JPH03129307A - Optical axis adjusting method for infrared optical system - Google Patents

Abstract

PURPOSE:To easily adjust the optical axis of the infrared optical system by providing a circumferential line which centers on the center of a lens on the surface of the lens. CONSTITUTION:When the designed permissible eccentricity quantity of the optical axis L is denoted as W, the circumferential line 5 which has width (d) satisfying 0<d<W and centers on the lens center is provided on the surface of the lens 1. After the lens 1 is fixed temporarily, a lens barrel 2 is rotated on a center axis of rotation while the line 5 is observed through a microscope 6 from the left side. The line moves up and down in an observed image by more than its width unless the lens 1 is aligned with the center axis of rotation of the lens barrel 2, so the lens 1 is moved slightly on a vertical plane of the optical axis L with an adjusting screw 3 to move up and down the observed image by a distance of less than the width (d) of the line 5, thereby aligning the optical axis L of the lens 1 with the center axis of rotation of the lens barrel 2. Consequently, the optical axis of the infrared optical system is easily adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a method for adjusting the optical axis of an infrared optical system consisting of a combination of a lens barrel and a lens.

[Conventional technology]

Generally, in an optical system, a lens and a lens barrel are bonded together by mechanical tightening or adhesive. At this time.

Considering the difference in thermal expansion coefficient between the lens and the lens barrel, a gap must be provided between the lens and the inner periphery of the lens barrel.

Therefore, when attaching the lens to the lens barrel, the position of the lens is determined by the positioning surface in the direction of the optical axis, but it has some degree of freedom on a plane perpendicular to the optical axis.

However, in general, in order to maintain the performance of an optical system, the central axis of rotation of the lens must accurately coincide with the central axis of rotation of the lens barrel. Conventionally, there is a configuration shown in FIG. 4 to meet such demands. In the figure (1) is the lens.

(2) is the lens barrel, (3) is the adjustment screw, (4) is the adhesive,
(7) is a collimator, (8) is an adjustment optical system, (9) is an image plane, and α0) is a focal plate. In the figure, collimator (7)
The light emitted from the lens aligns the optical axis with the rotation center axis of the lens barrel. In other words, the TA that passes through the optical system for which you want to align the optical axis.
The light passes through a light adjusting optical system 8) and reaches the image plane. Optical axis alignment is performed for each lens, but unless all lenses are attached to the optical system, the collimator light will not be focused on the image plane. Therefore, the focal length of the adjustment optical system is adjusted by passing the illumination optical system (8) through the collimator light, so that the collimator light is focused on the image plane. At this time, if a measurement chart in which a chart such as a cross is drawn on a transparent plate is used as the focus plate α, its image will be formed on the image plane (9).

In this state, when the m cylinder (2) is rotated around its rotation center axis, there will be no change in the image if the optical axes are aligned correctly, but if the optical axes are not aligned, the image will be mirror fm (21). As the image rotates, movement, rotation, change in size, blurring, etc. will occur.Adjust the position of the lens using the adjustment screw (3) to eliminate this image change, and when the image no longer changes, In other words, when the optical axes are aligned.

Fix the lenses (1) and m-tube (2) with adhesive (4) or the like.

Performing this sequentially for all lenses is the work of aligning the optical axis of the optical system.

[Problem to be solved by the invention]

As mentioned above, the conventional method aligns the optical axis by transmitting visible light and forming an image, and then measuring the image. Therefore, it cannot be applied to optical systems in the infrared layer where direct measurement cannot be performed. could not.

This invention was made to solve the above-mentioned problems, and its purpose is to easily align the optical axis of a lens with the central axis of rotation of a lens barrel in an infrared optical system that does not transmit visible light. It is something.

[Means to solve the problem]

A method for adjusting an optical axis of an infrared optical system according to the present invention.

When W is the optical axis and the allowable eccentricity in the design, the lens has a circumferential piece of cotton on the lens surface with a width d centered on the lens center that satisfies the relationship 0<d<W. .

[For production]

In this invention, optical axis alignment can be easily performed by aligning the line of the lens with the rotation center axis of the lens barrel.

〔Example〕

FIG. 1 is a cross-sectional view of an embodiment of the method for adjusting the optical axis of an infrared optical system according to the present invention. The lens (1) is a tel tube (2)
After being adjusted with the adjustment screw (3), it is fixed with adhesive (4). On the lens surface, there is a circumferential line (5) centered on the lens center with a width d that satisfies the relationship 0<d<W, where W is the optical axis and the eccentricity allowed in the design. . This line is a groove, protrusion, etc. line!
! It's fine as long as it's something you can recognize. Fig. 2 shows an example of a configuration for aligning the optical axis in the embodiment shown in Fig. 1. In Fig. 2, stm
The mirror (6) observes a circumferential line. In the example in Figure 1! @ (Since 51 is attached to the left side of all lenses in the figure, it is necessary to start attaching the lenses from the right side.

After temporarily fixing the lens (1).

From the left side of the lens, use the a sign mirror (6)! Observe (5).In this state, rotate the lens barrel (2) around the rotation center axis.The third rIA is an example of an observed image.If the rotation center axes of the lens and lens barrel do not match correctly, aWle＞(
6) of the protrusion [! During image measurement, the line moves up and down more than its own width, as shown in Figure 3(a). Now, by slightly moving the lens on a plane perpendicular to the optical axis using the adjustment screw (3), the observed image will be as shown in Figure 3 (b), that is, the line will move up and down the distance within your breath. do. In this state, if the width d of the line is allowed by the design and the eccentricity is W, if it satisfies the relationship 0<d<W, then the optical axis of this lens is aligned within the range of the eccentricity allowed by the design. There will be. At this point, lens (1) and #! Fix the cylinder (2) with adhesive (4). This work is performed sequentially, and when the work is completed for all lenses, the optical axis alignment work is completed.

[Effects of the Invention] As described above, according to the present invention, by providing a circumferential line centered on the lens center on the surface of the lens, it is possible to easily align the optical axis even in an infrared optical system. This has the effect of

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the optical axis adjustment method of an infrared optical system according to the present invention, FIG. 2 is a diagram showing an example of optical axis adjustment of the infrared optical system, and FIG. 3 is a head Wi mirror. FIG. 4 is a diagram showing an example of an optical axis alignment of a conventional optical system. In the figure, (1) is the lens, (2) is the lens barrel, (3) is the adjustment screw, (4) is the adhesive, (5) is the circumferential line, (6) is the
) is a microscope. (7) is the collimator, (8) the optical system, (9) l
Well, the image surface. QOI is a focusing plate. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] In an infrared optical system consisting of a lens and a lens barrel that holds the lens, the central axis of rotation of the lens and the optical axis of the infrared optical system (
Here, when W is the eccentricity (positional deviation) that is allowed by design between the rotation center axis of the lens barrel and the rotation center axis of the lens barrel, the circumference around the lens rotation center has a width d that satisfies the relationship 0<d<W. 1. A method for adjusting an optical axis of an infrared optical system, comprising: providing a line on a lens surface, and aligning the optical axis so that the line provided on the lens surface coincides with the rotation center axis of a lens barrel.