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'Progressive' car mirror is said to eliminate blind spots, distortion

Research team devises a side-view mirror that uses eyeglasses technology.

By Douglas Newcomb Jan 29, 2013 8:49AM

Blind spot mirror. Photo courtesy of Optic Letters.Automakers have been trying to prevent driver blind spots ever since the first side-view mirrors were invented. Instead of plunging ahead with cameras and sensors, three Korean researchers are proposing a simpler solution borrowed from eyeglasses.

Hocheol Lee and Dohyun Kim at Hanbat National University in South Korea and Sung Yi at Portland State University in Oregon have applied multifocal optics to side-view mirrors. That technology is used in "no-line multifocal" eyeglasses, commonly known as progressives, which simultaneously correct nearsightedness and a reduced focusing ability without the need for separate, distinct lenses as seen on bifocals.


They say their simpler design would create a mirror that’s free of blind spots, has a wide field of view and produces images that are accurately scaled to the true size of an approaching object -- and work for both sides of a vehicle.


In the U.S., the driver-side mirror is flat; objects appear undistorted in their true sizes so that the driver can more accurately gauge an approaching vehicle's distance and speed. But the optics of a flat mirror create an inherent blind spot.

A longtime but low-tech cure for the passenger side has been the traditional spherical convex mirror. Its curvature widens the field of view but creates another problem in the form of distortion. As anyone who has driven a car in the past few decades knows, “Objects in mirror are closer than they appear."


Automakers such as Ford have added smaller “blind spot” mirrors to vehicles and, of course, similar add-on solutions are available from the aftermarket. Lately we’ve seen more high-tech approaches in the form of blind-spot warning systems that use cameras and sensors to detect a vehicle in a driver’s no-see-'em zone, and Honda’s new Lane Watch feature uses a camera mounted under the passenger-side mirror to screen the blind spot on an in-dash display.

While a college professor last year used the design of a disco ball to create a mirror without blind spots, the researchers in South Korea and the U.S. say that a mirror manufactured with their new design would feature a curvature where the inner zone is for distance viewing and the outer zone is for near-field viewing to eliminate blind spots.

"The image of a vehicle approaching from behind would only be reduced in the progressive zone in the center," Lee said in a press release, "while the image sizes in the inner and outer zones are not changed." 

Progressive mirror concept (c) The Optical SocietyA European-spec aspheric mirror, top left, becomes flatter at the outside to give a better view of vehicles in the blind spot. A flat mirror, below left, is used in most U.S. cars. Above and bottom right is the progressive mirror. The blue lines indicate where the mirror focal lengths change. (The Optical Society)


Lee acknowledged that the horizontal progressive mirror does have some problems with binocular disparity, the slight difference between the viewpoints of a person's two eyes, and astigmatism, blurring of a viewed image due to the difference between the focusing power in the horizontal and vertical directions. But he said that these “minor errors” are positive trade-offs and that the researchers think their design will greatly expand the field of view and provide more reliable depth perception. Hence, no blind spot.


The researchers also say that the cost of manufacturing their mirror design would be less than current mirror designs with added small, wide-angle viewing sections. To prove their point, they used a conventional glass-molding process to manufacture a prototype horizontal progressive mirror and were able to produce a mirror with more than double the field of view of a traditional flat mirror.


Since mirror designs are stipulated by federal regulations, the new design would need to be approved for use in the U.S. before appearing on cars here. The researchers are hoping that automakers and their suppliers will eventually license the o mirror technology. Or maybe at least make them available in your local auto-parts store soon.

Jan 29, 2013 10:00AM
Cool!  A simple design that doesn't require expensive electronics.  I hope it finds its way to our shores. 
Feb 1, 2013 11:33PM

What a load, this new mirror STILL has the same problem that our current passenger side mirrors have, and that is it distorts the image. From the article -


A flat mirror, below left, is used in most U.S. cars. (image C)


and bottom right is the progressive mirror. (image D)


You notice that? yeah, image D looks smaller and farther away, exactly the same thing that our passenger side mirrors already do. They have changed absolutely nothing.


It's the same thing if you compare the images in (a) and (b). (a) being the Europe-spec mirror and (b) being the "new" progressive mirror.


So BOTH examples of this new mirror prove that the image given is smaller and farther away. You would still have to have “Objects in mirror are closer than they appear."  But isn't that the point, to get rid of that distortion and yet, still have a mirror that allows you to see wider angles? If that is what they are shooting for, then they failed. The distortion is still there and just as bad as it is now.


Why would you want these to come to our shores? So BOTH (drivers and passengers side) mirrors are distorted and have the  “Objects in mirror are closer than they appear" message.


1 more point, why are people trying to find a solution for a problem that doesn't exist? If you #1. Use your Mirror #2. LOOK over your shoulder and check #3. Use the technology that is available to you (crash avoidance, lane sensors, and other blind-spot warning systems that use cameras and sensors) There is absolutely NO reason you should change lanes into me. If all three of these can't stop you from hitting me than your license should be yanked because if these don't help you, nothing will, you're just an idiot that shouldn't be on the road. I hope this crap NEVER gets here, if it does the first thing I'm doing is yanking that crap off of my car and using the real mirror as it was intended, so objects appear undistorted in their true sizes so that the driver can more accurately gauge an approaching vehicle's distance and speed.

Feb 3, 2013 1:54AM
Dodge has got it right. The new mirror creates the very same problem it claims to have fixed. And if you can't already use what your car has got, then don't drive. I also hope these don't come here. I don't want distorted images on both sides of my car either.
Feb 4, 2013 5:48PM
You know that the Image (a) is the commercial aspheric mirror and the Image (b) is new progressive mirror. But, you could see that the aspheric mirror distorted more than the progressive mirror. 

Also, the examples of driving performances are down here.
(a) Aspheric mirror you tube:
(b) Progressive mirror ;
Feb 3, 2014 6:33AM
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Feb 5, 2013 10:31AM
Before somebody brings up how I cut off somebody on a five lane interstate. There were two lanes to my left, I was in the slow lane, turned on my turn signal, checked mirrors, and then got into lane two of the exit. Yes, I saw the four wheeler in lane one, I thought that he wanted the exit. Which is a natural assumption 1. being that he was in lane one of the exit, 2. he did not have a signal activated to show that he wanted lane two and was trying to get over. We both wanted the spot that I took, he honked and "showed me that I was #1" and started cursing. (Lesson? Don't use an exit to pass people on the right.) I have never been in an "at fault" accident in my life. I have over a million ticket and accident free miles.
Feb 5, 2013 10:03AM

Actually, "you could see that the aspheric mirror distorted more than the progressive mirror" isn't true. The mirror in A gives a better representation of what you're actually looking at. The point at which the mirror is angled is more distorted, but I would rather have that then then entire image being slightly distorted to minimize the distortion in one spot on the mirror. Besides, as mentioned, that is the Europe spec mirror, and I live in the US. My statement, technically, is correct. Image B is more distorted overall than image A. (Do you use the entire mirror, or just a half inch strip through the middle of it? If you use the entire mirror, A is better.) The true discussion here is of C and D because I live in the US.


I do not want both mirrors on my vehicles to show a misrepresentation of what/where the vehicle behind me is. Off the top of my head, I can only think of twice in my 35 years of driving that I cut off somebody, both times they were accelerating up an exit ramp to pass a line of vehicles on the right (and I had my turn signal on to show my intention of exiting). They had no intention of exiting, and on the second occasion, the guy was forced onto the exit and could not get back over, so he cussed me out because he was the idiot that didn't stay in the lane that he wanted, lol. No, I did not force him over, he was already there, it was a two lane exit and he was already in the furthest right lane 1, so when I got into exit lane 2, he just couldn't get back over in time to not take the exit.


In the 60's there was a curved aftermarket mirror, since then the mirror comprised of 100's (1000"s?) of flat surfaces, and now this. The one thing they all have in common? They were/are trying to make a mirror that gives a wide field of view without distortion. They all also create the very thing that they are trying to get rid of, distortion.


We need really an alternative way. Not really, if people USE what they have, they'd be fine. Only in severe situations have I noticed any problem with seeing other cars. Adjust your mirrors correctly, use your eyes, and if equipped, use the sensors, lane warnings etc. on the vehicle.


"Aspheric mirrors can be seen in most European cars there." That's there, not here. As stated, I don't want these here. I don't want distorted images on both sides of my vehicles., My car or my truck and trailer.


"I want you to realize that new mirror is better than any commercial Aspheric mirror." I want you to realize that it is not. A flat, true image is the best. You just can't do that on the passenger side effectively due to the distance of the driver from the mirror that they're trying to use.
I did watch the videos, yes, the progressive mirror doesn't have the distortion all in one spot so you see the whole car throughout the time it is there. But I still like the other mirrors better. It give you a better sense of distance to object and true object location. You put those progressive mirrors on some cars and see, people will cut others off more often because they thought that they had more room than they really have.
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