Topological type Ronchi grating groove depth optical checking method

Abstract

The invention provides an optical test method for phase-type Ronchi grating groove depth, which can precisely test the phase-type Ronchi grating groove depth with the cycle far larger than the operating wavelength thereof. The optical test method includes the steps as follows: 1. A spectrograph is used for recording the initial spectral curve I s (Lambda) of a working light source; 2. The emergent light of the working light source normally arrives on the surface of a phase-type Ronchi grating; 3. The spectrograph is used for recording the spectral curve Ig (Lambda) of the phase-Ronchi grating against the zero-order transmitted light of the working light source; 4. The zero order spectrum transmittivity of the phase-type Ronchi grating is computed; 5. The wavelength Lambda<min> corresponding to the minimal value Eta<min> of the zero order spectrum transmittivity of the phase-type Ronchi grating is determined according to the zero-order spectral transmittivity Eta<Lamba> of the grating; 6. Finally, the phase-type Ronchi grating groove depth is figured out. The method is applicable for testing the phase-type Ronchi grating groove depth with the cycle far larger than the operating wavelength. The test theory is simple and reliable; little equipment is required; the test cost is low; in addition, the Ronchi grating groove depth can be tested quickly and delicately without destruction.

Description

Optical Detection Method of Phase Ronchi Grating Groove Depth technical field The invention relates to the technical field of grating structure parameter measurement, in particular to an optical detection method for the groove depth of a phase-type Ronchi grating. Background technique Ronchi grating is a kind of grating with large period and low spatial frequency, the general space period is between 2-100μm. The shearing interference system with the Ronchi grating as the beam splitting element can be applied in the fields of optical system image quality evaluation, experimental mechanics and so on. Phase-type Ronchi gratings are transmission gratings made on transparent media such as optical glass, and their structure is shown in Figure 1. The refractive index of the grating material is n, the grating period is d, the grating line width is a, the grating groove width is b, the duty ratio is Δ=a / d, and the grating line height or groove depth is h. Groove depth is one of...

AI Technical Summary

Problems solved by technology

The measurement accuracy of the atomic force microscope is high, but the disadvantage of measuring the groove depth of the atomic force microscope is that the measurement period is long and the operation is complicated

The test of proslograph and atomic force microscope is easily affected by the external environment

Scanning electron microscopy needs to make a cross-section of the grating sample, which is difficult to make observation samples for thick samples, and is destructive to grating samples

In addition, the detection of the depth of the above-mentioned grating grooves belongs to special and relatively expensive instruments and equipment.

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