Exit pupil

Figure 9. The entrance and exit pupils are the surfaces where the entrance and exit rays coming from the different field positions cross each other. In different terms, the entrance pupil is the aperture of the optical system as seen by an observer located at the position of the object, or at the location of the image for the exit one.

Entrance and exit pupils are conjugates i.e. images of each other through the optical system. The real physical aperture may be neither of them, hut set hy a physical diaphragm or component contour, located... 

We have developed another bench for the measurement of the contrast value. Contrast measurement have been carried out on the MMA fabricated by Texas Instrument, in order to establish the test procedure (Zamkotsian et al., 2002a Zamkotsian et al., 2003). We can address several parameters in our experiment, as the size of the source, its location with respect to the micro-elements, the wavelength, and the input and output pupil size. In order to measure the contrast, the micro-mirrors are tilted between the ON position (towards the spectrograph) or the OFF position (towards a light trap). Contrast exceeding 400 has been measured for a 10° ON/OFF angle. Effects of object position on the micro-mirrors and contrast reduction when the exit pupil size is increasing have also been revealed. 

Figure 12. Schematic view of the projector used to launch 3 simultaneous Rayleigh beams into the sky. A spinning mirror Ml at an image of the exit pupil directed successive laser pulses into three separate beams (only 2 shown here) without causing beam wander on the primary mirror M2. Electronic synchronization was implemented between the motor and the laser.

The external geometric differential delay (see below) of an off axis source is exactly balanced within a Fizeau interferometer, resulting in fringes with the same phase on top of each source in the field. The position of a source may differ from the position of zero OPD in a Michelson interferometer depending on how dissimilar entrance and exit pupils are. The fringe contrast of off-axis sources also depend on the temporal degree of coherence of the detected light. 

The MTF curve can be described mathematically in terms of the above variables. As an example, the MTF [(7/( /)l of a lens employing incoherent illumination and a circular exit pupil is given by... 

The Zernike polynomials are functions of the polar coordinates (r, 0) of positions r and angle 6 in the exit pupil. Because the same point in the exit pupil is specified by 6 and (6 -1-360 deg), it is convenient for the polynomials to be expressed as functions of sin(u0) and cos(u0), where n is an integer." Although the Zernike polynomials comprise an orthogonoal polynomial series with an... 

Ophthalmic imagers often use a scanning technique with the pupil of the eye placed in the exit pupil of the scanning system [461]. This reduces image distortion and blurring due to the poor optical quality of the lens of the eye. Moreover, confocal detection can be used to suppress reflection, scattering, and fluorescence signals from the lens of the eye. 

Close the aperture diaphragm on the substage condenser so that its radius is 70-80% of the illuminated field (the exit pupil of the objective). Streening off the outer 20-30% of the exit pupil gives an approximate match between the NAs of condenser lens and objective lens. 

The 20-30% screening of the exit pupil is a rule of thumb, and the final adjustment of the aperture diaphragm alters image quality in various ways. As the aperture diaphragm is closed, resolution decreases, but both the contrast and the depth of field increase (see Note 7). As stated already, there should be no vignetting when the aperture diaphragm is adjusted, only a uniform variation in lighting intensity. 

We now consider the relation between the wave function in the object plane and in the image plane z = Zi conjugate to this, in which h(z) vanishes h(zi) = 0. It is convenient to calculate this in two stages, first relating irixi, yu Zi) to the wave function in the exit pupil plane of the lens, f Xo, ya, Za) and then calculating the latter with the aid of Eq. (62). Introducing the paraxial solutions G(z), H z) such that... 

These quadratic factors are of little praetical consequence they measure the curvature of the wave surfaee arriving at the specimen and at the image. If the diffraction pattern plane coincides with the exit pupil, then o = L We write h z.o) = / since this quantity is in practice close to the focal length, so that for the case Zd = Za,... 

In the paraxial approximation, the aperture function A is simply a mathematical device defining the area of integration in the aperture plane A = 1 inside the pupil and A = 0 outside the pupil. If we wish to include the effect of geometric aberrations, however, we can represent them as a phase shift of the electron wave function at the exit pupil. Thus, if the lens suffers from spherical aberration, we write... 

F-number The ratio of the focal length of a lens to the diameter of the exit pupil of that lens. The F-number of a well-corrected lens is the reciprocal of twice its numerical aperture. 

If the telescope is to have a sizable field of view, as measured by the angle a, then the eyepiece could become prohibitively large. To reduce the diameter of the eyepiece, sl field lens is installed near the secondary focal plane of the objective. The field lens, which may be part of the eyepiece, directs the principal ray toward the axis and allows the diameter of the eyepiece to be reduced. Typically, the focal length of the field lens may be chosen so that the principal ray intersects the eyepiece at its periphery. This shifts the location of the exit pupil somewhat toward the eyepiece and slightly reduces the eye relief ht-tween the eye and the eyepiece. When the field lens is built into the eyepiece, the second lens in the eyepiece is called the eye lens. 

Figure 4. Schematic of Kohler illumination A) Image-forming ray path B) IHuminaling ray path a) Eye b) Eyepiece c) Eyepiece field stop d) Exit pupil of objective e) Objective f) Specimen g) Condenser h) Aperture diaphragm i) Lamp field stop J) Light collector k) Light source...

The entrance pupil refers to the size and location of the entrance aperture between the light source and the remainder of an optical system. The exit pupil refers to the size and location of the exit aperture within an optical system (or train) just prior to the detector. 

Figure 14 Graph illustrating the variation in refractive depth of a ray as a function of the starting position of the ray within the exit pupil of the lens. The graph is plotted for lenses with a range of numerical apertures.

In cell biology a combination of high spatial, spectral (and sometimes also temporal) resolution is often desirable. This can be achieved using a fluorescence microscope equipped with a sensitive video camera as well as an emission monochromator. Usually the camera target is fixed in the image plane of the microscope, whereas the entrance slit of the monochromator is placed either in the image plane or in the exit pupil. 

Series I consists of the lamp filament, the front focal plane of the condenser (which is located at the aperture iris), the back focal plane of the objective and the exit pupil of the eye. 

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