JPH07243937A - Inspecting method for laser unit and device thereof - Google Patents

Abstract

PURPOSE:To provide a laser unit inspecting method capable of inspecting a laser unit with high accuracy in a short time and to provide a laser unit inspecting device used for it. CONSTITUTION:A laser beam Bo emitted from a laser unit 1 is radiated to a hologram 2 fixed slantly by the Bragg angle theta0 against the normal optical axis direction, the light quantity of the diffracted light Bd of the hologram 2 is detected by a light quantity sensor 3, and the optical axis direction of the laser beam Bo is detected. The reflected light Br of the hologram 2 is detected by a position sensor 4, and the optical axis position of the laser beam Bo is detected. The light quantity distribution of the transmitted light Bt of the hologram 2 is detected by beam scans 6, 7, and the beam diameter of the laser beam Bo is inspected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser unit inspection method and a laser unit inspection apparatus.

[0002]

2. Description of the Related Art A laser unit used as a scanning light source in a laser beam scanning device such as a POS scanner, an image scanner, a character scanner, a laser printer, a copying machine and a facsimile has a case as shown in a plan view of FIG. A configuration is provided in which a laser tube 102 and an optical lens 103 are provided inside 101.

This laser unit has the above-mentioned case 101.
Is fixed to a device by fixing the laser unit to a laser unit mounting part provided in the device such as the POS scanner, and the laser unit mounting part and the case 10 are fixed.
The mounting position relationship with 1 is such that a predetermined mechanical accuracy is satisfied. Therefore, whether the laser beam axis is irradiated in a predetermined direction or a predetermined position when it is attached to the device depends on the directional relationship between the optical axis direction of the laser beam emitted from the laser tube 102 and the case 101. Will depend on you.

Further, it is necessary that the laser beam emitted from the tube 102 has a predetermined diameter at the canning position of the object in order to reduce a scanning error, but the laser beam has a predetermined diameter. Whether or not it has a predetermined diameter at the turning position depends on the position of the optical lens 103 in the case 101.

Therefore, before the case 101 is attached to the apparatus, the optical axis 1 and the directional relationship between the optical axes of the laser beams emitted from the case 101 and the laser tube 102.
The laser unit is configured so that the position 03 can be adjusted.

That is, in order to adjust the direction and position of the optical axis of the laser beam, the case 101 has an X-axis direction orthogonal to the normal laser beam axis, as shown in the vertical sectional front views of FIGS. 5 and 6. And a pair of springs 104 and 10 directed to the X axis and the Y axis direction orthogonal to the normal laser beam axis.
5 and two pairs of adjusting screws 106 and 107 that are screwed into the case 101 so as to face the springs 104 and 105 at appropriate intervals in the regular optical axis direction.

Although not shown, a mechanism for adjusting the position of the optical lens 103 (or the laser tube 102) in the regular optical axis direction is provided in order to adjust the beam diameter at both the near and far points of the use area of the laser beam. .

Further, as shown in the sectional view of FIG. 7, a laser diode 202 and an optical lens 203 are provided in a case 201.
In such a case, a hole 204 having a diameter larger than that of the laser diode 202 is provided on the wall surface of the case 201, and a mounting screw 205 for fixing the laser diode 202 to the wall surface is loosened so that the position of the laser beam axis can be adjusted. Yes,
Further, although not shown, a mechanism for adjusting the position of the optical lens 203 in the regular optical axis direction in order to adjust the beam diameter of the laser beam is provided.

The laser diode 202 has a large laser beam spread, and its optical axis originally has no directivity.
Therefore, in order to intentionally adjust the direction of the laser beam emitted from the laser diode 202, the optical lens 20
The angle of the laser beam of No. 3 is adjusted.

Before the laser unit is attached to the equipment, it is detected whether or not the beam diameters at the optical axis direction, the optical axis position, and the perspective point of the usage area have the desired values, respectively. Adjustment screw 106/10
7 to adjust the optical axis direction and the optical axis position of the laser beam, or loosen the mounting screw 205 to laser diode 20.
The position of No. 2 is adjusted to adjust the optical axis position of the laser beam, and the position of the optical lens 203 is adjusted to adjust the beam diameter at both the near and far points of the use area.

By the way, the detection of the optical axis direction and the optical axis position of the laser unit (hereinafter referred to as the optical axis inspection) and the detection of the beam diameter (hereinafter referred to as the beam diameter inspection) are performed separately. The axis inspection is performed by the following method using, for example, a laser unit inspection device as shown in the side view of FIG.

First, the laser unit 101 is fixed to a mount 109 provided on one end of the beam 108 to emit a laser beam B, and a pinhole 110 is formed in the beam 108.
The target 111 having the above is placed, and while moving the target 111, it is inspected whether the laser beam B emitted from the laser unit 101 passes through the pinhole 110 at two points appropriately selected.

Whether or not the laser beam B passes through the pinhole 110 is visually judged from the laser unit 101 side, and when the laser beam B passes through the pinhole 110 at two points, the optical axis direction and the optical axis. The position is assumed to comply with the standard established in advance.

If not suitable, the adjusting screws 106 and 107 are successively operated on the spot as required, and the laser beam B passes through the pinhole 110 of the target 111 at at least the above-mentioned two points. And adjust the position. In the laser diode 202, the direction and the position of the optical axis are adjusted by adjusting the mounting position of the laser diode 202 and the lens 203 as described above.

In the beam diameter inspection, as shown in the side view of FIG. 9, instead of the target 111, the beam scan 1
Another target 113 provided with 12 is placed on the beam 108, and while sliding along the beam 108, the far and near points of the usage area where the beam diameter becomes a predetermined value are found, and the far and near points of this usage area are set in advance. It is detected whether or not the position is the set position.

For the laser unit which is not in the preset position, the optical lens 1 is continuously used on the spot.
03 (203) is moved back and forth to adjust the waist position, and then re-inspected, or both the near and far points of the measured use area are recorded, and the optical lens 10 is recorded at another place based on this recording.
After moving 3 (203) forward and backward to adjust the waist position,
Retested.

[0017]

As described above, in the conventional laser unit inspection method, the inspection of the optical axis direction and the optical axis position (hereinafter, these are collectively referred to as optical axis inspection) and the inspection of the beam diameter are performed. However, there is a problem that the inspection time becomes long because the steps are performed separately.

Further, since the optical axis inspection relies on the naked eye, there is a problem in that accuracy becomes low and high accuracy is required. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser unit inspection method that can inspect a laser unit with high accuracy in a short time, and a laser unit inspection device used for the same.

[0019]

In order to achieve this object, the following means are used. That is, as shown in FIG. 1, the laser beam Bo emitted from the laser unit 1 is applied to a hologram 2 which is fixed while being inclined by a Bragg angle θ _{0 with} respect to the normal optical axis direction, and the hologram 2 is diffracted. The light amount sensor 3 detects the light amount of the light Bd to detect the optical axis direction of the laser beam Bo, and the position sensor 4 detects the reflected light Br of the hologram 2 to detect the optical axis position of the laser beam Bo. The laser beam Bo is detected by detecting the light amount distribution of the transmitted light Bt of the hologram 2 by the beam scans 6 and 7.
It is characterized by inspecting the beam diameter of.

In order to implement the above method, the following device is used. That is, as shown in FIG. 1, a mounting base 8 for positioning and supporting the laser unit 1 and a laser beam emitted from the laser unit 1 at a predetermined position with respect to the laser unit 1 fixed to the mounting base 8. Bo
Of the hologram 2 inclined by the Bragg angle θ _{0 with} respect to the regular optical axis direction, a light amount sensor 3 for detecting the diffracted light amount of the hologram 2, and a position sensor 4 for detecting the position of the reflected light of the hologram 2. The beam scans 6 and 7 for detecting the light amount distribution of the transmitted light of the hologram 2 at a predetermined position.

Further, in order to detect the usable area of the laser beam Bo, a half mirror 5 is provided in the optical path of the transmitted light Bt of the hologram 2 in the above configuration, and the light quantity distribution of the transmitted light B6 of the half mirror 5 is determined. A first beam scan 6 for detection and a second beam scan 7 for detecting the light amount distribution of the reflected light B7 of the half mirror 5 are provided, and one between both beam scans 6 and 7 and the laser unit 1 is provided. The optical path length is a distance L1 from the far point of the use area of the laser beam.
Similarly, the optical path length between the other of the two beam scans 6 and 7 and the laser unit 1 is set to be the same as the distance L2 from the near point of the use area of the laser beam.

[0022]

[Operation] In the present invention, when the laser beam Bo emitted from the laser unit 1 is incident on the hologram 2,
Diffracted light Bd, reflected light Br, and transmitted light Bt of the laser beam Bo are obtained at the same time.

The amount of the diffracted light Bd changes depending on the angle θ formed by the laser beam Bo and the hologram 2, and this angle θ becomes the angle θ ₀ (Bragg angle) formed by the laser beam Bo and the hologram 2 in the normal direction. When they match, the amount of detected light becomes maximum.

Therefore, the light quantity of the diffracted light Bd is detected by the light quantity sensor 3, and it is determined whether the optical axis direction of the laser beam Bo is a predetermined regular direction depending on whether or not the value reaches the maximum value. Can be detected. Here, when the optical axis direction is not a regular direction, the light amount sensor 3 is used.
The adjustment screws 106 and 107 are turned so that the output of the optical axis is maximized, and the optical axis direction is adjusted.

The reflection direction of the reflected light Br does not change even if the optical axis position of the laser beam Bo moves in parallel. For example, in the case shown in FIG. 1, the optical axis position of the laser beam Bo is horizontal. If it moves in parallel (in the vertical direction in the drawing), the incident point of the reflected light Br on the position sensor 4 moves in the horizontal direction in the drawing in proportion to the amount of movement of the optical axis position.

Therefore, by detecting the position of the reflected light Br, it is possible to detect whether or not the optical axis position of the laser beam Bo is the position provided in advance. Here, the optical position sensor 4 is adjusted so that its output is minimized when the laser beam is in a predetermined position. Therefore, when the optical axis position is not a regular position, the output of the optical position sensor 4 is The optical axis position is adjusted by turning the adjusting screws 106 and 107 so that the value becomes minimum.

The light quantity distribution characteristic of the transmitted light Bt is as follows.
In general, the Gaussian distribution is used, so by measuring this light amount distribution at both the near and far points of the regular use area by beam scanning 6 and 7, the beam diameters at the far and near points of the regular use area are set in advance. Can be detected. Here, if the beam diameter is not a predetermined diameter at both of the perspective points, the optical lens 103
The position of (203) will be adjusted.

What is important is that the diffracted light B of the laser beam Bo is
Since d, reflected light Br, and transmitted light Bt are obtained at the same time,
The inspection in the optical axis direction, the inspection of the optical axis position, and the inspection of the beam diameter can be performed at the same time.

Further, without inspecting the optical axis position with the naked eye,
Since it is performed by the position sensor 4, even if the light amount of the laser beam Bo decreases, the contour of the laser beam Bo can be clearly determined by appropriately adjusting the gain.

Further, a half mirror 5 is provided on the optical path of the transmitted light Bt of the hologram 2, and a first beam scan 6 for detecting the light amount distribution of the transmitted light B6 of the half mirror 5,
A second beam scan 7 for detecting the light quantity distribution of the reflected light B7 of the half mirror 5, and both beam scans 6
The optical path length between one of 7 and the laser unit 1 is the same as the distance L 1 between the laser unit 1 and the far point of the use area of the laser beam, and the other of both beam scans 6 and 7 and the laser unit 1 When the optical path length between and is set to be the same as the distance L2 between the laser unit 1 and the near point of the use area of the laser beam, the beam diameter becomes a predetermined diameter between the near point and the far point. It will be possible to detect whether or not

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser unit inspection method and a laser unit inspection apparatus used therefor according to an embodiment of the present invention will be specifically described below with reference to the drawings.

As shown in FIG. 1, a laser unit inspection apparatus according to an embodiment of the present invention includes a mount 8 for fixing a laser unit 1, a hologram 2, a light quantity sensor 3, a position sensor 4, and a half. It has a mirror 5 and two beam scans 6 and 7.

As described above, in the laser unit 1, the direction of the laser beam emitted from the laser tube 102 housed in the laser case 101 is such that
As long as the direction is normal to the laser case 101
When attached to a device such as a P0S scanner, the laser beam is emitted in a prescribed direction, and the beam diameter also depends on the position of the optical lens 103 in the laser case 101. Further, the mounting accuracy of the mounting base 8 for fixing the laser unit 1 and the laser unit 1 is designed to be as high as the mounting accuracy of the laser unit 1 to the device.

The hologram 2 is fixed by being tilted by the Bragg angle θ _{0 with} respect to the regular optical axis direction of the laser beam Bo emitted from the laser unit 1 positioned and fixed on the mount 8.

The light quantity sensor 3 is arranged in the diffraction direction of the laser beam Bo incident on the hologram 2 in the regular optical axis direction. Further, the position sensor 4 is arranged in the direction of the reflected light Br of the laser beam Bo incident on the hologram 2 in the regular optical axis direction, and when the laser beam Bo is in the regular optical axis position, a predetermined value (for example, It outputs zero).

The half mirror 5 is arranged on the optical path of the transmitted light Bt of the hologram 2, and the first beam scan 6 is on the optical path of the transmitted light B6 of the half mirror 5 and the second on the optical path of the reflected light B7. The beam scan 7 of is arranged.

The sum of the distance L6 from the half mirror 5 to the first beam scan 6 and the distance L5 from the laser unit 1 to the half mirror 5 is one end of the normal waist position from the laser unit 1 (here, the laser beam is The lens 103 (20) [moves] on which the object to be irradiated is arranged
It is set equal to the distance L1 from 3) to the far point of the allowable distance).

The sum of the distance L7 from the half mirror 5 to the second beam scan 7 and the distance L5 from the laser unit 1 to the half mirror 5 is the other end of the laser unit 1 from the normal waist position (here, It is set to be equal to the distance L2 to the near point of the allowable distance).

Next, the procedure of the laser unit inspection method using this inspection apparatus will be described. First, the unadjusted laser unit 1 is positioned and fixed on the mount 8, and the laser beam Bo is made incident on the hologram 2.
Diffracted light Bd, reflected light Br, and transmitted light Bt are obtained.

The light quantity of the diffracted light Bd of the hologram 2 is shown in FIG.
As shown in the characteristic diagram of the diffracted light amount, changes depending on the angle θ of the hologram 2 with respect to the optical axis of the laser beam Bo, and becomes maximum when the laser beam Bo enters the hologram 2 from the Bragg angle θ ₀ (normal direction).

Therefore, the operator adjusts the adjusting screws 106 and 107 of the laser unit 1 so that the output of the light quantity sensor 3 becomes maximum, so that the laser beam is emitted in the normal direction. . When the laser diode 202 is used, the angle of the lens 203 with respect to the optical axis direction is adjusted.

When the laser beam Bo moves in parallel, the reflected light Br of the hologram 2 moves in parallel by a distance proportional to the moving distance. The position sensor 4 that receives the reflected light Br has a configuration in which the output thereof becomes zero (or maximum) when the reflected light Br is positioned at a regular position, and therefore, the operator outputs the position sensor 4 above. , And adjust the adjusting screws 106 and 107 so that they become zero (or maximum).

By the way, the beam diameter of the laser beam Bo is
As shown in the beam diameter distribution diagram of FIG. 3, the beam diameter between the far and near points of the use area is a standard value (for example, 30
0 μm) or less.

The light amount distribution of the transmitted light Bt of the hologram 2 in the radial direction shows a Gaussian distribution as shown in the light amount distribution chart of FIG. 4, and has an upper limit value Max. In the range of a predetermined light receiving amount or more (13% or more). The distance d from the lower limit value Min. Is the beam diameter.

Therefore, the beam diameter of the transmitted light Bt is measured by the two beam scans 6 and 7, and the position of the lens 103 (203) is adjusted so that the beam diameter is equal to or less than a predetermined value between the far and near points of the use area. Is adjusted.

As described above, when the laser beam Bo is incident on the hologram 2, the diffracted light B from the hologram 2 is generated.
Since d, the reflected light Br, and the transmitted light Bt are obtained, these inspections can be performed at the same time without being influenced by each other, and thus the inspection time of the laser unit can be significantly shortened.

Since the mounting 8, the hologram 2, the light quantity sensor 3, the position sensor 4, the half mirror 5, and the two beam scans 6 and 7 are fixed in positional relation to each other, it takes time to align them. This eliminates the need for labor, eliminates the possibility of causing a position error associated with the alignment, and eliminates the risk of causing an inspection error based on this position error.

Further, since the optical axis position is inspected by using the position sensor 4, highly accurate position adjustment can be expected, and the fatigue of the naked eye does not have to be a problem. It should be noted that in the above embodiment, two beam scans 6 and 7 are used, but one of these and half mirror 5 are omitted,
One beam scan may be moved forward and backward over both the near and far points of the regular use area on the optical path of the transmitted light Bt of the hologram 2.

[0049]

As described above, according to the present invention, the laser beam of the laser unit fixed to the mount is incident on the hologram, so that the diffracted light, the reflected light and the transmitted light of the hologram are simultaneously generated. Can be obtained.

Therefore, detection and adjustment of the optical axis direction based on the diffracted light of this hologram, detection and adjustment of the optical axis position based on the reflected light of this hologram, and detection and adjustment of the beam diameter based on the transmitted light of this hologram. Since it is possible to simultaneously perform and without affecting each other, the adjustment time can be shortened.

Further, since the position sensor is used for detecting the optical axis position, the optical axis position can be inspected with high accuracy and the fatigue of the naked eye does not become a problem.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a characteristic diagram of a diffracted light amount of a hologram.

FIG. 3 is a beam diameter distribution diagram of a laser beam.

FIG. 4 is a light amount distribution diagram of hologram transmitted light.

FIG. 5 is a plan view of a laser unit.

FIG. 6 is a vertical sectional front view of a laser unit.

FIG. 7 is a cross-sectional view of another laser unit.

FIG. 8 is a side view of a conventional example at the time of optical axis inspection.

FIG. 9 is a side view of a conventional beam diameter inspection.

[Explanation of symbols]

 1 Laser Unit 2 Hologram 3 Light Sensor 4 Position Sensor 5 Half Mirror 6 First Beam Scan 7 Second Beam Scan 8 Mounting Base Bo Laser Light Bd Diffracted Light Br Reflected Light Bt Transmitted Light B6 Transmitted Light B7 Reflected Light

Claims (3)

[Claims] 1. A laser beam (Bo) emitted from a laser unit (1) is supplied to a Bragg angle (θ
_The hologram (2) fixed by tilting ( _O ) is irradiated, and the light quantity of the diffracted light (Bd) of this hologram (2) is detected by the light quantity sensor (3) to determine the optical axis direction of the laser beam (Bo). Detect and
The reflected light (Br) of the hologram (2) is detected by the position sensor (4) to detect the optical axis position of the laser beam (Bo), and the light quantity distribution of the transmitted light (Bt) of the hologram (2) is beamed. A laser unit inspection method characterized by inspecting the beam diameter of a laser beam (Bo) by detecting it by scanning (6, 7). 2. A mounting base (8) for positioning and supporting the laser unit (1), and the laser unit at a predetermined position with respect to the laser unit (1) fixed to the mounting base (8).
Hologram tilted by the Bragg angle (θ _O ) with respect to the normal optical axis of the laser beam (Bo) emitted by (1) (2)
A light quantity sensor (3) for detecting the light quantity of the diffracted light (Bd) of the hologram (2), a position sensor (4) for detecting the position of the reflected light (Br) of the hologram (2), and the hologram (2)
And a beam scan (6, 7) for detecting the light amount distribution of the transmitted light (Bt) at a predetermined position of the laser unit inspection device. 3. A half mirror (5) is provided in the transmission optical path of the hologram (2), and the transmission light (B6) of the half mirror (5) is provided.
Both beam scans are equipped with a first beam scan (6) for detecting the light intensity distribution of the above and a second beam scan (7) for detecting the light intensity distribution of the reflected light (B7) from the half mirror (5).
(6 ・ 7) The optical path length between one side and the laser unit (1) is the same as the distance (L1) between the laser unit (1) and the far point of the area where the laser beam is used, and both beam scans are performed. The optical path length between the other side of (6 ・ 7) and the laser unit (1) is the distance (L
The laser unit inspection apparatus according to claim 2, wherein the setting is the same as in 2).