why isn't there glass lens & anti reflective coating for headlamp?

why isn't there a head lamp that made with glass lens & anti reflective coating? all head lamps on the market have cheap plastic lens.

I think glass would break. My headlamps get hit all the time. You name it they get tagged.

I agree that headlamps generally need to be tough. The problem is most aren't designed to be very tough to begin with. They aren't designed to deal with heat. They aren't able to run LEDs hard enough to produce enough light so that an AR coating will matter. There are a few of them which you could replace the existing plastic window with a glass one if you want to.

I agree that the glass would break. Headlights tend to have larger lenses than most flashlights. Many are not recessed for protection. Headlights are close to the eyes and there would be a lot more lawsuits if the glass on a headlight broke compared to the glass on a flashlight. Another problem with using glass lenses on headlights is the shape of the lens. Many lenses on headlights aren't circular. Plastic can be molded to any shape giving more potential for headlamp design. Glass lenses can't be. Aluminum flashlights are most if not all round tubes. Therefore it makes sense to use glass lenses because these also have the limitation of being round. Recessed behind metal, glass lenses can be strong and protected against bumps and drops. Recessed behind plastic, if the plastic bends on impact, it'll transfer that stress to the glass causing it to break. Try making a glass lens for a Black Diamond headlight. The lens will easily break, being totally exposed. You probably wouldn't be able to make the lens into that shape anyway with glass. Glass companies are a separate industry from the flashlight industry. Flashlight manufacturers have to adapt their designs to the sizes and shapes available for the glass they want to use. Plastic on the other hand, is a component of the body of a headlight as well as the lens. Therefore, companies that make headlights can form the lenses into whatever shape they want. By the way, I wouldn't consider the lexan lenses on my PT headlights as cheap plastic. Just because plastic lenses are used doesn't mean they are cheap pieces of junk.

I suspect the primary problem is weight and thickness.

There are a few high end caving headlmaps with tempered glass lenses. They are helmet mounted, heavy, expensive and big.

Heft is one of those things that makes a flashlight feel well made. Having a lens made out of glass won't affect the balance of the headlamp. You aren't slitting your own throat by making a lens out of glass.

A well made headlmp on the other hand, needs to be very light and extremely well balanced. A thick, heavy, glass lens cantelevered out on the end of the light, held upright by an elastic strap, really doesn't really help the "well built, balanced" feel.

I've been trying to get a glass lens for my BD headlmaps. It's just a round piece of glass I need, but it is a size I've never found.

mrme said:

I suspect the primary problem is weight and thickness.

There are a few high end caving headlmaps with tempered glass lenses. They are helmet mounted, heavy, expensive and big.

Heft is one of those things that makes a flashlight feel well made. Having a lens made out of glass won't affect the balance of the headlamp. You aren't slitting your own throat by making a lens out of glass.

A well made headlmp on the other hand, needs to be very light and extremely well balanced. A thick, heavy, glass lens cantelevered out on the end of the light, held upright by an elastic strap, really doesn't really help the "well built, balanced" feel.

I've been trying to get a glass lens for my BD headlmaps. It's just a round piece of glass I need, but it is a size I've never found.

Click to expand...

If you're looking specifically for tempered glass in an uncommon size, you're never going to find it. Tempered glass is only made in certain sizes and few shapes. Headlight makers actually have to adapt the headlight design an available size if they use tempered glass. Tempered glass is made in such a way that all of the stresses are around the edges of the glass. This makes it very strong. The problem with it is that there is no way to cut it to size without shattering it. If someone says they can cut tempered glass to size for you, they're lying and not selling tempered glass. Many headlight companies may be using other types of glass that can be cut.

You can get pyrex, sapphire, etc.
I think its price issue, has nothing to do with weight or thickness.
I've never had a lens crack or break on me, and I've dropped numerous flashlights. If anything, a headlamp should be able to withstand drop/impacts better than a flashlight, due to the shock absorbing body.

Hooked on Fenix said:

Headlights are close to the eyes and there would be a lot more lawsuits if the glass on a headlight broke compared to the glass on a flashlight.

Click to expand...

It's a non issue, how many stories have you heard where the lens breaks or shatters while the person is wearing it? It just doesn't happen. I'd be more concerned with glasses.

Well, many flashlights are glass--even $20 ones. Also, if you are tasking with them, paint, solvents, scratches, are just as big of dangers--if not certainties.