JPH0682083B2 - Polygon scanner surface tilt measurement device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon scanner surface inclination measuring device for measuring surface inclination of a polygon scanner using a light beam.

(Conventional Technology) FIG. 3 shows an example of conventional technology.

A beam splitter 2 is provided so as to split a substantially parallel light beam L1 emitted from a light source 1 into two, and a light beam L3 transmitted through this beam splitter 2 is a polygon scanner 3
The light beam reflected by is incident on the beam splitter 6 via the fθ lens 4b, and the transmitted light beam L3a is split by the first prism mirror 8b, and the first and second sensors 9e, 9
The light beam L3b of the other side is split by the second prism mirror 7 and is made incident on the third and fourth sensors 9c and 9d. At the moment when the powers of the light beams at the sensors 9c and 9d become equal. The sensors 9e and 9f detect the vertical light beam tilt. Further, the light beam L2 reflected by the beam splitter 2 is split by the third prism mirror 8a through the second fθ lens 4a and is incident on the fifth and sixth sensors 9a and 9b, and the vertical light beam Detect the tilt. Sensor first
The tilt of the light beam in the vertical direction detected by the sensors 9a and 9b is subtracted from the tilt of the light beam in the vertical direction detected by the sensors 9e and 9f to measure the surface tilt of the polygon scanner 3.

(Problem to be Solved by the Invention) In the conventional polygon scanner surface tilt measuring device, the power of the light beam fluctuates due to air fluctuations in a portion where the optical path through which the light beam passes through the air is long, and the measured value It appears as noise as shown in Fig. 4. Since the noise due to the fluctuation of air is as large as 0.7 ″, it is impossible to perform the trouble measurement with higher accuracy.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and will be described with reference to FIGS. 1 and 2 corresponding to the embodiments. The beam splitter 2 is provided so as to divide the substantially parallel light beam L1 into two, and the light beam L3 transmitted through this beam splitter 2 is reflected by the polygon scanner 3 and is incident on the beam splitter 6 via the fθ lens 4b. The transmitted light beam L3a is split by the first prism mirror 8b, and the first and second sensors
9e, 9f, and the other light beam L3b is split by the second prism mirror 7 and is made incident on the third and fourth sensors 9c, 9d to detect the respective light beam positions, and further the beam splitter 2 The light beam L2 reflected by the second fθ lens 4a
In the polygon scanner surface tilt measuring device, which is divided by the third prism mirror 8a via the beam splitter, is incident on the fifth and sixth sensors 9a, 9b, and detects the light beam position, the first fθ lens 4b and The optical axis between the first beam splitter 6 and the second fθ lens 4a and the third prism mirror 8a
Wind-shielding plastic or metal pipes 5a and 5b are respectively arranged so that the optical axis between the pipes 5a and 5b penetrates.

(Operation) According to the present invention, since the pipe made of plastic or metal is provided so that the light beam passes through the optical path of the measuring device, the air outside the pipe and the air through which the light beam passes are blocked, Noise due to air fluctuations is reduced.

(Embodiment) FIG. 1 is a block diagram of an embodiment according to the present invention, in which 1 is a light source, 2 is a beam splitter, 3 is a polygon scanner,
4a and 4b are fθ lenses, 5a and 5b are plastic pipes,
6 is a beam splitter, 7, 8a and 8b are prism mirrors, 9a,
9b, 9c, 9d, 9e and 9f are sensors. The surface tilt measuring device of the polygon scanner according to the present invention is the same as the conventional surface tilt measuring device described with reference to FIG.
Pipes 5a and 5b are provided in the optical path between 8a and the optical path between the fθ lens 4b and the beam splitter 6, respectively.

FIG. 2 shows the noise measured by the apparatus of this embodiment.
As a result of this noise measurement, in the conventional polygon scanner surface tilt measuring apparatus shown in FIG. 4, a maximum of 0.7 ″ noise is generated, whereas in the polygon scanner surface tilt measuring apparatus of the present embodiment, a maximum of 0.26 ″ is generated. It becomes noise and the pipes 5a, 5b
The noise due to the fluctuation of air is reduced by providing the.

The pipes 5a and 5b used in this example have an outer diameter of 18.1 mm and an inner diameter.
It is a 13.5 mm plastic pipe.

If the internal shapes of the pipes 5a and 5b are wavy when viewed in the longitudinal direction, it is possible to prevent irregular reflection of the light beam scanned by the polygon scanner 3 in the pipes 5a and 5b.

As described above in detail, according to the present invention, noise is 0.7 ″ in the conventional polygon scanner measuring device.
On the other hand, by providing a plastic or metal pipe in the part with a long optical path in the measuring device, it was possible to reduce the noise due to air fluctuations to 0.26 ″. It has the advantage that more accurate measurement of is possible.

[Brief description of drawings]

1 and 2 are a block diagram and a noise measurement value of an embodiment according to the present invention, and FIGS. 3 and 4 are a block diagram and a noise measurement value of a conventional example. 1 …… Light source, 2,6 …… Beam splitter 3 …… Polygon scanner 4a, 4b …… fθ lens 5a, 5b …… Plastic pipe 7,8a, 8b …… Prism mirror 9a, 9b, 9c, 9d, 9e , 9f …… Sensor L1, L2, L3, L3a, L3b …… Light beam

Claims (1)

[Claims] 1. A substantially parallel light beam emitted from a light source 1.
The beam splitter 2 is installed to divide L1 into two,
The light beam L3 that has passed through the beam splitter 2 is reflected by the polygon scanner 3 and is reflected by the fθ lens 4b.
Light beam that is incident on the beam splitter 6 via
L3a is divided by the first prism mirror 8b,
The other light beam L3b is split by the second prism mirror 7, and the third and fourth sensors 9c and 9f
The light beam L2 reflected by the beam splitter 2 is incident on the second fθ.
In the polygon scanner surface tilt measuring device which is divided by the third prism mirror 8a through the lens 4a and is incident on the fifth and sixth sensors 9a and 9b to detect the light beam position, the first fθ lens A windbreak pipe so that the optical axis between 4b and the first beam splitter 6 and the optical axis between the second fθ lens 4a and the third prism mirror 8a penetrate.
A polygon scanner surface tilt measuring device characterized by arranging 5a and 5b respectively.