microdiaphragm

Noun

 * 1) A very small diaphragm.
 * 2) * 1999, Oleg V. Angelsky, ‎Steen G. Hanson, ‎Peter P. Maksimyak, Use of Optical Correlation Techniques for Characterizing Scattering Objects and Media (page 180)
 * An amplitude spatial frequency filter consisting of several transparent and opaque concentric rings and having a microdiaphragm in the center is placed in the frequency plane of the objective lens.
 * An amplitude spatial frequency filter consisting of several transparent and opaque concentric rings and having a microdiaphragm in the center is placed in the frequency plane of the objective lens.