Best 3D Glasses – Passive Polarized vs Active Shutter 3D technology

3D glasses form a vital component of current 3D Display technology enabling stereoscopic vision and depth perception. As explained in greater depth in the 3D TV technology guide, we are able to perceive depth due to the fact that each of our eyes observes the same scene but at a slightly different perspective. When the individual images being viewed by each eye reaches our visual cortex, our brain automatically puts these images together and interprets information regarding the third dimension. Try tossing a ball back and forth with a friend with one eye shut and you will realize just how important the second eye is for us to perceive depth.

Panasonics Active Shutter 3D Glasses

Panasonic's Active Shutter 3D Glasses

Thus, ultimately any 3D display technology will rely on using a method to deliver separate images (or views) of the same scene to each eye. 3D glasses provide a very simple and elegant approach to achieving this. The idea behind them is simple enough, each eye piece allows the image meant for the corresponding eye to pass through while blocking the image meant for the other eye.

3D Glasses can be divided into two primary technologies, Active and Passive. Active glasses are usually powered and involve moving or switchable elements in the glasses that “actively” discriminate the incoming image so as to provide a different image to each eye. In direct contrast, Passive glasses do not rely on any powered or movable elements. They usually rely on some special type of optical material that helps discriminate between the images meant for each eye.

Active Shutter 3D Glasses

Active shutter glasses are currently a very popular choice amongst consumer electronics giants who are investing in 3D display technology. The primary reason for this is that this technology requires a very minimal modification to current HDTV displays and as a result it is much easier to develop and perfect. The individual eye pieces of these glasses incorporate liquid crystals and a polarization filter so that when a voltage is applied, the glass turns dark and prevents light from transmitting through. Thus the left and right eye glass can be shuttered alternatively in this manner and this shuttering effect is synced with the refresh rate of the display. The 3D TV displays a frame for the left and right eye alternatively and the sync with the active shutter glass ensures that each eye only ever views the image it is meant to see. As is probably evident, because of the way these displays work, the effective refresh rate of the TV is halved. This is why 3D Ready TVs have to have a minimum refresh rate of 120 Hz (meaning 60 frames per second for each eye).

So how will Active Shutter Glasses affect your 3D experience? Well, it is actually a very simple and elegant solution to providing stereoscopic vision using existing display technology. The pros and cons of this technology is listed below and will probably help answer some of your questions.

Advantages of Active Shutter Glass Technology

  • Probably the cheapest 3D technology in the short term. This is because this technology only needs a refresh rate enhancement for current LCD and Plasma TVs, something that isn’t too hard or expensive to do. In addition a syncing unit will be required to sync the TV to the active shutter glasses
  • Lower price point does not come at the expense of 3D image quality.
  • Backward compatible with some of the high-end 3D capable TVs that were sold in 2008 and 2009
  • Displays are based on very mature LCD, DLP and Plasma technology which means that most of the quirks are already ironed out and prices shouldn’t be prohibitive.

Some drawbacks of Active Shutter glasses

  • The constant shuttering might bother some who are very sensitive to low refresh rates and cause flickering. This will be true of the lower end 120 Hz displays which only provide an effective refresh rate of 60 Hz. However, 3D display manufacturers have already announced many TV models with refresh rates of 240 Hz and even 480 Hz! These high refresh rates will easily get rid of any such complaint one might have of the 120 Hz displays
  • Glasses are battery powered. This is one major drawback that is not particularly easy to alleviate. Due to the nature of the technology the glasses need to apply a potential to “shutter” the glasses. It also needs additional power to communicate and sync with the TV. Running low on batteries while watching a movie will surely be a very annoying experience. So if you are planning to buy one, be prepared for this. It shouldn’t be hard to deal with though. It’s just like your PS3/XBOX360 wireless controllers to be honest. Just set them up at the charging dock when you aren’t watching 3D television, and that should make sure that they are charged and ready to go when you need them
  • While the 3D displays using this technology will be inexpensive themselves, the glasses will be more expensive than their passive counterparts due to their complexity. This means that it might be a bit prohibitive to own many active shutter glasses for when you have friends come over to watch a 3D movie. However, it is most likely that they will be well subsidized by the display manufacturers in an effort to encourage widespread 3D TV adoption.

That pretty much sums up the active shutter technology and its pros and cons. It is definitely the most mature 3D technology at the moment when it comes to personal 3D capable home theater systems for the home user and promises a fantastic 3D experience.

Passive Polarized 3D Glasses

RealD Polarized 3D GlassesThe simplest passive 3D glasses that most of us are all familiar with are color anaglyph glasses…those cheap red-green or red-cyan glasses that you have used at some point or the other. These glasses do not have any “active” or powered components on the glasses. Instead, they rely some optical effect to discriminate between two images projected on a screen, each meant for a different eye. In the case of anaglyph glasses, the images for the left and right eye were projected using two projectors on the same screen and due to the color tints on each eye piece, a separate image was delivered to each eye. However, this technology has severe limitations, chief amongst them being the poor color fidelity due to the use of tinted glasses. The muted colors lead to a very surreal, uncomfortable and visually jarring 3D experience which prevents the viewer from being immersed in the 3D environment.

More recently, there has been resurgence in Passive 3D Glasses technology due to technological progress that has enabled Digital projectors such as those used by RealD and IMAX 3D to display commercial movies at movie theaters in true 3D. These systems rely on exploiting a property of light called polarization. If you are interested in the details of this technology check out my article explaining how 3D TV technology works. To explain it very generally, this technology relies on discriminating between two images projected on the same screen by 2 separate projectors based on the polarization of the light used to project the image. As shown in the figure below, when light of one polarization encounters an eye-piece that is polarized in the opposite direction, it cannot pass through. On the other hand, if both the lens and the light have the same polarization, then the light passes through the lens unimpeded. Thus, each eye piece has the opposite polarization and the image projected on the screen consists of two images, each possessing a different polarization and perspective, meant for one eye. In this manner, a separate image is delivered to each eye.

In commercial 3D projectors used in theaters, the projector technology relies on Circularly polarized light which works in a similar manner but also allows the viewer to tilt his or her head without degrading the image quality. These projectors also save on costs since they can alternatively generate right circularly polarized and left circularly polarized images in rapid succession without the need for two independent projectors.

We have listed the advantages and some of the disadvantages of this technology below

Advantages of Passive Polarized 3D Glasses

  • Provides excellent rejection between the left and right eye views thus getting rid of any ghosting issues in the 3D videos
  • Guaranteed flicker free 3D experience
  • Provides amazing visuals and very rich colors
  • Passive 3d Glasses are extremely cheap. You can easily stock up on them if you are planning to have a big Super Bowl party where you want to show off your fancy 3D TV. Additionally, there is a good chance that the glasses you kept from when you went to the theater will actually work for your passive polarized 3D display

Some disadvantages to keep in mind

  • This technology is currently limited to front-projection systems. This means that it is easier to use in projectors but hard to implement in regular flat screen 3D Tvs. This is primarily because it is very hard for the light to retain it’s polarization property when it interacts with a screen. For front-projection systems, a special silver screen is used to reflect the light while maintaining the polarization of the projected images.
  • This projection technology is currently very expensive and will appeal only to the hardcore 3D addicts out there. Silver screens aren’t cheap either!
  • This technology is not compatible with current mature display technologies such as LCD, Plasma and DLP. This means that any new technology that is developed will still be in “Beta” mode and will probably take a couple of years before the kinks are ironed out.

The Verdict

So which type of 3D display technology should you go with? As things stand at the moment, we would very strongly recommend Active Shutter based 3D TVs. As listed above, this is based on very mature and robust display technologies and will also be very competitive when it comes to pricing. While passive polarized glasses are attractive in their passive nature, this display technology will still take a few years to mature before it will truly challenge active shutter based systems. Of course, chances are that in the next few years someone will develop a 3D TV that doesn’t require glasses… Well, at least we can hope that they do :-).

37 comments

  • Best3DTV (5 years)

    Agreed Ed, but I do think it will be quite some time before we get to that kind of technology. Additionally, if the regular goggles (without augmented reality) don’t catch on, it might be harder for folks to put more money into developing the augmented reality stuff.

    Having said that, I’m sure DARPA has probably been pouring massive amounts of money into augmented reality glasses. Hopefully something good will come out in the next decade or so.

  • kammodo (5 years)

    “Of course, chances are that in the next few years someone will develop a 3D TV that doesn’t require glasses”

    Phillips 3D WOW technology has been out for a little while now. I believe this requires no glasses.

  • Edison Birth (5 years)

    Ed, your 3D TV guide is excellent; thank you very much for providing us, consumers, with your unbiased technical expertise and comments. However, you should consider revising/updating your guide and verdict on active versus passive glasses for 3D TVs. In my opinion, Active Shutter based 3D TVs, should no longer be recommended, despite the big push by the major 3D TV manufacturers in that direction.
    Reason: on May 28, 2010, a new 47-inch TFT LCD flat panel 3D TV was introduced at the Society for Information Display (SID) trade show in Seattle. This 3D TV set works with very inexpensive passive polarized glasses, which are free from flicker and crosstalk, and therefore, they do not cause dizziness, eye tiredness and headaches, as the active shutter 3D glasses do.
    Therefore, I have decided to postpone buying my 3D TV set until I can get one of those with passive circular polarized glasses in the stores.

  • Morg (5 years)

    I want to agree with Edison Birth. I have not purchased a 3d set yet as I have been sold on passive glasses. The flashing motion in the active glasses gives me a headache, whereas the passive technology does not. Ironically the passive vs active subject is the exact reason I stumbled onto this site in the first place. I have yet to find anyone truly do a professional side by side comparison of the technologies. All the articles I have found are written from a secondhand standpoint. Meaning they state what the “industry facts” are… but clearly haven’t compared the performance of the technologies. Currently LG is selling a complete line of passive 3d models in the UK. Other than that, JVC has a single professional model. I want more hard info on the REAL….TESTED differences. I have seen the passive JVC (very briefly, once) and the 3d performance was outstanding. I have also seen numerous active setups and all had crossover and ghosting caused by missed lcd flashing and all also gave me eye strain…….I’ll be waiting for more info on passive glasses technology……..

  • D Crane (5 years)

    I think the article is self-contradictory. First it says of passive 3D that

    “the muted colors lead to a very surreal, uncomfortable and visually jarring 3D experience”, then it says:

    Advantages of Passive Polarized 3D Glasses
    * Provides amazing visuals and very rich colors

    • Best3DTV (5 years)

      Hi there,

      Sorry for the confusion. Actually there isn’t any contradiction. The first line you quoted about muted colors, etc. is with regards to old anaglyph glasses technology (which is also a form of passive 3D). The advantages listed later on are with regards to passive polarized glasses, which are different from anaglyph glasses and are very good solutions for providing a good 3D stereoscopic image to the viewer.

  • alexandre (5 years)

    these very weak not talked about the difference in the contrast of active and passive glasses

  • dil (5 years)

    can panasonic 3d glasses be used with sony 3d tva

  • blah (5 years)

    The article should mention that circularly polarized glasses exhibit greater ghosting than shutter solutions, especially in high-contrast situations, because circular polarization filter does not block the light completely (getting rid of ANY ghosting??).
    In case of linear polarisation, this is way better (3x), but you cannot tilt your head to not break the effect – another disadvantage.

  • blah (5 years)

    also, the difference in contrast (brightness increase needed) between active and passive glasses should be mentioned.

  • starguy (5 years)

    I wear eyeglasses and am having trouble finding any info on which 3D glasses work better with eyeglasses. I’m thinking about getting a Panasonic 3D plasma.

  • Jason Shouler (5 years)

    To me the advantages of passive over active is overwhelming – and not just in theory but in practice too.

    Due to pricing I started with an active system (which to be fair IS impressive on first use) but once you then move to a passive system then the superiority at every level become apparent. That’s probably not the best way to buy a 3D TV but it does at least prove the grass is sometimes greener on the other side!

    I bought the LG 47LD950 which by the way is also excellent for spectacle wearers as the circular polarized glasses supplied easily fit over the top (you can buy 3rd party glasses anyway or simply visit your local cinema for extra pairs)

  • […] importantly, there is no flicker effect that causes dizziness or headache. With the shutter 3D technology glasses, it might have been a personal matter because some people felt dizzy and some didn’t. So for the […]

  • […] for the 3D glasses, the design wasn’t bad. But since it was the shutter glasses technology, it was uncomfortable, and its price and recharging the battery were a nuisance, which prompted me […]

  • Looky (4 years)

    Considering comments I resigned from buying active 3d LG TV set. But before I buy a little bit more expensive LG passive 3d I would ask if any of you can tell me what happens if you tilt your head? What is all that talking about ghosting – what does it mean?!
    Thanks

  • Jason Shouler (4 years)

    There is NO ghosting at all with passive sets (compared to active anyway). Ghosting normally means the image from one eye bleeds into the other eye (more correctly referred to as cross-talk).

    As circular polarizing technology is used this means you can tilt your head quite a bit (the image will become 2D at 90° though)

Leave a Reply

Your email address will not be published. Required fields are marked *

Go to Top