Optics

“ By inspecting a dead carcass we shall never discover the principle of life; by inspecting a dead eye, or a camera obscura, we shall never discover the principle of vision. Yet, though there is no seeing in a dead eye, or in a camera obscura, optics deal exclusively with such inanimate materials; and hence the student who studies them will do well to remember, that optics are the science of vision, with the "fact" of vision left entirely out of the consideration. ”

“ Optics, like Astronomy, has for its object of inquiry, first, the laws of phenomena, and next, their causes; and we may hence divide this science, like the other, into Formal Optics and Physical Optics. The distinction is clear and substantive, but it is not easy to adhere to it in our narrative; for, after the theory had begun to make its rapid advance, many of the laws of phenomena were studied and discovered in immediate reference to the theoretical cause, and do not occupy a separate place in the history of science, as in Astronomy they do. ”

“ Let us hope, however, that the science of optics has now become so familiar to most educated people, that no such thing as a real imposition can take place, although at the present day there are so many exhibitions of the marvellous that ordinary observers have the greatest difficulty in accounting for them. ”

“ Thus, that there should be eyes capable of seeing, the laws of optics must be satisfied, reflection, refraction and the rest, just as exactly in the making of an eye as in that of a telescope. De facto they are satisfied. ”

“ Comparative sight is a far more important question than comparative anatomy. It is no matter, though we sometimes walk—and it may often be desirable to climb—like apes; but suppose we only see like apes, or like lower creatures? I can tell you, the science of optics is an essential one to us; for exactly according to these infinitely grotesque directions and multiplications of instrument you have correspondent, not only intellectual but moral, faculty in the soul of the creatures. Literally, if the eye be pure, the body is pure ”

“ Writing on Optics, he says: “’Tis pleasant to undeceive the eye in the common accidents of life, and to see it approach, in some measure, towards that certainty of judging and apprehending visibles that it will attain to at the day of resurrection, when it will be above the power of being cheated by concave or convex, or deluded by a refraction or reflection. This may, in a great measure, be accomplished in this world by such as give themselves up to the study of optics.” ”

“ Optics certainly appertain to the most important and completest branch of physics, and yet the undulatory theory of light, which we accept now as the indispensable basis of optics, rests on an unproved hypothesis, on the subjective assumption of an ethereal medium, whose existence no one is in a position to prove objectively in any way. ”

“ The peculiar appearances known as spectres in optics are certain illusions of vision in which an object is apparently presented to the view which does not really exist. In such cases either the brain, the retina, or the optic nerve are unnaturally excited, and made sensitive to an appearance that, physically speaking, does not exist. There is such a close connexion between the senses and the mind, that we continually, and without knowing it, transfer to the physical world that which belongs to the domain of thought. ”

“ Let the eye be kept steadily in one place, and take a distinct view of the object. We know, from the principles of optics, that the rays from any one point of this object, whether they pass through the centre of the eye, or at any distance from the centre which the breadth of the pupil will permit, do all unite again in one point of the retina. ”

“ The successive inductions by which Optics made her advances, might, of course, be treated in the same manner as those of Astronomy, each having its prelude and its sequel. But most of the discoveries in Optics are of a smaller character, and have less employed the minds of men, than those of Astronomy; and it will not be necessary to exhibit them in this detailed manner, till we come to the great generalization by which the theory was established. ”

“ He treats particularly the problem of optics, and physiological optics is the study of perception by means of the sense of sight. We see things in the external world through the medium of light which they direct upon our eyes. The light strikes the retina, and causes a sensation. The sensation brought to the brain by means of the optic nerve becomes the condition of the representation in consciousness of certain objects distributed in space.... ”

“ The object of this work is "to treat theoretical optics in a complete and uniform manner on the new foundation of the simultaneous vibration of etherial and ponderable particles, and to substitute a consistent and systematic new structure for the present conglomerate of more or less disconnected principles." Such a work demands a critical examination, which should not be undertaken from any narrow point of view. Any faults of detail will be readily forgiven, if the author shall give the theory of optics the πού στώ which it has sought so long in vain. ”

“ In the conflict of manifold opinions, and the great variety of hypotheses which seemed to promise nothing but endless disputes, the highest idea of the science of optics that prevailed, was that of something in relation to light which might be plausibly advanced and confidently maintained. It was reserved for Newton to produce a revolution in the mode of treating this branch of knowledge, as well as that of physical astronomy. ”

“ Physical optics, on the other hand, has for its ultimate object the elucidation of the question: what is light? It investigates the nature of the rays themselves, and, in addition to determining the validity of the axioms of geometrical optics, embraces phenomena for the explanation of which an expansion of these assumptions is necessary. ”

“ Of all the senses none is more frequently the seat of such deceptive judgments than that of sight; and in the science of physiological optics a very considerable share of attention is claimed by optical illusions. For the purposes of convenience, we may draw a distinction between these illusions, which are the direct result of certain properties or imperfections of the eye as an optical instrument, and those which arise from obliquities of judgment in interpreting the sensations optically impressed upon the retina of the eye. ”

“ Optic′ian, one skilled in optics: one who makes or sells optical instruments; Op′tics (sing.) , the science of the nature and laws of vision and light; Optim′eter, Optom′eter, an instrument for measuring the refractive powers of the eye; Optom′etry, the measurement of the visual powers.—Optic axis, the axis of the eye—that is, a line going through the middle of the pupil and the centre of the eye. ”

“ And it is only fair to point out that any one so ignorant of the simplest laws of optics as to share the popular notion that it does, is not competent to testify in this matter. Let the experimenter hold up between his eye and a clear, moonless night sky, a white card so inclined as to permit him to see its upper side. ”

“ It is not necessary to be thoroughly acquainted with the science of optics in order to see. A man may look through a telescope before he can define the refraction or reflection of light. Now all that is included in the word salvation hangs on this simple condition. ”

“ Next after astronomy the science of physical optics has furnished the most beautiful instances of the prophetic power of correct theory. These cases are the more striking because they proceed from the profound application of mathematical analysis and show an insight into the mysterious workings of matter which is surprising to all, but especially to those who are unable to comprehend the methods of research employed. ”

“ In order to illustrate the meaning of still further, we use an analogy from optics, namely the relation between image and object. From the pure optical standpoint, object and image are interchangeable. ”

“ This confused appearance of the OBJECT doth therefore seem to be the MEDIUM whereby the mind judgeth of distance in those cases wherein the most approved writers of optics will have it judge by the different divergency with which the rays flowing from the radiating point fall on the PUPIL. No man, I believe, will pretend to see or feel those imaginary angles that the rays are supposed to form according to their various inclinations on his eye. ”

“ The beginning of optics [6] will be to look up at the light, a thing natural to children; for the instant it becomes visible, they turn their eyes to it. They must, however, be watched, and not be permitted to look with fixed eyes on excessive light and brilliance, strongly affecting the power of vision, especially at first, lest that power be weakened, or extinguished by overstraining. Let them have the means of seeing moderate light, especially of a green color, and gradually anything that shines. ”

“ The point is, can we make a better one or must we be content with patching up the old one? Take an illustration. Scientists tell us that from the point of view of optics the human eye is a clumsy instrument poorly contrived for its work. ”

“ Not that I would complain of the association sanctioned by common parlance. A sound knowledge of at least the principles of general physics is necessary to the cultivation of any department. The predominance of the sense of sight as the medium of communication with the outer world brings with it dependence upon the science of optics; and there is hardly a branch of science in which the effects of temperature have not (often without much success) to be reckoned with. ”

“ Optical Instruments.—There were practical inventions in optical instruments long before this century. Achromatic and other lenses were known, and the microscope, the telescope and spectacles.
The inventive genius of this century in the field of optics has not eclipsed the telescope and microscope of former ages. ”

“ In Astronomy indeed, besides knowing the rules which guide the appearances, and resolving them into the real motions from which they arise, we can refer these motions to the forces which produce them. In Optics, we have become acquainted with a vast number of laws by which varied and beautiful phenomena are governed; and perhaps we may assume, since the evidence of the Undulatory Theory has been so fully developed, that we know also the Causes of the Phenomena. ”

“ The majority of those who have written touching the various parts of Optics have contented themselves with presuming these truths. But some, more inquiring, have desired to investigate the origin and the causes, considering these to be in themselves wonderful effects of Nature. ”

“ In optics certain lenses are needed for the reception and refraction of light; in chemistry a certain combination of elements is necessary to produce magnetism or electricity, and you may have these elements ever so perfect, and without the wire you cannot use them to convey intelligence ”

“ More acute observers would see that something more than mere invention had been at work, and would suppose that the drawings had been the result of marvellously careful induction, made by comparing the phenomena observed in the dead eye with the symptoms of living patients. At last, in the new civilization, someone living outside the tempest of rival theories, and studying optics for himself, would re-discover the principle of the ophthalmoscope, make one, and actually see living retinas. ”

“ The laws of optics, which show you an object in the water where it is not, and break a right line, are in entire accordance with those which make the sun appear to you with a diameter of two feet, although it is a million times larger than the earth. ”

“ Why has not Man a microscopic eye? For this plain reason, Man is not a fly. Say, what the use, were finer optics given, T'inspect a mite, not comprehend the heaven? ”

“ Suffice it to note how measureless the superiority, as a mere piece of mechanism, of an average eye to the finest of telescopes, and how just, nevertheless, is the telescope-maker's claim to praise for skilful adaptation to the laws of optics, when he has succeeded in a faint and feeble imitation of some minor part of nature's visual apparatus. ”

“ Chalmers seated among his friends on the Moderator’s chair––we find an exemplification sufficiently striking of the laws on which this seemingly mysterious power depends. They are purely structural laws, and relate not to the mind, but to the eye,––not to the province of the metaphysician, but to that of the professor of optics. The lens of the camera obscura transmits the figures to the prepared paper, on quite the same principle on which in vision the crystalline lens conveys them to the retina. ”

“ Many improvements and discoveries in optics and optical instruments have been made during the century, due to the researches of such scientists as Arago, Brewster, Young, Fresnel, Airy, Hamilton, Lloyd, Cauchy and others, and of the labours of the army of skilled experts and mechanicians who have followed their lead. ”

“ the difference is as great between The optics seeing, as the objects seen. All manners take a tincture from our own; Or come discolour'd, through our passions shown; Or fancy's beam enlarges, multiplies, Contracts, inverts, and gives ten thousand dyes. ”

“ They appear to us as men like ourselves, liable to perplexity and failure, instead of coming before us, as Newton does in the history of Physical Astronomy, as the irresistible and almost supernatural hero of a philosophical romance. 93
The main subdivisions of the great advance in physical optics, of which we have now to give an account, are the following:—
1. The explanation of the periodical colors of thin plates, thick plates, fringed shadows, striated surfaces, and other phenomena of the same kind, by means of the doctrine of the interference of undulations. ”

“ Physical optics, which was developed during the 19th century, in order to account for interference and diffraction represents light as a wave. (I have no idea if this is correct.) Awadewit (talk) 02:43, 14 April 2009 (UTC) How about, Developed during the nineteenth century, physical optics accounts for diffraction and interference by modeling light as a wave.? User:ScienceApologist Adopted your version. Awadewit (talk) 19:11, 18 April 2009 (UTC) Together, geometrical and physical optics encompass classical optics, a system of models capable of describing and predicting many optical phenomena. ”