JPH06174418A - Focal position detecting device for condensing lens - Google Patents

Abstract

PURPOSE:To efficiently calculate the accurate focal position from the convergent diameters at the front and rear points of the focal position and the shift quantity of a condensing lens by providing the shift quantity detecting means of the condensing lens and a sensor arranged with light receiving elements in a matrix shape. CONSTITUTION:A motor 9 is driven to move a condensing lens 4 to the first measuring position, and the shift quantity of the condensing lens 4 is applied to a focal position calculating device 13 from a position detecting device 11. A laser oscillator 1 is operated, a laser beam 2 is radiated on a sensor 5 via a reflecting mirror 3 and the condensing lens 4, and the voltage proportional to the light reception quantity of photoelectric transfer elements 6 is generated. The voltage is compared with the threshold value by a convergent diameter detecting device 12 and binarized, then the number N1 (convergent diameter) of the elements 6 receiving the laser beam 2 is obtained in the X-direction or the Y-direction of the sensor 5. The shift quantity L2 of the lens 4 and the convergent diameter N2 are likewise obtained at the next measurement position, the focal position is calculated 13 from these values, and the focal position is obtained accurately and efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus position detecting device for detecting the focus position of a condenser lens.

[0002]

2. Description of the Related Art A laser processing machine, particularly a laser processing machine using a carbon dioxide gas laser, is widely used for cutting and drilling due to its large output energy. However, since the wavelength of the laser light oscillated by the carbon dioxide gas laser is 10.6 μm (far-infrared region), the focus position cannot be visually confirmed.

When a hole having an extremely small diameter of 0.1 mm or less is machined so as not to damage the surrounding area, it is required that the focal position of the condenser lens is accurately aligned with the machined portion. For this reason, conventionally, a material that is relatively easy to process, such as an acrylic plate, was used as the sample, and the laser beam was irradiated to multiple points while changing the distance between the condenser lens and the sample, and the size of the irradiation mark formed there was measured. Then, the focus position of the condenser lens is estimated based on the result.

[0004]

In such estimation of the focus position, not only the accurate position cannot be detected, but also the irradiation mark is repeatedly measured by a microscope and the workability is poor.

In view of the above circumstances, an object of the present invention is to provide a focusing position detecting device for a focusing lens which can detect the focusing position of the focusing lens efficiently and accurately.

[0006]

In the present invention, drive means for moving the condenser lens in the direction of its optical axis, and position detection means for detecting the amount of movement of the condenser lens moved by this drive means. , A sensor in which a plurality of light receiving elements are arranged so as to face the condenser lens and arranged in a matrix, and the diameter of the light condensed by the condenser lens on the sensor is determined based on the output of the sensor. A focus diameter calculating means for calculating and a focus position calculating means for calculating the focus position of the condenser lens based on the outputs of the position detecting means and the focus diameter calculating means are provided.

[0007]

Then, the focusing lens is moved to determine the focusing position of the focusing lens from the focusing diameter and the moving amount of the focusing lens at two points before and after the focusing position of the focusing lens of the laser light emitted to the sensor. calculate.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the figure, reference numeral 1 is a laser oscillator, which oscillates a laser beam 2. 3 is a reflector. 4 is a condenser lens. Reference numeral 5 denotes a sensor, in which a plurality of photoelectric conversion elements 6 are arranged in a matrix. Reference numeral 7 denotes a driving means, which includes a feed screw 8 arranged parallel to the optical axis of the laser beam 2 reflected by the reflecting mirror 3, a motor 9 for driving the feed screw 8, and a female screw screwed to the feed screw 8. The mounting plate 10 thus formed is provided. Reference numeral 11 denotes a position detecting means, which is composed of a linear scale, a linear pulse encoder, and the like. Reference numeral 12 denotes a condensed diameter calculating means, which is connected to the sensor 5. Reference numeral 13 denotes a focus position calculation means, which is a focused diameter calculation means 12 and a position detection means 11.
It is connected to the. In addition, 14 is a semi-transparent mirror, and the sensor 5
Is arranged so as to reflect a part of the laser light 2 in order to prevent the damage.

With such a configuration, when the driving means 7 is at the origin position, the distance L0 between the condenser lens 4 mounted on the mounting plate 10 and the sensor 5 is measured, and the focus position calculation means 13 is measured.
Register in.

The motor 9 is operated to move the condenser lens 4 to the first measurement position A. At this time, the movement amount L1 of the condenser lens 4 is applied from the position detection means 11 to the focus position calculation means 13. When the laser oscillator 1 is operated to oscillate the laser light 2, the laser light 2 is reflected by the reflecting mirror 3 and is irradiated onto the sensor 5 through the condenser lens 4. At this time, each photoelectric conversion element 6 that constitutes the sensor 5 generates a voltage having a magnitude proportional to the amount of received light.

The condensing diameter detecting means 12 is provided for each photoelectric conversion element 6
The voltage output from the sensor 5 is compared with a preset threshold voltage and binarized.
Regarding the direction, the photoelectric conversion element 6 receiving the laser light
Is selected, and the number of photoelectric conversion elements 6 receiving the laser light in the row or column (having a binarized output of 1) N1 (the laser light focused on the sensor 5). 2 condensing diameter).

The motor 9 is operated to move the condenser lens 4 to the next measurement position B in the optical axis direction. At this time,
The movement amount L2 of the condenser lens 4 (that is, the focus position of the condenser lens 4) is applied from the position detection means 11 to the focus position calculation means 13. After the condenser lens 4 is stopped, the number N of photoelectric conversion elements 6 receiving the laser beam 2 is the same as the above.
Ask for 2.

As shown in FIG. 3, the focus position calculating means 13 calculates, from the distance L0, the moving amounts L1 and L2 and the numbers N1 and N2 and the moving amount L2, L3 = L2.NI / (N1 + N2) (1) ◆ L4 = L0-L1-L3 (2) ◆ From L4 = L0-L1-L2N1 / (N1 + N2) (3) ◆, the focal position of the condenser lens 4 is calculated.

Since the focal position of the condenser lens 4 can be calculated as described above, by providing such a detection device in the laser processing apparatus, the focal position of the condenser lens 4 can be efficiently and accurately measured. Can be detected.

[0015]

As described above, according to the present invention, the drive means for moving the condenser lens in the optical axis direction, and the position detection for detecting the movement amount of the condenser lens moved by the drive means. Means, a sensor in which a plurality of light receiving elements are arranged so as to face the condensing lens, and the plurality of light receiving elements are arranged in a matrix, and based on the output of the sensor, Since the condensing diameter calculating means for calculating the diameter and the focal position calculating means for calculating the focal position of the condensing lens based on the outputs of the position detecting means and the condensing diameter calculating means are provided, it is efficient and accurate. Moreover, the focus position of the condenser lens 4 can be detected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a focus position detection device for a condenser lens according to the present invention.

FIG. 2 is a perspective view showing a condensed state of laser light on a sensor.

[FIG. 3] Calculation of a focus position in a focus position detection device of a condenser lens

[Explanation of symbols]

 4 Condensing lens 5 Sensor 6 Light receiving element 7 Driving means 11 Position detecting means 12 Condensing diameter calculating means 13 Focus position calculating means

Claims (1)

[Claims] 1. A focus position detecting device for detecting a condensing position of a condensing lens, comprising: driving means for moving the condensing lens in its optical axis direction; and condensing lens moved by the driving means. A position detecting means for detecting the amount of movement, a sensor arranged so as to face the condenser lens and having a plurality of light receiving elements arranged in a matrix, and a sensor for collecting the light on the sensor based on the output of the sensor. A condensing diameter calculating means for calculating the diameter of the light condensed on the optical axis and a focal position calculating means for calculating the focal position of the condensing lens based on the outputs of the position detecting means and the condensing diameter calculating means are provided. A focus position detection device for a condenser lens, which is characterized in that