6:37 PM PT -- Orange County D.A. Todd Spitzer is ripping the judge.

In a statement to TMZ, Spitzer says ... "Driving under the influence must have consequences. When a judge gives someone who not only drove with a blood alcohol level of .24 - three times the legal limit - but then ran away from the scene of an DUI collision a slap on the wrist, you are sending a message that DUIs are not serious crimes that demand accountability."

Spitzer adds ... "Judge London clearly felt otherwise and not only gave her a court offer, but dismissed the hit and run charge in the interest of justice. This is not justice. We as a society need to wake up and address the very real - and often deadly - consequences of driving under the influence."

Shannon Beador will avoid jail time in her DUI case ... because a judge just sentenced her to 3 years of probation.

The 'RHOC' star learned her fate Thursday, and was sentenced to 36 months informal probation, fines and fees, plus 40 hours community service and a 9-month alcohol program.

Shannon did not show face in the Orange County courtroom, instead having her attorney appear on her behalf to enter her plea of no contest to one count DUI and one count driving with a blood alcohol content of .08% or more.

The judge dismissed one count of hit-and-run with property damage.

In new legal docs, obtained by TMZ, Orange County D.A. Todd Spitzer tried to convince the judge to give Shannon a harsher sentence -- he wanted her to also serve 30 days in jail, but the judge ruled otherwise.

TMZ broke the story ... Shannon was arrested in September after slamming her car into a Newport Beach home, with surveillance footage showing her car zipping through a residential area before her crash.

In the docs, the D.A. says she had a .24% BAC after the crash ... and she suffered a fractured left wrist, plus cuts and bruising to her left eye. Shannon's since paid for the property damage.

BTW ... Shannon's still set to appear at BravoCon this weekend in Vegas.