Measuring the focal length of a camera lens in a smart-phone with a ruler

2019 ◽  
Vol 57 (1) ◽  
pp. 54-54 ◽  
Author(s):  
Jun Wang ◽  
Wenqing Sun
Keyword(s):  
Focal Length ◽  
Smart Phone ◽  
Camera Lens

Testing The White Sands Missile Range (WSMR) 100 mm Focal Length Rotating Prism Camera Lens

1978 ◽  
Author(s):  
Charles R. Hayslett ◽  
William H. Swantner ◽  
Richard A. Buchroeder
Keyword(s):  
Focal Length ◽  
Camera Lens ◽  
White Sands

The Camera Lens Design of 3D Low Light Level Color Night Vision System

2014 ◽  
Vol 568-570 ◽  
pp. 598-603
Author(s):  
Juan Li ◽  
Zhao Hui Liu ◽  
Chao Mei
Keyword(s):  
Vision System ◽  
Focal Length ◽  
Spectral Band ◽  
Chromatic Aberration ◽  
Light Level ◽  
Night Vision ◽  
Low Light ◽  
Camera Lens ◽  
Good Imaging ◽  
Color Night Vision

Two camera lenses for 3D low light level color night vision system are designed in CODE V. The panchromatic sensitive camera lens works in a wide spectral band 400nm-1000nm, yellow green-sensitive camera lens works in a band of 400nm-600nm.The two camera lenses have same parameters, such as focal length 120mm, relative aperture 1/2, the field angle of 5.26 °. In the design of two camera lenses, we split and complex cooke triplet lens, the chromatic aberration is balanced by adding a binary diffractive surface. The results of design show that sensitive panchromatic camera lens and yellow-green-sensitive camera lens, in the all field of view, when the Nyquist frequency is 77.5 (lp / mm), all MTF is larger than 0.6; the axial chromatic aberration of sensitive panchromatic camera lens is 0.056mm. Two camera lenses have good imaging performance.

Factors Affecting the Impression of Vehicle Speed Gained from a Video Recording

1995 ◽  
Vol 81 (2) ◽  
pp. 472-474
Author(s):  
Stuart Lines ◽  
John Searle
Keyword(s):  
Traffic Accidents ◽  
Marked Effect ◽  
Focal Length ◽  
Video Recording ◽  
Vehicle Speed ◽  
Factors Affecting ◽  
Camera Lens ◽  
Accident Scene

During court hearings arising from traffic accidents, videotaped recordings are often used to give a ‘drive through’ view of the accident scene. A panel of 24 subjects evaluated the impression of speed created by such recordings. Focal length of the camera lens has a marked effect.

Research of the Aerial Camera Lens to Eliminate the Secondary Spectrum

2014 ◽  
Vol 644-650 ◽  
pp. 4076-4079
Author(s):  
Zheng Liang
Keyword(s):  
High Resolution ◽  
Simple Structure ◽  
Focal Length ◽  
Optical Design ◽  
Effective Size ◽  
Optical Material ◽  
Objective Lens ◽  
Topographic Mapping ◽  
Camera Lens

Aerial cameras are widely used in resource surveys, topographic mapping, military reconnaissance and many other fields. This paper introduced the sort of aerial camera, the development in our country and abroad about the theory of secondary spectrum. In order to meet the requirement for simple structure and high-resolution, the optical design of the apochromatism objective lens of aerial camera is achieved by common optical material. Objective’s focal length is 400mm, relative aperture is F/4 and work waveband is 420nm~850nm. Designing results show that the MTF of every field above 0.75 in 60lp/mm and satisfy the requirements of imaging for large frame array CCD whose effective size is 36mm×48mm.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

A Superconducting Microscope

1971 ◽  
Vol 29 ◽  
pp. 10-11 ◽  
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson
Keyword(s):  
Liquid Helium ◽  
Focal Length ◽  
Vacuum System ◽  
Objective Lens ◽  
Electrical Instability ◽  
Radiation Shields ◽  
And Control ◽  
Thermal Oscillations ◽  
Flux Pump

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

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