JPH0220679A - Focal position detecting device and focus follow-up mechanism for laser device - Google Patents

Abstract

PURPOSE:To detect a focal position without bringing a working table to movement control by providing a means for receiving the reflected light of an optical image by a detection use laser light on an object to be irradiated in each position by moving a condensing lens, and deriving a variation characteristic of a light receiving output. CONSTITUTION:A condensing lens 3 is set to an initial position, a detection use laser light 8 is brought to image formation on a working surface 5, and its optical image 10 is obtained. A reflected light from the working surface 5 is allowed to transmit through the condensing lens 3 and a half mirror 4 and received by a photoelectric converting means 11, and the maximum width of a binarized image in said initial position is detected by a focal position arithmetic means 15. By driving a Z table 17 by this output, the condensing lens 3 is moved by a prescribed distance. Subsequently, the maximum width of the binarized image is derived again by the photoelectric converting means 11 and the focal position arithmetic means 15. By repeating this operation, a relation of a position of the condensing lens 3 and the maximum width of the binarized image is derived, the minimum value of the maximum width is detected therefrom, and the position of the condensing lens 3 at that time is outputted as a focal position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a device for detecting the focal position of a laser beam in a laser processing device, etc., and a focus tracking system. This relates to a mechanism for performing L.

[Prior Art] FIG. 4 is a configuration diagram showing a focal position detection device of a conventional laser beam illumination device disclosed in, for example, Japanese Patent Application Laid-Open No. 59-159290. In the figure, (1) is a processing laser beam;
(2) is a half mirror - (3) is a condenser lens, (4) is a half mirror - 1 (5) is transmitted through a half mirror (2) and a condenser lens (3), and is reflected by a half mirror (4). This is the processing surface onto which the processing laser beam (1) enters at a substantially right angle, and forms the upper surface of a processing table (6) that is movable in the direction of the incident axis (Z-axis) of the processing laser beam (1). (7) is the machined surface (5
). (8) is a half mirror (2) so that it is coaxial and confocal with the processing laser beam (1).
The detection laser beam (9) passes through the condenser lens (3), is reflected by the half mirror (4), and is irradiated onto the processing surface (5). ), (101 is the optical image of the detection laser beam (8) focused on the XY plane (7) -0υ scans the XY plane (7) A photoelectric conversion means as a light image detection means which receives the light image f1G and outputs it as an electric signal (15 is a light image from the photoelectric conversion means αD (binarization which converts the output of I) into a binary image circuit,
tiz is a maximum width detection circuit that detects the maximum width of a binarized image;
0 is a focus position detection circuit that detects the focal position of the detection laser beam (8) from the change in the maximum width of the binarized image when the processing table (6) is moved in the Z-axis direction. circuit(
12. The maximum width detection circuit f131 and the focus position detection circuit 041 constitute a focus position calculation means (1ω).

Next, the operation will be explained. First, the processing table (6)
is set at a predetermined initial position, and in this state one machining surface (
The detection laser beam (8) is imaged on the XY plane (7) of 5) to obtain the optical image Q[). Photoelectric conversion means +111 is x
The Y plane (7) is scanned, and the binarization circuit (Sakura) further converts the optical image QG for each scanning line into a binarized image as coordinate values.

The maximum width detection circuit 03 detects the maximum width at the initial position from the above binarized image. Focus position detection circuit (141
is the minimum value of this maximum width based on the relationship between the maximum width of the binarized image found by sequentially moving the processing table (6) in the Z-axis direction and the position of the processing table (6). is detected, and the position of the processed surface (5) at that time is output as the focal position.

[Problem to be solved by the invention]

Since the conventional focus position detection device is configured as described above, in order to operate this detection device, it is necessary to control the movement of the processing table (6) in the Z-axis direction, that is, in the vertical direction. By the way, since the processing table (6) is used to place the workpiece, if the workpiece is large or heavy, an even larger processing table (6) is required.

Therefore, if the workpiece is assumed to be as described above, there is a problem that the processing table (6) becomes large and the mechanism for controlling its movement becomes large and expensive.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain a focus position detection device and a focus tracking mechanism for a laser device that enable detection without controlling the movement of a processing table. .

[Means for Solving the Problems 1] A focal position detecting device according to the present invention includes a predetermined detection laser generating means, a light image detecting means, and a condenser lens that is moved in the direction of its optical axis. The apparatus is equipped with a focus position calculation means for calculating a focus position from a change in the output of the optical image detection means.

Another type of condensing lens detects the amount of deviation from the output of the optical image detection means and a value corresponding to the focal point position, and controls the movement of the condensing lens in the direction of its optical axis in accordance with this amount of deviation. It is equipped with movement control means.

[Effect]

In this invention, the condensing lens is sequentially moved from its initial position, and the reflected light of the optical image by the detection laser beam on the object to be irradiated at each position is received, and the change characteristics of the received light output with respect to the condensing lens position. The focal position is calculated from this characteristic.

In addition, other methods detect the amount of deviation from the focal position,
The condenser lens is controlled to move in the direction of its optical axis so that the amount of deviation becomes zero.

〔Example〕

FIG. 1 is a configuration diagram showing a focal position detection device of a laser processing apparatus in an embodiment of the present invention.

In the figure, (1)-(5) It is located between the half mirror (4) and the processing surface (5) so that.

Then, this condensing lens (3) is
It is attached to the table (1η) and is movable in the Z-axis direction.

0 seconds is an xY child table as an object to be irradiated having a processing surface (5), on which the object to be processed is placed.

Next, the operation will be explained. First, the condenser lens f31 is set at a predetermined initial position, and in this state.

A detection laser beam (8) is focused on the processing surface (5) to obtain an optical image fill. Then, the reflected light from the processed surface (5) passes through the condensing lens (3) again, and further passes through the half mirror (4), and is received by the photoelectric conversion means Uυ. The operation of the focal position calculation means 4 is the same as the conventional one, and the photoelectric conversion means (
The maximum width of the binarized image at the initial position is detected from the output of 11J. This output sends a signal to the Z table (171), and the Z table (171) is driven to move the condensing lens (3) by a predetermined distance. In this state, the photoelectric conversion means (111 and focal position Calculation means 15)
(Make sure to find the maximum width of the binarized image. By repeating the above operations sequentially, find the relationship between the position of the condenser lens (3) and the maximum width of the binarized image, and from this, calculate the minimum width of the maximum width. The value is detected and the position of the condenser lens (3)' at that time is taken as the focal position.

Therefore, the operation of the XY child table 1 mark, which is the processing table, is not involved in the above operation at all. That is, in this detection device, the relatively small and lightweight condensing lens (3) is
Table (machining table 01 that only needs to be controlled by 1η and is likely to be enlarged in consideration of the expected workpiece)
Since there is no need to control the movement of O, the device can be made smaller and less expensive.

FIG. 2 shows an embodiment of the related invention.
An automatic focus tracking Pa1 mechanism is constructed using the focus position detection device according to the invention described above.

In the figure, +1+ +2+ +31 +51 (81
Country f is the same as in Figure 1. However, the processing laser beam (1) is emitted from a processing laser oscillator fixed to the vibration isolation stage 0 of the apparatus. Also, half mirror (
2) is also fixed to the vibration isolation stage Ogl via the arm CD. Furthermore, the condensing lens (3) is set in the cylinder and is attached to the lower end of the mR (24+) via a rotatable revolver. The object is attached to the vibration isolation stage (19) so as to be vertically movable via the mounting jig (to).The object emits a detection laser beam (8), and This is a focus detection sensor that receives the reflected light of the lens and detects the focal position from its output.It is attached to the lens barrel (2Φ, and its details will be described later.For example, the detection laser beam (8)
The half mirror 1 attached to the lens barrel (241) is connected to the focus detection sensor (the first output signal Cable for transmitting data to the vertical slide mechanism,
■ is a monitor lamp that emits the monitor light Gυ, ■ is a half mirror for making the monitor light Gl) incident on the condensing lens (3) coaxially with the processing laser beam (1) - on the monitor lamp side and half mirror ( 2) are both lens barrels (2)
installed on. Yoshi is a monitor head that is attached to the upper end of the lens barrel (241) and detects the monitor light G11 reflected from the processed surface (5), and the Foundation is a color CRT that is connected to the monitor head (to) via a cable device. be.

Next, details of the focus detection sensor punishment will be explained with reference to FIG. In the figure, ■ is a detection laser oscillator as a detection laser generation means that emits a detection laser beam (8);
The half mirror 1■ is a detection laser detection +7 sensor as a light image detection means, and CBl is a focus detection mechanism, and the focus detection mechanism fence and the vertical slide mechanism □□□ are used to control the movement of the condenser lens ■ Configure.

Next, the operation will be explained. The light passes through the processing laser oscillator (2), is focused by the condenser lens (3), and is irradiated onto the processing surface (5). On the other hand, the detection laser beam (8) emitted from the detection laser oscillator (A) in the focus detection sensor □ passes through the half mirror, is reflected by the half mirror □□□, and changes its direction downward. The light passes through the half mirror (2) and is focused by the condenser lens (3) to form an optical image on the processing surface (5). Then, the reflected light passes through the half mirror [Yes] (2) again, and the half mirror ■ and (To)
The light is reflected by each of them and reaches the detection laser detection sensor ■. This detection laser detection sensor has a large number of microscopic detection elements integrated on a flat surface, and quantitatively measures the detection laser light received from the output distribution of each element. The output of the laser detection sensor for detection is output to the focus detection mechanism ■, and the focus detection mechanism ■ detects the processing surface (5
) is exactly at the focal position, the amount of deviation from a preset value corresponding to the output signal for the optical image is detected, and the amount of movement of the condensing lens (3) corresponding to the amount of deviation is calculated. A signal corresponding to the amount of movement is sent to the vertical slide mechanism (5). When this amount of deviation becomes zero, the signal to the vertical slide mechanism (to) also becomes zero, and the condenser lens (3) moves to the processing surface (5).
) is set at that focal position.

In addition, the monitor light l31) from the monitor lamp ■ is
After being reflected by the half mirror ■, it passes through the condensing lens (3) and is irradiated onto the processing surface (5), and the reflected light is reflected by the half mirror [
Yes] (2) and (2) are passed through and input to the monitor head device. Therefore, the situation with focus tracking IL of 1 or more is color CR.
It can be monitored by TC341.

As described above, there is no need to control the movement of the processing table OQ, which is generally large and heavy, and only the small and lightweight condensing lens (3) needs to be controlled; The detection laser oscillator (to), the detection laser detection sensor, and the condensing lens control means f4 (along with I) are attached to a common lens barrel QΦ and are integrated, so the device is small, lightweight, and inexpensive. Thus, rapid focus tracking is realized.

Note that the optical image detection means 0D■ in each of the above embodiments receives the reflected light from the processed surface (5) via the condenser lens (3). By adding a half mirror between the processing surface (5) and the processing surface (5), a configuration may be adopted in which the reflected light is received without passing through the condensing lens (3).

Moreover, although each of the above embodiments has been described with reference to the case where it is applied to a laser processing device, these inventions can also be applied to other systems that use laser light, such as a laser measurement device.

〔Effect of the invention〕

As described above, the present invention calculates the focal position from the change in the output of the optical image detection means when the condensing lens is moved in the direction of its optical axis, so it is relatively small and lightweight. It is sufficient to control the movement of the lens, and there is no need to control the movement of the processing table, which is generally large and heavy, making the detection device small, lightweight, and inexpensive.

In addition, the amount of deviation from the focal point position is detected from the output of the optical image detection means, and the movement of the condensing lens is controlled in the direction of its optical axis so that the amount of deviation becomes zero, making the mechanism compact.
It is lightweight, inexpensive, and can achieve rapid focus tracking.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a focus position detection device for a laser processing device in an embodiment of the present invention, FIG. 2 is a configuration diagram showing a focus tracking mechanism for a laser processing device in an embodiment of another related invention, FIG. 3 is a block diagram showing details of the focus detection sensor shown in FIG. 2, and FIG. 4 is a block diagram showing a conventional focus position detection device for a laser processing apparatus. In the figure, (1) is the laser beam for processing, (3) is the condenser lens, (5) is the processed surface as the irradiated object, (8) is the laser beam for detection, and (9) (to) is for detection. A detection laser oscillator as a laser generation means, n1lB a light image, (lυ a photoelectric conversion means as a light image detection means, 19 a focal position calculation means, a blade a detection laser detection sensor as a light image detection means, (4G is a condensing lens movement control means. The same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a device for detecting the focal position of the laser beam of a laser device that focuses the laser beam on an object to be irradiated via a condensing lens, the optical axis is the same as the optical axis of the laser beam. a detection laser generating means for emitting a detection laser beam from which the detection laser beam is focused on the irradiated object via the condensing lens; and reflection of a light image formed on the irradiation object by the detection laser beam. A light image detection means for receiving light; and a focus position calculation means for calculating the focus position from a change in the output of the light image detection means when the condenser lens is moved in the direction of its optical axis. A focal position detection device for a laser device, characterized by: 2. In a focus tracking mechanism of a laser device that focuses a laser beam on an object to be irradiated through a condensing lens, the object to be irradiated is focused from the same optical axis as the optical axis of the laser beam through the condensing lens. a detection laser generating means for emitting a detection laser beam focused on the object; a light image detection means for receiving a reflected light of a light image of the detection laser beam formed on the irradiated object; The amount of deviation between the output value of the image detection means and a preset value corresponding to the output value for the optical image at the focal position is detected, and the condensing lens is adjusted so that the amount of deviation becomes zero. A focus tracking mechanism for a laser device, comprising a condensing lens movement control means for controlling movement in an axial direction.