JPH035704A - Optical axis aligning device for cemented lens - Google Patents

Abstract

PURPOSE:To make the focal length of the cement lens constant even if the focal length is different and to form an image of light on an image pickup means by converging light which is transmitted through a concentric grating into invariably one optical-axis beam through the cemented lens. CONSTITUTION:A reference lens 5 among lenses to be cemented is exactly fixed with a chuck 6 and an adjusting lens 7 is placed across an adhesive; and the optical axis beam of the cemented lens of those two lenses 5 and 7 is detected by a camera 10 and an image processor 11 operates the gravity center position (XG,YG) of the image. The adjusting lens 7 is moved finely by a micrometer head 8A and adjusted in its position so that the gravity center position (XG,YG) is aligned with the gravity center position beam (XGO,YGO) of the image based upon the optical axis beam of a master lens. Consequently, the optical axis of even a cemented lens which differ in focal length can gener ally and easily be aligned.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to optical axis alignment and attachment of a cemented lens, and more particularly, to a lens optical axis alignment device when making a cemented lens by bonding a plurality of lenses. It is something.

[Prior Art] When a plurality of lenses are bonded together to create one cemented lens, it is necessary to align the optical axes of each lens. Conventionally, in the case of such optical axis alignment work, Mainly visual inspection. That is, first, a plurality of lenses are pasted together with adhesive, and then a beam of light is made to enter the lens, and the outer diameter of the lens is rotated with the lens attached to a fixing member, in order to suppress the deflection of the beam at that time. I was trying to adjust the lens by moving it accordingly.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, there are individual differences due to visual inspection, and furthermore, it is difficult to maintain a constant optical axis alignment accuracy due to fatigue due to repeated operations.

In addition, since the focal length of each lens to be worked on differs, there is the problem that it takes time and effort to replace and adjust the auxiliary lens to form a light beam image on the camera each time the lens to be worked on changes. Ta.

An object of the present invention is to focus on the above-mentioned conventional problems, and to solve the problems, it is an object of the present invention to provide an optical system for a cemented lens that can perform general and easy optical axis alignment even for cemented lenses with different focal lengths. An object of the present invention is to provide an alignment device.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides means for generating a parallel light beam, a concentric grating that transmits the parallel light beam, and a first of the lenses to be cemented. means for holding the lens with high precision; means capable of minutely displacing the second lens superimposed on the first lens; and detecting an image of light transmitted through the grating, the first lens, and the second lens. and a means for detecting the position of the center of gravity from the image of the light detected by the imaging means. It is characterized in that an image of the light from the generating means is formed.

[Function] According to the present invention, the light transmitted through the concentric grating is always focused into one optical axis beam via the cemented lens.
Even if the focal lengths of the cemented lenses differ, it is possible to always form a constant light image on the imaging means, and optical axis alignment can be performed for general purposes.

[Examples] Examples of the present invention will be described below in detail and specifically based on the drawings.

FIG. 1 shows an embodiment of the invention. Here, 1 is a laser light source, 2 is a collimator using a lens to obtain a parallel beam line, 3 is a concentric grating provided in a direction perpendicular to the beam line, 4 is a half mirror, and 5 is a lens to be joined. 6 is a chuck that holds the reference lens 5 with high precision, 7 is an adjustment lens that is superimposed on the reference lens 5, 8 is a high-precision micrometer for slightly displacing the adjustment lens 7, and 9 is a micrometer. Meter drive motor,
10 is a camera for capturing an image of the optical axis beam from the lens as will be described later, and 11 is an image processing device in which a light image based on the optical axis beam imaged by the camera 1G is manually input as a signal.

FIG. 2 shows the drive system of the adjustment lens 7. The adjustment lens 7 is held against the head 8A of a high-precision micrometer 8 from two directions, and is also held against the head 8A of a high-precision micrometer 8 from the opposite direction by a compression spring 12. is biased towards. Therefore, by slightly moving the two micrometers 8 by appropriate amounts, the adjustment lens 7 can be slightly displaced in any direction within a two-dimensional plane.

Further, the concentric grating 3 shown in FIG. 1 has bright areas and dark areas formed in a concentric pattern, and the pitch thereof is set to, for example, 50 μm. Therefore, in the present invention, optical axis alignment is performed as described below by utilizing the light diffraction phenomenon that occurs when the parallel beam of laser light obtained through the collimator 2 passes through the grating 3. When the parallel light beam 13 passes through the bright part 3A of the grating 3 as shown in FIG. 3, the light rays become discrete due to a diffraction phenomenon.

In this case, the diffracted light having one diffraction angle θ is transmitted through a lens (here, a cemented lens is schematically shown) 14 for each circular bright part 3^ provided concentrically as shown in FIG.
After passing through, the light is focused on one point on the optical axis. Note that similar condensation is performed for other diffracted lights, and thus the optical axis beam 15 appears to be one beam of light that is a continuation of these condensed diffracted lights. However, this phenomenon occurs in the same way no matter how the focal length of the lens changes, and the present invention utilizes this phenomenon to align the optical axis of the cemented lens according to the following procedure.

That is, first, as a preliminary preparation, a master lens bonded together with great precision is prepared, and this is fixed to the chuck 6 shown in FIG. 1. Then, the optical axis beam of this master lens is detected by the camera lO, and the center of gravity position (Xoo, yao) of the image is calculated using the image processing device 11.

Next, the reference lens 5 of the plurality of lenses to be bonded is accurately fixed with the chuck 6, and the adjustment lens 7 is placed on the lens 5 via adhesive.
The optical axis beam of the cemented lens formed by these two lenses 5.7 is detected by the camera lO, and the image processing device 11 calculates the barycenter position (x(1, yc+)) of the image.Then, this barycenter position (xa, ya) is the barycenter position beam (Xao, yao) of the image based on the optical axis beam of the master lens previously determined.
Adjust the position of the adjustment lens 7 by slightly moving it with the micrometer head 8^ so that it matches the .

By performing the above processing, the optical axis of the cemented lens whose position has been adjusted can be made to coincide with the optical axis of the master lens, and the light beams 1 and 1 h can be correctly aligned.

In the embodiment described above, part of the operation for aligning the optical axis was performed manually, but the micrometer head 8
A servo motor is used for feeding A, and a microcomputer is used to calculate the center of gravity position (Xa, Va) determined by the image processing device 11 and the center of gravity position (XGO, yGO) determined by the optical axis beam of the master lens. If the drive amount of the servo motor is calculated in real time based on the comparison, the entire optical axis alignment operation can be performed automatically and consistently.

[Effects of the Invention] As explained above, according to the present invention, light from a light source is focused on a predetermined optical axis regardless of the focal length of the lens to be cemented. In this way, there is no need to change the auxiliary lens each time the ray image of the lens to be cemented is formed on a camera placed at a predetermined distance from the lens, and optical axis alignment can now be performed in a general-purpose manner.

[Brief explanation of the drawing]

Fig. 1 is a block diagram schematically showing an example of an optical axis alignment device for a cemented lens according to the present invention, Fig. 2 is a block diagram of a fine adjustment means for an adjustment lens according to the present invention, and Fig. 3 is a block diagram schematically showing an example of an optical axis alignment device for a cemented lens according to the present invention. FIG. 4 is an explanatory diagram of the diffraction phenomenon of light by the grating. FIG. 4 is an explanatory diagram of the optical axis beam forming operation according to the present invention. 10... Camera, If... Image processing device, 13... Parallel light flux, 15... Optical axis beam. DESCRIPTION OF SYMBOLS 1... Laser light source, 2... Collimator, 3... Grid, 5... Reference lens, 6... Chuck, 7... Adjustment lens, 8... Micrometer, 9... Motor, Figure 1 Figure 2 17-

Claims (1)

[Scope of Claims] 1) means for generating a parallel light beam; a concentric grating that transmits the parallel light beam; and means for holding with high precision a first lens of the lenses to be cemented; means capable of minutely displacing a second lens superimposed on the first lens; an imaging means for detecting an image of light transmitted through the grating, the first lens, and the second lens; and the imaging means means for detecting the position of the center of gravity of the light from an image of the light detected by the image pickup means, regardless of the focal length of the lens to be cemented, the light from the means for generating the parallel light flux to the imaging means An optical axis alignment device for a cemented lens, characterized in that an image is formed.