JPH0697310B2 - Laser beam light scanning characteristic measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a scanner unit using a rotary polygon mirror (polygon mirror) used in, for example, a laser printer and the like. The present invention relates to a laser beam light scanning characteristic measuring device for measuring a target surface tilt angle and a scanning linearity of a laser beam light reflected by a rotating polygon mirror and output from a scanner unit.

(Prior Art) Generally, a rotary polygon mirror is a reflecting mirror formed of a polyhedron, and is widely used for a laser printer, a bar code reader, and the like that require high-speed and high-precision optical scanning.

For example, in a laser printer, a laser beam light output from a laser oscillator is reflected by a rotating polygon mirror that rotates at high speed, and the reflected beam light linearly scans the surface of a photosensitive drum to form an electrostatic latent image. . The sharpness and resolution of this electrostatic latent image are influenced by the swing width of the reflected beam light reflected by the rotating polygon mirror on the surface of the photosensitive drum (image is formed here), and are formed on the surface of the photosensitive drum. A clear image cannot be obtained because the electrostatic latent image is missing or uneven.
The swing width of the reflected beam light on the photosensitive drum surface is determined by the surface tilt angle between the adjacent mirror surfaces of the rotary polygon mirror.

Further, recently, a scanner unit in which a laser oscillator, a rotary polygon mirror, an optical system, and the like are integrated has been developed, and by incorporating a surface tilt correction lens in the scanner unit, the reflected beam light on the photosensitive drum surface can be A method has been adopted to reduce the swing width.

However, in this case, although the surface tilt angle of the rotary polygon mirror can be corrected to some extent, the scanning of the reflected beam light on the photosensitive drum surface is affected by the optical system such as the surface tilt correction lens. Bending in a direction orthogonal to the scanning direction makes it impossible to obtain accurate linearity. For this reason, the electrostatic latent image formed on the surface of the photoconductor drum is missing or uneven, and a clear image cannot be obtained.

Therefore, accurately knowing the dynamic plane tilt angle of the rotary polygon mirror and the scanning linearity of the laser beam light reflected by the rotary polygon mirror and output from the scanner unit is extremely important in determining the performance of the scanner unit. It becomes important.

Conventionally, it has been known to measure with an autocollimator for static surface tilt angle measurement of a rotating polygon mirror alone. In this measuring method, after a rotary polygon mirror and a motor for rotating the rotary polygon mirror are assembled, the static surface tilt angle is measured by an autocollimator while rotating the rotary polygon mirror.

In addition, the measurement of the scanning linearity of the reflected beam light should be performed by plotting the height deviation of the autocollimator as the rotary polygon mirror rotates when measuring the plane tilt angle as described above. You can

Further, as to the measurement of the tilt angle, as disclosed in, for example, “Optical Technology System Design Course”, published by Trikeps Co., Ltd., Yoshisuke Takekita, II. System design of optical system in laser printer ”. , A method of irradiating and projecting a laser beam, preparing a slit in the sub-scanning direction, and measuring it by knowing the change in the laser power in it, or simply a laser on a rotating polygon mirror rotated by a motor. There is a method of irradiating a beam of light, guiding the reflected beam of light to a screen separated by a predetermined distance, and measuring the amount of change in the sub-scanning direction on the screen.
In this case, it is preferable that the distance between the rotary polygon mirror and the screen is as long as possible, and it is said that measurement is easy at about 10 m.

However, each of these conventional measuring methods has a problem that it takes a long time to measure, and it is impossible to measure at an actual product level, and the latter method has a problem that the measuring apparatus itself becomes large.

(Problems to be Solved by the Invention) As described above, according to the present invention, in the conventional measuring method, it takes a long time to measure, it is impossible to measure at an actual product level, and the measuring device becomes large. It was made to solve the problem, and the dynamic plane tilt angle of the rotating polygon mirror and the scanning linearity of the laser beam light that is reflected by the rotating polygon mirror and scans the scanned surface linearly are highly accurate. In addition, it is possible to provide a laser beam light scanning characteristic measuring device that can perform automatic measurement in a short time and in a form that conforms to the product actually used, and does not increase the size of the measuring device itself. To aim.

[Configuration of the Invention] (Means for Solving the Problems) A first laser beam light scanning characteristic measuring device according to the present invention measures a scanning characteristic of a laser beam light that linearly scans a surface to be measured. Detection means for detecting the scanning position information of the laser beam light in the direction orthogonal to the scanning direction at least at three positions in the scanning direction of the laser beam light at the same position as the surface to be scanned, and the detection means. And means for measuring the scanning linearity of the laser beam light according to each scanning position information detected by the means.

A second laser beam light scanning characteristic measuring device according to the present invention is a device for measuring a scanning characteristic of a laser beam light that linearly scans a surface to be scanned, and at the same position as the surface to be scanned, The detection means for detecting the scanning position information of the laser and the light beam in the direction orthogonal to the scanning direction of the laser beam light, the movement control means for moving the detection means in the scanning direction of the laser beam light, and the movement control means An arithmetic unit that measures the scanning linearity of the laser beam light in accordance with the scanning position information at least at three points in the scanning direction of the laser beam light obtained from the detection unit as the detection unit moves. ing.

A third laser beam light scanning characteristic measuring device according to the present invention is for measuring a scanning characteristic of a laser beam light which linearly scans a surface to be scanned. Detection means for detecting scanning position information of the laser beam light in a direction orthogonal to the scanning direction of the laser beam light, movement control means for moving the detection means in the scanning direction of the laser beam light, and the movement control means in the movement control means. A means for previously obtaining position error information in a direction orthogonal to the scanning direction of the laser beam light, and at least three locations in the scanning direction of the laser beam light obtained from this detection means in accordance with the movement of the detection means by the movement control means. A correction unit that corrects each scanning position information by using the position error information, and a correction unit that corrects each scanning position information corrected by the correction unit. And a calculating means for measuring a scanning linearity of the laser beam.

A fourth laser beam light scanning characteristic measuring device according to the present invention is a device for measuring a scanning characteristic of a laser beam light which is reflected by a rotary polygon mirror and linearly scans a surface to be scanned. A first position for detecting scanning position information of the laser beam light corresponding to each surface of the rotary polygon mirror in a direction orthogonal to the scanning direction at at least one position in the scanning direction of the laser beam light at a position equivalent to Second detecting means for detecting the scanning position information of the laser beam light in the direction orthogonal to the scanning direction at at least three positions in the scanning direction of the laser beam light at the same position as the scanning surface. When,
The dynamic surface tilt angle of the rotary polygon mirror is measured according to each scanning position information detected by the first detecting means, and the dynamic surface tilt angle of the rotating polygon mirror is measured according to each scanning position information detected by the second detecting means. And a calculation means for measuring the scanning linearity of the laser beam light.

(Operation) The first laser beam light scanning characteristic measuring device according to the present invention is provided with a laser beam beam scanning direction orthogonal to the laser beam light scanning direction at least at three points in the scanning direction at the same position as the actual surface to be scanned. The scanning position information of the light is detected, and the scanning linearity of the laser beam light is measured according to the detected scanning position information. Thereby, for example, the scanning linearity of the laser beam light which is reflected by the rotary polygon mirror and linearly scans the surface to be scanned is automatically measured with high accuracy in a short time and in a form conforming to the actual product. be able to. In addition, the measuring device itself does not become so large and can be configured compactly.

A second laser beam light scanning characteristic measuring device according to the present invention is the first laser beam light scanning characteristic measuring device, wherein a detecting means for detecting scanning position information is moved in the laser beam scanning direction. By this, at least 3
It is designed to detect the scanning position information of the location,
With this, at least three scanning position information can be detected by a single detecting means. Therefore, the structure can be made more compact and the cost can be reduced.

A third laser beam light scanning characteristic measuring apparatus according to the present invention is the same as the second laser beam light scanning characteristic measuring apparatus in a direction orthogonal to the laser beam scanning direction in the movement control means for moving the detecting means. The position error information is measured in advance, and each scanning position information obtained from the detecting means is corrected using the position error information. This makes it possible to correct the amount of mechanical displacement caused by the movement control of the movement control means, and eliminates the need for positional accuracy between the detection means and the movement control means. It becomes possible to measure with.

A fourth laser beam light scanning characteristic measuring device according to the present invention is a rotary polygon mirror at a position equivalent to an actual surface to be scanned, which is orthogonal to the scanning direction at least at one position in the laser beam light scanning direction. The scanning position information of the laser beam light corresponding to each surface is detected, and the scanning position information of the laser beam light in at least three positions in the scanning direction of the laser beam light is detected, and the detection is performed. The dynamic plane tilt angle of the rotary polygon mirror is measured according to the scanning position information corresponding to each surface of the rotary polygon mirror at at least one position, and the laser beam is measured according to each scanning position information at the above-mentioned at least three positions. It measures the scanning linearity of light.
Thereby, the dynamic plane tilt angle of the rotary polygonal mirror and the scanning linearity of the laser beam light reflected by the rotary polygonal mirror and linearly scanning the surface to be scanned, with high accuracy and in a short time, In addition, it is possible to automatically measure in a form according to the actually used product. Further, the measuring device itself does not become so large, and can be made compact.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

In FIG. 1, a rotary polygon mirror 12 fixed to a rotary shaft of a scanning motor 11 is irradiated with laser beam light output from a laser oscillator 13 through a collimator lens 14, and a reflected beam L thereof causes an Fθ lens. A predetermined position (a position equivalent to the actual surface to be scanned) is linearly scanned via 15 and the surface tilt correction lens 16.

Scanning motor 11, rotary polygon mirror 12, laser oscillator
13, the collimator lens 14, the Fθ lens 15 and the surface tilt correction lens 16 are integrated as a scanner unit 17. The scanning motor 11 is driven by the motor drive circuit 18, and the laser oscillator 13 is driven by the laser drive circuit 19.

A light receiving unit 20 is provided at the predetermined position to receive the reflected beam light L. The light receiving section 20 is configured by arranging, for example, two light receiving elements (for example, pin diodes) 20 ₁ and 20 ₂ in parallel to the scanning direction S of the reflected beam light L.
The light receiving elements 20 ₁ and 20 ₂ receive the reflected beam light L to generate a data reading signal, a reading strobe signal, and the like.

The front of the light receiving element 20 ₂ of the light receiving portion 20, the light shielding portion 21 (e.g. the edge with a razor blade) to cut off is provided an incident of the reflected light beam L by increasing. The light blocking portion 21 is moved up and down with respect to the drawing by a stepping motor 22. Photosensors 23 ₁ and 23 ₂ are provided at the up and down moving ends of the light shielding part 21, respectively.The upper sensor 23 ₁ is for preventing overrun, and the lower sensor 23 ₂ is located at the origin position of the light shielding part 21. It is used to detect the occurrence and to prevent overrun.

Here, the light receiving unit 20, the light shielding unit 21, the stepping motor 22, and the sensors 23 ₁ and 23 ₂ are integrated as a detection unit 24 for detecting scanning position information of the reflected beam light L.
The stepping motor 22 is driven by a motor drive circuit 25, and the sensors 23 ₁ and 23 ₂ are connected to the sensor interface circuit 26, respectively.

The detector 24 is guided by a guide member (not shown) to be reciprocally movable in the scanning direction of the reflected light beam L (direction of arrow R in the drawing), and is moved by, for example, a stepping motor 27. Then, the stepping motor 27 is driven by the motor drive circuit 28.

The both ends and the middle of the movement path of the detection unit 24, the photosensor 29 _{1-29 5} is provided. Sensor 29 ₁ for overrun prevention scanning start point side, for the sensor 29 ₂ which detects that the detection unit 24 is positioned at the scanning start point, the sensor 29 ₃
To detect that the detection unit 24 is positioned at the scanning midpoint, the sensor 29 ₄ in order to detect that the detecting unit 24 is located at the scanning end point, the sensor 29 ₅ overrun prevention of scanning end point side Used for. Each sensor 29 ₁ to 29 ₅ is connected to the sensor interface circuit 26, respectively.

The microprocessor 30 is used as a control unit that controls the entire control, and the motor drive circuit 1 is connected from the microprocessor 30 via the parallel input / output interface circuit 31.
8. Control signals are sent to the laser driving circuit 19 and the motor driving circuits 25 and 28 to control the scanning motor 11, the laser oscillator 13, and the stepping motors 22 and 27, respectively.

The output signals of the sensors 23 _1, 23 _2, 29 ₁ to 29 ₅ are sent to the microprocessor 30 via the respective sensor interface circuit 26 and parallel input-output interface circuit 31.

The laser light ON / OFF signal indicating whether or not the reflected beam light L is applied to each of the light receiving elements 20 ₁ and 20 ₂ of the light receiving unit 20 is waveform-shaped by the amplifier circuit 32 and the face-down interface circuit.
Sent to 33. The face-down interface circuit 33 performs signal processing based on the output signals of the respective light receiving elements 20 ₁ and 20 ₂ and sends it as data to the microprocessor 30 via the parallel input / output interface circuit 31, and the microprocessor 30 stores the memory 34. Memorized in.

Reference numeral 35 is a personal computer for reprocessing data and inputting correction data, 36 is a CRT display device connected to the personal computer 35, and 37 is a printer connected to the personal computer 35.

Next, the operation in such a configuration will be described with reference to FIGS.

In FIG. 2, P ₁ , P ₂ and P ₃ indicate detection points for detecting the scanning position information of the reflected beam light L, P ₁ is the scanning start point,
P ₂ corresponds to the scanning midpoint and P ₃ corresponds to the scanning end point. A ₁ , A
Reference numerals ₂ and A ₃ indicate ideal reference positions (corresponding to the origin position of the light shielding portion 21) when there is no mechanical displacement, and correspond to detection points P ₁ , P ₂ and P ₃ , respectively. B _1, B _2, B ₃ is the scanning direction of the distance (the reflected light beam L from the reference position A _1, A _2, A ₃ at each detection point P _1, P _2, P ₃ to the scanning point of the reflected light beam L S
And (scanning position information in the orthogonal direction). C ₁ , C ₂ , C ₃ are X, X at each detection point P ₁ , P ₂ , P _{3 with} respect to the reference position A ₁ , A ₂ , A ₃ .
The amount of mechanical displacement of the Y axis (positional error information in the direction orthogonal to the scanning direction S of the reflected beam light L caused by the movement of the detection unit 24) is shown.

First, after the scanner unit 17 for measurement is set in a predetermined position with a jig, the mechanical displacement amount C ₁ caused by the movement of the detection unit 24 at each detection point P ₁ , P ₂ , P ₃ Measure C ₂ and C ₃ . Thus, for example by using such well-known dial gauge, first measure the position now positional shift amount C ₁ in the detection point P ₁ of the detection unit 24, then the position deviation by a position in the detection point P ₂ the detector 24 the amount C ₂ measured, then positions the detector 24 to the detection point P ₃ for measuring the positional deviation amount C ₃ with. Then, the amount of positional deviation (positional error information) C ₁ , C ₂ , C ₃ for each of the detection points P ₁ , P ₂ , P ₃ obtained by measuring in this way is input as correction data using the personal computer 35. Then, it is stored in the memory 34.

After that, the actual measurement operation is started. First, the detection unit 24 is positioned at the detection point P ₁ and measurement is performed. That is,
The motor drive circuit 18 drives the scanning motor 11, and the laser drive circuit 19 drives the laser oscillator 13. Then, the rotating polygon mirror 12 rotates and the laser oscillator
A laser beam light is output from 13, the rotating rotary polygon mirror 12 is irradiated with this laser beam light, and the reflected beam light L scans in the direction of arrow S in the figure. At this time, the light shielding part 21 is lowered to the origin position as shown in FIG.

Here, the actual reflected beam light L scans a slightly different position as shown in FIG. 4 depending on the dynamic plane tilt angle of the rotary polygon mirror 12. In this figure, the rotary polygon mirror 12 is, for example, 8
The case of a surface is shown.

Now, when the rotation of the scanning motor 11 becomes stable, the microprocessor 30 drives the stepping motor 22 to gradually raise the light shielding portion 21 from the origin position. Then, the light shielding unit 21 also gradually blocks the reflected beam light L corresponding to each surface of the rotary polygon mirror 12. Further raising the light blocking portion 21 blocks all the reflected beam light L.

Therefore, the microprocessor 30 blocks the reflected beam light L for each surface of the rotary polygon mirror 12 and the moving distance of the light blocking portion 21 from the time when the reflected beam light L is blocked until it is completely blocked. The position information of the portion 21, that is, the scanning position information B ₁ of the reflected beam light L for each surface of the rotary polygon mirror 12 that is blocked by the light shielding portion 21 is stored as data.
Remember in 34. The moving distance of the light-shielding portion 21 and the scanning position information B ₁ of the reflected light beam L are obtained by the respective light-receiving elements 20 ₁ ,
20 ₂ and the number of drive pulses of the stepping motor 22 that moves the light shielding unit 21.

In this way, after storing the necessary data in the memory 34, the microprocessor 30 sets the predetermined position (the position of the light shielding part 21) based on each data of the memory 34 (moving distance of the light shielding part 21 and scanning position information B ₁ ). The shake width of the reflected beam light L of is calculated. In this case, the microprocessor 30 corrects the scanning position information B ₁ in the memory 34 using the position error information (position shift amount) C ₁ stored in advance in the memory 34, and the corrected scanning position information B ₁ Is used to calculate the swing width of the reflected beam light L. The corrected scanning position information B ₁ is stored in the memory 34.

Next, the microprocessor 30 calculates a dynamic plane tilt angle of the rotary polygon mirror 12 by performing a predetermined calculation based on the obtained swing width and the distance from the rotary polygon mirror 12 to the light shielding unit 21.

It is assumed that the distance from the rotary polygon mirror 12 to the light shielding unit 21 is known in advance and is stored in the memory 34, for example. In this case, the positional relationship between the rotary polygon mirror 12 and the light shielding portion 21 should be the same as the positional relationship between the rotary polygon mirror and the photosensitive drum surface of the actual product used as shown in FIG. 3 (b). Thus, the swing width of the reflected beam light L on the photosensitive drum surface of the rotary polygon mirror 12 can be obtained, and the dynamic plane tilt angle of the rotary polygon mirror 12 can be calculated.

Thus, when the measurement at the detection point P ₁ is completed,
Then the detection unit 24 is successively moved between the detection point P _2, P _3, respectively perform the same measurement operation at each detection point P _2, P _3.

When the measurement of the dynamic plane tilt angle at each of the detection points P ₂ and P ₃ is completed in this way, the microprocessor
30 is the scanning position information B ₁ , B obtained when measuring the dynamic plane tilt angle.
₂ and B ₃ , that is, the corrected scanning position information B ₁ , B ₂ and B ₃ stored in the memory 34, the scanning straight line of the reflected beam light L output from the scanner unit 17 is measured. In other words, connected by a straight line for example the scanning position of the reflected light beam L at the detection point P _1, P ₃ in Figure 2, the detection point P ₂
The scanning linearity of the reflected beam light L is measured by obtaining the geometrical difference from the scanning position of the reflected beam light L in.

According to the laser beam light scanning characteristic measuring device described above, at the position equivalent to the actual surface to be scanned, the laser beam light scanning corresponding to each surface of the rotary polygon mirror in the direction orthogonal to the scanning direction of the laser beam light is performed. The position information is detected, and the dynamic plane tilt angle of the rotary polygon mirror corresponding to the detected scanning position information corresponding to each surface of the detected rotary polygon mirror is measured. At this time, by measuring the dynamic surface tilt angle at each of, for example, three points (scanning start point, scanning middle point, scanning end point) in the scanning direction of the laser beam light, the scanning position information of the laser beam light at the three points is obtained. Is obtained, so 3
The scanning linearity of the laser beam light output from the scanner unit is measured according to the scanning position information of the location.

Thereby, the dynamic plane tilt angle of the rotary polygon mirror at three positions and the scanning linearity of the laser beam light reflected by the rotary polygon mirror and output from the scanner unit are simultaneously calculated.
Moreover, it is possible to perform automatic measurement with high accuracy and in a short time, and in a form that matches the actual product used. In addition, the measuring device itself does not become so large as compared with the conventional one, and can be configured compactly.

Further, by moving the detection unit for detecting the scanning position information in the scanning direction of the laser beam light, for example, the scanning position information at each of the three positions is detected, so that the single detection unit can detect the scanning position information at the three positions. Can be detected. Therefore, the structure can be made more compact and the cost can be reduced.

Furthermore, the mechanical displacement amount (positional error information) in the direction orthogonal to the scanning direction of the laser beam light caused by the movement of the detection unit is measured in advance at each of three detection points, and at the time of actual measurement, The scanning position information detected at the detection point is corrected using the position error information.

This makes it possible to correct the amount of mechanical misalignment caused by movement of the detector, and eliminates the need for positional accuracy when attaching the scanner unit and detector to a jig. It becomes possible to measure with.

It should be noted that in the above-described embodiment, 3 in the scanning direction of the laser beam is used.
The dynamic plane tilt angle was measured at each position, but it is not always necessary to measure at three positions.
You only have to do it in places. In that case, the scanning linearity of the laser beam light is measured by first detecting the scanning position information of the laser beam light at each of the three detection points, and then the scanning position information of the three positions detected above is detected. The dynamic plane tilt angle of the rotary polygon mirror may be measured based on one piece of scanning position information.

[Effects of the Invention] As described above, according to the present invention, the dynamic plane tilt angle of the rotary polygon mirror and the laser beam light that is reflected by the rotary polygon mirror and linearly scans the surface to be scanned. Laser beam light scanning characteristic measuring device that can measure linearity automatically with high accuracy in a short time and in a form that matches the actual product used, and the measuring device itself does not become so large. Can be provided.

[Brief description of drawings]

The drawings are for explaining one embodiment of the present invention. FIG. 1 is a general configuration diagram, FIGS. 2 and 3 are diagrams for explaining the operation, and FIG. It is a figure which shows a mode that a different position is scanned according to the dynamic surface tilt angle of a rotary polygon mirror. 11 ... Scanning motor, 12 ... Rotating polygon mirror, 13 ... Laser oscillator, 17 ... Scanner unit, 20 ... Light receiving part, 20 ₁ ,
20 ₂ …… Light receiving element, 21 …… Shading section, 22 …… Stepping motor, 24 …… Detection section, 27 …… Stepping motor, 30
… Microprocessor, 31… memory.

Claims (4)

[Claims] 1. A method for measuring a scanning characteristic of a laser beam light which linearly scans a surface to be scanned, the method comprising: measuring at least three positions in a scanning direction of the laser beam light at a position equivalent to the surface to be scanned. Detection means for respectively detecting scanning position information of the laser beam light in the scanning direction and orthogonal direction, and computing means for measuring the scanning linearity of the laser beam light according to each scanning position information detected by the detection means. An apparatus for measuring scanning characteristics of laser beam light, comprising: 2. A method for measuring a scanning characteristic of a laser beam light that linearly scans a surface to be scanned, wherein the laser beam is in a direction orthogonal to a scanning direction of the laser beam light at a position equivalent to the surface to be scanned. Detection means for detecting scanning position information of the light beam, movement control means for moving the detection means in the scanning direction of the laser beam light, and movement of the detection means by the movement control means A laser beam light scanning characteristic measuring device for measuring the scanning linearity of the laser beam light according to each scanning position information in at least three positions in the scanning direction of the laser beam light. . 3. A laser beam light for linearly scanning a surface to be scanned, wherein the scanning characteristic of the laser beam light is measured at a position equivalent to the surface to be scanned. Detecting means for detecting the scanning position information of the light beam, movement control means for moving the detecting means in the scanning direction of the laser beam light, and position error in the movement control means in the direction orthogonal to the scanning direction of the laser beam light. A means for obtaining information in advance, and each scanning position information at least at three points in the scanning direction of the laser beam light obtained from the detecting means by the movement of the detecting means by the movement controlling means, using the position error information. Correcting means for respectively correcting and measuring the scanning linearity of the laser beam light according to each scanning position information corrected by this correcting means Laser beam scanning characteristic measuring apparatus characterized by comprising a calculating means that. 4. A method for measuring a scanning characteristic of a laser beam light which is reflected by a rotary polygon mirror and linearly scans a surface to be scanned, wherein the laser beam light is scanned at a position equivalent to the surface to be scanned. First detecting means for respectively detecting scanning position information of the laser beam light corresponding to each surface of the rotary polygon mirror in a direction orthogonal to the scanning direction at at least one position in the direction, and a position equivalent to the surface to be scanned. In the scanning direction of the laser beam light, second detection means for respectively detecting the scanning position information of the laser beam light in the direction orthogonal to the scanning direction in at least three locations, and the first detection means. The dynamic plane tilt angle of the rotary polygon mirror is measured according to each scanning position information, and the above-mentioned according to each scanning position information detected by the second detecting means. Laser beam scanning characteristic measuring apparatus characterized by comprising a calculating means for measuring a scanning linearity of Zabimu light.