“Vision 2027: Changing Scene & Planetaria of the future”

Piyush Pandey, Director, Nehru Planetarium, Mumbai, Pin 400018

piyush1953@gmail.com

The year 1923 was a milestone in that a demonstration of the first equipment for a projection planetarium took place in Carl Zeiss, Jena. Some kind of planetarium existed even 357 years back from now. The Gottorp Globe was the predecessor of the modern planetarium. It dates back to 1650, as a reminder of the fun side of science. It had a 3-metre-diameter hollow globe decorated with mythological pictures of the constellations on it inside and a map of the world on the outside. It was turned by water power. People sat inside in candlelight. Czar Peter the Great of Russia received it in 1713 as a present from the Duke of Holstein-Gottorp, whose ancestors had built it in a palace garden to amuse and amaze visitors.
Before 1962, the idea of a planetarium must have been alien to most of our fellow citizens. That year the Birla Planetarium (now known as the M. P. Birla Planetarium) was set up in Calcutta (now Kolkata). About 15 years later, this planetarium started functioning here in Bombay (now Mumbai). In between, Baroda (now Vadodara) too had its own planetarium in July 1976. With the initial lull, 1980 onwards we saw a speedy growth of the numbers. Planetariums were set up in almost all the parts of the country. Today there are two states that have three public planetaria each; they are West Bengal and Uttar Pradesh. The second position is probably enjoyed by Maharashtra for the moment but it may change very soon as many states have plans to set up planetaria and this tally which remained steady for one and a half decade after the first planetarium may now change every year.
In the next few five years the current number 30 may easily swell to 50. All the three major suppliers of opto-mechanical type of planetarium equipment, Zeiss, Goto and Spitz are represented in India in that numerical order, the last one had only one installation but with the Kurukshetra planetarium coming up its tally goes to two. The new entrant was the Evans & Sutherland of USA that installed its first Digistar 3 in Asia in 2003 here in this planetarium. Even that status of Mumbai was short lived. Two years later Gorakhpur acquired a planetarium of the same kind and we hear that installation of a Digistar3 is going on in Nasik at the time of writing of this article.
The Digital Planetarium that came to India in 2003 had been there for many years in other parts of the world. The first prototype digital planetarium was produced in April 1983 by Evans & Sutherland and was installed at the Science Museum of Virginia in Richmond (USA). Then in 1985 it we upgraded it to the final version that was christened Digistar I. It was followed by Digistar II a few years later. This introduced the planetarium world to the digital technology. For the first time, audiences were able not only to see the stars, but also to fly through the stars in three dimensions. This technology gives you the power to make your presentations soar to new heights in imagery and realism. All that you wish to show on your dome is generated on a computer system and displayed with the help of video projectors. For smaller domes just one projector at the centre fitted with a fisheye lens would suffice but for larger domes more projectors, usually six, project side by side to cover the dome with adequate brightness. The automation is superb so much so that the operator need not sit at the console; she may as well sit among the audience and use a small palm held device to start the pre-rendered planetarium presentation [1].
In the past four years the digital projection technology has also changed. In this planetarium we have video projectors that are based on 3-colour, CRT display system. The next type of video projectors that came to the scene a few years back were based on Digital Light Processing technology (more famous by its acronym DLP) [2].
The DLP technology is based on an optical semiconductor called a Digital Micromirror Device, or DMD chip that was invented in 1987 by Texas Instruments. The DMD is a very precise light switch that enables light to be modulated digitally via millions of microscopic mirrors arranged in a rectangular array. Typically each mirror is spaced less than 1 micron apart. They have the capability of switching on and off thousands of times per second and can thus direct light towards, and away from, a pixel space. The ratio of the off/on timing determines the level of grey seen in the pixel. The latest DMD chips can produce up to 1024 shades of grey. This property combined with a 6 panel colour wheel (2 RGB) is used to produce more than 16 million colours. Further innovation in this area has resulted in contrast ratios greater than 3000:1 with much improved colour reproduction. This became possible with Texas Instruments’ new HD2+ design that incorporates an additional colour (dark green) into the colour wheel.
Laser based projection system: A new breakthrough in video projection technology came about four years back, it uses laser light to produce up to 32 million pixels from a single projector. The credit for this integration of technology into planetarium projection system goes to Evans & Sutherland. At the heart of this technology lies the Grating Light Valve Modulator (GLV) developed by Silicon Light Machines. Those who wish to learn about this technology may refer to a nice article in a webzine by D. M. Bloom [3].
One of the fundamental breakthroughs for this new projector is a tiny linear array of movable mirrors, known as the GLV. The GLV is a micro-electro-mechanical system (MEMS), in that it is a silicon microchip that happens to have physically movable parts onboard. In this case, the movable parts are tiny mirrors controlled by on-chip electronics. By moving these mirrors, the GLV is able to modulate light and form the basis for a projected display. Using GLV technology has the advantage of the high contrast ratio, fill ratio, and brightness. In addition, GLV technology can provide high resolution, low power consumption, and digital grey-scale and colour reproduction.
Such device consists of parallel rows of reflective ribbons. Alternate rows of ribbons can be pulled down approximately one-quarter wavelength to create diffraction effects on incident light. When all the ribbons are in the same plane, incident light is reflected from their surfaces. By blocking light that returns along the same path as the incident light, this state of the ribbons produces a dark spot in the viewing system. When the movable ribbons are pulled down, diffraction produces light at an angle that is different from that of the incident light. This light produces a bright spot in a viewing system.
The Grating Light Valve uses reflection and diffraction to create dark and bright image areas. [figure courtesy D.M. Bloom]
The packaged GLV subsystem can include additional electronic interface circuits for higher integration and lower cost.
The GLV device is used to build a relatively simple display system. Video input is format converted and then fed to a digital driver. The latter interfaces directly with the GLV device. Light is diffracted by the GLV device into an eyepiece for virtual display, or into an optical system for image projection onto a screen.
By passing the source’s white light through dichroic filters, red, blue and green light is made to fall on three separate GLV devices. Diffracted light is collected and directed through the optical system to a viewing screen. This represents a much smaller and lower-cost solution to the three-CRT projection systems.
One of most important advantages of the new Laser Projector is the characteristic of a "gap-free" pixel. All the forms of video display technology have visible breaks, or gaps between neighbouring pixels. In the illustration we can see that the CRTs, LCDs and DLP-based projectors have gaps in both the vertical and horizontal directions resulting in unpleasant distortions of the image.
Sony’s 4K SXRD In 2005, a year after development of the SXRD Sony came up with further improved 4K SXRD [4]. SXRD stands for Silicon X-tal Reflective Display, x-tal being the abbreviation for crystal. This device has a high-resolution (4096H X 2160V) and contrast ratio of 4000:1.
The outstanding picture quality generated by SXRD is due to the large number of pixels contained within the image area of the device. This has been achieved by minimizing both the size of each individual pixel and the space between pixels. This technology will be covered in more detail in the presentation of Mr. Scott Niskach and we shall have the proof of the pudding under the dome later this afternoon.
Future of technology What has the future in store for us in terms of technology? Two technologies have already proven themselves in commercial advertising display segment. The first one is the high intensity LED matrix. In this city you have such a board that I have noticed on the marine drive. Its display is so bright that it stands out in full clarity even during daylight.
In the coming years we can hope much higher pixel intensity (though we do not really need it in the domed environment) and pixel density. Already some manufacturers [5] have brought out densities of the order of 10.000 pixel/m² generated by virtual controlling.
In my vision 2027, when this planetarium would be 50 I visualise a dome full of LEDs, no projectors, very simple interfaces, very little power consumption and negligible maintenance.
Another technology that is knocking at the doors is the E-ink or E-paper. Though invented in 1970s by Nick Sheridon at Xerox's Palo Alto Research Centre it is making its presence felt only now.
Some of the mobile phones have already been fitted with such display systems. An early version [6] of electronic paper consisted of a sheet of very small transparent capsules, about 40 micrometres across containing an oily solution and black dye, with numerous white titanium dioxide particles suspended within. The particles are slightly negatively charged, and each one is naturally white. The microcapsules are held in a layer of liquid polymer, sandwiched between two arrays of electrodes, the upper of which is made from indium tin oxide, a transparent conducting material. The two arrays are aligned so that the sheet is divided into pixels, which each pixel corresponding to a pair of electrodes situated either side of the sheet. The sheet is laminated with transparent plastic for protection, resulting in an overall thickness of 80 micrometres about twice that of ordinary paper. The network of electrodes is connected to display circuitry, which turns the electronic ink 'on' and 'off' at specific pixels by applying a voltage to specific pairs of electrodes. Other research efforts into e-paper have involved using organic transistors embedded into flexible substrates including attempts to build them into conventional paper. Who knows future planetariums may be made domes made of e-paper?
A third possibility, that would of course mean death of public planetarium, may come from virtual reality area. That too is already there in the form of video games, play stations, aircraft pilot trainer, etc. Here you see a picture of a US Navy personnel getting parachute training using VR. All that a smart manufacturer has to do is pack in a PC the 3-D planetarium software that would be displayed on a device looking like large pair of spectacles.
Eventually the PC may take over! There are other ways the public planetarium can become a cultural dinosaur and gradually meet its extinction. If we do not devise more educative programmes not only for astronomy but any type of subjects that can be taught under the dome, if we cannot ensure by the quality of our programmes that will ensure repeat visits, if we cannot devise programmes in astronomy that cater to the school & college curricula we will eventually push ourselves to such a future. At that point of time folks, the PC will take over from us! References: [1] Piyush Pandey, “Button Pushers”, Proceedings of the Second International Conference for Science Communicators – Man & Universe, 2003 [2] http://www.dlp.com/ [3] D. M. Bloom http://www.siliconlight.com/webpdf/pw97.pdf [4] http://www.sony.net/SonyInfo/News/Press_Archive/200405/04-027E/ [5] http://www.leuro.com/english/index.html [6] http://en.wikipedia.org/wiki/Eink & http://en.wikipedia.org/wiki/E_Ink