Most Fridays, when he is finished with his last class at American University, Ahmed catches a bus or hitch-hikes to the Maryland suburbs and his job as a waiter in a quiet, candlelit restaurant. On a good night, he takes in $30 or more in tips.

For the 23-year-old Iranian, this mundane routine is always risky. Every time he puts on his red-and-black uniform and picks up a tray, he is breaking the law. By the terms of his student visa, off-campus jobs are off-limits.

Now that President Carter has ordered the Immigration and Naturalization Service to seek out and deport Iranians who violate the terms of their student visas -- which prohibit working without permission, dropping out of school or committing a violent crime -- the risk has increased considerably.Unauthorized employment such as Ahmed's is the most common violation. Local immigration officials say.

The prospect of departation, however, moves Ahmed to only the slightest of possible shrugs. "Either I stay and finish up my studies or they deport me and that's that," said Ahmed, whose real name is something else entirely.

"It doesn't really matter very much," he added. "I don't necessarily choose that road [deportation] but if it happens, it's all right."

Short, dour, mustachioed and Marxist, Ahmed is a walking stereotype of the Iranian student whom Americans have suddenly learned to hate. He is a committed opponent of the U.S. government and supports the student seizure of the U.S. Embassy in Tehran because "I support any anti-imperialist action."

He is a perpetual demonstrator who long ago lost count of the number of antishah rallies he attended, but says matter-of-factly that he participated in the antishah riot near the home of the shah's sister in Beverly Hills, Calif.

"I went to Chicago and California, to Beverly Hills for demonstrations. A group of us would get together and rent a van, 30 or more of us squeezed into it. I've seen this country through demonstrations."

He also is matter-of-fact about his work."Once I asked permission. I said my parents earned about $500 a month together. They couldn't pay my tuition and support me. The immigration people said, 'No way -- your reason is not good enough.'"

". . . So there is no choice. If you've gotta work, you've gotta work."

Yet for all this, his approach to everyday life and its tasks could have been copied from a handbook on the American work ethic. He is thrifty, quiet, neat, polite, and hard-working -- in the summertime, he spends seven days a week at the restaurant making $3,000 or more before he returns to school in the fall.

He earns another $3,700, he says working at the restaurant during the school year, and gets between $1,000 and $1,500 a year from his parents, who live in a Rockville-sized city in the norhthern Iranian province of Azerbaijan.

When his tuition of $2,200 a semester and his $125-a-month room in a family home near AU are paid for, he has a little more than $2,000 left to spend each year on clothing, food, accessories and entertainment. And he manages.

Clothing for him is the standard student uniform: jeans and a button-down shirt, neatly pressed and carefully worn. Food is the haphazard fare at the Mary Graden cafeteria, eaten at haphazard moments. He has few accessories -- an expensive watch, two cameras (one Pentax, one Zenith) and a class ring from the suburban Washington high school he attended when he first came to the U.S.

Most of the rest of his money goes to buy books on leftist political thought. He estimates he has 1,500 to 1,600 books, some on the shelves of the room he shares with another Iranian student, some piled into the boxes he collected to handle the overflow. Any other entertainment, for him, always revolves around politics and costs nothing but time.

"For me, personal goals -- for instances, what would I do about getting a girlfriend -- these things are secondary, not important. That doesn't mean that I don't have one and don't want one. The important thing is that I don't just go spend time at her house. This is not productive."

At another moment, he looked around the hazy jumble of tables, students and smoke in the cafeteria and said, "When I come to the cafeteria, I have a purpose doing it -- to talk to someone new [new Iranian students], to ask them to become a member [of the Iranian Student Association].

"Any kind of social activity, for me, involves politics."

The youngest of four children -- and the only member of his family still in the U.S. -- Ahmed says that he is also the only member of his family to take an interest in politics. His eyes were first opened, he said, by seeing the violent police reaction to a demonstration at the University of Tabris when he was in the eight grade.

"When you speak of politics in the U.S., it means a different thing than when you speak of politics in Iran," he said. "In Iran, under the shah everything is politics. If you want to read a book, say the Communist Manifesto, which is progressive or banned, you have to hide it. You change the cover on the book.

"If someone sees you reading that, you go to jail for six months. Everything is poltical. Carrying a book, reading a book has political consequences. . . My parents thought I should be an engineer or a technician or something. But I decided to study politics."

He readily concedes that his political opinions and his politically consumed life style are not typical of all Iranian students, and other observers say the range of opinions and lifestyles among the Iranian students differs little, in fact, from that of their American couterparts.

But Ahmed's working habits -- and his bland defiance of student visa requirements -- are mimicked by many other Iranians, according to one official of the Immigration and Naturalization Service.

Of the 1,800 or more Iranians studying at schools in the District, about 12 percent are probably in violation of their visas said Kellogg Whittick, district director for the local district of the INS.

"The larger percentage of this group will be illegal workers, people still maintaining their student status but engaging in unlawful employment," Whittick said.

In the next month, he said, INS agents will interview every local Iranian student. One of the questions they will ask will be "Are you working."

"If they say, 'Are you working', I'll say no," said Ahmed. "If they prove I am, well, I won't have much choice but to say yes . . . When you work in a restaurant you know you're in jeopardy . . . The institutions, the systems make me do such a thing."

The decision to try and hunt out all Iranians who are violating their via requirements, he said, is "racist . . . consider that everyone has a right to work . . . this is a basic right under any system'."

What about the bachelor's degree he is on the verge of getting? "It's not a matter of degrees.It's a matter of knowing the subject and then working with what you know . . . I considered when I came it was good to go to a masters or a PhD (degree) but it wasn't a problem if I couldn't. It wasn't the main goal."

Should we be deported before he finishes his studies, Ahmed said, "I could teach. If I couldn't find a job teaching maybe I could do journalism . . . It doesn't matter what you do or where you're working, you could still advocate your ideology"

But what reception would his Marxist ideology receive in an Iran run by the Ayatollah Khomeini, whose strict Islamic principles have given him little love for communists?

"Ideology always gets you into trouble," replied Ahmed, with the same patient, unemotional tone he used during an entire afternoon of classes and conversation. "That won't change."