EXHIBIT 99(B)
                                                                   -------------

                                 CERTIFICATIONS


I, Gregory G. Towle, Financial Controller and Treasurer (Principal Financial and
Accounting Officer) of Spire Corporation (the "Company"), certify that:

1.   I have reviewed this quarterly report on Form 10-QSB of the Company.

2.   Based on my knowledge, this quarterly report does not contain any untrue
     statement of a material fact or omit to state a material fact necessary to
     make the statements made, in light of the circumstances under which such
     statements were made, not misleading with respect to the period covered by
     this quarterly report.

3.   Based on my knowledge, the financial statements, and other financial
     information included in this quarterly report, fairly present in all
     material respects the financial condition, results of operations and cash
     flows of the Company as of, and for, the periods presented in this
     quarterly report.

4.   The Company's other certifying officer and I are responsible for
     establishing and maintaining disclosure controls and procedures (as defined
     in Exchange Act Rules 13a-14 and 15d-14) for the Company and have:

     a)   Designed such disclosure controls and procedures to ensure that
          material information relating to the Company, including its
          consolidated subsidiaries, is made known to us by others within those
          entities, particularly during the period in which this quarterly
          report is being prepared;

     b)   Evaluated the effectiveness of the Company's disclosure controls and
          procedures as of a date within 90 days prior to the filing date of
          this quarterly report (the "Evaluation Date"); and

     c)   Presented in this quarterly report our conclusions about the
          effectiveness of the disclosure controls and procedures based on our
          evaluation as of the Evaluation Date.

5.   The Company's other certifying officer and I have disclosed, based on our
     most recent evaluation, to the Company's auditors and the audit committee
     of the Company's board of directors (or persons performing the equivalent
     functions):

     a)   All significant deficiencies in the design or operation of internal
          controls which could adversely affect the Company's ability to record,
          process, summarize and report financial data and have identified for
          the Company's auditors any material weaknesses in internal controls;
          and

     b)   Any fraud, whether or not material, that involves management or other
          employees who have a significant role in the Company's internal
          controls.

6.   The Company's other certifying officer and I have indicated in this
     quarterly report whether or not there were significant changes in internal
     controls or in other factors that could significantly affect internal
     controls subsequent to the date of our most recent evaluation, including
     any corrective actions with regard to significant deficiencies and material
     weaknesses.


Dated: May 15, 2003                      By:  /s/ Gregory G. Towle
                                             -----------------------------------
                                             Financial Controller and Treasurer
                                             (Principal Financial and Accounting
                                              Officer)