CN1308655C - Self-scanning projection measuring device for two-dimensional configuration outline - Google Patents

Abstract

The invention discloses a two-dimensional profile self-scanning projection measurement device, which includes a laser, a beam expander, an optical slit, a cylindrical mirror assembly, a CCD and a controller which are sequentially located on the same optical path, and the optical slit is located on the optical slit for linear scanning and driven by it to move along the X direction; the length of the optical slit is greater than the width of the measured geometric body section in the Y direction, and its slit width is smaller than the measurement resolution in the X direction; the cylindrical mirror assembly consists of a cylindrical mirror, or a cylinder It consists of a mirror and an imaging lens group, and the controller is used for motion control and acquisition and processing of measurement signals. The minimum measurement resolution in the long direction (X) of the present invention is 20 μm, and the minimum measurement resolution in the width direction (Y) is 1 μm, and there is no relative motion between the measured object and the measurement system, that is, there is no motion error. Because the quality of the moving parts is very small, the working limit frequency of its scanning is greater than 200Hz. The invention has the characteristics of short optical path, simplicity and low optical noise, and also has the characteristics of simple structure, convenient manufacture and good stability.

Description

A two-dimensional profile self-scanning projection measurement device

technical field

The invention relates to a projection measurement device, in particular to a two-dimensional profile self-scanning projection measurement device with different length and width direction measurement resolutions for back-projected parallel light.

Background technique

As a powerful projection imaging measurement tool for obtaining two-dimensional geometric shapes, the two-dimensional profile optical scanning device has been widely used in geometric shape measurement research. In recent years, scholars have conducted a lot of research on this technology, and have been mainly focusing on two-dimensional contour scanning devices with the same measurement resolution in the length and width directions.

A typical two-dimensional profile projection imaging measurement method is proposed in the article "Detection Method of Car Lamp Contact Sheet" (see "Optical Instruments", 1998, 20(2): 3-7). It is characterized by using an area array CCD (charge-coupled device) as the sensor, the same measurement resolution in the length and width directions, and there is a calibration error. This measurement technique is effective, but when the ratio of the length and width of the measured object is large (>10) and the measurement resolution requirements of the length and width are different (ratio>5), its measurement effect is significant worse.

In the article "Recognition of Wear Amount of Train Wheel Tread" (see "Journal of Huazhong University of Science and Technology", 2000, 28(7): 51-53), a scanning projection imaging measurement method of two-dimensional contour is introduced. It uses a linear array CCD image sensor, and the measured object moves relative to the measuring system to measure the two-dimensional shape. Its system structure is large and has motion errors.

Contents of the invention

The object of the present invention is to provide a two-dimensional profile self-scanning projection measurement device, which has no motion error and small structure.

A two-dimensional profile self-scanning projection measurement device provided by the present invention is characterized in that the device includes a laser, a beam expander, an optical slit, a cylindrical mirror assembly, a CCD and a controller, and the optical slit is sequentially located on the same optical path. It is located on the optical slit linear scanner and driven by it to move along the X direction; the length of the optical slit is greater than the width of the measured geometric body section in the Y direction, and its slit width is smaller than the measurement resolution in the X direction; the cylindrical mirror assembly is a cylinder The surface mirror, or composed of a cylindrical mirror and an imaging lens group, the controller is used for motion control and acquisition and processing of measurement signals.

The invention adopts a back-projected large collimated laser beam, an optical slit and a linear scanner to realize the two-dimensional scanning of the section profile of the measured geometric body. The present invention uses an optical slit linear scanner to measure the size in the X direction, and uses an optical slit and a CCD to measure the size in the Y direction, so as to solve the problem that the ratio of the length and width dimensions of the measured object is large (>10) and long, The problem that the measurement resolution in the width direction can be different (ratio > 5). Compared with the conventional two-dimensional scanning method, the minimum measurement resolution of the self-scanning measurement of the two-dimensional shape profile in the long direction (X) is 20um, and the minimum measurement resolution in the width direction (Y) is 1um, and the measured object and The measuring system has no relative motion, ie no motion error. Because the quality of the moving parts is very small, the working limit frequency of its scanning is greater than 200Hz. The invention has the characteristics of short optical path, simplicity and low optical noise, and also has the characteristics of simple structure, convenient manufacture and good stability.

Description of drawings

Fig. 1 is the structural representation of a kind of specific embodiment of the present invention;

Fig. 2 is a schematic structural view of another embodiment of the present invention;

Fig. 3 is a schematic diagram of the control principle of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and example the present invention is described in further detail.

The present invention defines a Cartesian coordinate system as follows: the direction perpendicular to the light slit is X (ie, the length direction); the direction of the light slit is Y (ie, the width direction); and the direction of the rear-projected parallel light is Z.

As shown in Fig. 1, the present invention comprises laser device 1, beam expander mirror 2, optical slit 4, cylinder lens assembly 6, CCD7 and controller 8 that are positioned on the same optical path in turn, and optical slit 4 is positioned on optical slit linear scanner 5 , the measured geometric body 3 is located between the beam expander 2 and the light slit 4 .

The optical slit linear scanner 5 is used to drive the optical slit 4 to move along the X direction, and the optical slit automatically obtains the size information in the Y direction.

The laser 1 is a low-power laser.

The beam expander 2 can be a single beam expander or a plurality of beam expanders spliced in the length direction, and the length of the beam expanded by the beam expander 2 should be greater than the length of the geometric object to be measured.

The optical slit 4 is an elongated slit whose length is greater than the width of the measured geometric body section in the Y direction, and whose slit width is smaller than the measurement resolution in the X direction.

The optical slit linear scanner 5 may use an electrically driven mechanical device, and its movement repeat positioning accuracy (including deflection error in the XY plane) is smaller than the measurement resolution in the X direction.

The cylindrical lens assembly 6 is composed of a cylindrical lens and an imaging lens group. When the Y-direction imaging ratio is 1:1, only one cylindrical lens can be used in the cylindrical lens assembly 6 .

The CCD7 may be a linear array CCD or an area array CCD.

The controller 8 is used for motion control and acquisition and processing of measurement signals. First, the controller 8 supplies power to the laser 1, drives the optical slit linear scanner 5 and obtains its position signal. Secondly, the controller 8 drives the CCD7 and obtains the signal in the Y direction. Finally the controller 8 performs signal processing.

The laser beam emitted by the laser passes through the beam expander to form a large collimated laser beam and irradiates the measured geometric body. Part of the light emitted by the light source is blocked by the contour of the measured geometric body, and the other part passes through the light slit 4 and the column in turn. The mirror assembly 6 is irradiated on the CCD7 to form a specific Y coordinate value corresponding to the cross-sectional profile of the measured geometric body at a specific X coordinate value. This specific Y coordinate value corresponds to the specific photosensitive unit of the CCD7, which is converted into a photoelectric sensor by the CCD7 The signal is sent to the controller 8; at the same time, the controller 8 records the corresponding X coordinate value. The controller 8 controls the optical slit linear scanner 5 to drive the optical slit 4 to move along the X direction to obtain the specific Y coordinate values corresponding to all specific X coordinate values of the measured geometric body cross-sectional profile, and the controller records the Y coordinate values and the corresponding The X coordinate value of the measured geometric shape, thus obtaining the set of X and y coordinate values of the measured geometric body cross-sectional profile, that is, the digitalized measured geometric body cross-sectional profile --- the two-dimensional outline.

As shown in FIG. 2 , the measured geometric body 3 can also be placed between the light slit 4 and the cylindrical lens assembly 6 .

Example:

In this embodiment, a laser with a power of mW is used, for example, a semiconductor laser with a wavelength of λ=0.670 μm. The beam expander can be composed of a lens group with a beam expansion factor greater than 10 times, for example, a concave lens with a focal length of -15mm and a convex lens with a focal length of 200mm, and the distance between the lens groups can be fine-tuned. The optical slit is a long slit with a width less than 1 mm and a straightness error of 1/10 of the slit width; the optical slit linear scanner can be a pair of rotating shafts. The cylindrical lens assembly can be composed of a cylindrical lens and an imaging lens group. The CCD can be a linear array CCD or an area array CCD.

The present invention has poor performance in measuring the two-dimensional profile of the same measurement resolution in the length and width directions, but the ratio of the dimensions in the length and width directions is large (>10) and the measurement resolution requirements in the length and width directions are different ( In the measurement of the measured object whose ratio>5), the present invention has obvious advantages.

The present invention is not limited to the examples described above, and those skilled in the art can implement the present invention by adopting various implementation modes according to the content disclosed in the present invention.

Claims (1)

1, a kind of self-scanning projection measuring device for two-dimensional configuration outline, it is characterized in that: this device comprises laser instrument (1), beam expanding lens (2), light slit crack (4), cylindrical mirror assembly (6), CCD (7) and the controller (8) that is positioned at successively on the same light path, light slit crack (4) is positioned on the light slit crack rectilinear scanner (5), and is driven along X to moving by it; The length in light slit crack (4) greater than tested geometrical body cross section Y to width, its seam wide less than X to Measurement Resolution; Cylindrical mirror assembly (6) is made of cylindrical mirror or cylindrical mirror and imaging lens group, and controller (8) is used for the collection and the processing of motion control and measuring-signal.

Images