JPH03220438A - Measuring apparatus of projection of surface of polygon scanner - Google Patents

Abstract

PURPOSE:To reduce noises resulting from the fluctuation of the air by so providing wind protecting pipes as to allow optical axes between a polygon scanner and a first prism, between the polygon scanner and a beam splitter and between the polygon scanner and a first light source to pass therethrough, respectively. CONSTITUTION:In the title measuring apparatus, plastic or metallic wind protect ing pipes 2c-2a are provided in a manner to pass through each optical path between a polygon scanner 3 and a prism mirror 5, between the polygon scanner 3 and a beam splitter 4 and between the polygon scanner 3 and a light source 1a, respectively. Accordingly, the air outside the pipes 2a-2c is shut from the air where the light beams L1-L3 pass, whereby the noises due to the fluctuation of the air can be reduced, ensuring highly accurate measurement. If the pipes 2a-2c with undulatory inner shape in the longitudinal direction are used, the irregular reflection of the light beam scanned by the polygon scanner 3 within the pipes 2b, 2c can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a polygon scanner surface entry/exit measuring device that measures the surface entrance/exit of a polygon scanner using a light beam.

(Conventional technology) FIG. 2 shows an example of a conventional technique.

A substantially parallel light beam L1 emitted from a light source 1a is reflected by a polygon scanner 3, and a light beam L3 is incident on a first prism mirror 5a, split, and made incident on first and second sensors 6c and 6d. Further, after the light beam L12 emitted from the light source 1b is reflected by the polygon scanner 3 and is reflected by the beam splitter 4,
It is divided by the prism mirror 5b and enters the third and fourth sensors 6a and 6b, and at the moment when the output powers of the sensors 6a and 6b become equal, the first and second sensors 6c,
6d is measured, and the amount of horizontal positional deviation of the light beam L3 is detected.

The amount of entry and exit from the surface of the polygon scanner 3 is detected from this amount of positional deviation.

(Problems to be Solved by the Invention) In the conventional polygon scanner surface entry/exit measuring device, the power of the light beam fluctuates due to fluctuations in the air in the portion where the light beam passes through the air with a long optical path length, causing noise and noise in the measured values. It appears. Because of the large noise caused by this air fluctuation, it was not possible to perform surface entry and exit measurements with higher accuracy.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and when explained with reference to FIG. 1 corresponding to an embodiment, the present invention has a light source 1a
A substantially parallel light beam L1 emitted from the polygon scanner 3 is reflected by the polygon scanner 3, and the light beam L3 is incident on the first prism mirror 5a and split, and is then split into the first and second sensors 6c.
, 6d, and further emitted from the light source 1.
After the light beam reflected by the polygon scanner 3 is reflected by the beam splitter 4, it is split by the prism mirror 5b and sent to the third and fourth sensors 6a and 6.
Polygon scanner surface entry/exit measurement is performed by measuring the output powers of the first and second sensors 6c and 6d at the moment when the output powers of the sensors 6a and 6b become equal, and detecting the position of the light beam L3. In the apparatus, the optical axis between the polygon scanner 3 and the first prism mirror 5a, the optical axis between the polygon mirror 3 and the beam splitter 4, and the optical axis between the polygon mirror 3 and the light source 1a pass through. Windproof plastic or metal pipes 2a, 2b, and 2C are respectively arranged so as to prevent wind.

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

(Embodiment) FIG. 1 is a polygon scanner surface entry/exit measuring device showing a configuration diagram of an embodiment of the present invention.

1b is a light source, 2a, 2b, 2c are plastic or metal pipes, and 3 is a polygon scanner.

4 is a beam splitter, 5a and 5b are prism mirrors,
6a, 6b, 6C, and 6d indicate sensors. light source 1
The light beam generated from a is reflected by a polygon scanner 3 through a pipe 2a, and after passing through a pipe 2C, it is split by a prism mirror 5a and sent to sensors 6c, 6.
incident on d.

The light beam generated from the light source 1b passes through the beam splitter 4, passes through the pipe 2b, is reflected by the polygon scanner 3, passes through the pipe 2C again, is bent downward by the beam splitter 4, and is reflected by the prism mirror 5b. Six sensors 6a are divided and input to sensors 6a and 6b.

6b serves as a trigger and is a sensor 6a.

At the moment when the powers measured by 6b become equal, sensor 6
The power of the light beam incident on points c and 6d is measured, and the horizontal positional shift of the light beam is calculated based on the ratio. Since this positional deviation is caused by the movement of the polygon scanner 3 into and out of the plane, the amount of inflow and outflow from the plane can be detected from the amount of positional deviation.

By providing the pipes 2a, 2b, and '2c, noise in the measured values due to air fluctuations is reduced.

Note that if the pipes 2a, 2b, and 2C have internal shapes that are wavy when viewed in the longitudinal direction, the pipe 2a is scanned by the light beam by the polygon scanner 3.

Diffuse reflection within 2b and 2C can be prevented.

(Effects of the Invention) As described above in detail, according to the present invention, noise caused by air fluctuations can be reduced by providing a plastic or metal pipe in the long optical path length part of the measuring device. This has the advantage that more accurate measurement of entry and exit from the polygon scanner surface is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1... Light sources 2a, 2b, 2c...Plastic pipe 3/Polygon scanner 4...Beam splitter 6a, 6b, 6c, 6d = sensor LL, L2. L3...Light beam

Claims (1)

[Claims] The substantially parallel light beam L1 emitted from the light source 1a is reflected by the polygon scanner 3, and the light beam L3 is incident on the first prism mirror 5a, split, and made incident on the first and second sensors 6c and 6d, and further The light beam L2 emitted from the light source 1b is reflected by the polygon scanner 3, and after being reflected by the beam splitter 4, the light beam L2 is split by the prism mirror 5b and enters the third and fourth sensors 6a and 6b. , 6b become equal, the first and second sensors 6c, 6d
In a polygon scanner surface entry/exit measuring device that measures the ratio of the output powers of and detects the position of the light beam L3,
The optical axis between the polygon scanner 3 and the first prism mirror 5a, the optical axis between the polygon mirror 3 and the beam splitter 4, and the optical axis between the polygon mirror 3 and the light source 1a pass through. Windproof pipes 2a, 2b, 2c
A polygon scanner face entrance/exit measuring device characterized by having the following.