(a) Applications for license shall be sent to the Board and shall be accompanied by the prescribed examination fee and by satisfactory proof that the applicant—
(1) is twenty-one years of age or over (birth certificate or similar evidence thereof);
(2) is of good moral character as shown by at least two letters from qualified physicians or optometrists in the State from where he comes;
(3) is not addicted to intemperate use of alcoholic stimulants or narcotic drugs; and
(4) is a graduate of a school or college of optometry approved by the Board of Optometrical Examiners.
(b) This section shall not be construed to exclude any bona fide research worker whether an alien or a citizen who does not practice for a fee and such worker shall not be required to pay the usual license fee nor to submit to an examination.