DE2228236B2 - Mirror lens - Google Patents

Description

The invention relates to an optical system with a mirror lens which has an annular concave Contains main mirror and a secondary mirror that carries the light from the main mirror to the area of the image plane reflects near the center opening of the main mirror.

A mirror lens contains one or more reflective surfaces, hereinafter referred to as mirrors be drawn and used to create an image in contribute to a desired image level. A well-known lens of this type contains an annular, concave main mirror, which directs the incoming rays to a secondary mirror of smaller diameter that throws back on the optical axis in front of the Main mirror, el. H. / wipe the main mirror and the object that is located. The secondary mirror throws that Light from the main mirror back to the area of the image plane near the central opening of the main mirror.

In the case of such a known mirror objective, the area of the secondary mirror is not minimized exploited because the beam reaching up on him after the Reflection on the main mirror has a circular cross-section

It is the object of the invention to specify an optical system in which the middle area of the secondary mirror is used to improve performance.

This object is achieved according to the invention for an optical system of the type mentioned at the beginning solved that within the central area formed by the inner diameter of the secondary mirror ^

ίο becomes, an independent, axially arranged, mapping optical system is provided

The invention therefore uses the middle area of the secondary mirror to create a second optical system with the mirror lens on common-γ samer optical axis to be arranged.

Mirror lenses have a wide range of uses and generally always will used when a relatively small field of view (not larger than approx. 15 °) with a relatively large aperture ratio, for example of 1: 1.0, should be included, especially if a small focal length on the image side is required These applications are, for example, targeting or direction finding devices and Given night vision devices that can work with infrared radiation. The terms "radiation", "Representing", "reflecting" etc. should be understood in this sense in the following description.

If the mirror lens is used, for example, in a target device, then another optical system a crosshair fade-in system can be provided. In this case, the images of the the object recorded with the mirror lens and the cross-hairs recorded with the fade-in system superimposed on each other in the image plane, this area for example by the cathode surface of a Image intensifier tube can be formed.

In other applications of the mirror objective, a second objective, for example an objective of the inverted telephoto type, can be provided as an axially arranged, imaging optical system, so that the object can be viewed with different magnifications. In this case, the overall system can contain a diaphragm or a shutter, whereby only the mirror lens or the further lens is switched on in each case. Lenses of the inverted telephoto type are hereinafter referred to for short as inverted telephoto lenses.
The axially arranged, imaging optical system can have at least one lens together with the mirror objective. For example, the mirror lens can contain a lens in front of the main mirror which carries the secondary mirror on its rear side and is also part of the inverted telephoto lens. A front lens can be provided, which is also part of the inverted telephoto lens and is located in front of the lens carrying the secondary mirror. This also forms part of the further optical system. In connection with these possibilities it should be pointed out that the terms "front" and "rear" refer to the

μ The direction of entry of the light into the mirror lens is to be understood, ie the light that falls from the front onto the main mirror.
Embodiments of the invention are in

described below with reference to the figures. It shows

F i g. 1 a mirror lens,

2 shows a lens in the manner of an inverted one Telephoto lens which, in the case of a mirror lens according to FIG. 1 can be used,

Fig. 3 and 4 a further possibility of use an inverted telephoto type lens in a mirror lens,

F i g. 5 and 6 show another way of using an inverted telephoto type lens in FIG a mirror lens and

F i g. 7 a mirror lens which is suitable for the installation of a crosshair fade-in system.

Numerical data for four exemplary embodiments of a mirror lens are given together with numerical data for examples of a simultaneously used inverted telephoto lens according to an overall system according to the invention in the following tables, in which Ri, Ri ... are the radii of curvature of the individual, successively arranged surfaces of the lens where the light falls and that

Example I - Table A
Mirror lens - focal length 7.194 positive sign indicates a curvature that is convex with respect to the front side and the negative sign indicates a curvature that is concave with respect to the front side. D \, Di .. , denote the axial thickness of the respective lens. Si, Si ... denote the air gaps between the individual lenses. The tables contain diu refractive indices and the Abbe numbers nu Vderfürdic Linser used glasses, and also the effective openings of the individual surfaces and, if the mirror objective

ίο in question, the diameter of the central opening of the annular surfaces. In the case of ring parts smrl the thickness values D \, D ₂ and the distances S \, S: in the tables nominal values which indicate the corresponding values for the axial thickness and the distances if the respective surfaces were complete.

Table A for Example I relates to a mirror lens with a simple front lens (R ₁ , R ₂ ) on which the light is incident first, a simple second lens (Rs, A ₄ ), a main mirror (Ri) and a secondary mirror (R ₆ ), which receives the light reflected at the main mirror and reflects it back onto the image plane (FIG. 1).

radius

Thickness or distance refractive index

Abbezahl V Effective
opening diameter
the central opening 64.2 8.00
8.00 3.60
3.60 64.2 8.00
8.00 2.40
2.40 8.00 360

R, + 12.207 ßl 0.941 1.517 R ₂ OO S. 0.8137 Ri -10.239 D ₂ 0.345 1.517 Ra -51.21 S ₂ 4.3504 Aluminized Rs -13.693 Flat glass S ₁ 3.5411 Aluminized R _b OO Flat glass

3.74

1.60

Table B for example I relates to an inverted telephoto lens arranged in the mirror lens according to Table A on a common optical axis. It is made up of six simple lenses (Λ | to Ri ₂ ) (Fi * ,. 2).

Example I - Table B

Inverted telephoto lens - focal length 2.00

radius

Thickness or distance refractive index Abbe number

Effective opening

Ri +4.630 D ₁ 0.2380 R ₂ -27.870 S, 0.0490 Ry -26.650 D ₂ 0.1040 R * + 1.1620 S ₂ 3.5440 R> +4.9360 Dx , 0.3820 R " -2.1740 S, 0.0280 Ri -6.8177 /), 0.1040

1,755

1.517

1,517

1.755 2 ", 6

04.2

64.2

27.6

1,800 1,800 1,800 1,800

2.100 2.HX) 2.KX)

Kndiu

Thickness or Ahsliind Hn-ch / ahl Ahhe / .ilil

Effective

opening

As +2.6602

Λ., +21.4100

/ fm -2.3782

/ f _M +1.9570

W ₁ , ι 12.8800

.V, 0.1721

lh 0.335O

.Vi 0.04X0

I) ₁ , 0.3330

1.517

1,517 64.2

64.2

2.100 2.100 2.100 2.1 (X) 2, KX)

The mirror lens according to Table A has an image-side back focus of 3.0625, measured from the top of the surface / ?, ₂ . The inverted telephoto lens, which usually consists of a diverging front group (R \ to Ri) and a converging rear group (R ', to /? _I2 ) with a large distance behind the front group, is partially, that is, at the rear group, within the middle Openings of the front and second lens of the mirror lens attached. However, the two objectives have no common components and are each constructed in such a way that a suitable correction of aberration is achieved for the respective angle of view and the respective relative aperture.

The mirror lens is corrected so that a maximum usable angle of view of 4 ^{= is included} with a relative aperture ratio of I: 0.89, leading the inverted telephoto lens is corrected in this way.

Example II - Table C
Mirror lens - focal length. · "M 17 that a maximum usable angle of view of 15 ° with a relative aperture ratio of I: 2 is included. The complete system enables the same object to be viewed alternately with two different magnifications, and an adjustable aperture is provided, see above that only one of the two lenses is switched on.

The glasses used enable the optical system to be used in the spectral range between 500 nm and 800 nm. The extremely short one is remarkable Total length of the mirror lens. The image plane passing through the cathode surface of an image intensifier tube can be formed, is arranged just before the vertex of the concave main mirror.

Table C for example II concerns a mirror lens which has a simple front lens (Rt, R2), a simple second lens (Ri, Ra), a main mirror (R5), a secondary mirror (Rb) on the back (R *) of the second lens and three lenses (Ri to Λ12) behind the secondary mirror in front of the image plane (Fig. 3).

R.icliiis

Thickness oiler distance refractive index Abbe number

Effective
opening

Center opening diameter

+ 10.7100
+ 39.9100
- 7.4690
-72.0000
-11.6200

R ₁ , -72.0000

R- +2.6300

R, -10.4400

R " -8.1511

R ₁₁ , + 2.6600

Γι ι "I Tl 1 Λ

/? ,, +46.5200

D 0.750

■ V; 6.7! 2

D (1.250

.S ": 3.049

5 ₃ 3,049

5 ₄ 1.582 D _} 0.400

5 ₅ 0.060 D ₄ 0.100 S, 0.748 D ₅ 0.125

1,517

1,517

Aluminized flat glass

Aluminized glass

1,755

1.805

1.805 64.2

64.2

27.6

25.4

25.4

8,200
8,200
6,200
6,200
6,200

2.960

2,200
2,200
2,200
2,200
1,100
1,100

3.00 1.48

Table D for example II relates to an inverted telephoto lens which is arranged on the optical axis of the mirror lens according to Table C and consists of nine lenses, namely eight simple lenses (R ₁ to K, h) and a rear double lens (R \ i to R \ <>) (Fig. 4).

Example Il - Dragonfly 13

Inverted telephoto lens - focal length 2, (K)

radius

R ₁ + 10.7100 You 0.750 R; I 39. ') I (K) • V, 0.505 R; +4,695 You 0.280 Λ, -5.6077 S; 0, (XM 5,176 You 0.122 Ri- + 1,065 S, 2,761 R- OO You 0.5 (K) R \ OO S ₁ 0.125 «* ·> + 137.7 D, 0.3X9 /? ,,, -2.025 S, 0.082 Marg -7,625 A, 0.100 R _r +2,594 S, 0.118 Rl-, + 10.825 D ₁ 0.473 »Ή -2,850 S ₁ 0.044 /?, - +2.0453 D ^ 0.539 Λ | 6 +602.41 S, 0.471 Λ.- -72,000 D; 0.200 «18 -7,469 0.250 A _1. , -72,000

Thickness or distance Hrceh / ahl

1,517 1,755 1,518 1,519 1,518 1,755 1.518 1,518

1.518

1.517

Ahbc / ahl I. Effective
opening 64.2 (8.20)
(8.20) 27.6 1.60
1.60 64.1 1.60
1.60 60.4 1.85
1.85 64.1 1.85
1.85 27.6 1.85
1.85 64.1 1.85
1.85 64.1 1.85
2.00 64.1
64.2 2.00
(6.20)
(6.20)

The mirror lens according to Table C has a bilateral focal length of 0.061, the image plane is located just behind the vertex of the surface i? _{5 of} the main mirror. This lens has a maximum usable angle of view of 4 ° with a relative aperture ratio of 1: 0.89. The small diameter lenses just before the image plane are of particular interest. The dual lens (R7 to Rio) is primarily used to correct the primary spherical aberration and astigmatism created by the primary mirror and the larger diameter lenses in front of it. The last lens An, Ru) is primarily a lens of low refractive power. A sufficient degree of freedom is achieved through the areas AV to A12 to enable a high aberration correction and at the same time a curvature value for the rear surface (RU) of the second lens which ensures that the secondary mirror (Rt) is supported

The inverted telephoto lens according to Table D keeps the front lens and the second lens (R \, R2 and R3, Ra) of the mirror lens as the front component (R \, «y and the rear element (R \ g, Rig) of its rear double lens The remaining lenses of the inverted telephoto lens are arranged in an adapted manner between the two mentioned lenses of the mirror lens. It must be taken into account that the small diameter surfaces AV to R \ 2 of the mirror lens are arranged in the beam path of the inverted telephoto lens Ä12 to the image plane, which is the same for the inverted telephoto lens and for the mirror lens, has the consequence that these lenses (Rj to Ä12) practically do not affect the position of the image plane of the inverted telephoto lens, since this has a sufficiently large depth of field Lenses of this lens are of course made for good aberration

lionskorrektiir, also taking into account the areas, can be switched on alternately to one and the same

Rj to R \ 2 small diameter of the mirror lens. Object with different magnifications

It is therefore possible to view with a mirror lens. Furthermore, a mechanism for moving

Lens behind the secondary mirror. the further from the movement of the main mirror and the focusing of the

If the image plane is removed, these lenses can be provided as a mirror lens. By the

essential part of the axially arranged, imaging front lens to the rear occurring »constriction

The optical system can take advantage of the focus mechanism behind the

middle opening of the mirror lens works. front lens within its overall nominal diameter

The inverted telephoto lens according to Table D has to be provided.

a maximum usable angle of view of 15 ° with an m Table E for example III relates to a mirror lens

relative aperture ratio of I: 2. The complete similar to that according to Table C with the

The system should differ in the range of visible light that the double lens and the lens less

can be used, and according to Example I is a diaphragm refractive power behind the secondary mirror (Rf ₁ ) through a

arranged in such a way that the two objectives are optionally replaced with thick single lenses (Ri, R «) (Fig.>).

Example III - Table V. Mirror Lens - Focal Length 7.15

Kadιus + 13.85 thickness or AhStIiIHl H rech / a hl R, -39.89 lh 1.07 1.569 R ^ -9.012 .V ₁ 5.298 R, -52.90 0.232 1,699 Ri -12.65 .V, 2.923 R, Aluminisicrtes Flat glass -52.90 .V-, 2.923 Ru / Moominized Glass +3.005 -V ₄ 1.129 R- -128.8 1,439 1.567 R. .s \ 0.4347 R; OO 0.080 1.569 Ru,

Ahhc / .iiii i Effective diameter O ITn u Ii μ the MitleliilTnuni; 8.198 2.86 56.13 8,198 2.86 5.66 30.07 5.66 5.64 2.73

2.84 1.2X

1.88 42.84

1.88

1.38 56.13

1.38

Table F for example ill concerns an inverted telephoto lens on the optical axis of the mirror lens according to Table E. This inverted telephoto lens has eight lenses, seven single lenses (Rι to R _M ) and a rear double lens (R, _s to R, 7). (Fig. 6)

Example III - Table F

Inverted telephoto lens - focal length 2,000

radius +4.265 thickness or distance Refractive index Abbezahl V Effective opening Ri -7.0713 1.40 Tuesday 0.186 1,755 27.6 Ri -4,445 1.40 Si 0,201 R, + 1.075 1.40 D ₁ 0.100 1.517 64.2 R ₄ OO 1.40 S ₂ 2.517 R ^ OO 1.85 Tuesday 0.500 :, 519 60.4 R " 1.85 S, 0.125

Il

rortset / ιιημ -25.75 thickness or Ahs-aiul Brecli / alil Ahhc / ahl I Effective K.kIius ΟΠ η uni! -1.992 1.85 Ri 0.325 1,517 64.2 -49.613 1.85 /? » s. _t 0.010 1-2,8055 1.85 R; D-, 0.100 1,755 27.6 + 8.2S 1.85 Rl « .S ", 0.113 -2.9236 1.85 «Μ / Λ, 0.321 1,517 64.2 + 1.8107 1.85 -V " 0.010 +7.053 1.S5 «Ι ·. ß- O.3 (i9 1,517 (> 4.? -5.6077 1.85 Κι. .V- 0.946 -9.012 1.85 Λ ,, ßs 0.200 1,699 30.1 -52.90 (5.66) 0 .. 0.232 1,699 30.1 (5.66)

The mirror lens according to Table E has an image-side focal length before 0.0312, the image plane is located just behind the vertex of the surface (R ^) of the main mirror. The lens has a maximum usable angle of view of 4 ° with a relative aperture ratio of 1: 0.89. The double lens used to correct the astigmatism of the objective according to Table C is replaced by the simple, thick lens (Rj. Rs) , which serves the same purpose. At the same time, it causes a flattening, so that a special lens is not required for this purpose. Instead, a translucent plate is placed very close to the image plane.

The front lens of the mirror lens is ring-shaped. so that the inverted telephoto lens (Table F) can be passed through, but this contains the second lens (Rj, R *) of the mirror lens as the rear element (R \ i, Ru) of the rear double lens.

The complete system is for use in the visible light range and contains a screen and, if necessary, a focusing device. This Mechanism can be provided in a unit that from the main mirror, the second lens with the secondary mirror and the thick lens behind the Secondary mirror exists, so that both lenses depending on alternating switching on can be focused. The inverted telephoto lens has a maximum usable angle of view of 15 with a relative aperture ratio of 1: 2. It is designed so that it creates an image on the same plane as the mirror lens. Both lenses have a high Performance in the context of \ berrationskorrt.-ktur.

Table G for Example IV relates to a mirror lens made up of an annular. konka \ en Hauptsiiegel (R \), a secondary mirror (R :), which holds the loan; from the main mirror to the area of the image plane in: ier near the central opening of the main mirror, and three lenses (R _s to R _f ) / between the .Sekundärspiegel and the image plane consists (F: g. 7).

Example IV - Table G
Mirror lens - focal length 5.72

radius thickness or distance Glass Effective By opening knife the Middle- opening R ₁ -19.5100 Aluminized 3.80 1.80 Flat glass 5, 3.9643 R ₂ +32.5863 Alumipated 2.25 0.376 Flat glass Si 2.211 Λ, -4,4028 1.081 D \ 0.126 Thallium Bromoiodide

Continuation

radius

Thickness or distance of glass

Effective opening

Middle oil diameter

A ₄ +8.2800

/? 5 +4.7536

R _h -9.0472

R ₇ +5.6900

A _x +538.1125

5 ₃ 0.002 D, 0.309

5 ₄ 0.526 D ₃ 0.183

ThaHium bromide iodide

Thallium bromoiodide 1.081 1.081

1.081 1.081

1.081

The mirror lens according to Table G had a maximum usable angle of view of 5 ° for a relative aperture ratio of 1: 1.43. It is for Application for infrared radiation and has an image-side focal length of 1.0954, so that the image plane about 0.2 is located behind the vertex of the main mirror

The unused central area of the objective has a smaller cross section than in the previous examples and is used to adapt an axial jo arranged optical system, which consists of a cross-hair fade-in system, which also works with infrared radiation. This system is built in the usual way and is therefore not specially described. Ls is arranged in such a way that it directs a crosshair image onto the infrared-sensitive area of the image plane of the mirror lens, whereby it must be taken into account that the lenses R ₃ to Rg are present as part of the mirror lens. In this fourth example, the axially arranged optical system normally operates simultaneously with the mirror lens, so that no diaphragm device is required. However, a focusing mechanism can be provided. It should be noted that the optical systems of Examples I to HI can also work with crosshair fade-in devices instead of inverted telephoto lenses, which depends on the particular application.

For this purpose 3 sheets of drawings

Claims (7)

Patent claims: 1. Optical system with a mirror lens that has an annular concave main mirror and a secondary mirror contains the light from the main mirror to the area of the image plane in the Reflects near the central opening of the main mirror, characterized in that within the central area formed by the inner diameter of the secondary mirror an independent, axially arranged imaging optical system is provided. 2. Optical system according to claim 1, characterized in that the axially arranged optical System has at least one lens together with the mirror lens. 3. Optical system according to claim 1 or 2, characterized in that the axially arranged optical system is an inverted telephoto type lens. 4. Optical system according to claim 3, characterized in that a locking mechanism or a diaphragm for switching on only the mirror lens or only the inverted telephoto lens is provided 5. Optical system according to claim 3 or 4, characterized in that the mirror lens contains a lens in front of the main mirror, which carries the secondary mirror on its rear side, and furthermore part of the ·; reverse telephoto lens is 6. Optical system according to claim 5, characterized in that dat a mirror lens Has front lens, öie a part of the inverted telephoto lens and in front of the .it the secondary mirror provided lens is arranged. 7. Optical system according to one of the preceding claims, characterized in that the At least one mirror objective that supports the correction of the astigmatism and the curvature of field Lens between the secondary mirror and the image plane and that this lens is part of the axial arranged imaging optical system is