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All kinds of optical elements can be incorporated into the optomechanical constraint equations, following the same procedures as discussed in previous chapters. This chapter will present the flat-fold mirror, the powered mirror, the window, the diffraction grating, and the prism.
The flat-fold mirror shown in Fig. 4.1 uses three coordinate systems: one for the object, one for the mirror, and one for the image. Since a flat-fold mirror changes the direction of the optical axis, these coordinate systems might not be either parallel or congruent. The magnification of the flat fold mirror is 1.0.
With light coming from left to right, the object coordinate system has its origin at the point where the object crosses the incident optical axis (or its projection, as shown in the figure). Note that the object in this case is behind the mirror. Its positive Z axis is opposed to the direction of the incident light, and its Y-axis direction is upward. The X axis completes a right-handed coordinate system for the object of the mirror.
The mirror’s coordinate system has its origin at the point where the optical axis intercepts the mirror surface; its positive Z axis is normal to the mirror surface on the incident side, and the Y-axis direction is upward (on the same side of the incident axis as the object’s Y axis). The X axis completes a righthanded coordinate system for the mirror.
The image’s coordinate system has its origin at the point where the image crosses the reflected optical axis. Its positive Z axis is against the imaging light (toward the mirror), and its Y axis is an image of the object’s Y axis. The image’s X axis completes a right-handed coordinate system. Note that the image’s X axis has flipped to the opposite side of the mirror’s Y-Z plane from the object’s X axis.
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