A former world karate champion and instructor has been jailed for 30 months after admitting a series of child sex offences.
Tim Stephens, 50, from Poole, admitted 43 sexual offences between 2005 and 2011, including trying to send an indecent picture of himself to a pupil.
Bournemouth Crown Court heard that none of the other charges were linked to his karate classes.
Police found more than 38,000 indecent images of children at his home.
Stephens, who competed for Great Britain during the 1980s, had a 25-year coaching career around Poole after retiring from the sport as world number one and was crowned world champion on three occasions, it was heard.
Police discovered hard drives and computers storing a combination of still and moving indecent images in an upstairs bedroom at his home in Alcester Road, Poole, when he was arrested last July.
'Catalogue of criminality'
The court also heard he attempted to send a picture message to a pupil's mobile phone, but their model did not allow for picture messages to be received.
At a hearing in February, he admitted one charge of attempting to cause a child to watch a sexual act, nine of voyeurism, one of distributing indecent images of children, five of taking indecent photographs of children and three of making indecent images of children.
He also pleaded guilty to 23 offences of possessing indecent images and a charge of assault by penetration on a former girlfriend in 2005.
Mark Worsley, prosecuting, said analysing the images had severely tested the resources of Dorset Police's hi-tech crime unit.
He said: "Officers say this grew into an obsession, which he allowed to get out of control."
Julia Woodward, from the Crown Prosecution Service, added: "He was well known in the community for being the local karate teacher... and there is no doubt that he used this local fame to gain the confidence of many."
Judge Peter Johnson said the offences represented a "catalogue of criminality".
Stephens was also banned from working with children and put on the sex offenders register for life.