Section 73H. The board may refuse to grant or may suspend for a definite time or may revoke any license of any person found guilty of fraud, deceit or misrepresentation or in aiding or abetting the same in connection with any application or taking of an examination for license, or who has rendered himself unable to properly carry on his work as a licensed dispensing optician as a result of the voluntary use of intoxicating liquors or drugs, or for conviction in any court of the commonwealth of a crime involving moral turpitude or for the violation of any provision of sections seventy-three C to seventy-three L, inclusive, or of any rule or regulation of the board; provided, that the board gives such person a written notice, at least ten days before the date of the hearing, specifying any charges that may have been made against him, and setting forth the time and place for hearing said charges. Such hearing shall be conducted by the board, and three members shall constitute a quorum. The person accused shall be given opportunity to produce testimony in his own behalf, shall be confronted by witnesses against him, and shall be allowed representation by counsel. The board may compel the production of documents at any hearing, and the attendance of witnesses who shall testify under oath, administered by any member of the board. The fee for witnesses shall be three dollars per day for attendance and five cents per mile for travel. If the board after such hearing refuses to grant, or revokes or suspends the license of any person, it shall forthwith notify such person of its decision in writing. The provisions of section sixty-four shall apply to any person whose license or authority has been refused, suspended or revoked.