The invention relates to a bar-type phase diaphragm and a 4f phase-concerned nonlinear imaging
system and a
nonlinear refractive index metering method based on the
system, relating to the technical field of
optics, and solving problems that a manufacturing process of a circular phase object is complex, requirements on light beams are high during the measurement of a Z scanning
system, samples are broken easily due to repeated
irradiation on a focus, the sensitivity is low and the error is large. The bar-type phase diaphragm consists of a bar-type phase object and a
circular diaphragm. The 4f phase-concerned nonlinear imaging system of the bar-type phase diaphragm consists of a
half wave plate, a polarization
prism, a
beam expander, a bar-type phase diaphragm, an
image sensor, an energy referring system and a 4f imaging system. The energy referring system consists of a
beam splitter, a second total-reflection mirror, a middle filtering sheet, a third convex lens, a third total-reflection mirror and a first total-reflection mirror. Two convex lenses of the 4f imaging system are coaxially and confocally arranged, the first convex lens is an incidence lens, and the second convex lens is an emergence lens. The 4f phase-concerned nonlinear imaging system disclosed by the invention is applied to the field of
optical communication, optical information process and the like.