JPS6116706Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention collimates the laser beam emitted from the semiconductor laser light source by a first lens system, shapes it into an elliptical beam by a second lens system, and collimates the laser beam emitted from a semiconductor laser light source.
This invention relates to an improvement in a light beam control device that forms an image through a lens system.

This type of light beam control device is widely used when forming an electrostatic latent image on a recording medium, but in this case, a rotating mirror is actually provided between the second and third lens systems. It is designed to scan the recording medium.

In such optical beam control devices, in order to create a constant circular beam, a complicated third lens system has conventionally been used, and conventional semiconductor lasers have been used to control the optical output of the semiconductor laser light source. Since the back side output of the light source is used, the package of the semiconductor laser light source has become complicated.

This invention is intended to solve the above-mentioned drawbacks.
The object is to provide a light beam control device with a simple structure.

Embodiments of the invention will now be described with reference to the drawings.

Fig. 1 is a perspective view showing the optical output distribution of a laser beam emitted from a laser diode, and Fig. 2 is a perspective view showing an embodiment of the optical beam control device according to the present invention. 2 is a collimator lens (first lens),
3 is a shaping lens (second lens), 4, 4 is a pair of mirrors, 5 is an imaging lens (third lens), 6
is a photodetector, and 7 is an output control circuit. The mirrors 4, 4 are provided at a constant angle with the optical axis and symmetrically with respect to the optical axis with a predetermined gap S therebetween.

The optical output distribution of the laser beam emitted from the laser diode 1 has an elliptical cross-sectional shape as shown in FIG. The beam is shaped into an elliptical beam with the shape shown in . Since the gap S between the mirrors 4 and 4 mentioned above is selected to be equal to the diameter of this elliptical beam in the minor axis direction, both ends of the elliptical beam in the major axis direction, that is, the portion shown with diagonal lines in FIG. 4 toward the photodetector 6, and only the central portion of the nearly circular shape passes between the mirrors 4 and 4 and is reflected by the imaging lens 5.
The image is formed into a roughly circular shape. The light reflected by the mirrors 4, 4 passes through a lens 8 and forms an image on a photodetector 6. The photodetector 6 detects this and sends a signal,
This output is input to the laser diode 1 via a control circuit 7 that stabilizes the laser light output of the laser diode 1.

As described above, according to the present invention, the laser beam that has been shaped into an elliptical beam by the second lens system is blocked by mirrors at both ends in the long axis direction of the ellipse, and the approximately circular portion at the center is blocked by mirrors. Since the image is formed by the third lens system through the gap between the mirrors, it is possible to obtain a substantially circular image without using a particularly complicated lens system as the third lens system. It is possible to simplify the lens system. In addition, the parts of the elliptical beam other than the central part are reflected by a mirror and incident on a photodetector, and the output of the photodetector that detects this light is used to control the optical output of the semiconductor laser light source. Therefore, it is not necessary to use the backside output of the semiconductor laser light source, and the semiconductor laser package can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the optical output distribution of a laser diode, Fig. 2 is a perspective view showing an embodiment of the light beam control device according to the present invention, and Fig. 3 is an elliptical beam shaped by the second lens system. This is an explanatory diagram of the part reflected by the mirror and the part passing through the gap between the mirrors. In the figure, 1... laser diode (semiconductor laser light source), 2... collimator lens (first lens system), 3... ... Shaping lens (second lens system), 4 ... Mirror, 5 ... Imaging lens (third lens system), 6 ... Photodetector, 7 ... Control circuit,
8...It is a lens.

Claims (1)

[Scope of utility model registration request] In the light beam control device, the laser beam emitted from the semiconductor laser light source is collimated by a first lens system, shaped into an elliptical beam by a second lens system, and imaged through a third lens system, wherein the second lens system collimates the laser beam. , a pair of mirrors are provided between the third lens system at a predetermined angle with the optical axis to block the light passing through both ends of the elliptical beam in the long axis direction so as to form a substantially circular beam; 1. A light beam control device comprising: a photodetector for detecting laser light reflected by the semiconductor laser; and a control circuit for stabilizing the output of the semiconductor laser light source using the output of the photodetector.