Aspheric + secondary optics

18 posts / 0 new
Last post
Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk
Aspheric + secondary optics

Using a secondary optics is a rare design decision. It can greatly improve optical performance by redirecting light that would otherwise hit flashlight head, but for some reason few makers do it.
I’d like to compile knowledge on available aspheric+precollimator setups. I’d like to also try to quantify the throw loss, but so far I lack data to do that. I welcome any help.

So…what secondary optics are there in the wild?

As you can see…this post is very incomplete. May I get help with extra information to put in here?

Also: any idea why so few makers do it? Adding a smaller lens as a precollimator doesn’t sound like an expensive change…
Any other thoughts?

Relevant read:
Automotive matrix systems with improved efficiency
http://www.candlepowerforums.com/vb/showthread.php?277082-pre-collimator
http://budgetlightforum.com/node/5882
http://www.candlepowerforums.com/vb/showthread.php?273932-Aspheric-lens-...
http://budgetlightforum.com/node/45585

Edited by: Agro on 04/30/2019 - 04:08
Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk

Thanks Agro, that’s an interesting topic.
I found a cool paper that may be relevant to the discussion:
Automotive matrix systems with improved efficiency

maukka
maukka's picture
Offline
Last seen: 2 hours 51 min ago
Joined: 12/31/2015 - 04:15
Posts: 1826
Location: Finland
Agro wrote:
Thanks Agro, that’s an interesting topic.

What?

Good list Agro!

EasyB
Offline
Last seen: 2 months 3 hours ago
Joined: 03/09/2016 - 15:24
Posts: 1679
Location: Ohio

In my first thread on the forum I explored precollimator lenses a bit. With some beam size and intensity measurements

http://budgetlightforum.com/node/45585

With a high quality precollimator lens the beam intensity doesn’t decrease much (~5%), while the beam area can increase by more than 2x. Effectively doubling the OTF lumens of the flashlight.

scianiac
scianiac's picture
Offline
Last seen: 6 days 20 hours ago
Joined: 02/05/2015 - 18:50
Posts: 211
Location: Northeast, US

Having tried all of these I would say they are mostly rare because they are more complicated and not always suitable for mass production. The reflector + lens for instance is real hard to do if you want to use the lens to capture all the light the reflector doesn’t use because you have to somehow mount the lens floating in the middle of the reflector. Mounting the lens to the front lens actually works pretty well and is pretty easy but you only capture a small portion of the light and produce beam artifacts in the process. This is what I did and I did end up with a C8 at just under 300kcd but not a ton of that is actually from the lens. And really what you are doing is just making a really hard to assemble TIR.

And that brings me to the use of TIRs, TIRs are great if you’re main goal is total efficiency of OTF lumens and you’re willing sacrifice in some areas to get it. TIRs are made to capture as much light as possible and do so from a domed LED which will already be more efficient in terms of lumens, not to mention this means you have a better range of LED options like the 70.2 which you can’t dedome (funny enough you also can’t slice it and drive it nearly as hard as with it’s dome, many good 70.2s were sacrificed to learn that). And this was what I was trying to accomplish in the Storm, to still have a some serious throw but do so with a ton of lumens in the beam, not wasted as wash or inside the head. Using a TIR with a small high intensity LED would be mostly a waste, you would lose throw from optical losses and your total lumen output would still be pretty low, but paired with a high output LED you can really pump out some serious lumens at very respectable throw where all those lumens are used in that throw, not lighting up your feet. If you back me into a corner I would say the “cons” are potentially a little more loss in intensity than the pre-collimator lens and beam artifacts (which aren’t that bad unless you’re white wall hunting) and you do get a nice round beam instead of a square.

Co-owner/Engineer at STO Flashlights.

Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk

I found another stock implementation of what looks like TIR + aspheric:
http://www.ledengin.com/files/products/lenses/FXCM-7-H_FCX-53-01-0R.pdf

LouieAtienza
Offline
Last seen: 1 month 1 week ago
Joined: 11/17/2018 - 15:15
Posts: 593
Location: New York

I believe the STO Storm of Ra has a TIR/aspheric combimation…

edit: Guh, I somehow missed this was already mentioned up top

LouieAtienza
Offline
Last seen: 1 month 1 week ago
Joined: 11/17/2018 - 15:15
Posts: 593
Location: New York

The Chauvet Q-Spot 260 used a Luminus CBT-90 (or CST-90) and two lenses in an adjustable-focus design. I always wanted to get one of these and pop a CFT-90 in there as it’s capable of driving the LED at 27A max… Then swap the lenses out to make it a mega-thrower (if I remember correctly the original literature had a 1M candela rating!)

Theodore41
Offline
Last seen: 5 hours 16 min ago
Joined: 02/20/2016 - 12:57
Posts: 918
Location: Athens Greece.
Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk

One thing that might have been obvious to some just appeared in my head.
There might be others who haven’t noticed as well so I’ll share it.

Zoomies tend to be hard to waterproof because they change volume while zooming. They can’t be air-tight so they are hard to make water-tight.
Separating the head into 2 compartments, one tight and the other not, would enable good waterproofing. Maybe not something that would result in great beam underwater but at least it would prevent damage.

This is quite natural to do with a dual-lens zoomie as long as the first lens doesn’t move. Like with Xiaomi FZ101.
Therefore a dual lens zoomie can fairly easily overcome one of the major drawbacks of zoomies.
Note that the first lens might be a regular projection lens or a TIR sealing it is just the same job.

LouieAtienza
Offline
Last seen: 1 month 1 week ago
Joined: 11/17/2018 - 15:15
Posts: 593
Location: New York

The solution would be to have the optics move inside a completely sealed body. Bonus points for filling the entire chamber with an inert gas like nitrogen Cash

Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk

LouieAtienza wrote:
The solution would be to have the optics move inside a completely sealed body. Bonus points for filling the entire chamber with an inert gas like nitrogen Cash

It can be done, in 2 ways:
  • move the lens inside, keep the one outside fixed
    • I believe it was considered on BLF – and rejected for some reason. Bad beam I think
    • also – zooming itself is hard. Servo motors? Magnetism? Complexity.
  • build a chamber around the regular zoomie head
    • increases size
    • adds the same complexity to zooming

Therefore I believe that a sealed chamber inside is a better option for general-purpose lights.
High-end or diving might be different.

LouieAtienza
Offline
Last seen: 1 month 1 week ago
Joined: 11/17/2018 - 15:15
Posts: 593
Location: New York

Agro wrote:
LouieAtienza wrote:
The solution would be to have the optics move inside a completely sealed body. Bonus points for filling the entire chamber with an inert gas like nitrogen Cash

It can be done, in 2 ways:
  • move the lens inside, keep the one outside fixed
    • I believe it was considered on BLF – and rejected for some reason. Bad beam I think
    • also – zooming itself is hard. Servo motors? Magnetism? Complexity.
  • build a chamber around the regular zoomie head
    • increases size
    • adds the same complexity to zooming

Therefore I believe that a sealed chamber inside is a better option for general-purpose lights.
High-end or diving might be different.

Or, just put your flashlight in a ZipLok bag. A heluva lot cheaper. And you can find them in virtually any supermarket. But in terms of:

Quote:
** also – zooming itself is hard. Servo motors? Magnetism? Complexity.

That’s quite simple. A thumb screw is easily sealable, and that can be attached either to a screw, or pinion that engages with a gear rack.

Not sure what your application is. If you just need rain resistance, even a regular zoomie would be mostly fine If you’re trying to make a diving zoomie then I don’t think you have much of a choice but make the entire optics system contained and adjustable in the body, otherwise you’d reach a depth where the zoomie head would be inoperable or possibly catastrophically fail because of pressure.

kikkoman
kikkoman's picture
Offline
Last seen: 17 min 38 sec ago
Joined: 05/03/2012 - 08:08
Posts: 201
Location: Austria

If the light is big enough, one might be able to fit a pressure equalization valve somewhere. (See Pelican cases – it’s a GoreTex membrane basically.)

Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk

LouieAtienza wrote:
Agro wrote:
LouieAtienza wrote:
The solution would be to have the optics move inside a completely sealed body. Bonus points for filling the entire chamber with an inert gas like nitrogen Cash

It can be done, in 2 ways:
  • move the lens inside, keep the one outside fixed
    • I believe it was considered on BLF – and rejected for some reason. Bad beam I think
    • also – zooming itself is hard. Servo motors? Magnetism? Complexity.
  • build a chamber around the regular zoomie head
    • increases size
    • adds the same complexity to zooming

Therefore I believe that a sealed chamber inside is a better option for general-purpose lights.
High-end or diving might be different.


Or, just put your flashlight in a ZipLok bag. A heluva lot cheaper. And you can find them in virtually any supermarket.

LouieAtienza wrote:
Not sure what your application is. If you just need rain resistance, even a regular zoomie would be mostly fine If you’re trying to make a diving zoomie then I don’t think you have much of a choice but make the entire optics system contained and adjustable in the body, otherwise you’d reach a depth where the zoomie head would be inoperable or possibly catastrophically fail because of pressure.

There is also intermediate step – kayaking. Putting the light under water is a part of the sport but it doesn’t have to work there well. And extreme depths are not required.
Zip bag works there…and is used a for many things…but a waterproof light is just more convenient.
But more importantly – this matters to other users. Because it enables rating the light as IPX8 as opposed to IPX6. This difference means a lot to many of those who simply want “good” w/out having specific waterproofing needs.
LouieAtienza wrote:
Quote:
** also – zooming itself is hard. Servo motors? Magnetism? Complexity.

That’s quite simple. A thumb screw is easily sealable, and that can be attached either to a screw, or pinion that engages with a gear rack.


Interesting. I remeber seeing such discussion but w/out a successful solution. Maybe it’s just my memory or maybe you can immediately find solutions that are hard to BLFers. Thumbs Up
LouieAtienza
Offline
Last seen: 1 month 1 week ago
Joined: 11/17/2018 - 15:15
Posts: 593
Location: New York
Agro wrote:
LouieAtienza wrote:
That’s quite simple. A thumb screw is easily sealable, and that can be attached either to a screw, or pinion that engages with a gear rack.
Interesting. I remeber seeing such discussion but w/out a successful solution. Maybe it’s just my memory or maybe you can immediately find solutions that are hard to BLFers. Thumbs Up

Methinks it’s rather simple… Same principle as a gate valve you have in the water mains – a sealed post. From there, what ever means you desire to convert rotary motion to linear is possible. The ratings of the seals would determine how far you could submerge the light as the pressure would multiply as you go further down. I would guess you’d need heavier gage walls for the battery components. I am not versed enough in battery technology to know what effects that would have on batteries.

Agro
Agro's picture
Offline
Last seen: 2 hours 26 min ago
Joined: 05/14/2017 - 11:16
Posts: 4125
Location: Ślōnsk

kikkoman wrote:
If the light is big enough, one might be able to fit a pressure equalization valve somewhere. (See Pelican cases – it’s a GoreTex membrane basically.)

Initially when I read this post I thought that fitting a valve on a light would take a lot of space.
But later…I got a different vision.
To describe it, let me start with SK68. It is applicable to many different designs but it’s relatively easy to explain with such starting point.
So…SK68. It has a number of fins on the fixed part of the head. These are perpendicular to the light’s axis.
Let’s turn them, so they are longitual.
Then – the bottom of the fins is a solid tube. Let’s remove it. Now fins are able to support the head.
Instead of the solid tube that’s one piece with the rest of the head, take a separate one. And not solid – a mesh.
Wrap GoreTex or another fabric-attached membrane around the mesh and put below the fins.

So…it has quite large membrane are relatively to the head volume. Is that enough to enable easy zooming?
Also, I’m not happy about membrane exposition – it is quite easy to pierce it.
But maybe with some refinements it has a chance of working?

kikkoman
kikkoman's picture
Offline
Last seen: 17 min 38 sec ago
Joined: 05/03/2012 - 08:08
Posts: 201
Location: Austria

I have no grasp of how permeable that stuff is, but it appears, VERY:

https://www.gore.com/system/files/2018-11/GORE-Pressure-Vents-Datasheet-...