Sec. 1.02. CREATION OF POLICE PENSION FUND. A police pension fund is hereby authorized in a municipality that adopts this Act. Once a pension fund is adopted in a municipality as provided by Section 1.03 of this Act, any right or privilege accruing to any member under the fund is a vested right according to the terms of this Act and may not be denied or abridged through any change in population or other condition of applicability prescribed by Section 1.01 of this Act. The pension fund shall continue to operate and function regardless of whether the municipality continues to meet the conditions of applicability defined by Section 1.01 of this Act.