Though opposition in Congress seems a foregone conclusion, Saudi Arabia's Ambassador Faisal Alhegelan was the picture of optimism last night over the proposed sale of the AWACS radar reconnaissance planes to his country. At a Saudi Embassy dinner honoring Vice President George Bush and Barbara Bush, Alhegelan said he had no doubts that the sale, which President Reagan has called an essential element of his Middle East policy, will go through when Congress takes it up early next month.

Among Alhegelan's guests were Sen. John Tower (R-Tex.), chairman of the Senate Armed Services Committee; presidential counselor Edwin Meese; Commerce Secretary Malcolm Baldrige; Deputy Secretary of State William P. Clark; the ambassadors of Portugal, Italy, Syria and the Organization of American States, and members of the banking establishment, including Import-Export Bank president William Draper, World Bank president Alden W. Clausen and Morgan Guaranty chairman Lewis Preston.

Portugal's Ambassador Futscher Pereira voiced uncertainty over threats by Portuguese air controllers to support U.S. controllers by refusing to handle air traffic to and from the U.S. via the Azores. "Don't get me involved in that one," Pereira said.

Guests also included a number of George and Barbara Bush's Texas friends, including Houston banker Ben Love. "What nobody seems to understand is that Texans will go anywhere for a free meal," said Love, turning his attention to the four-course dinner of lobster and filet mignon.

West German automobile heiress Christina von Opel was one of 21 mothers freed from prison by French President Francois Mitterrand. Von Opel, who has a 6-year-old-daughter, had been serving a reduced sentence for drug smuggling.

A spokesman at the Elysee Palace explained Mitterrand's concern for the psychological and social problems that might be suffered by the children of imprisoned mothers. "This presidential amnesty for the women is also for the children," Mitterrand stated in a communique.

Von Opel, 31, granddaughter of Opel's founder, Adam von Opel, had been serving a reduced five-year sentence after conviction in November 1979 as a ringleader of a hashish smuggling operation on the French Riviera.

Yoko Ono, wife of the late John Lennon, told the London Daily Mirror that she does not "particularly hate the person who pulled the trigger. I have strong emotions of sorrow and hate and resentment -- but where do you put them?"

Putting those feelings into perspective has taken strange routes with Ono. After her husband was shot she stayed in bed for almost three months continuously and followed a diet of chocolate cake and mushrooms. Reasoned Ono, "What was there to stay healthy for, anyway?"

Mark Chapman, Lennon's confessed murderer, is awaiting sentencing for the shooting in New York last Dec. 8.

Punk-rock star Wendy O. Williams was granted a continuance yesterday after her lawyer said the air traffic controllers' strike had prevented her from appearing to answer a battery charge in Chicago.

A free-lance photographer has accused the lead singer of the Plasmatics of beating him July 14 as he tried to photograph her as she jogged along the shores of Lake Michigan.

Photographer David Barnes, who said he suffered a bruised forehead and a skinned elbow in the alleged incident, also failed to appear in court because he was in New York on business, according to his lawyer, Thomas Conners.

Circuit Judge Odas Nicholson continued the case until Sept. 22.

"If music feeds the soul, then Harry's music meant food for millions," New York Gov. Hugh Carey said Tuesday at Hofstra University of the late Harry Chapin. "It is up to us to see it play on undiminished."

The musician's widow, Sandy, urged business and political leaders to continue the work of her husband, who was killed in an auto crash on Long Island last month. She said it has been 10 years since Chapin gained notice for his ballad "Taxi." "Just imagine," she said, "what all of you can accomplish in the next 10 years."

David Williams, the lawyer for Mickey Rooney and Redd Foxx, has pleaded no contest in Los Angeles to $21,000 in forgeries.

According to deputy district attorney Robert Youngdahl, Williams forged Rooney's signature on a contract with Marble Arch Production Co. for a prospective NBC television movie in June 1980. Williams allegedly deposited a check for $10,000 from the production company in his bank account to hold for Rooney as a signing fee. Rooney testified in a preliminary hearing that he fired the lawyer after he admitted the alleged embezzlement.

Nearly three months later, Williams began working for Foxx and allegedly forged the comedian's signature on two $5,000 checks and cashed them. He also allegedly intercepted a $1,100 check mailed to Foxx, forged Foxx's signature again and entered his own name as payee to cash it.

Williams entered his plea to avoid a state prison term. He will be sentenced in October and faces a possible county jail term and probation.