# How is Gravity on IMAX (3D)?

**URL:** <https://boards.straightdope.com/t/how-is-gravity-on-imax-3d/670581>\
**Category:** Cafe Society\
**Created:** [October 7, 2013, 12:44pm UTC](https://boards.straightdope.com/t/how-is-gravity-on-imax-3d/670581 "2013-10-07T12:44:09Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\
**Post date:** [December 20, 2013, 1:01am UTC](https://boards.straightdope.com/t/how-is-gravity-on-imax-3d/670581/21 "2013-12-20T01:01:21Z")

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> [@Chronos](#):
>
> Laser light sources for a theater projection system? I’ll believe that when I see it. Visible-light lasers have an atrociously poor efficiency, which means that enough laser light to illuminate a screen is going to dump a ludicrous amount of heat into the projection room, as well as racking up the costs for the electricity usage.

On the contrary, existing xenon lamps already generate a “ludicrous amount of heat” in the booth, and since that white light has to be filtered down to the RGB primaries, lots of it is wasted.

Lasers, on the other hand, can generate light in precisely the primary colors needed, without as much waste, and their light can be transmitted by fiber optic cable into the projector, so that heat is kept out of the booth. (But from my understanding, they still generate less heat, and consume less power, than the xenon lamps, for a given screen brightness.)

The chief benefit provided by lasers is that they will be able to provide much more light, and illuminate larger screens, than existing xenon lamps. As **Cinephile530** and I were discussing, high light levels are essential for good 3D.

As I said, all the major digital cinema manufacturers are working on it, the three major DLP producers and IMAX have all demonstrated laser systems, and the first permanent installation is set for the [Cinerama Theater in Seattle](http://www.geekwire.com/2013/paul-allens-cinerama-theater-install-worlds-laser-projector/) early next year.

[Barco’s laser prototype.](http://www.barco.com/en/News/Post/2013/7/23/A-peek-behind-the-curtain-Barcos-prototype-laser-projector)

[Christie’s public demo in Burbank last spring.](http://www.christiedigital.com/en-us/news-room/press-releases/pages/laser-projection-demonstration-lights-up-gijoe.aspx)

[Imax’s laser demo last month.](http://variety.com/2013/film/news/imax-demos-new-laser-technology-to-mostly-bright-reception-1200856572/)

[NEC and Laser Light Engines’ demo in Burbank last month.](http://www.soundandvision.com/content/its-laazzeer)

This last article makes an important point that may not be obvious to everyone:

> [@](#):
>
> Laser projectors, as contemplated for digital movie presentations, do not shine laser beams directly on the screen, as in a laser light show. Instead, they’re used simply as a light source for familiar types of digital projectors, such as DLP and LCoS. Lasers of appropriate red, green, and blue wavelengths are combined to produce white light. The latter is then diffused sufficiently to flood the imaging chips; it’s those chips that produce the picture, as they do with today’s lamp-based light sources.

I should note that the prototypes and early production units from Barco, Christie, and NEC/LLE are using this method, because they are starting with existing projectors and replacing the xenon lamphouse with a diffused laser light source. However, the IMAX laser system, which is based on patents developed by and acquired from Kodak, will use lasers to generate the primaries directly. This is why it won’t be available for about a year.

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