JPS59214730A - Lens-decentering measuring device - Google Patents

Abstract

PURPOSE:To obtain a bright index image with high contrast, by utilizing a polarizing prism, thereby eliminating substantially almost all the decrease in amount of light from an index, and eliminating almost all the flares. CONSTITUTION:A back surface mirror 15 is constituted as a 1/4 wavelength plate, whose one surface is a reflecting surface. Therefore, linearly polarized light, which is inputted to the back surface mirror 15, is reflected as linearly polarized light, which is crossed at a right angle with said linearly polarized light. The light is reflected by a polarizing prism 14 after passing through a total reflection prism 6 and directed to the center of a sphere of a decentering measuring surface of a lens to be checked 9 through an image forming lens 8. The decentering measuring surface of the lens to be checked 9 is located at a position of auto-collimation. Therefore, the linearly polarized light, which is reflected by the decentering measuring surface goes in the reverse direction. The light is reflected by the polarization prism 14, reflected by the back surface mirror 15 through the total reflection prism 6, and then inputted to the polarization prism 14 through the total reflection prism 6 again. Since the polarizing direction is rotated by 90 degrees, the light is transmitted. The linearly polarized light transmitted through the polarization prism 14 is reflected by an index plate 13. Since the light passes the 1/4 wavelength plate twice, the polarizing direction is rotated by 90 degrees.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to eccentricity 1ri of each lens surface when the camera lens, microscope objective lens, etc. are assembled in a lens frame and twisted.
-f::Relating to a lenticular heart measuring device for measuring.

As this lens eccentricity measuring device, for example, the stationary lens decentering measuring device shown in FIG. 1 by Nyusof (5c11uch) of Soais, East Germany is known. In Fig. 1, 1 is a light source, 2 is a lens, 3 is an index, 4.5 (is a semi-transparent mirror, 6 is a total reflection prism, 7 is a reflecting mirror, 8 is an imaging lens,
9 is a lens to be tested, and 1o is an eyepiece lens. The light from the index 3 illuminated through the light source 1 and the lens 2 is reflected by the semi-transparent mirrors 4 and 5 and enters the total reflection prism 6. After being totally reflected within the total reflection prism 6, the light enters the vaginal total reflection prism. 6
The light emitted from the
The beam enters the beam, passes through the semi-transparent mirror 5, and passes through the imaging lens 8 toward the spherical center of the eccentricity measurement surface of the lens 9 to be tested.

The light reflected from the polarized IL/measurement surface travels backwards and passes through the second half mirror 4, which is reflected by the semi-transparent mirror 5, and reaches a position P that is conjugate with the index 3.
image is formed. The above relationship is obtained when the eccentricity measurement surface of the test lens 9 is at the autocollimation position and the amount of eccentricity of the eccentricity measurement surface is zero, and the autocollimation for each eccentricity measurement surface of the test lens 9 is The position of can be adjusted by moving the total reflection prism 6 in the direction of the arrow.

If the eccentricity measurement surface is eccentric, the image of the index at position P is shifted in the direction perpendicular to the optical axis based on the amount of eccentricity of the eccentricity measurement surface, so the amount of eccentricity of the eccentricity measurement surface can be determined from this amount of shift. be measured. However, in this lens eccentricity measurement device, the light passes through the semi-transparent mirror many times, resulting in a large drop in light intensity, and in reality, it becomes 1/64 of the initial light intensity.At the same time, the light lost in the semi-transparent mirror is extremely large. Since this is a source of large flare, the image of the index obtained near the position P has very poor contrast, which is a practical problem.

In view of the following two points, the present invention aims to provide a lens eccentricity measuring instrument that minimizes the decrease in the amount of light and therefore causes almost no flare harmful to measurements. a polarizing beam splitter that transmits (reflects) the light from the index, and a polarizing beam splitter that transmits (reflects) the light from the index; The 1/4 wavelength plate and reflection surface perpendicular to the optical path are arranged, and it is reflected by the reflection surface and travels backwards. After that, it is reflected (transmitted by a small amount) by the i, t+, and beam splitter. A projection optical system that guides the light to the eccentricity measurement surface of the test lens, and a projection optical system that reflects the light on the eccentricity measurement surface, passes through the projection optical system, is reflected by the beam splitter (passes through the beam), and is further reflected by the quarter-wave plate 1. So, I/4 wave J again
(Lens eccentricity characterized by including an optical system that guides the light transmitted (or reflected) by the beam smitter through a plate out of the optical path...]
Purpose of writing is descriptive.

The present invention will be explained below with reference to the embodiment shown in the drawings. In FIG. 2, the same 44 components (
(The same reference numerals apply to theory 1. If Ij is omitted, 11 is a polarizing plate, 12 is a quarter-wave plate, and 13 is a reflection plate whose surface on the side of light source 1 has an index I3a due to a slit-shaped aperture. 14 is a polarizing prism (or polarizing beam splitter); 15 is a back surface consisting of a 1/4 wavelength plate whose left side in the figure is configured as a reflective surface; The mirror 16 is a polarizing plate.The light from the light source 1 is set so that it becomes linearly polarized light that can be transmitted through the polarizing prism 14 after passing through the index plate 13.

Since the embodiment of the present invention is constructed as described above, the light that illuminates the index 13a of the index plate 13 from the light source 1 through the lens 2 is first converted into linearly polarized light by the polarizing plate 11, and then becomes linearly polarized light. The /4 wavelength plate 12 converts the light into circularly polarized light. The elliptical polarized light that illuminates the index 13a becomes linearly polarized light again by the index plate 13.
The light passes through the polarizing prism I4, enters the total reflection prism 6, is totally reflected inside the prism, and then enters the back mirror 15. Since the back mirror 15 is configured as a 1/4 wavelength plate with one side being a reflective surface, the linearly polarized light incident on the back mirror 15 is reflected as linear polarized light orthogonal to the linearly polarized light, and then passes through the total reflection prism 6 again. After passing through, it is reflected by the polarizing prism 14 and goes through the imaging lens 8 toward the spherical center of the eccentricity measurement surface of the lens 9 to be tested. Since the eccentricity measurement surface of the test lens 9 is located at the autocollimation position by moving the total reflection prism [ ) in the direction of the arrow as in the case of FIG. 1, the eccentricity θ
1j The linearly polarized light reflected by the fixed object goes backwards and passes through the polarizing prism 1.
4, is reflected by the back mirror 15 via the total reflection prism 6, and then enters the polarization prism 14 via the total reflection prism 6 again, but since the polarization direction has been rotated by 90', it passes through the polarization prism 14. do. flHj optical prism 14
The linearly polarized light that has passed through is reflected by the index plate 13, but at this time it passes through the 1/4 wavelength plate twice, so the polarization direction is 90°.
° Rotated. Therefore, the image of the index 13a enters the polarizing prism 14 and is reflected by it, and the polarizing plate 16
and can be observed through the eyepiece lO. Note that the polarizing plate 16 is disposed perpendicular to the polarization direction of the observation light and is useful for removing flare.

FIG. 3 shows a second embodiment, in which the light source system and the test lens system are interchanged compared to the actual MM example shown in FIG.
The polarizing prism 14' differs from the polarizing prism shown in FIG. 2 by 90 degrees in terms of the polarization direction of the incident light from the light source. Therefore, the reflection and transmission at the polarizing prism 14' are reversed, and the overall operation is similar to the embodiment shown in FIG.
This second embodiment is particularly suitable when the reflection characteristics of the polarizing prism become yellow depending on the direction of the cemented surface.

FIG. 4 shows a third embodiment, which basically has the same structure and function as the embodiment shown in FIG. >'0,17
Indicator plate consisting of a flat glass plate configured as a reflective interior with a and arranged at a slight inclination to the optical axis 2. The inclination of the index plate 17 causes the image of the index 17a to be out of focus if the amount of deviation from the optical axis is large; This has the advantage of reducing flare. Furthermore, if a laser is used as a light source, the polarizing plate 1 is not necessary, and the amount of light is further reduced.

As described above, according to the present invention, by using a polarizing prism, there is virtually no reduction in the amount of light from the index, and therefore there is almost no flare, so it is brighter and has a higher contrast than before. In addition, since the surface of the lens to be tested is generally coated with a film that prevents fouling against visible light, the reflected light from the red evening light (if ultraviolet rays are used for the purpose of measuring eccentricity) is used as illill constant light. :j) The image of the indicator becomes larger and brighter! 4) Anti-reflection of a fixed surface 4) Opposite direction due to the anti-reflection of a fixed surface 3, which requires a sensitive detection element, so red 1
) l line.

When using ultraviolet rays as measurement light, the image of the index cannot be seen with the naked eye, so a detection device such as a sensor that is sensitive to the measurement light used is used at the position where the index image is formed. It is 63 inches to measure the amount of eccentricity of the eccentricity measurement surface.In the following embodiments, a polarizing prism is used for tilting, but it is not limited to this. Good to have.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional lens eccentricity measuring instrument, and FIG. 2 shows an embodiment of the lens eccentricity measuring instrument according to the present invention.
3 and 4 are schematic diagrams showing other embodiments of the present invention. 1... Light source, 2... Lens, 3... Index,
4. 5... Semi-transparent mirror, 6... Total reflection prism, 7...
・Anti-Q6 mirror. ．． 8... Imaging lens, 9... Test lens, 10... Eyepiece lens, II, 16...
・(rtδ light plate, 12...1/4 wavelength plate,] 3
, 1. 7... Index plate, 141, 4'... Polarizing prism, 15... Back mirror. Agent Yasushi Shinohara

Claims (2)

[Claims] (1) An index illuminated with polarized light, a polarizing beam splitter that transmits (or reflects) the light from the index, and an optical path of the light transmitted (or reflected) by the polarized beam splitter in order from the light source side. A 1/4 wavelength plate and a reflective surface perpendicular to the optical path are provided, and the light reflected by the reflective surface and reflected (or transmitted) by the beam splitter is guided to the eccentricity measurement surface of the test lens. The beam is reflected by the projection optical system, the decentered measurement surface, is reflected back (or transmitted) by the beam splitter via the projection optical system, and is further transmitted to the reflecting surface of the quarter-wave plate 1 and again via the quarter-wave plate. and an optical system that guides the light transmitted (split and reflected) by the beam splitter out of the optical path. (2) Lens eccentricity according to claim (1), characterized in that the indicator is illuminated with polarized light in a wavelength range in which the antireflection effect of the antireflection coating on the eccentricity measurement surface of the lens to be tested is low. Measuring instrument.