Optical-axis sentence example
- The chief objections to the method are that, as one star is in the axis of the telescope and the other displaced from it, the images are not both in focus of the eye-piece,3 and the rays from the two stars do not make the same angle with the optical axis of each segment.
- 6 This most important improvement would permit any two stars under measurement each to be viewed in the optical axis of each segment.
- Where accurate differential observations or photographs involving other than instantaneous exposures have to be made, the additional condition is required that the optical axis of the telescope shall accurately and automatically follow the object under observation in spite of the apparent diurnal motion of the heavens, or in some cases even of the apparent motion of the object relative to neighbouring fixed stars.
- The Gaussian theory, however, is only true so long as the angles made by all rays with the optical axis (the symmetrical axis of the system) are infinitely small, i.e.
- It is readily seen that if the optical system be symmetrical, the origins of the co-ordinate systems collinear with the optical axis Object J Barrel shaped Cushion shaped Distorted image FIG.Advertisement
- Illuminating Systems Most microscopic observations are made with transmitted light; an illuminating arrangement is therefore necessary, and as the plane of the object is nearly always horizontal or only slightly inclined, the illuminating rays must be directed along the optical axis of the microscope.
- This concentration is most easily produced by sliding or revolving diaphragms. A series of holes of different sizes perforate a revolving disk below the stage plate at an equal radial distance from the axis of the disk, so that the holes can be brought under the preparation in turn, the centre of the diaphragms always being a continuation of the optical axis of the microscope.
- A changeable diaphragm is placed at the upper end of a short tube which can be moved in a case below the stage in the direction of the optical axis.
- An essential in all rough and fine adjustments is that the motion must always be parallel to the optical axis of the microscope, so that the same point in the object remains in the centre of the field.
- To obviate mistakes the optical axis of the microscope must coincide with the revolving axis of the plate, and the revolving plate has a central position C to keep this condition fulfilled.Advertisement
- This interpolation can, of course, be accomplished with the aid of a micrometer-microscope whose optical axis is normal to the plate, provided that the plate is mounted on slides which enable the observer to bring the reseau-squares successively under the microscope.
- The screw Q serves to adjust the axis of O i to coincidence with the centre of the lines of the solar spectrograph, and the screw G then serves to move the slide 132 till the optical axis of 0 2 is coincident with the centre of the lines of the stellar spectrograph.
- Now, if a graduated circle B B is attached to the declination axis, together with the necessary verniers or microscopes V V for reading it (see Transit Circle), so arranged that when the telescope is turned on the declination axis till its optical axis is parallel to A A the vernier reads 0Ã‚° and when at right angles to A A 90Ã‚°, then we can employ the readings of 2 Herschel, Phil.
- A second mirror N, placed at 45Ã‚° to the optical axis of the object-glass, reflects rays from a star at the pole; but by rotating the box which contains this mirror on the axis of its supporting tube T a star of any declination can be observed, and by combining this motion with rotation of the polar axis the astronomer seated at E is able to view any object whatever in the visible heavens, except circumpolar stars near lower transit.
- Upon an axis concentric with the declination axis is carried a plane mirror, which is geared so as always to bisect the angle between the polar axis and the optical axis of the telescope.Advertisement