Laser solves data relay problem for Hopkins Medical library avoids costly cables in linking buildings.


The problem was this: Johns Hopkins' Welch Library needed to transmit data between two buildings on opposite sides of a street but didn't want the expense or headache of laying costly underground cables.

What to do? The answer for Larry Nichols, network services manager for the Johns Hopkins Medical Institutions, hit like a bolt of lightning.

Well, it wasn't exactly a lightning bolt. It was a laser beam.

Rejecting the conventional approach, which would have required digging up the street and paying Chesapeake & Potomac Telephone Co. to lay underground cable, Mr. Nichols chose instead to install an infrared laser system that can transmit data on the electronic magic carpet of laser beams.

The system, which is being installed, consists of two camcorder-sized laser units that are placed on rooftops and wired into the main communication system.

When activated, the units act like a fiber optic connection -- without the fiber -- as they send electronic messages through the air between buildings.

Mr. Nichols says there are many advantages to the laser beam system: It doesn't require special licenses to operate, underground cables aren't needed, it's half as expensive as conventional systems and it's portable -- the units can be packed up and moved like suitcases.

"You can't do that with cable buried under the street," Mr. Nichols says.

The library's system is expected to be operational within a few weeks, he says.

Hopkins' dilemma is typical of problems faced by many businesses in urban areas, where infrastructures don't often allow for easy extension of communication lines, says Mike Berman, vice president of sales and marketing for Laser Communications Inc. of Lancaster, Pa.

The company, which manufactured the system being used by Hopkins, says it has several hundred systems in operation around the world. Those customers include large businesses from the Fortune 100 list and smaller ones.

Current infrared laser technology does have a few drawbacks. For one, laser sites can't be more than 3,300 feet away from each other or the laser beam degrades. And there can't be any physical obstacles, such as trees or other buildings, blocking the path of the laser.

Nature can also be a problem. Laser beams are foiled by heavy fog, particles of which interfere with transmission. The same goes for heavy rain -- 4 to 5 inches an hour -- and heavy snow -- 2 to 3 inches an hour.

However, if the distance between sites is short enough, say 30 to 40 feet, even some of those handicaps can be dismissed, Mr. Berman says.

And the merits of infrared laser technology often outweigh the drawbacks. That was the case at Hopkins a few years ago, when the School of Hygiene and Public Health needed to link its main building with a few rowhouses that had been converted into office space.

The school considered setting up a microwave system but rejected that option after determining that it would be too expensive and that obtaining the proper licenses would take too long.

The school opted for a system sold by Laser Communications.

Today, about 430 people regularly use the laser system to send electronic mail, internal memos and other school communications, says Andrew Frake, assistant director of the school's computing center.

Mr. Frake says the laser system has operated nearly flawlessly since 1989, when it was installed on a trial basis.

Weather has never been a problem for transmission, he says, but there has been one recurring problem that has nothing to do with laser beams, nature or infrared technology.

"Our main problem is when construction workers in the vicinity of the devices choose to move the units or hang their coats on them. That causes an interruption," he says. "But other than that, we haven't had any problems."

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