levels. You want to spend your valuable photons when you need them, and you don't want to blind your colleagues while having a coffee, so we need at least two, more preferably three. Strobes and so on can be useful, but not at the expense of complicating things or making them less reliable. Remember, if things are difficult in surface and having no stress… what would happen down there when you are on a real dangerous situation??

 

[PeLu]

Javier, I agree with most of your statements, but let me add my comments from my long experience:

...Can you imagine a worse place to be left in the dark?

yes, many of them .-) Come caving with us......

One single LuxIII (80 lm) fitted with the proper reflector was more than enough to beat the performance of carbide lamps.

What poor carbide lights do you have .-) OK, serious: As I mentioned many times before, a usual CB carbide light has a very different characteristic: Everyone lights for everyone, that means your light also helps others. From this point of view the light outside your vision is not wasted.
Only when you disagree with this concept, your statement makes sense.

A diffuse spot is important as long as we need more light in our central vision field.

It looks like a spotless diffuse light is less fatiguing when you have to use it a very long time. Both concepts have their benefits (and fans).
It is very interesting watching people who have the choice. A brighter spot forces your eye more or less to look at the direction most of the time, which is not a good thing.

At the end, if you take your time and money to plan a caving expedition in Africa or a expedition in Antarctica you will take care of having enough batteries with you, and you won't trust on the remote hypothetical gas station to supply you.

There are no expeditions I'm aware of (and I have been the last decade) where members do not need a lot of other electrical equipment, especially laptop computers for managing the exploration results, so charging a light is no no problem any more, at least nothing which should be avoided as it was 25 years ago.
Having a primary backup battery is a very good thing, anyway. I usually carry one for my caving light.

 

[traplight]

You have definately got an eye (and logistics!) for nice spot and peripheral flood.

I plugged a few numbers into formZ with several reflector setups and a cree XR-E 7090 Q5 rig...

But first a couple questions:
1. Considering an average of 110 total lumens, 3-3.7Vf, and draws of 350maH (HI), 100maH(MED) and 25maH(LO) according to CREE's spec sheet ( http://www.ledsupply.com/docs/cree-xre.pdf page 8 at bottom)... what percentage of lumens would be commited to the hotspot, and what percentage dispersed as flood?
2. Is it possible to achieve a 120deg flood and a 10-15deg hotspot with a single conventional reflector?

As you know, current hyper/parabolic reflectors can be made to produce virtually any size hotspot at the expense of intensity toward the larger spreads. After playing around with some refraction and reflection numbers, a nice little idea presented itself with the possibility of producing a nice tight spot and a relitively large spill (into the 100deg+ range). By adding, and if the tired eyes didn't get the best of me, a small oddly shaped lip to the upper 1/3 portion of the reflector (on the inside), it seemed possible to reflect the non-collimated (as in the photons which had yet to be organized for throw) waves into a very obtuse reflection pattern.
Not sure if this has been tried before, but it looks promising with only one variable as yet undefined:

Will their be a shadow ring of significant size separating the spill from the spot?...

Just to check, i ran 3d wall reflection scenario with as many numbers as i could remember (e.g. - wall reflection, color temperature, polished reflector spectrum absorption constants.. the whole nine yards). Everything looked pretty good until i realized that the siz of the room i created to check it out was only 3x3x3m and the ambient diffused light, reflected around the 'virtual' room, lit everything up like a nuke!

Will work on it in spare time and see if things can work out...

 

[Barbarin]

Javier, I agree with most of your statements, but let me add my comments from my long experience:

yes, many of them .-) Come caving with us......

Thank you for the comment and the offer!!

What poor carbide lights do you have .-) OK, serious: As I mentioned many times before, a usual CB carbide light has a very different characteristic: Everyone lights for everyone, that means your light also helps others. From this point of view the light outside your vision is not wasted.
Only when you disagree with this concept, your statement makes sense.

I do not disagree with the idea of giving light to others, but when it comes to efficiency the results is that this spread light is just being used for our colleagues on very brief moments, because when caving you are usually taking care about what you have in front of you. What I want to mean is that it would be great if we can have 180, 240 or more light pattern, but the expense of energy needed for this is too much when you compare it with the real usage of this lighting area. The key is optimization.

It looks like a spotless diffuse light is less fatiguing when you have to use it a very long time. Both concepts have their benefits (and fans).
It is very interesting watching people who have the choice. A brighter spot forces your eye more or less to look at the direction most of the time, which is not a good thing.

The key here, as pointed by traplight, is how much spot and how much spill. On regular hand held lights the difference from spot to spill is like 200 to 1. A lot more on "throwie" lights. Changing this proportion is what makes don't getting tired with the spot. Something like 50 to 1 seems the magic number. Also the size of the spot , how tight it is, is important, and also the transition. If it is too narrow, or the transition too abrupte you have the sensation of looking through a small hole. Anyway, the possibility of adjusting the reflector, or even changing it is something to ve considered seriously.

There are no expeditions I'm aware of (and I have been the last decade) where members do not need a lot of other electrical equipment, especially laptop computers for managing the exploration results, so charging a light is no no problem any more, at least nothing which should be avoided as it was 25 years ago.
Having a primary backup battery is a very good thing, anyway. I usually carry one for my caving light

.

Good point. Keep in mind also that this headlamp is not intended just for caving, but for SAR, and some other uses. In this cases there could be no time to charge them and every minute counts. Quality Li-IONs and their very low self discharge rate makes them very predictable too.

Thanks for your input

 

[Barbarin]

You have definately got an eye (and logistics!) for nice spot and peripheral flood.

I plugged a few numbers into formZ with several reflector setups and a cree XR-E 7090 Q5 rig...

But first a couple questions:
1. Considering an average of 110 total lumens, 3-3.7Vf, and draws of 350maH (HI), 100maH(MED) and 25maH(LO) according to CREE's spec sheet ( http://www.ledsupply.com/docs/cree-xre.pdf page 8 at bottom)... what percentage of lumens would be commited to the hotspot, and what percentage dispersed as flood?

Thanks for your input traplight.

I haven't done the calculation, but keeping in mind that the lux reading on the hot spot could be average from to to the end of transition area like 25 to 1 against the flood area, it is easy to calculate.

2. Is it possible to achieve a 120deg flood and a 10-15deg hotspot with a single conventional reflector?

Yes, perfectly.

As you know, current hyper/parabolic reflectors can be made to produce virtually any size hotspot at the expense of intensity toward the larger spreads. After playing around with some refraction and reflection numbers, a nice little idea presented itself with the possibility of producing a nice tight spot and a relitively large spill (into the 100deg+ range). By adding, and if the tired eyes didn't get the best of me, a small oddly shaped lip to the upper 1/3 portion of the reflector (on the inside), it seemed possible to reflect the non-collimated (as in the photons which had yet to be organized for throw) waves into a very obtuse reflection pattern.
Not sure if this has been tried before, but it looks promising with only one variable as yet undefined:

Yes, I have been trying with a mirror or highly reflective PVC . It seems that you can "cut" a portion of the upper area that you are probably not using, and redirect that light to teh area of interest.

Will their be a shadow ring of significant size separating the spill from the spot?...

Rings are our enemies (unless we want a searchlight). As explained a soft and gentle transition is a must.

Just to check, i ran 3d wall reflection scenario with as many numbers as i could remember (e.g. - wall reflection, color temperature, polished reflector spectrum absorption constants.. the whole nine yards). Everything looked pretty good until i realized that the siz of the room i created to check it out was only 3x3x3m and the ambient diffused light, reflected around the 'virtual' room, lit everything up like a nuke!

Every cave is different pending on the material. I have been on some which are black marble, but I have been also skiing at nights... As long as it is not predictable when are you going to use your headlamp is better to no let this data to play the game. I just consider "pitch black"

Will work on it in spare time and see if things can work out...

Again, thank you.

 

[Barbarin]

Question:

Single die o multidie?

Taking as a starting point that what we need is at least three output levels, as it was descibed by Tobias (pause, work and spot -in this case high) and keeping in mind the aproximative outputs could be:

1. Pause: 5-10 lm.
2. Work: Arround 100-120 lm.
3. High: As nuch as possible

We have two options. Go for a single die (CREE, KLC8, P4) or a multidie (P7, MCE)

So things will be on high 240 lm or near 450 lm.

1. Using a multidie means higher efficiency when on work level, but not that much. For example, to get 120 lm from a single die we need to push the emitter to 380 mA; 340 mA from a multidie. 12% better. Increasing runtime from 6 hours to 6 h 40 min on a single Li-ION
2. Using a multidie would mean also a much more powerfull "high mode". For example, at 1400 mA we would be getting 450 lm. (less than 90 minutes runtime) A single die could achive 240 lm at 1000 mA (140 minutes runtime) and the efficiency improves with the multidie 89 lm /watt vs 66 lm/watt that means 34%.

So it seems the multidie is the way to go, but there are some cons:

1. We need a larger reflector, that means bulkier and heavier light. Is that a pricing you are ready to pay 100% of the time you use the headlamp for having a better "high mode" you will use just a 10% of the time?
2. Pricing will increase. LED, driver, reflector, parts... We are talking about a MSRP increasing about 28-30 %.

So resuming.

SINGLE DIE:

1. Pause: 5-10 lm. (more than 72 h.)
2. Work: 100-120 lm. 6 h.
3. High: 240 lm. 2h, 20 min.


MULTIDIE:

1. Pause: 5-10 lm. (more than 72 h.)
2. Work: 100-120 lm. 6 h 40 minutes.
3. High: 450 lm. 1h, 30 min.

Weight and volume will increase by 20% on a multidie. Price by 30%.

Javier

 

[Barbarin]

Very simple CAD drawing to have an idea about what I'm thinking about:

Lenght from tailcap to opposite cap, less than 80 mm.

Lenght from front lens to back, less than 63 mm.

Diameters: Lens/Head 42 mm. Tailcap 28 (It a slightly modded Barbolight U-15/U-04 Tailcap).

Weight (goal) less than 200 gr (batteries included).

The version here displayed in the one with single die emitter.

Javier

 

[DM51]

The name of the headlamp is "Hellmeet", a kind of word game as this headlamp will be used very often on a helmet

There's a second word-play here - the word "hell" means "bright" in German.

 

[Barbarin]

hmm .... I like it! Thank you.

 

[PeLu]

I do not disagree with the idea of giving light to others, but when it comes to efficiency...

Yes, for your concept of a small and light lamp you are absolutely correct.

The key here, as pointed by traplight, is how much spot and how much spill.

There are lights were you can adjust this ratio and it is quite interesting what people feel comfortable with on medium and longer trips (> 8 hours).

The point is, that it also depends very much on the kind of cave. In a smaller passage, a pure flood is perfect. If you move in larger rooms, some added spot is sometimes helpful.

And BTW, the darkest caves I remeber are lava tubes. We even discussed if absolute darkness is darker here when you switch off your lights .-)

I could do some measurements on my favorite Scurion settings if you want (about the spot/flood ratio)

Making a light for a single 18650 cell or 2 CR123 is a very good thing.

One additional advantage of a four-die Led is that the illuminated spot is four times as large and so the glare in the other's eyes is a lttle bit less.

5lm is plenty for a pause light. I remember when I got my first ActionLight I. The high setting was around 8-9lm, IIRC. It was my main caving light for many years.

 

[traplight]

Some more observations:

-because it seems that this project has been precluded with the usage initially oriented towards caving and 'limited light' situations, it appears that a few slight changes will have to be made. The reflector cutout below...

The reflector lip's bottom angle must be 120deg in order to reflect stray light towards the 120deg output region. With this setup it is possible, within 90%+ accuracy to achieve a hotspot and a corona extending 60deg into the periphery range of site. The relative amount of light dispersed equated to ~68% of the forward emitted light falling into a 8-15deg cone at dead center. The remainder of the light, and subsequently 'ring free' transition light, disperses to the spill with about 5% of the light reaching the furthest reaches.
By creating a cylinder at the top of the reflector, it is possible to keep the protective front lens deeper into the reflector assembly... reducing the possiblity of breakage.

The following diagram shows the throw at 5-10deg center, 10-20deg offcenter, 30-60deg concentrated spill, and 60-120deg periphery spill.

After playing with the location of the lip for a few hours, the following conclusions arrived:

- by moving the lip further back, while still maintaining a perfect cylinder up to the edge of the reflector, in increments of .25mm, yeilded a smoother transition between the hotspot and the spill, but also increased the radius of the hotspot.
- changing the location of the emitter reflector cup deeper within the reflector yielded the same results as above.
- changing the location of the emitter to a more shallow location within the reflector yielded a 3-5% loss in forward light and a loss of ~3-5deg in the spill scope (roughly down to 105deg periphery).


With the new ideas regarding emitter efficiency/trade-offs of multi die vs. single, it stands to be said that each will have their advantages. 350-400 lumens of light dispersed with a 15-25deg hotspot will effectively light up distance as the same amount of throw from a single die chip. It all comes back down to :

1. runtime vs. light vs. weight
2. throw vs. spill
3. economy and price per unit

While caving may be an example of the units form, there wil be others who will use it for summit breaks, camping, work related, and various other 'in-the-dark' activities. The balance, as you have said, is not only the most important thing regarding ouput, but also in ratio to application.

There is however a solution already in the works for a low-mass heatsink/body for MC-E based emitters...

let me know if you'd like some numbers on the reflector

 

[Barbarin]

.. and here the multidie version

Dimensions as previosuly described, but head diameter increases to 53mm and distance from lens to opposite side is 68 mm.

Javier

 

[Tobias Bossert]

Hi Barbarin,
it is a very good idea to start public discussion upon technical details befor designing a new commercially manufactured headlamp.

I propose to start by specifying the addressed application of the new headlamp at first.

We all know, that there exists no optimum solution covering all applications, because the requirements for different applications are so different. There are many headlamps out on the market, which try to suit for multiple applications and with most of them this is their main disadventage!
On the other hand, the market for only one single application (especially for caving) may be of no commercial interest for a manufacturer.
So you should ask first: Users, what are your requirements?

I'm caver specialized on lage caves - therefore my point of view is single-sided. Cavers specialized on diving may have quite different requirements even!

What cavers do really need in large caves?

First of all, for about 90% of the day, a light for walking, climbing and crawling.
This task seems to be easy, but it isn't. The old discussions on throw versus flood (or beam versus spill or even selfish versus social) reflects this.
In large caves you find quite different situations.
Running along big tunels you need a lot of light. You need some portion directed forwards as throw (for finding where to go), you need enough spill (to catch the room threedimentional) and you need an increased portion of spill in front of your feet (to avoid stumbling).
Moving in narrow passages you need less overall light and you can do without throw. Crawling needs also no throw and even less overall light.
The first situation demands for a throw portion, the other two do not need throw but there is no problem to catch all three situations by a fixed throw/spill combination variing the power level only, because throw does not impair when not needed.
It makes no sense to have the throw in the center of the spill. The throw should be horizontal but the spill should be asymmetric: downwards more than upwards. As I found out, power needed for a reasonable spill is mutch higher than for throw. My actual test device uses 75% of power for spill and only 25% for throw.
At the moment no commercial optics allows to generate that from one single LED. It would be of interest whether it is possible to achieve that. But so far, these requirements would demand for at least two LEDs and optics.

Secondly you need a stand by light for pauses and during biwaking
This is used for may be about another 9% of time. There is no specific requirement to its beam pattern, so you can use the same combination you use over 90% of time too.

This would be a "standard headlamp". But every caver uses additional lamps in large caves, since the above is the replacement of old carbide lamp only.

As third part you "need" a thrower without spill
In large caves you oftenly meet places where you have to decide, whether it is promising to descent a pit or to climb up a shaft. The time you use this thrower is very short (below 1% of time), but it should be as focussed as possible. There should be as less spill as possible, because spill will illuminate the forground and prevent you from seeing the background.
Ok, ok, this is the field of normal flashlights indead, and many of us have a separate handheld thrower for these fiew seconds in the backpack.
It would be very desirable to integrate this feature into the headlamp and to avoid a second device in the backpack if possible.

As a fourth part you "need" an extremely strong short term light source
In large caves you oftenly enter huge halls, which remain black with your normal light. The thrower without spill does not help, because it would stamp out a small portion of the wall or ceiling only. The time you use this thrower is very short (below 1% of time), but it should be as strong as possible. May be you can realize this with the mainlight you use for 90% of time too, but it makes no sense to concentrate this light more downwards, but in case the headlamp is mounted inclineable you can compensate that by adjusting.
At the moment it seams to be easier to realize that with a separate LED/optic in the headlamp.


As you can see now, the needs for caving, climbing, outdoorsports, diving etc. is so different, that it is not shure, whether you can find an new combination which really improves the situation with respect to the actual situations: No one of the commertial headlamps comply with cavers needs really. The best one at the moment is Scurion, but it still does not cover all requirements...

Regards Tobias

 

[Barbarin]

Yes, for your concept of a small and light lamp you are absolutely correct.

There are lights were you can adjust this ratio and it is quite interesting what people feel comfortable with on medium and longer trips (> 8 hours).

Making an easily focusable headlamp (field, no tools) would increase the cost and complexity of the design, so althought not the ideal solution for everyone to find the balance by making some samples and testing them would be in my opinion to make a light more based on reliability than on customization options.

The point is, that it also depends very much on the kind of cave. In a smaller passage, a pure flood is perfect. If you move in larger rooms, some added spot is sometimes helpful.

Agree, but as long as we don't know previosly how much time we are going to spend on every kind of room, and if we want to keep the design simple and small, for reliability and compactness it would be better if we can find that proportion which is not the optimal for any situation, but a compromise for every.

And BTW, the darkest caves I remeber are lava tubes. We even discussed if absolute darkness is darker here when you switch off your lights .-)

Did you ever read about cavediving on a lava tube in Canary Island named "Tunel de la Atlantida"? Is an incredible place I would like to try. Probably it is darker than a black marble one as there is no reflexion at all... is a "black hole"

I could do some measurements on my favorite Scurion settings if you want (about the spot/flood ratio)

That would help for sure!!

Making a light for a single 18650 cell or 2 CR123 is a very good thing.

Yes, but unfortunately it has some design limitations, so we can not have everything.

One additional advantage of a four-die Led is that the illuminated spot is four times as large and so the glare in the other's eyes is a lttle bit less.

Agree completely. If you take a look at the CAD drwaings you will see that they are not that big, so unless there is demand for a cheaper version maybe we should led to the multidie one.

5lm is plenty for a pause light. I remember when I got my first ActionLight I. The high setting was around 8-9lm, IIRC. It was my main caving light for many years.

Do you have an Action Light? I loved that light, IMO it was a light too advanced for its time. It had features that has been included many years later.

 

[Barbarin]

Some more observations:

-because it seems that this project has been precluded with the usage initially oriented towards caving and 'limited light' situations, it appears that a few slight changes will have to be made. The reflector cutout below...

The reflector lip's bottom angle must be 120deg in order to reflect stray light towards the 120deg output region. With this setup it is possible, within 90%+ accuracy to achieve a hotspot and a corona extending 60deg into the periphery range of site. The relative amount of light dispersed equated to ~68% of the forward emitted light falling into a 8-15deg cone at dead center. The remainder of the light, and subsequently 'ring free' transition light, disperses to the spill with about 5% of the light reaching the furthest reaches.
By creating a cylinder at the top of the reflector, it is possible to keep the protective front lens deeper into the reflector assembly... reducing the possiblity of breakage.

The following diagram shows the throw at 5-10deg center, 10-20deg offcenter, 30-60deg concentrated spill, and 60-120deg periphery spill.

After playing with the location of the lip for a few hours, the following conclusions arrived:

- by moving the lip further back, while still maintaining a perfect cylinder up to the edge of the reflector, in increments of .25mm, yeilded a smoother transition between the hotspot and the spill, but also increased the radius of the hotspot.
- changing the location of the emitter reflector cup deeper within the reflector yielded the same results as above.
- changing the location of the emitter to a more shallow location within the reflector yielded a 3-5% loss in forward light and a loss of ~3-5deg in the spill scope (roughly down to 105deg periphery).


With the new ideas regarding emitter efficiency/trade-offs of multi die vs. single, it stands to be said that each will have their advantages. 350-400 lumens of light dispersed with a 15-25deg hotspot will effectively light up distance as the same amount of throw from a single die chip. It all comes back down to :

1. runtime vs. light vs. weight
2. throw vs. spill
3. economy and price per unit

While caving may be an example of the units form, there wil be others who will use it for summit breaks, camping, work related, and various other 'in-the-dark' activities. The balance, as you have said, is not only the most important thing regarding ouput, but also in ratio to application.

There is however a solution already in the works for a low-mass heatsink/body for MC-E based emitters...

let me know if you'd like some numbers on the reflector

Thank you very much for your work, in fact I love the idea of the partial lip. Main problem is that it can not be made by machining, but by plastic injection, and that means lot money to start with .

On the other hand a plastic reflector is a must if we want to keep weight down.

My own testings with a mirror or highly reflective PVC have been made doing things as simple as this:

The dark grey area is the mirror faced to the emitter. Reduces the output on the upper section increasing on the lower section. Although the spot keeps centered on geometric terms it is not on output terms. Can you do some testing with this solution??

Althought some of the guidelines are defined or heavily influenced by compactness and reliability , there is a lot of job to be done.

Javier

 

[Barbarin]

Hi Barbarin,
it is a very good idea to start public discussion upon technical details befor designing a new commercially manufactured headlamp.

I propose to start by specifying the addressed application of the new headlamp at first.

Thank you Tobias.

The application is influenced in this case by my own experience as caver and cavediver. (Reliability and waterproofness first) But as long as this should led to a commercial product we can say that main purpose of this one will be SAR on any situation, from caving to mountain climbing, or even firefighting.

One of the most demanding applications a headlamp can face is caving, so the input of cavers is greatly appreciated, and we can say that a modern caving headlamp would be satisfactory on a very high percentage for SAR duties, but not perfect. But also a headlamp designed for SAR on every situation would be great for caving althought not the perfect one.

We all know, that there exists no optimum solution covering all applications, because the requirements for different applications are so different. There are many headlamps out on the market, which try to suit for multiple applications and with most of them this is their main disadventage!

Well, this is the challenge.. isn't it?

On the other hand, the market for only one single application (especially for caving) may be of no commercial interest for a manufacturer.
So you should ask first: Users, what are your requirements?

I have already a lot of input from many users on many different uses, but never is enough if the goal is so ambitious.

I'm caver specialized on lage caves - therefore my point of view is single-sided. Cavers specialized on diving may have quite different requirements even!

I think no one in this world can give us the all the points of view we need.

The procedure here is to show a basic design and to try to adjust it to the highest percentage of satisfaction to every user, and giving every potential use a weight into the total. In some way it is a limiting starting point, but if we start from zero this will end on chaos.. for sure.

What cavers do really need in large caves?

First of all, for about 90% of the day, a light for walking, climbing and crawling.
This task seems to be easy, but it isn't. The old discussions on throw versus flood (or beam versus spill or even selfish versus social) reflects this.
In large caves you find quite different situations.
Running along big tunels you need a lot of light. You need some portion directed forwards as throw (for finding where to go), you need enough spill (to catch the room threedimentional) and you need an increased portion of spill in front of your feet (to avoid stumbling).
Moving in narrow passages you need less overall light and you can do without throw. Crawling needs also no throw and even less overall light.
The first situation demands for a throw portion, the other two do not need throw but there is no problem to catch all three situations by a fixed throw/spill combination variing the power level only, because throw does not impair when not needed.
It makes no sense to have the throw in the center of the spill. The throw should be horizontal but the spill should be asymmetric: downwards more than upwards. As I found out, power needed for a reasonable spill is mutch higher than for throw. My actual test device uses 75% of power for spill and only 25% for throw.
At the moment no commercial optics allows to generate that from one single LED. It would be of interest whether it is possible to achieve that. But so far, these requirements would demand for at least two LEDs and optics.

At the end there are a lot of common points with many other extreme duties. The reason is because places and situations can change, but our eyes and our visual needs remain.
I really like to see that we have converged to the same conclusions from different aproaches. Undoubtely a perfectly matched beam for a headlamp means a not centered spot. As you can see on above posts there are ways to get this by complex optics, so if we can gave up the idea of a perfect flood light, we con do this with just one LED, which is almost a must for compactness.

Secondly you need a stand by light for pauses and during biwaking
This is used for may be about another 9% of time. There is no specific requirement to its beam pattern, so you can use the same combination you use over 90% of time too.

Completely agree with that. A low level light is a must, nit just for caving, but for map reading, breafings.. As you say there is no need for a specific pattern.

This would be a "standard headlamp". But every caver uses additional lamps in large caves, since the above is the replacement of old carbide lamp only.

This part is very important on the following question.

As third part you "need" a thrower without spill
In large caves you oftenly meet places where you have to decide, whether it is promising to descent a pit or to climb up a shaft. The time you use this thrower is very short (below 1% of time), but it should be as focussed as possible. There should be as less spill as possible, because spill will illuminate the forground and prevent you from seeing the background.
Ok, ok, this is the field of normal flashlights indead, and many of us have a separate handheld thrower for these fiew seconds in the backpack.
It would be very desirable to integrate this feature into the headlamp and to avoid a second device in the backpack if possible.

My question here is: Are you going to pay the complexity, cost and weight of a thrower integrated in your headlamp during 100% of the time you are wearing it it for a feature you are going to use just 1% of the time?

Definetively it would be difficult to justify on a SAR headlamp. Also keep in mind that having two separate flashlights means added security.

Of course is much more confortable to put you hand in the switch of your lamp and change the pattern for long throw than looking for the thrower into the backpack. But what about the continuous disconfort of 50-60 extra grams in your head-neck? There are now very compact throwers (we are about to release one with focusable spot with no spill at all).

As you explained before every caver does carry more than one light always, so if we will never get rid off having to carry more lights, why is so desirable to have a thrower integrated on the helmet? In my opinion it woudl be better to design a good thrower and a system to carry it ready to be used and protected at the same time.

As a fourth part you "need" an extremely strong short term light source
In large caves you oftenly enter huge halls, which remain black with your normal light. The thrower without spill does not help, because it would stamp out a small portion of the wall or ceiling only. The time you use this thrower is very short (below 1% of time), but it should be as strong as possible. May be you can realize this with the mainlight you use for 90% of time too, but it makes no sense to concentrate this light more downwards, but in case the headlamp is mounted inclineable you can compensate that by adjusting.
At the moment it seams to be easier to realize that with a separate LED/optic in the headlamp.

This design is very easy to adjust on angle, and if we decide to to for he multidie we are talking about 450 lm on high mode, which should be enough for most of the cases.

As you can see now, the needs for caving, climbing, outdoorsports, diving etc. is so different, that it is not shure, whether you can find an new combination which really improves the situation with respect to the actual situations: No one of the commertial headlamps comply with cavers needs really. The best one at the moment is Scurion, but it still does not cover all requirements...

Being realistic, no one can design or make a light that will match perfectly every situation, but 80%+70%+80%+50% (average 70%) is more than 70%+42%+35%+99%. (average 61%)

I don't want to convince anybody that this could be the best headlamp for any use ever, of course for some specific uses there will be better options. By the moment I know that matching on a high percentage what an experienced caver needs is a very good starting point.

Thanks for you time and thoughts.

Regards,

Javier

 

[traplight]

hola...

Yes, the reflector with the lip cannot be machined in 1 piece, but with a little tweaking of the outside reflector portion, it can be done with 2... Think 'screw-in bezel' with the lip built in!

Ran a few tests on your reflector, and if interpreted it correctly, you added a non-flat reflector shim at the top to produce a greater light output at the bottom of the output?

here's the reflector i came up with:

and the resulting output:

there is a fairly large amount of increased light output at the lower area near the hotspot and also extending past the primary lens corona. It is fairly safe to say that considering a dispersion of 100deg from most emitters, you'll get a relatively same output. Worse comes to worst, we an make the shim a little more oblique and throw in a devil tail at the bottom of the reflector to create a :devil: beamshot ...a signal light to compete with batman's!

In the event you were referring to adding a completely flat shim to the upper portion of the reflector, the result would be roughly the same with the exception of spikes extending towards the top right and left of the spill.

Presently, the room is 800X800X800mm. The reflector cup for the emitter is 86mm from the back 'wall'. all walls are painted an 'off-white' with a standard knock-down splatter finish. BUT... I'm far from getting the actual numbers proper for for duplicating the reflectivity of a common painted white wall. If anybody has any specific constants for:

1. ambient reflection
2. diffuse reflection
3. specular reflection
4. RGB absorption
5. light transmission per micron

... it would make the beam simulation, and subsequent 'virtual beamshots', a lot more accurate In the future (like maybe late spring?) it will be possible to simulate radiosity in different environments.

On another note, it appears you've got a very nice focusing reflector setup with your latest model torch. If this could be adapted to a headlamp, you'd be lightyears ahead of the competition.

Tobias, your input has been taken as very effective real-world experience. Would you say that during your ventures, your practical light usage is common to most 'splunkers?

I haven't had the opportunity to get technical in several months... please forgive my diving into the shallow end of the optoelectronics design category.

About a year ago there was a funded project to create a liquid cooled capillary headlamp running 3 XR-E's at 1000maH.. The money ran out as did the health of the poor chap who was funding ... Hence my extreme interest in sharing as much as i can with anyone interested in creating a worthy and somewhat affordable handsfree lighting solution

 

[Barbarin]

I'm amazed by your work.. thank you very much indeed.

Well, sorry for my english, but I did not understand this sentence:

It is fairly safe to say that considering a dispersion of 100deg from most emitters, you'll get a relatively same output. Worse comes to worst, we an make the shim a little more oblique and throw in a devil tail at the bottom of the reflector to create a :devil: beamshot ...a signal light to compete with batman's!

You mean you don't like the resulting beam?

I'm doing it by using a flat mirror, and the results are quite similar. In practical terms you are removing light from the upper side of the beam to put it on your foot, and that was what we wanted.

Tomorrow will post some beamshots.

BTW, I hope not to run out of funds or health!!

Javier

 

[traplight]

chillidos!.. mi espanol no es bueno

Gracias para los elogios!

Actually i think the beam is very appropriate and original. It will open the doors for quite a few designers as well... imagine beamshaping with elliptical hyperbolas!

The problem we encounter when working with non-round and non-90deg angles is milling. Casting is expensive with aluminum due to the setup and the high flow temperatures. Current 6061/7075 metals are even more difficult to work (tolerances with flow prevent casting from reaching smaller recesses).

Plastic is a viable option. There are quite a few to choose from, and the setup is relitively low cost for even small proto runs. I've personally worked with 30% hollow core fiber reinforced delrin and this stuff really hates to flow mold. There are other plastic composites that can help with heat distribution and sinking like corian (it has alumina ceramic particles in preset composition ratios) ; an extremely tough, impact resistant, scratch resistant, and a high melting temp.

When you really start looking into the different composite materials out there.. it warps the brain :huh:

If i have the time, i'll set up a larger virual room, create a floating measurement radius, and work with some different types of emitter/reflector combinations.

buenas noches amigo

 

[jch79]

Very simple CAD drawing to have an idea about what I'm thinking about:

Javier,

When you say "cables are to be avoided", does that mean that the battery pack is integrated into the headlamp, as one piece? It looks like it from this design, but I wanted to make sure that's what you're talking about.

Thanks,
John