Science Interviews


Sun, 19th Feb 2012

Pocket Projectors and Touch Screen Tables

Dr Nic Lawrence, Light Blue Optics

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Helen -   Light Blue Optics is a Cambridge based company developing lasers to project images and to turn any surface into a touch screen.  Nic Lawrence is the co-founder and heís here to explain how it works.  Well Nic, thanks for joining us.  Weíve got another piece of fantastic technology kit in the studio with us today and this is called Light Touch...

Nic -   That's right.

Helen -   Itís a black box.  Itís 20 centimetres tall, 5 centimetres wide, and currently, you might just be able to hear it.  The little fan is going.  Itís projecting a beautiful clear image onto the desk in front of us.  And I think you've just been playing a game on it!  Itís doing all sorts of different things and I want one.  Maybe you can start off by telling us why you made this particular thing and what kind of things it can do?

Argon laser beam separated into several beams at different wavelengthsNic -   The light touch is probably best thought of as having all the functionality of an iPad but without a physical screen.

Helen -   Weíre just using the desk here...

Nic -   It acts just like a touch screen, except the table becomes the touch screen itself.  We created this really as a development of some technology which we developed when the four of us who started the company were in Cambridge University, in the engineering department.  Weíd all been doing our research on the use of lasers and in particular, steering lasers using liquid crystals.  The reason why that's interesting and has real applications is that all of us were excited about the idea of having a mobile phone or a really small gadget from which you project a large image.  You see it in all the films and the fundamental problem really is one of efficiency.  Most display technologies waste most of the light because when you form an image, you block the light.  If you're using lasers and in particular, if you're using holographic displays like we are here, then what you do is you have the opportunity to steer the light to where you want it.  So you create light and dark not by blocking light and wasting it, but by steering it to where itís needed.  The company Light Blue Optics was really formed around that technology on ways to do it efficiently.

Helen -   So how are lasers being used in this gadget to get the image that weíre looking at?  I'm currently very pleased because of the beautiful picture of a turtle coming out which is very suitable for me.  How are you creating that image and where do lasers come into it?

Nic -   In the system, we have three lasers Ė one red, one green, one blue.  They are turned on and off very quickly and they are used to illuminate a very small liquid crystal on a silicon chip.  And on that chip, we don't put pictures.  We put what look like random patterns and of course, they're not, they're diffraction patterns.  When the light hits the display and itís reflected, the LCOS (Liquid Crystal On Silicon) chip, as itís called, it changes the delay of the light at different points.  That causes the light to interfere with itself and by the process of diffraction, as you travel a certain distance away, that forms a pattern.  And of course, what weíre trying to do here is to work backwards from the pattern, which is the image, to try and work out what diffraction patterns we need to put on that chip.

Helen -   So how do you do that?  How do you create those diffraction patterns?  Is that something that I'm going to be able to grasp?

Nic -   You get some very clever scientists, put them in a room and feed them pizza.

Helen -   Pizza, okay.  Got it!

Nic -   Basically, some of my colleagues, very talented in the maths area, developed some algorithms for doing it.  Itís a very hard computational problem and what we came up with was really a way of cheating.  So, if you understand how your eye works, it forms an image over time.  What you see is not just an instantaneous pattern but itís the integration of lots of separate patterns.  What we did is work out how to produce approximate versions of the image very quickly and different versions of them and if you display them very quickly, you fool the eye into seeing a high quality image, and that was really the fundamental breakthrough that some of my colleagues came up with.

Helen -   And you mentioned already that itís about efficiency to get a really bright image.  Why is it that lasers are better than using other things like lights or LEDs, things like that?  What's going on there that's making this brighter and more clear and beautiful than perhaps an alternative?

Nic -   From an image point of view, lasers are great because you can get very deep and rich colours.  You can address a very large amount of the colour spectrum.  But the real advantage over LEDs and things like that is that you have more control.  You could control not just the amplitude, how much of it is there, but the phase.  And by doing that, that's what allows you to steer it, that's what allows you to design very compact optics so you can shrink the system much more.

Helen -   And I've been playing with this, moving things around with my fingers.  Itís a touch screen.  That's also based on laser technology as well, isn't it?  That was something that already existed and you've added it in so that, although this is not just a screen, we can touch and move things around as well.

Nic -   Yes.  The concept has been around a while.  In the past, you've been able to buy laser keyboards where you could type on the table.  We started there and weíve adapted and improved the technology.  So it uses an invisible infrared laser and as you touch the screen, thereís a camera in the system that sees reflections and that's how the touch works.

Helen -   You mentioned to me just before we came on the show that this particular box isn't actually available anymore because you're doing the next generation of things, but what has this one been used for?  What sort of applications?  Where might we see this around and about and what sort of things is it doing?

Nic -   When we set out designing it in the first place, we thought of it as a consumer device and in actual fact, your customers will always tell you differently what they want to use it for, and most of them wanted to use it for restaurants and bars so people could sit at the table and order the food and drinks themselves.

Helen -   So I could look and see what would I want and Iíd press the button and then that would go straight to the kitchen and tell them what I wanted to order.

Nic -   Exactly.  And the reason is, if you had an iPad doing it and you have ketchup on your fingers, then that's pretty gross.

Helen -   That is gross.  I hadnít thought of that.  Good point.  Are they also installed in some fast-food restaurants where you can play games on them?

Nic -   That's right.  Those are couple of pilot stores in the midlands that built these into the tables and apparently, they had to almost install a ticketing system for the kids to ration them.

Helen -   Excellent!  But you're moving forwards.  You're looking at the next generation of these gadgets.  What's next for the laser touch screens?

Nic -   Weíre pretty excited about the next version that's being developed.  Itís mainly being developed in our office in America and itís really a continuation to principle.  Making even smaller systems, small enough to fit inside a very slim phone, even more efficient.  The idea is itís something that will allow you to take your iPhone of the future and project a large image using virtually no battery, and maybe even do the touch as well.

Helen -   Thanks, I look forward to finding a way of watching movies!


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