A Modulated Profile Measurement System and Method Based on Tilt Focusing and Rotational Scanning

A profile measurement and rotary scanning technology, applied in the field of optical measurement, can solve the problems of complex device, small measurement range, harsh measurement conditions, etc., and achieve the effect of expanding measurement depth and flexible measurement system

CN112880590BActive Publication Date: 2021-12-07SICHUAN UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2021-12-07

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Abstract

The invention discloses a modulation profile measurement system and method based on oblique focusing and rotational scanning. By placing the grating obliquely on the optical axis, the clear image plane becomes an oblique plane in the measurement space, and a high reflective mirror is placed behind the projection lens. The optical axis is deflected by nearly 90°, and the rotating mirror makes the fringe clear. The imaging surface completes the scanning of the entire surface of the measured object. The CCD camera captures the fringe pattern carrying the surface information of the object synchronously through the beam splitter. Using phase shift technology, the fringe The modulation degree curve of each pixel is obtained from the light intensity information, and the height of each pixel can be reconstructed by using the known system mapping parameters according to the obtained modulation degree peak number. The invention adopts rotary scanning instead of axial scanning, so that the measuring system is more flexible and compact, and the oblique placement of the grating can also significantly expand the measuring depth.
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Description

technical field

[0001] The invention relates to the technical field of optical measurement, in particular to a modulation profile measurement system and method based on oblique focusing and rotational scanning. Background technique

[0002] Coaxial technology, also known as vertical measurement technology (MMP: Modulation Measurement Profilometry), the axis of the projector and the camera are coaxial, which can overcome the occlusion shadow problem caused by triangulation. There are three general vertical measurement techniques now, the first is to move the measured object, and reconstruct the three-dimensional according to the relationship between the degree of modulation and the height, but it is only applicable to the telecentric system; the other is to fix the object and the imaging system, by moving The projection part of the system, such as moving the projector, or moving the grating, or using the zoom lens to achieve zooming, thereby establishing the relationship betw...

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Embodiment Construction

[0040] The specific embodiments of the present invention are described below so that those skilled in the art can understand the present invention, but it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes Within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

[0041] After the sinusoidal fringes pass through the projection objective lens, the fringe pattern on the focusing plane is the clearest, and the fringe modulation degree is also the highest, and the modulation degree gradually decreases before and after the imaging plane (FIP: focused image plane), showing a Gaussian distribution, such as figure 1 shown.

[0042] The system such as figure 2 As shown, it includes the foll...