Hello everyone, this is my first post on BLF!
I'm a casual flashlight enthusiast and surgical resident. Being familiar with flashlights and LEDS with advancements in tint and CRI, I've been disappointed to see the offerings for surgical loupe mounted headlights - invariably these are marginally bright enough, cool-tinted, and ridiculously expensive for what is being offered.
I followed the BLF Q8 development and dipped my toes into modding with a spring bypass on my own Q8. Obviously I have a lot to learn and take in, but I'm certain I can build something much better for far less money. I'm also getting into 3D printing and modeling in Fusion 360, so I'd like to build something from the ground up. I need some help with the basics of choosing proper components as a first step to seeing if this is feasible.
This is the sort of product I'm hoping to emulate and improve upon:
https://www.orascoptic.com/products/headlights/endeavour-xl
These retail for more than $600!
Characteristics I'm aiming for:
- Battery (3-4x 18650) and driver housed in a hip mounted pack, leaving only the light weight LED/PCB, small heat sink, and lens mounted on my loupes
- At least 100 OTF lumens. I'm not sure how these companies are measuring light output, but Orascoptic claims 85 lumens on their more powerful light.
- Even beam filling the field of view through the magnified loupes. The example I linked claims 2.5" beam at 12" working distance, which should be about right. I'll likely need a convex/aspheric lens like in a cheap zoomie light to achieve even brightness across the beam. I know I'll lose a lot of output this way, but I think the even light will prevent distracting changes with small head movements
- Neutral white tint with high CRI to match overhead operating room lights
- Continuously adjustable brightness would be nice, either with a potentiometer or through firmware like Narsil
Here is what I have come up with so far:
LED:
CREE XP-E: small size should result in more efficient light output for an aspheric lens in fixed "zoom" configuration. I can adjust the lens distance as needed to create the perfect final spot size at my working distance. I found these on some fairly small PCBs:
The PCB size and whatever heat sink I devise will likely be the limiting factor in how much light output I can get from this device since there isn’t a whole lot of mass to pull heat away
Lens: I think around 20mm will provide a good balance of capturing enough light and not being too obstructive or heavy. Any input on selecting a size?
Driver:
This is where I need the most help.
To figure out the output current I’ll eventually need I’d like to estimate OTF lumens based on the efficiency of the aspheric lens. CREE publishes luminous flux for all their LEDs which I assume is the total lumens out. Does anyone have a formula or resource for finding out how much will make it out the front?
I’m fine with using either a driver designed for a flashlight or a larger one since either way it will be hidden in the battery pack.
Some firmware with continuously adjustable brightness or ability to use a potentiometer would be ideal. Are there drivers from BLF lights available?
A few possibilities that I’ve found so far:
https://www.ledsupply.com/led-drivers/buckpuck-dc-led-drivers
https://www.ledsupply.com/led-drivers/flexblock-buck-boost-dc-led-driver
Let me know what you think and if you have any suggestions!