DE3126566A1 - Electron-optical imaging system - Google Patents

Abstract

A description is given of an electron-optical imaging system having an electron picture (image) tube whose phosphor (fluorescent) screen and/or photocathode are concavely curved relative to the electron picture tube in an aspherically rotationally symmetrical manner in such a way that the radius of curvature increases from the inside outwards. The object field or the image field of the downstream or upstream optical system is curved in accordance with the curvature of the phosphor screen of the photocathode. The type of curvature provided according to the invention permits not only a compact design of the electron picture tube, but also renders possible a simple optical system with a high relative aperture and small aberrations (image errors).

Description

-V-

Electron optical imaging system

The invention is based on an electron optical system

Imaging system according to the preamble of claim 1 or 9. Such imaging systems are for example in the case of image converters or residual light intensifiers, ■ jO turns.

Electron-optical imaging systems are known whose electron picture tube is concave (towards the tube) Has a luminescent screen with a spherical curvature.

Electron picture tubes with a concave luminescent screen can, due to more favorable electron-optical conditions can be built much smaller and lighter than tubes with a flat fluorescent screen. However, it has proven to be difficult emphasized, the object field of the downstream optical system the spherically curved luminescent screen adapt. Optical systems with a spherically curved object field not only require a large number of expensive ones optical elements, but are also optical systems with a flat object field in image quality inferior. Therefore, in the vast majority of cases, electron-optical imaging systems with a flat fluorescent screen are used used despite the large dimensions.

The above explanations apply analogously to the photocathode of the picture tube or the image field of the upstream optical recording system to;

The invention is based on the object of an electron-optical Imaging system according to the preamble patent claim 1 or 9 in such a way that at low Dimensions a good image quality is achieved even with a high aperture.

According to the invention, this object is achieved in the case of electron optical systems Imaging systems according to the preamble of patent claim 1 or 9 by those in the characterizing part of the patent claim 1 and 9 specified features solved. Optical systems with aspherical-rotationally symmetrical curved Object or image field, the radius of curvature of which increases from the inside to the outside, can - as in accordance with the invention has been recognized - image quality is just as good as optical systems with a flat object or image field.

] 0 In addition, such optical systems Relatively simple to set up even with a high aperture »so that the optical system has small dimensions can. The small dimensions of the picture tube are (largely) coincident with the curvature Object or image field executed curvature of the luminescent screen or the pnotocathode possible. So that has electron optical imaging system according to the invention small dimensions an excellent image quality.

Further developments of the invention are given in the subclaims.

For example, in claim 2 is an advantageous form of the object field or of the luminescent screen. With curvature given by electron-optical conditions of the luminescent screen in the area close to the axis, the aspherical parameter K is dependent on the focal length and the image angle of the optical system are determined so that an equally good image quality of the optical system as is achieved in a system with a flat object field.

According to claim 3, the faceplate on which the luminescent screen is applied, be designed as an element of the optical system.

By arranging at least one biconcave lens near the luminescent screen according to claim 6, the image quality is further improved.

ι 'Λ:

The structure according to claim 7 allows an angled Beam path in the 'optical system, so that the electron-optical imaging system is adapted to special requirements or can be set up to save space.

The invention is explained below using an exemplary embodiment with reference to the drawing in which the exemplary embodiment is shown in section described.

An electron picture tube 1, which is only partially shown, has a luminescent screen. 3 mounted on a faceplate 2. The surface R1 * of the faceplate 2 carrying the luminescent screen 3 is curved so as to be aspherical, rotationally symmetrical, concave towards the electron picture tube 1, that the radius of curvature increases from the inside to the outside.

The visible image produced by the electron beam of the picture tube in a known manner on the luminescent screen 3 is imaged by means of an optical system A whose sharply imaged object field corresponds to the surface r1 or the luminescent screen 3. The optical system A has a large relative aperture so that it provides a bright picture of the phosphor screen image. The faceplate 2, the second surface r2 of which is also concavely curved, is included in the optical system 4. The common axis of the optical system U and the picture tube 1 is denoted by 5.

The optical system consists of two with a great distance "arranged lens groups I and II. The radii ri of the individual surfaces of the optical system, the assigned lens thicknesses di or air gaps Ii as well as the refractive indices η and Abbe's numbers ν of the for

e e

the individual lenses used are in given in the following table.

31265G6

yabel le

r1 aspherical surface according to claim 2 with K = -2.0 and C = 1 / 37.57 dl = 2.43 n _e = 1.624 v _g = 36.11 r2 = - 37.57

11 = 3.41
r3 = 78.37

d2 = 1.58 n _e = 1.694 V ₄₅ = 54.5

r4 = - 56.16

12 = 1.96

r5 = 120.74

d3 = 2.50 n _e = 1.694 v _& = 54.5 r6 = - 66.02

13 = 3.96
r7 = -328.51

d4 = 3 ", 20 n _e = 1.813 V _e = 25.2

r8 = - 95.6.9 ■

14 = 2.11
r9 = - 116.60

d5 = 7.47 n _e = 1.694 V ₃ = 54.5 r10 = 36.79

15 = 66.54
r11 = 97.81

d6 = 5.34 η = 1.813 V = 25.2 rl 2 = co

16 = 0.59 '' r13 = 985.79

d7 = 12.80 n _e = 1.623 'v _g = 60.0

r14 = 62.13

17 = 1.07

rl 5 = 1922.35

d8 = 9.60 η = 1.623 ν = 60.0 e e

r16 = 108.35

Relative opening 1: 1.90
Focal length f = 100

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Claims (9)

Claims ι '1. / Electron-optical imaging system with a ^x - ■ 'electron screen, which creates a visible image on a luminescent screen concave to the electron screen, and with (an optical system for displaying the image on the luminescent screen, characterized in that the luminescent screen (3) and the object of the optical system (4) coincide approximately and are so aspherically-rotationally · symmetrically curved that the radius of curvature increases from the inside to the outside. 2. Imaging system according to claim 1, characterized in that the distance ζ in the direction the optical axis (5) between the vertex of the luminescent screen (3) or the object field and a point on the luminescent screen or the object field with the height h is given by: z = ch ² / (1 + / i- (K + 1) c ² h ² ) where c is the constant of curvature and K is the aspheric parameter which is a fourth between -0.5 and -10. 3. Imaging system according to claim 1 or 2, characterized in that the luminescent screen (3) is arranged on a faceplate (2) whose second surface (r2) is also curved concavely. 4. imaging system according to claim 3, characterized in that the second surface (r2 is spherical, and its radius of curvature is 0.5 to 5 times as large as the near-axis radius of curvature of the Luminous screen (3) is. 5. Imaging system according to claim 3 »characterized in that the second surface (r2) has the same shape as the fluorescent screen (3). 6. Imaging system according to one of the preceding claims, dadur.ch characterized in that the optical system (4) near the luminescent screen has at least one biconcave Has lens. 7. The imaging system of any of the preceding claims, characterized in that the optical system (A) consists of two large distance, arranged lens groups (I, II), so that it ^is between the lens groups, a deflecting mirror or prism insertable · 8. Imaging system according to one of the preceding claims, characterized by the following data: Π aspherical surface according to claim with K = -2.0 and C = 1 / 37.57 d1 = 2.43 η = 1.624 ν = 36.11 ee r2 = - 37.57 11 = 3.41 r3 = 78.37 • · d2 = 1.58 n _e = 1.694 · v _& = 54.5 r.4 ■ = - 56.16 12 = 1.96 r5 = 120.74 'd3 = 2.50 n _e = 1.694 V _g = 54.5 r6 = - 66, O2 . . 13 = 3.96 r7 = -328.51 d4 = 3.20 η = 1.813 ν = 25.2 ee r8 = - 95.69 14 = 2.11 -Jr- r9 = - 116.60 d5 = 7.47 n _e = 1.694 V _e = 54.5 r10 «36.79 15 ■ 66.54 r11 = 97.81 d6 »5.34 n _e = 1.813 v _e = 25.2 r12 = op 16 = 0.59 r13 = 985.79 d7 = 12.80 n _e = 1.623 v _e = 60, O r14 = 62.13 17 = 1.07 r15 = 1922.35 d8 = 9.60 n _e = 1.623 V ₀ = 60.0 r16 = 108.35 relative aperture 1: 1.90
Focal length f = 100 where ri are the radii of curvature, di the lens thickness, Ii the air gaps η are the refractive indices, and with ν the missing numbers e are designated. 9. Electron optical imaging system in which a optical recording system creates an image on a photocathode of a picture tube, characterized in that both the image field of the optical Aufnahraesystem and the photocathode are so aspherical-rotationally symmetrical concave to the cathode ray tube that the The radius of curvature increases from the inside out.