Meiji Techno C-Mount Adapters with reductions lenses are easily removed from the optical path by simply removing the black colored lens piece and then re-attaching the camera to the tube directly when higher on-screen magnification is needed. Click HERE to try our On-Screen Magnification Calculator Page to see how different combinations of objectives, auxiliary lenses, c-mounts, camera chip sizes and monitor sizes effect the magnification seen on the monitor screen.

Vintage C-mountLens

C- and CS-mount lenses are both threaded lens mounts found on most industrial CCD cameras and lenses. The difference between C and CS-mount equipment is the distance between the flange of the lens (the part of the case that butts up against the camera) and the focal plane of the lens (where the CCD sensor must be positioned). This is known as the flange back distance.

Note that a very small gain or loss difference for the two polarization directions can be sufficient for obtaining a stable linear polarization, provided that there is no significant coupling of polarization modes within the laser resonator.

C-Mountlenssize

There are also partially polarized states of light. These can be described with Stokes vectors (but not with Jones vectors). Further, one can define a degree of polarization which can be calculated from the Stokes vector and can vary between 0 (unpolarized) and 1 (fully polarized).

In many respects, light can be described as a wave phenomenon (→ wave optics). More specifically, light waves are recognized as electromagnetic transverse waves, i.e., with transverse oscillations of the electric and magnetic field.

One distinguishes left and right circular polarization (see Figure 2). For example, left circular polarization means that the electric (and magnetic) field vector rotates in the left direction, seen in the direction of propagation. For an observer looking against the beam, the rotation of course has the opposite direction.

If the oscillations of the horizontal and vertical electric field vector do not have the same strengths, one has the case of an elliptical polarization, where the electric field vector, projected to a plane perpendicular to the propagation direction, moves along an ellipse.

There are also azimuthally polarized beams, where the electric field direction at any point is tangential, i.e., perpendicular to a line through the point and the beam axis.

Your first plot shows the magnetic and electric field in phase – which is wrong. The magnetic field is made from the changing electric field. The two fields swap energy back and forth. Hence the magnetic field is at a maximum when the electric field has the largest rate of change, that is, at zero E field. The magnetic field zeros in strength when the electric field rate of change is zero, at it's peak. These are a simple consequence of Maxwell's Equations and is covered in most any text on E&M. The worst error I have found in years of use of your marvelous resource!

As one can see, image sensors in cameras are actually quite small. The smaller the sensor, the more inherent magnification. The larger the sensor, the better the resolution with less magnification.

I would have been glad to finally remove a serious mistake, but I believe my equations are correct. They agree with those in various textbooks and e.g. also in Wikipedia. Your argument concerning energy swapping back and forth between electric and magnetic fields looks somewhat plausible but is not accurate.

C Mount Lensebay

The polarization state of light often matters when light hits an optical surface under some angle. A linear polarization state is then denoted as p polarization when the polarization direction lies in the plane spanned by the incoming beam and the reflected beam. The polarization with a direction perpendicular to that is called s polarization. These indications have a German origin: s = senkrecht = perpendicular, p = parallel.

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A circular polarization state can mathematically be obtained as a superposition of electric field oscillations in the vertical and horizontal direction, both with equal strength but a relative phase change of 90°. Effectively, this leads to a rapid rotation of the electric field vector – once per optical cycle – which maintains a constant magnitude.

In the simplest case, a light beam is linearly polarized, which means that the electric field oscillates in a certain linear direction perpendicular to the beam axis, and the magnetic field oscillates in a direction which is perpendicular both to the propagation axis and the electric field direction. The direction of polarization is taken to be the direction of the electric field oscillations (i.e., not the magnetic ones). For example, a laser beam propagating in <$z$> direction may have the electric field oscillations in the vertical (<$y$>) direction and the magnetic field oscillations in the horizontal (<$x$>) direction (see Figure 1); it can be called vertically polarized or <$y$>-polarized. In a different perspective, this is also shown in the second part of Figure 2.

As new cameras come into the market each month, it is a never ending task to stay informed. Meiji Techno Co., Ltd. is committed to developing quality camera adapters for the most viable makes, models and form factors.

C-mount camera

The polarization state of monochromatic light is often described with a Jones vector, having complex electric field amplitudes for <$x$> and <$y$> direction, if propagation occurs in <$z$> direction. That Jones vector may be constant over some area across the beam, or it may vary, for example for a radially polarized beam (see above). The effect of optical elements such as waveplates, polarizers and Faraday rotators can be described with Jones matrices, with which the Jones vectors can be transformed by multiplication. (One assumes a linear relationship between input and output amplitudes.) A whole sequence of such optical elements can be described with a single Jones matrix, which is obtained as the product of the matrices corresponding to the components.

Meiji Techno cameras have "CS" mounts so they can also accommodate "C" mounts when a spacer is first threaded onto the camera providing the additional 5mm per the "C"-Mount specification as shown above.

To compensate for too much mag or to match more closely the microscope FOV, one can use c-mounts with reduction lenses in order to adjust the field of view seen on the monitor. The reduction lens you require will depend on the chip size of your camera so if your camera has a 1/2" image sensor, you'll want the 0.45X c-mount. See the table at right for other adapter suggestions. Experienced users have an assortment of reduction lenses to accommodate different situations or specimens as c-mounts are relatively inexpensive.

Note that radial or azimuthal polarization state requires a zero electric field strength and thus also a vanishing optical intensity on the beam axis; it is not compatible with a Gaussian beam, for example. Radially polarized beams frequently exhibit a kind of donut profile.

The C-mount lens specification for flange back distance is 17.53 mm, and on CS-mount lenses it is 12.53 mm. However, on Point Grey cameras, these physical distances are offset due to the presence of both a 1 mm infrared cutoff (IRC) filter and a 0.5 mm sensor package window. These two pieces of glass fit between the lens and the sensor image plane. The IRC filter is installed by Point Grey on color cameras; in monochrome cameras, the IRC is replaced with a transparent glass window. The sensor package window is installed by the sensor manufacturer. The refraction of these glass components requires an offset in the flange back distance from the nominal values.

C-Mount Macrolens

Sensor sizes are often designated using fractions such as 1/1.8" or 2/3" which are larger or smaller than the actual sensor diagonal dimension. This sensor size designation goes all the way back to standard sizes given to Vidicon camera tubes developed in the 1940's and is unfortunately, still in use today.

If you have a CS-mount camera and a C-mount lens, you can add a 5mm spacer to obtain the correct focus. If, however, you have a C-mount camera and a CS-mount lens, correct focus cannot be achieved.

As image resolution is most desirable in all microscopy applications, 1/4" chips are just not well suited for microscopy while the 1/2" and 2/3" chip cameras strike a better balance between magnification, resolution and the size of the virtual image that the camera is seeing which to the eye appears much like a flashlight beam.

C-Mount ZoomLens

Linearly polarized light can be depolarized (made unpolarized) with a polarization scrambler, which applies the mentioned random polarization changes, or at least quasi-random changes.

The degree of linear polarization is often quantified with the polarization extinction ratio (PER), defined as the ratio of optical powers in the two polarization directions. It is often specified in decibels, and measured by recording the orientation-dependent power transmission of a polarizer. Of course, the extinction ratio of the polarizer itself must be higher than that of the laser beam.

As explained above, a waveplate or other birefringent optical element may rotate the direction of linear polarization, but more generally one will obtain an elliptical polarization state after such an element. True polarization rotation, where a linear polarization state is always maintained (just with variable direction), can occur in the form of optical activity. Some optically active substances such as ordinary sugar (saccharose) can produce substantial rotation angles already within e.g. a few millimeters of propagation length. Optical activity can be accurately measured with polarimeters.

A radially polarized laser beam may be generated from a linearly polarized beam with some optical element, but it is also possible to obtain radially polarized emission directly from a laser. The advantage of this approach, applied in a solid-state bulk laser, is that depolarization loss may be avoided [4]. Furthermore, there are applications benefiting from radially polarized light.

On the other hand, the polarization state of the laser output can be disturbed e.g. by random (and temperature-dependent) birefringence, such as occurs e.g. in optical fibers (if they are not polarization-maintaining or single-polarization fibers) and also in laser crystals or glasses as a result of thermal effects (→ depolarization loss). If the laser gain is not polarization-dependent, small drifts of the birefringence may lead to large changes of the polarization state, and also a significant variation in the polarization state across the beam profile.

A c-mount adapter for your microscope without a lens in it, is merely a connector for your camera. What you'll get is a "direct image" on the monitor screen, which is more magnification than what is seen in the eyepieces due to the inherent magnification with image sensors and microscopes. While this arrangement is fine for some users, others require an image on the monitor that looks more like the Field Of View, or FOV, that is seen in the microscope eyetubes.

There are cases where polychromatic light can be described with a single Jones vector, since all its frequency components have essentially the same polarization state. However, the polarization state is substantially frequency-dependent in other cases.

Of course, the polarization can have any other direction perpendicular to the beam axis. Note that a rotation of the polarization by 180° does not lead to a physically distinct state.

C-mountlensadapter

Fully polarized states can be associated with points on the so-called Poincaré sphere. Partially polarized states correspond to points inside that sphere; unpolarized light is represented by the point at its center.

The V-5MM is included with all the CK Series Analog Video Cameras that Meiji sells and supports. The adverse result that can happen when a spacer is not installed is a phenomenon known as "vignetting".

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In the previous cases, the direction of the electric field vector was assumed to be constant over the full beam profile. However, there are light beams where that is not the case. For example, there are beams with radial polarization, where the polarization at any point on the beam profile is oriented in the radial direction, i.e., away from the beam axis.

c-mountlensmicroscope

While optical activity usually results from the presence of chiral molecules, with a concentration difference between the two possible enantiometers, it can also be induced by a magnetic field in a substance which is not naturally optically active. That is called the Faraday effect, and is exploited in Faraday rotators and Faraday isolators.

A light beam is called unpolarized when the analysis with a polarizer results in 50% of the power to be in each polarization state, regardless of the rotational orientation. Microscopically, this usually means that the polarization state is randomly fluctuating, so that on average no polarization is detected. Note that such fluctuations are not possible for strictly monochromatic light.

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Jones vectors can be used only for fully defined polarization states, not for unpolarized or partially polarized beams (see below) having a stochastic nature.

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