star wars - What Purpose Did the Laser Gates in "The Phantom Menace" Serve?

In this question about Obi-Wan crossing all the laser gates during the duel with Darth Maul, there's this good screen shot of the laser gates:

Which raises a question I've wondered about over and over. What is the purpose of these gates? If they were for security, they would not be opening and closing regularly, allowing people to go through. Anything else that might be effected by the gates opening and closing (such as air circulation) could be controlled with physical doors and wouldn't pose the threat to life or safety that lasers would.

So what purpose do dangerous laser gates like this actually serve?

Answer

The script is not explicit on their purpose :

INT. THEED - POWER GENERATOR ELECRIC BEAM - HALLWAY
The SITH LORD, followed by QUI-GON, enters a long hallway filled with a series of deadly rays that go on and off in a pulsing pattern that shoots down the corridor every minute or so. DARTH MAUL makes it down several walls of deadly rays before they close. QUI-GON is one wall away from the DARK LORD. OBI-WAN is just starting into it and is five walls way from DARTH MAUL.

But, according to Wookieepedia Qui-Gon Jinn article, it's a security system.

While his Padawan rushed to catch up, Jinn and Maul moved on, passing through an impenetrable laser shield security system to one of the cooling pits.

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UPDATE :

I finally found a well buried article on wookieepedia : Laser gate. It also explain the reason why they are cycling on and off.

Laser gates, also known as electron walls, were designed to protect high-security or dangerous areas by sealing them off with a wall of energy. Laser gates were installed in the Theed Generator Complex on Naboo. The barriers were strong enough to easily block a lightsaber strike and would vaporize any matter that touched them. These gates were crucial to the death of Qui-Gon Jinn at the hands of Darth Maul as the laser gates prevented Jinn's Padawan, Obi-Wan Kenobi, from coming to his aid against the Sith. However, the generators were unable to keep up the immense energy needed to power the gates, and so they would cycle on and off approximately every five minutes. Each gate remained open for only around ten seconds before cycling on again.