An Oxford University academic found with 3,000 child abuse images compared himself to "someone who starts a sticker collection and wants the whole set", a court heard.
Philosophy lecturer Peter J King, 63, taught at several Oxford colleges from the 1980s until last month.
Girls as young as five were pictured in the indecent images found on his computer equipment.
He was jailed for seven months at Oxford Crown Court.
The court heard King was cautioned in 2008 after police found child abuse images on his equipment.
King, of Churchill, near Chipping Norton, Oxfordshire, claimed he used them as research for a paper later published on the ethics of child pornography.
He was then arrested at his home in August 2018, where police found indecent images and also discovered that he had visited a Russian file-sharing website.
James Mulholland, representing King, said the defendant had admitted an "addiction or compulsion" to "repeatedly but intermittently" look at indecent images of children.
King most recently taught students at Pembroke College, Oxford.
It said it had suspended him on 19 February, when he informed them he was due to appear in court the next day.
King had admitted three counts of making indecent images of a child and another of possessing prohibited images of a child.
Judge Maria Lamb said two "no comment" interviews with police in 2018 and 2019 appeared to show King had accepted his guilt "rather late".
She said he had compared having the pictures to a "sticker collection" to a probation officer who was preparing his pre-sentence report.
As well as the prison sentence, King will be subject to a Sexual Harm Prevention Order for 10 years.
Paula Appiah, from the CPS, said: "King held an esteemed position at a prestigious university, but his actions fell far short of the law.
"The law is in place to protect young children and we are dedicated to bringing perpetrators of this crime to justice."