Achromatic Lens Research Articles

The Lister Centenary Celebrations in London

ON April 5, 1827, there was born at Upton, in Essex, one who was destined to achieve more for the happiness of mankind than was vouchsafed to almost any other human being. Joseph Lister was the fourth child and second son of Joseph Jackson Lister, a prosperous wine merchant and also an eminent scientific worker, and fellow of the Royal Society, to whom we owe the production of the achromatic lens. He studied medicine at University College, London, and in 1852 took the M.B. degree and became also a fellow of the Royal College of Surgeons.

The scattering of light by liquid boundaries and its relation to surface tension. —Part II

In the first paper, a description was given of the scattering of light by metallic liquid surfaces, particularly of the manner in which the intensity and state of polarisation of the scattered rays vary with the angle of incidence of the primary rays and the direction of observation. We now proceed to consider the phenomena observed when the clean and dust-free surface of a transparent liquid is strongly illuminated. Whereas in the case of metals we have a very few substances which are liquid at ordinary temperatures, an enormous variety of transparent liquids is available for the purpose of the present study. In fact, at the time the investigation was taken up, an extensive collection of pure organic chemicals had been obtained from Kahlbaum, and bulbs containing some 64 different liquids, rendered dust-free by repeated distillation in cacuo , were ready for a programme of quantitative studies of the internal lightscattering. This collection naturally proved very convenient also for the purpose of the comparative study of the surface-scattering, and the extended observations made possible by its aid served to bring out very clearly the influence on the phenomenon of the surface tension of the liquid, and thus to establish its molecular nature. As already remarked in the first paper, in the case of transparent fluids, the surface-scattering is accompanied by the internal-scattering within the liquid when a pencil of light is concentrated upon the surface, but the two effects are distinguishable from each other in several particulars. By using a good achromatic lens to focus a well-defined image of the sun on the boundary, the surface opalescence appears as a sharply bounded circular or elliptic disc of light, whose aspect varies very much with the direction of observation while that of the internal-scattering does not. The colour of the surface opalescence is also much less blue than that of the internal-scattering, and, indeed, by contrast with it appears nearly white. Green, yellow and red filters held in front of the eye diminish the brightness of the volume effect much more (in increasing order) than they do that of the surface effect, and hence assist greatly in studying or photographing the latter phenomenon. The brightness of the surface-scattering also varies with the direction of observation, while that of the internal-scattering in dust-free liquids is practically invariable. In the case of oblique incidence of the primary beam, the surface-opalescence is conspicuously brighter when viewed in directions adjacent to those of the reflected or transmitted pencils than in other directions. In fact, it then stands out very clearly, and may be distinguished even with liquids such as carbon disulphide or nitrobenzene, in which the internal-scattering is so strong that it usually overpowers the surface effect.

A Small Measuring Microscope

A DESCRIPTION of a small measuring microscope devised by us may be of interest to readers of NATURE. The optical elements are extremely simple, consisting of a Ramsden eyepiece having a scale, divided on glass, which is permanently fixed in the focal plane. As the device is intended mainly for the observation and measurement of opaque objects, a thin parallel plate of glass is inserted at an angle of 45° between the lenses (Fig. 1). This serves to reflect diffused light on to the object observed and interferes very little with perception and measurement. In an eyepiece with a long working distance or using only an achromatic lens, the reflector may be interposed between the scale and the first lens. The instrument is, of course, equally available for the observation of transparent or aerial objects.

Note on achromatism with one glass

Systems composed of thin lenses of the same kind of glass and achromatised by selecting suitable positions for the components are members of the class [AD] [BC], so that if the object is real the image is virtual. Apochromatic systems constructed from normal achromatic lenses belong to the same class. The outstanding aberrations for systems constructed of a single glass but belonging to other classes are of considerable magnitude.

On the colours of the striæ in mica, and the radiation from laminar diffracting boundaries

The phenomenon which forms the subject of this paper was briefly described in a preliminary communication in ‘Nature,' made jointly by Prof. C. V. Raman and the author of this paper, accompanied by a short but suggestive note by Lord Rayleigh. It is observed when a clear sheet of transparent mica is placed in front of a good achromatic lens, and examined by the well-known Foucault “knife-edge” test, otherwise referred to also as the Topler “Schlieren” method. The arrangement is shown in fig. 1. White light from a slit, S (illuminated by a half-watt incandescent lamp of 100 C.P.), is incident upon the lens, L, which forms an achromatic image of the slit at some distance from the lens. A knife-edge, K, is put in the focal plane, and so placed that the light coming to a focus in the ordinary way is completely cut off. The telescope, T, with its objective just behind the plane of the knife-edge, is pointed towards the lens, and is focussed on the surface of the mica (M. M.) placed immediately in front of the lens.

Obituary notices of fellows deceased

Joseph Lister was born at Upton in Essex on April 5, 1827, and like many other men who have attained great eminence, belonged to a Quaker family. His father, Joseph Jackson Lister, who was in business in London, occupied his leisure time in scientific researches, more especially in researches in connection with the perfection of the microscope; indeed, it is to his researches that we owe the final perfection of the achromatic lens, which has proved such an essential instrument for microscopical work. He was a man of great accuracy of thought, and a hard worker, and his influence on Lord Lister's character and career was very profound; indeed, Lord Lister himself was never weary of stating how much he owed to his father's early training. It may be noted, in passing, that his father was himself a Fellow of the Royal Society, and that his brother and one of his nephews have also received that honour. Lister's medical training commenced at University College, and while there he came under the influence of Sharpey, who was then Professor of Physiology, and of Thomas Graham, who was Professor of Chemistry. Sharpey especially exercised great influence in directing his thoughts to the study of Physiological problems, which ultimately formed the basis of his great life work; indeed, while still a student he made observations on the contractile tissue of the iris which attracted a considerable amount of attention among physiologists, both in this country and abroad, and he followed that up by work on the muscular tissue of the skin. Both these papers were published in the 'Quarterly Journal of Microscopical Science,' in 1853.

Solar eclipse expedition to Kalaa-es-Senam, Tunis

When the Court of the University of Glasgow made to me an unsolicited grant of £50 to see the eclipse, I decided to take active part in its observa­tion, though in a small way. Together with Mr. Franklin-Adams I accepted the invitation of Mr. Andrew Crookston, Glasgow, to observe it at his mines at Kalaa-es-Senam, Tunis. The station lies 33 m. 30 s. east of Greenwich (from map) at a latitude of 35° 45' 19" as determined from pole-star observations. Its altitude above sea-level is 953 metres. It is about 40 miles from Morsott, a station on the railway from Bona to Tebessa. I set myself the problem to determine from a series of correctly-timed photographs the law according to which the light of the corona decreases with the distance from the sun. I designed mechanisms by which 10 exposures are automatically made on one plate, the mechanisms being governed electrically by a pendulum clock. I employed two cameras, one with a Cooke triple achromatic lens of 3½ inches aperture and 60 inches focal length, which belongs to the Glasgow spectrograph, the other with a Ross portrait lens of 2 inches aperture and 12 inches focal length. They were fed by a cœlostat of 8 inches aperture, which had been kindly lent to me by the Royal Dublin Society. In front of the two object-glasses a rotating shutter was mounted which served both cameras. The rotating shutter has four oblong apertures, 90° apart; it is rotated by clockwork driven by a spring, and its motion is governed by the armature of an electro­magnet. When the armature is attracted the shutter rotates through 45°, bringing an opening opposite the object-glasses, and when it is released it turns again 45°, when the shutter shuts off the light. The contacts are made by a pendulum clock, and they are so devised that make or break can occur only when the pendulum is at or near its position of rest. I arranged for live exposures of 1 second duration, and five exposures lasting respec­tively 3, 9, 20, 46, and 89 seconds. Their actual durations are 0·86, 0·82, 0·80, 0·82, 0·87, 2·82, 9·02, 20·84, 45·91, and 89·04 seconds, as determined automatically on the chronograph. At the first four exposures of 1 second, different screens, each with 13 holes, are in front of the object-glasses. At the first exposure the screen leaves about one-sixteenth of the object glasses free, at the second one-eighth, at the third one-fourth, and at the fourth one-half. These screens are geared to the clockwork which rotates the shutter.

Our Astronomical Column

A NEW ACHROMATIC OBJECT-GLASS.—It is well known that in consequence of the irrationality of dispersion the nominally achromatic object-glass is really very far from achromatic. There is always a residual colour, frequently called the secondary spectrum, so that the images of bright stars are surrounded by halos of blue and red light. For this reason a refracting telescope designed for visual observations cannot be employed for photography. Many attempts have been made to correct this colour aberration of the achromatic lens, but the plans hitherto suggested have never been practically adopted, owing to difficulties of construction, or to the imperfect durability of the glasses employed. Mr. H. D. Taylor, optical manager to Messrs. T. Cooke and Sons, has recently taken up the question, and he appears to have come very near to a practical solution of the problem. He has aimed at producing an objective which shall be (1) almost perfectly achromatic; (2) equally well corrected for photographic purposes as for visual purposes; (3) capable of practical construction in large sizes; and (4) of ordinary durability.

Phenomena Developed by Heliostatic Star-Disks

A HELIOSTAT of the highest class is doubtless beyond the means of ordinary observers, but such an instrument as the one now described is readily obtainable. Three sets of achromatic lenses forming a focal power of forty at ten inches, or a miniaturing power of one-fortieth, are in general sufficient. If formed into a microscopic object-glass, the front is turned towards the sun. The glass then refracts a beautifully small star-disk, which, owing to the large angular aperture of the combination, remains steadily in view for several hours. The optical characters of this disk vary considerably with the quality of the lenses; practically a very fine one-quarter by Powell and Lealand produces disks of remarkable beauty and precision. In some cases a plane mirror is conveniently attached to reflect the oblique solar rays.

4. On the best Arrangement for producing a Pure Spectrum on a Screen

In experiments on the spectrum, it is usual to employ a slit through which the light is admitted, a prism to analyse the light, and one or more lenses to bring the rays of each distinct kind to a distinct focus on the screen. The most perfect arrangement is that adopted by M. Kirchhoff, in which two achromatic lenses are used, one before and the other after the passage of the light through the prism, so that every pencil consists of parallel rays while passing through the prism.But when the observer has not achromatic lenses at his command, or when, as in the case of the highly refrangible rays, or the rays of heat, he is restricted in the use of materials, it may still be useful to be able to place the lenses and prism in such a way as to bring the rays of all colours to their foci at approximately the same distance from the prism.

New process in the making of glass for achromatic lenses for telescopes

New process in the making of glass for achromatic lenses for telescopes

The chemical foci of achromatic lenses

The chemical foci of achromatic lenses

The chemical and visual foci of achromatic lenses

The chemical and visual foci of achromatic lenses Get access E. S. E. S. Search for other works by this author on: Oxford Academic Google Scholar Notes and Queries, Volume s1-VI, Issue 161, 27 November 1852, Page 515, https://doi.org/10.1093/nq/s1-VI.161.515a Published: 27 November 1852

On photographic self-registering meteorological and magnetical instruments

The apparatus employed by the author at the Kew Observatory, and which he terms the Photo-Electrograph, is described by him in the following words:—“ A rectangular box, about sixteen inches long and three square, constitutes the part usually called the body of a kind of lucernal microscope. A voltaic electrometer (properly insulated, and in communication with an atmospheric conductor) is suspended within the microscope, through an aperture in the upper side, and near to the object end. That end itself is closed by a plane of glass, when daylight is used, and by condensing lenses, when a common Argand lamp is employed. In either case an abundance of light is thrown into the microscope. Between the electrometer and the ether, or eye-end of the microscope, fine achromatic lenses are placed, which have the double effect of condensing the light upon a little screen, situated at that eye-end, and of projecting a strong image of the electrometer, in deep oscuro , upon it. Through the screen a very narrow slit, of proper curvature, is cut (the chord of the arc being in a horizontal position), and it is fitted into the back of a case, about two-and-a-half feet long, which case is fixed to the eye-end of the microscope, at right angles with its axis, and vertically. Within the case is suspended a frame, provided with a rabbet, into which two plates of pure thin glass can be dropped, and brought into close contact by means of six little bolts and nuts. This frame can be removed at pleasure from a line, by which it is suspended, and the line, after passing through a small aperture (stopped with grease) cut through the upper end of the long case, is attached to a pulley (about four inches in diameter), fixed, with capacity of adjustment, on the hour arbor of a good clock. Lastly, counterpoises, rollers, springs, and a straight ruler are employed for ensuring accurate rectilineal sliding of the frame, when the clock is set in motion. “A piece of properly prepared photographic paper is now placed between the two plates of glass in the moveable frame; the frame is removed (in a box made purposely for excluding light), and is suspended in the long case ; this is closed, so as to prevent the possibility of extraneous light entering with it; the clock is started, and the time of starting is noted.

X. On photographic self-registering meteorological and magnetical instruments

The Council of the Royal Society having, in April last, granted to me, out of the Donation Fund, fifty pounds “for the purchase of magnetical and meteorological instruments” necessary to the prosecution of experiments in which I was then (and had been long previously) engaged, I feel very anxious to express, now, my deep sense of obligation for its munificence, and to endeavour to show that successful and satisfactory results, in great measure due to the timely assistance thus kindly afforded, have been attained. It would be superfluous to speak of those proposals of other gentlemen, or of my own, for self-registering, photographically, the variations of the declination magnet and the thermometer which were made previously to the use of good achromatic lenses, for projecting, upon photographic paper, a sharp image, magnified to any required degree, of that part of the instrument whose motions are to be registered .

On the construction and use of single achromatic eye-pieces, and their superiority to the double eye-piece of Huyghens

The author observes, that experience has shown it to be impracticable to make a telescope even approach to achromatism, by employing the same object-glass with an astronomical, as with a terrestrial eye-piece: for if the focus of the blue rays from the object-glass be thrown forwards, as it must be in order to make it impinge upon the focus of the blue rays of the terrestrial eye-glass, then there will be produced a great over-covrection for the astronomical eye-glass; and vice versa . Hence it appears that the application of Huyghenian eye-pieces to refracting telescopes, is incompatible with the conditions of achromatism, throughout the entire range of magnifying power; and that in reflecting telescopes they unavoidably introduce dispersion, because they are not in themselves achromatic. These defects the author proposes wholly to obviate, by substituting for the Huyghenian eye-pieces, single achromatic lenses of corresponding magnifying power; consisting of the well-known combination of the crown-lens, and its correcting flint-lens, having their adjacent surfaces cemented together; thus avoiding internal reflections, and enabling them to act as a single lens. The achromatic eye-pieces which he uses were made by Messrs. Tulley and Ross, and are of the description usually termed single cemented triples .

An account of concave archromatic lens, adapted to the wired micrometer, which has been named Macro-micro , from its power to increase the primary imae of telescope without increasing the diameter of the wires in the micrometer

The application of a concave achromatic lens to the wired micrometer of a telescope, arose out of the series of trials that were made for the purpose of correcting the aberrations of the eye-glasses applied to the telescope constructed by the author for the Royal Society, with a fluid-correcting lens, on the plan suggested by Professor Barlow. The concave lens, being interposed between the object-glass and the eye-glass, and being at the same time achromatic, combines the advantages of doubling the magnifying power, without a corresponding diminution of light, and without altering the apparent distances of the threads of the micrometer. The results of the trials made with telescopes to which this addition was made, are given in a letter to the author from the Rev. W. R. Dawes, of Ormskirk; from which it appears that Mr. Dollond’s method was attended with complete success. Mr. Dawes states, that, in order to put its illuminating power to a severe test, he had examined with this instrument the satellites of Saturn and the minute companion of k Geminorum, but could discover no decided difference in the apparent brightness of the former, allowance being made for the difference in the power employed; and the latter star was seen quite as distinctly with a much smaller power. Extracts are subjoined from a letter of Professor Barlow’s to the author, containing formulæ for the construction of the lens.

XI. An account of a concave achromatic glass lens, as adapted to the wired micrometer when applied to a telescope, which has the property of increasing the magnifying power of the telescope without increasing the diameter of the micrometer wires

When the application of any optical or other arrangement is found to be useful, a correct statement of the manner in which it became so is essentially requisite, in order that each person who may have had a share in bringing it forward may have his due proportion of the merit. The achromatic lens which I have applied to the wired micrometer, and which has been found to produce such very considerable advantages to that instrument, arose out of a trial that was made at the suggestion of Professor Barlow, for the purpose of improving the chromatic aberrations which affected the field of the eye-glasses ap­plied to the telescope invented by that gentleman with a fluid correcting lens, and made by myself for the Royal Society.

XII. On the principle of construction and general application of the negative achromatic lens to telescopes and eyepieces every description

The great advantage which has attended Mr. Dollond’s ingenious application of the negative achromatic lens to the micrometer eyepiece, seems to make it desirable that the principles on which that lens is constructed, and its general application, should be more fully illustrated than is done in the short extract made from my letter to Mr. Dollond, and given by him in his recent paper in the Philosophical Transactions. In my original fluid telescope, the negative lens was employed for the double purpose of lengthening out the focus and correcting the colour of the front lens; and the great advantage of the lengthening principle was manifested by the high penetrating power of the instrument in the centre of the field. Unfortunately, however, the perfect part of this was very limited, so that when Mr. Dollond constructed the second telescope for the Royal Society, I gave up this advantage for the sake of enlarging the held; but I found that by this means much of the penetrating power of the former telescope was lost; for although I had the same aperture, many small stars which were before very perspicuous were in this instrument seen only with difficulty and under advantageous circumstances of weather, absence of moonlight, &c.