JPH03282228A - Beam-diameter measuring apparatus - Google Patents

Abstract

PURPOSE:To make it possible to measure the diameter of a beam accurately by moving a beam across a knife edge member having a light screening part with a light deflecting part at a constant speed, and detecting the change in amount of transmitted at this time. CONSTITUTION:An autofocusing beam 4 is focused and condensed on the surface of a knife edge member 5 by driving a lens 3. The deflecting amount A of a beam 1 of a light deflecting part 2 is adjusted so that the beam crosses an edge part 8 at a constant speed. When the focused and condensed light crosses the edge part under this state, a part of the beam is screened with a screening part 7. The other part is transmitted through a transparent part 6. Thus the intensity of the beam is changed. An optical sensor 9 receives the change in intensity of the beam, and photoelectric conversion is performed. Thus a transmitted light-amount signal (a) is obtained. The signal is analyzed by a well known method, and the diameter of the beam is computed. Therefore, the amount of the reflected light of the beam is not fluctuated, and the stable focus gain is obtained. In this way, the diameter of the beam can be measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a beam diameter measuring device, and particularly to a beam diameter measuring device for measuring the diameter of an exposure beam of an optical disk master exposure device.

[Conventional technology]

A conventional beam diameter measuring device includes a knife member having a knife-shaped light blocking area formed on a flat transparent substrate, a moving means for the knife member in which the knife member vertically crosses the beam at a constant speed, It was comprised of an optical sensor section that receives the beam transmitted through the knife member and photoelectrically converts it.

Next, a conventional example will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a conventional example.

The beam diameter measuring device shown in FIG. 2 uses a known autofocus means using an autofocus beam 4.
The lens 3 is driven to cause the beam l focused on the surface of the knife member 5 to be moved across the knife part 8 at a constant speed in a moving direction B perpendicular to the optical axis of the beam l by a moving means lO.

In this state, when the knife section 8 crosses the beam 1, a part of the beam 1 is blocked by the light shielding section 7, and the intensity of the beam 1 transmitted through the transparent section 6 increases as the light shielding section 7 blocks the beam 1. Change.

This intensity change is received by the optical sensor section 9, and the transmitted light amount signal a obtained by photoelectric conversion is analyzed by a known method to calculate the beam diameter of the beam 1.

[Problem to be solved by the invention]

However, the above-mentioned conventional beam diameter measuring device uses a knife member having a light blocking area formed by vapor deposition of a metal thin film on a part of a transparent substrate, and the reflectance is measured on both sides of the knife part. When the knife part crosses the beam, the reflected light amount of the autofocus beam changes greatly, the focus gain becomes unstable, the beam cannot be focused on the surface of the knife part, and the beam is not focused at the focal plane. The drawback was that the beam diameter could not be measured accurately.

[Means to solve the problem]

The beam diameter measuring device of the present invention includes: a knife member having a light blocking area formed in a knife shape on a flat transparent substrate; and a light deflection unit that moves a beam incident position on the knife member at a constant speed. , and an optical sensor section that receives the beam transmitted through the knife member and photoelectrically converts it.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

The beam diameter measuring device shown in FIG.
to focus and condense the light.

The light deflection section 2 adjusts the amount of deflection A of the beam 1 so that the focal point of the beam on the surface of the knife member 5 crosses the knife section 8 at a constant speed.

In this state, the focal point of the lens is at the knife part 8.
When crossing the beam 1, a part of the beam l is blocked by the light shielding part 7, and the intensity of the beam l transmitted through the transparent part 6 changes as the light shielding part γ blocks the beam 1. This intensity change is received by the optical sensor section 9 and photoelectrically converted to obtain a transmitted light amount signal a, which is analyzed by a known method to calculate the beam diameter.

Here, as the optical deflection unit 2, an AO deflector (for example, HO
This can be achieved by using YA Corporation's A-200) or EO deflector.

〔Effect of the invention〕

The beam diameter measuring device of the present invention moves a knife member having a light blocking area as a part and calculates the beam diameter from the change in the amount of light transmitted through the knife member when the knife crosses the beam. is fixed, the amount of deflection of the beam is adjusted by an optical deflector, and the beam diameter is calculated from the change in the amount of light transmitted through the knife member when the focal point of the beam focused on the surface of the knife member crosses the knife member. As a result, the reflected light amount of the autofocus beam does not fluctuate, a stable focus gain is obtained, and the beam can always be focused on the surface of the knife member, making it possible to accurately measure the beam diameter at the focal plane. be.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of the conventional technology. l...beam, 2...light deflection section, 3...
... Lens, 4 ... Autofocus beam, 5 ... Knifetsu member, 6 ...
・Transparent part, 7... Light blocking part, 8... Knife part, 9... Optical sensor LIO... Moving means, A... Deflection amount, B ...Moving direction, a...
...Transmitted light amount signal.

Claims (1)

[Claims] a knife edge member having a light blocking area formed in a knife edge shape on a flat transparent substrate; a light deflector that moves a beam incident position on the knife edge member at a constant speed; and the knife edge member. A beam diameter measuring device comprising: an optical sensor section that receives a transmitted beam and performs photoelectric conversion.