偏转对电子束上屏束径的影响

彩色显像管中，电子束经偏转系统偏转后在屏的边角处的尺寸比中心部分尺寸大。为了解决偏转散焦，日本松下公司推出了ＤＡＦ枪。然而随着ＨＤＴＶ的发展，电子束束流和偏转角都越来越大，此时仅靠调节动态聚焦电压不能完全补偿过聚焦以及大束流下空间电荷效应的影响。本文研究了大束流、大偏转角情况下造成偏转散焦的原因，提出在调节动态聚焦电压的同时适当改变电子束进入主聚焦透镜的入射角，从而改善电子束经偏转后的上屏质量。     

提高9″显象管边缘分辨率的实验研究

本文从分析9″显象管电子枪的结构特点出发,讨论了影响荧光屏上电子束光点尺寸的三个主要因素:透镜放大率、球面象差和空间电荷效应。提出了用减小调制极孔径,增大调制极与加速极之间的距离等方法来减小电子束最小交叉截面的尺寸和电子束的发散张角;并且以调整电子枪在显象管内的位置,即增大它与偏转线圈之间的相对距离,来减小偏转线圈杂散磁场所引起的偏转散焦;从而有效地改善了整管的聚焦性能,并明显地提高了边缘部分的分辨率。 试验结果和批量生产的管子测试表明:上述方法是卓有成效的,其边缘分辨率能提高50线以上。     

光热光束偏转方法测量激光束特征参数

本文叙述了光热光束偏转方法的基本原理,介绍了一种新的应用光热光束偏转方法测量聚焦激光束的特征参数及聚焦透镜焦距的方法。实验测量了经单一锗透镜聚焦后的CO_2激光束的腰斑半径和位置,同时确定了聚焦锗透镜的焦距,其结果与实际情况一致。     

Correction of deflection-aberrations by analog computer

For wide-angle deflection (±25°) of microspot tubes (spot size-8 microns), dynamic correction of focal length (DCF) alone is no longer capable of conserving resolution. It is found, however, that complete recovery of ultra-high resolution (3000 lines per inch) is practical by adding dynamic correction of astigmatism (DCA) to DCF. The laws of error distribution on the tube face are found to be quadratic functions of position coordinatesxandy. Dynamic correction thus requires an ideal product generator that obeys the associative law of multiplication out to large amplitudes. A special beam-deflection type of computer tube has been developed. It operates on the principle of deflecting a square beam across a quadrantal target. An analog computer using three of these "roving-square tubes" (RST's) generates all three dynamic corrections as required by DCF and DCA. Photographs of deflected television microimages show the effectiveness of this analog computer in presenting approximately 9000 spot diameters, or 80 million dots, within a 3-inch square.     

About scan magnification of TV picture tubes

In a television receiver the horizontal deflection is of critical importance because of the high deflection power. Recently various proposals have been published, according to which the electron beam is to be deflected over a small angle only, in order to diminish the deflection power. Subsequently this small deflection angle is to be increased by an electrostatic or magnetic lens. In the present paper, it is shown with the aid of general laws of electron optics that such a scan magnification by an electrostatic or magnetic lens necessarily causes a decrease of the resolution, and thereby, of the quality of the television picture, unless known possibilities of increasing the resolution are employed simultaneously. The calculation also affirms that with magnetic deflection, unlike electrostatic deflection, post-acceleration does not lead to a significant reduction in deflection power with unchanged resolution.     

The design and performance of grid-controlled, high-perveance electron guns

The focusing electrode and a probe projecting through the cathode serve as control electrodes for the current from a convergent-beam electron gun. The principal advantage of this type of "grid" is that there is no interception of the high-current-density beam by the probe-grid. This paper presents the design procedure and experimental results for typical probe-gridded guns. The design procedure is used to obtain the desired perveance, beam diameter, and approximate laminar electron flow. The probe geometry that results in a minimum beam distortion is discussed. The range of values of amplification factor obtainable and the influence of probe geometry on this factor are discussed. The magnetic field required for focusing the beam from a probe-gridded gun is compared with that required for perfect laminar flow and for focusing the beam from a nongridded gun of similar design. An electrolytic tank in conjunction with an analog computer was used to plot electron trajectories, with the effect of space charge included, for the probe-gridded gun and a similar nongridded gun. A comparison of the electron optics of the gridded and nongridded gun is made. Electrical breakdown and beam current during the interpulse time are problems considered. Methods used to minimize electrical breakdown and interpulse beam current are presented. Several models of probe-gridded guns were constructed. The measured characteristics of these guns demonstrate that the advantages of grid control can be obtained with only a minor effect on gun perveance and beam focusing.     

Triode electron injection systems for hollow beams

Novel electron guns, in which a conical hollow electron beam is projected at a large angle to the axis into a coaxial deflection region, were tested. The guns have a triode structure so that the perveance can be varied easily. The strong deflection increases the effective perveance of the beam and makes the trajectories insensitive to current variations. In the form of a device with the gun at a large radius and projecting the beam inward, the electron paths are sensitive to scattering in the gun. The inverted gun, projecting the beam outward, is relatively free from this difficulty. The systems generally behave as expected, and should be quite useful for initiating variable-current hollow electron beams in various available focusing arrangements.     

A new high-performance color picture tube: The mask-focusing color tube

From a technical point of view, improvements of conventional color picture tubes could be regarded as having reached their limits. In this respect, we have found that the mask-focusing tube can achieve further improvements when combined with the black-matrix technique, a high-performance gun, dot screen structure, high-matrix transparency, and large gun electrode diameter. Two-fold improvements of brightness and contrast have been obtained with mask transparency twice that of conventional tubes, 22-percent higher matrix transparency, and mask-focusing. A 20-30 percent less deflection power has also been achieved with 110° deflection, neck diameter, and 1:2 mask-focusing voltage ratio. A 20-percent less spot diameter and a sharp beam distribution have been obtained by a new multistage-focusing electron gun in a delta arrangement in the 35.5-mm neck diameter.     

A microspot tube with very high resolution

A 5-inch microspot tube with a spot size of 8 to 9 microns and a beam current of 1.5 µa is described. The neck of this tube uses an accelerating spiral anode, in combination with a decelerating prefocus lens. This combination stretches the 6-inch neck structure to an effective length of 13 to 16 inches. The resulting demagnification of 0.6 permits realizing the above spot size as an electron image of a 1/2 mil object-aperture. The latter is illuminated with a current density of 20a/cm²by a microgun, which uses an impregnated cathode at 2a/cm². The microgun operates by the FRM principle ("Focus Reflex Modulation"). An improved vapor-reacted screen is employed, whose light output is more than tripled from previous types of transparent phosphors.     

Focus reflex modulation of electron guns

High resolution and low drive features have been successfully combined in a new type of electron gun for cathode-ray tubes. The gun has a spot-defining aperture of 0.007 inch upon which emission from a large cathode area is concentrated by a retarding electron lens. This unit modulates the beam by electron reflection, while focusing it upon the aperture ("Focus Reflex Modulation"). Immediately ahead of the aperture, a modulated virtual cathode is formed with an emission capability of over four amperes per square centimeter. A1000-microa beam with a 6° divergence is controlled by a signal of 12 volts centered at ground potential. Highlight brigntness of 250 foot lamberts was read at 17,500 volts, while more than 500 lines were resolved on a television test pattern. In more recent forms of the FRM gun,1600 microa are measured in the screen return, out of1800-microa cathode current. This is 88 per cent over-all transmission, using the same defining aperture (0.007 inch). 18 volts of drive signal will completely modulate the above current.     

彩色显像管中主聚焦透镜的研究

在COTY系统中,采用XL透镜来改善会聚性能,减小会聚/聚焦之间的矛盾。XL透镜可以在不损失聚焦性能的前提下缩小束间距提高会聚特性。但是在XL透镜中边束像差比中束大得多,为了进一步降低像差,本文提出在XL电子枪中采用OLF透镜来扩大透镜的孔径,改善分辨率。本文给出了三维计算机程序,对主聚焦透镜进行三维计算,得到了球差系数和其它光学参量。这些数据证实了在新的方案中球差确实被降低,而且会聚特性也得以改善。     

Astigmatic electron gun for the beam-indexing color television display

Though the beam-indexing color television display has some obvious advantages when compared with other display systems, the electron-optical demands are very high. First, these demands and the imaging system to be used are discussed. It turns out that the beam must be astigmatic to obtain optimum performance. The beam shape is prescribed by the deflection-coil design. This beam shape, giving rise to a vertically elongated spot of sufficiently small dimensions, is obtained by using an astigmatic gun of special design in combination with a simple rotation-symmetrical focusing lens. After a general discussion of the focusing properties of this combination, the intensity distributions along both the minor and the major axis of the spot on the screen are calculated and compared with experiments. The gamma of the beam current characteristic is measured as well as calculated. Its dependence on the beam current is small up to beam currents of about 3 mA. Moreover, the cathode loading is calculated as a function of the beam current. Without special means of dynamic correction, satisfactory color reproduction in normal picture material is obtained up to peak currents of 1.5 mA in 110°-25 in tubes. Higher beam currents would be attainable in the absence of a residual deflection error which causes a tilt of the spot near the corners of the screen. The structure of the picture is quite acceptable at a triplet pitch of 1.2 mm without using a lenticular screen.     

一种应用于激光微烧蚀的光学聚焦系统简化设计方法

针对激光微推力器对光学聚焦系统结构紧凑、聚焦光斑尺寸小以及避免羽流污染的特殊要求,采用传统的光线追迹法研究单透镜直接聚焦、双透镜准直聚焦两种典型方案光学设计方法。针对低功耗半导体激光器光纤耦合输出的芯径和数值孔径条件,在50m级聚焦光斑约束下,研究单透镜聚焦系统设计方案,得到了透镜厚度、焦距、工作距等设计参数的关系;研究准直聚焦光学系统的双透镜系统设计方案,得到了透镜厚度、透镜中心距、工作距等设计参数特征关系。针对两种典型光学设计方案,给出了工程应用设计参数。文中提出的设计方法避免了复杂的光学设计过程,可为激光微推力器激光光束微尺度聚焦提供一种简单实效的方法。     

A microwave electron velocity spectrograph

An electron-velocity spectrograph is described which can be used to measure the velocity distribution of electrons in a high-density electron beam modulated at microwave frequencies. The spectrograph employs a crossed electric and magnetic deflection system, has a resolution of less than one per cent in velocity, and a deflection region of very short length in order to minimize space-charge effects in the instrument. Results of measurements made with the instrument on a Brillouin-focused, gap-modulated electron beam of microperveance one are given. Measurements made on the dc beam indicate that nonlaminar flow effects are important for focusing fields of the order of and greater than the Brillouin focusing condition. Measurements of the RF velocity distribution at a point in the beam near the cavity gap have been found to agree with the predictions of kinematic bunching theory. A consequence of small-signal, space-charge-wave theory is that RF velocities should go to zero at a point in the beam a quarter of a reduced plasma wavelength from the cavity gap. This is confirmed by measurements made with this spectrograph.     

Gridded electron guns for high average power

The design and performance of electron guns producing high-average-power beams which are controlled by an intercepting-type grid are described. The design consists of a modification of the design of Pierce-type electron guns to allow for the effect of grid insertion, and calculation of the amplification factors based on the potential distribution. The performance is evaluated in terms of the beam shapes and average beam powers obtainable. Measured amplification factors are compared with calculated values. Factors influencing the measured beam shapes are discussed. Trajectories of electrons emitted as secondaries from the grid and those of electrons deflected by the lens effect of the grid wires were plotted using an analog computer and electrolytic tank. The shapes and focusing properties of electron beams from similar gridded and nongridded guns are compared. Expressions relating the average beam power capability to the gun and grid dimensions are developed. The calculated average beam power capabilities are compared with measured values. Average beam power as high as 8 kw has been obtained with electron guns of a size suitable for use in X-band twt's.     

The principle and test results of a large-raster no-mesh return-beam electron-camera readout system

An electrostatic deflecting lens (EDL) return-beam, electron-camera readout system has been developed and tested. The unique features of the system are the following: 1) there is no field stopping mesh used, therefore, ultra-high resolution becomes possible; 2)the normal landing condition is obtained by making the deflection center coincide with the focal point of the final lens; 3) a large number of beam spot diameter scans are obtained; and 4) magnification factor of the system M is smaller than one. The system was tested at electron landing energies from 70 V to 14 kV. In a 2.86 cm × 2.86 cm raster scan, the typical on-axis modulation transfer function (MTF) at a spatial frequency of 100 lp/mm is 0.67 for high-energy landing and 0.55 for low-energy landing. The linear scan is better than 7000 spot diameters at high-energy landing and around 6000 at low-energy landing. The test results indicate that with some design modification, the EDL system can be used for low-energy surface-scanning electron-microscope (SEM) applications.     

The mirror-matrix tube: A novel light valve for projection displays

A completely sealed-off electron beam-addressed light valve offering high reliability, low thermal impedance, and low-voltage operation is described. It is suitable for projection displays and is capable of producing bright high-contrast images with full gray-scale range and long-term storage. The light valve is contained as the faceplate in an otherwise standard, sealed-off 1½-in diameter vidicon tube and utilizes conventional focusing and deflection components. The target, which is fabricated of refractory materials using high-yield semiconductor-processing techniques, is composed of a dense matrix (500 elements/in) of aluminized silicon-dioxide membranes (~ 3000-Å thickness) which are supported centrally on small silicon posts (4-5 µm high) above a transparent sapphire faceplate. These flat, stress-free oxide membranes can be deflected electrostatically (up to 4°) when addressed with the electron beam. Thus an intensity-modulated display of the deposited charge pattern on the "mirror matrix" is produced when this type of light valve is used in conjunction with reflective schlieren optical arrangement, Mechanical and optical considerations have led to a special 4-leaf geometry of the mirror elements, enabling operation at low-voltage levels (175 V) and a high optical gating efficiency (~ 50 percent) to be achieved. Large-screen (2½-by 3½-ft) displays with up to 35-fL highlight brightness ( ×5 screen gain), 15:1 contrast ratio, and 400 TV lines resolution have been demonstrated. In addition, single-frame displays (1/30-s writetime) with full gray scale storage (of many hours) have been achieved. Preliminary studies using higher density mirror matrices (1000 elements/in) show that the display resolution can be extended to 600 TV lines/picture height.