TWYMAN & GREEN INTERFEROMETER -- D-302L
(AS MODIFIED BY D. O. HENDRIX)

The Twyman & Green Interferometer modified by the late Mr. D. O. Hendrix is for testing the quality of optical elements such as windows, wedges, prisms or plane mirrors in any combination.  It employs parallel beams of light and it is the effect of the optical elements under test on these beams which is measured by the instrument.  These beams are affected by the surface quality as well as the homogeneity of the glass.

Use of this Interferometer shows the sum of the errors contained in an element or in an entire assembly.  These errors can then be corrected by re-working one or more surfaces to compensate for the total error.  In other words, the Interferometer permits examination of an optical train as a whole and then correction of any of the surfaces just as if a simple system containing but one element were being corrected.

• Features:
  • Measures optical homogeneity of optical elements or systems
  • Operational simplicity eliminates costly set-up time
  • Permanent records for future reference
  • Certification of accuracy traceable to National Institute of Standards and Technology

For more theory of operation, please refer to the Principles of Interferometry Application Note.

Detailed Specifications:

• Optional Accessories:
  • P/N 104-0150-302 Fringe Analysis System eliminates any human error in evaluation of your parts
  • P/N 105-2761-302 Video Camera & Monitor with integral camera power supply.  With this option readings become very easy even for unskilled personnel.  Repeat readings are more accurate and faster.  The camera eliminates any errors from parallax and greatly reduces eye fatigue.  This option is easily added to existing Model D-271's.
  • P/N 105-2703 1" Retro-Reflecting Corner Cube