FORT LAUDERDALE, Fla. — A federal judge threw out the conviction and sentence yesterday for an Iranian woman who had pleaded guilty in a scheme to illegally obtain American-made military night vision goggles for Iran.

U.S. District Judge James Cohn allowed Shahrazad Mir Gholikhan to withdraw her April plea because she had mistakenly been told in court she would get no additional prison time. Days after her plea, prosecutors said a mistake was made in her sentence guidelines calculation, resulting in an unexpected 29-month sentence.

“Everybody contemplated a sentence of time served,” Judge Cohn said at a hearing. “She had every right to rely on that.”

Ms. Gholikhan, a 30-year-old mother of two, traveled to America on her own last year to face a 2005 indictment charging her and her ex-husband with conspiring to obtain thousands of Generation III goggles for Iran. The sophisticated goggles cannot be exported without a license, and such items cannot go to Iran under any circumstances because of an American embargo.

Now that her guilty plea to one count of conspiracy to export defense articles without a license has been voided, Ms. Gholikhan said in a brief courtroom interview that she wanted to fight the charges at the risk of a maximum penalty of 60 years behind bars.

“I can’t wait for the trial,” she said, smiling at the prospect despite the chains on her wrists and ankles.

Judge Cohn set a tentative trial date of July 28 for Ms. Gholikhan, who has been held without bail since December. Assistant U.S. Attorney Michael Walleisa said she would be tried on all seven counts of the grand jury indictment.

Mr. Walleisa had argued that Ms. Gholikhan could not withdraw her plea because she clearly knew Judge Cohn didn’t have to follow the original recommendation of time served. But Ms. Gholikhan’s attorney, Bill Barzee, said she shouldn’t be forced to pay for the courtroom error.

“The only reason she pleaded guilty is because they promised to let her go,” Mr. Barzee said.

Ms. Gholikhan and her husband were tracked in 2004 by undercover American Immigration and Customs Enforcement agents on suspicion of trying to arrange the purchase of 3,500 pairs of night goggles. They were arrested after a hotel meeting in Vienna, Austria, and held for a month there before returning to Iran.

Prosecutors were unable to extradite either Ms. Gholikhan or her ex-husband from Iran, which has no extradition treaty with America. Ms. Gholikhan decided to travel to South Florida in December to clear up the case, in which she said she played only a minor role as translator and go-between.

The mistake in calculating the sentence occurred because certain factors involving potential threats to American national security were not taken into account, court papers show.