His blunt comments came as head teachers took the unprecedented step of voting to demand the Director of Public Prosecutions (DPP) launch a criminal investigation into claims that Mr Woodhead lied on oath.
Mr Woodhead has faced constant criticism - and demands for his sacking - since The Independent revealed that he had told a student audience that relationships between sixth-formers and teachers could be "educative and experiential".
The spotlight then fell on Mr Woodhead's relationship with a young woman, Amanda Johnston, with claims that they started their affair while she was a sixth-former.
Mr Woodhead has signed an affidavit saying that they started a nine- year affair after they both left the Gordano school in Bristol, where he was a teacher, in the Seventies.
Last night Mr Woodhead, in his frankest comments since the storm erupted, said: "If your critics cannot fault the logic of your argument, they will attack your reputation.
"The teacher unions have been trying to get rid of me since I was appointed. The NAHT's [National Association of Head Teachers] action today is their latest attempt. No doubt it will serve to generate more columns of newsprint and minutes of airtime. So be it.
"There is nothing I can do to prevent these attempts to distract me from my job as Chief Inspector. As far as I am concerned, it is business as usual."
Speaking in York before the annual conference of the Independent Schools' Association, Mr Woodhead added: "I shall, that is, continue to run Ofsted, support the Secretary of State for Education in his crusade to raise educational standards, and do everything that I can to ensure every child in this country receives the education he or she deserves."
His comments coincided with the decision last night by the NAHT to call formally for a criminal investigation. David Hart, the union's general secretary, said it was essential to "clear up question-marks" over allegations that Mr Woodhead had an affair with a pupil.
Cathy Woodhead has claimed that her ex-husband admitted the affair at the time. Former colleagues have said the relationship was common knowledge at the school.
David Blunkett, the Secretary of State for Education, told the House of Commons last week that there was no evidence to disprove Mr Woodhead's sworn statement.
Mr Hart rejected Mr Woodhead's assertions that the union was conducting a witch hunt. He asked his union's national ruling council to back his call for police intervention.Reuse content