US3451744A - Self-adjusting slit mechanism - Google Patents

Self-adjusting slit mechanism Download PDF

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Publication number
US3451744A
US3451744A US558481A US3451744DA US3451744A US 3451744 A US3451744 A US 3451744A US 558481 A US558481 A US 558481A US 3451744D A US3451744D A US 3451744DA US 3451744 A US3451744 A US 3451744A
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Prior art keywords
slit
jaw
cam
slit jaw
variable
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Expired - Lifetime
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US558481A
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English (en)
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Charles F De Mey
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Applied Biosystems Inc
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Perkin Elmer Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/04—Slit arrangements slit adjustment

Definitions

  • variable slit jaws should be coplanar, their edges should remain exactly parallel, and each edge should remain an equal distance from a xed center line (namely, the line along which the two edges would meet when the variable slit mechanism is completely closed), at all variable slit width settings.
  • the problem of maintaining the correct relationships between a pair of movable slit jaws defining a single variable width slit becomes compounded by the fact that a pair of such variable slits is often required (for example, in spectrometers), and there is the additional requirements that each of the variable slit mechanisms track so as to maintain a certain desirable relationship (which is often merely equality) at all slit width settings.
  • prior successful variable slit mechanisms and especially those which are synchronously paired have required extreme precision in manufacture, assembly, and alignment, and have for this reason been relatively expensive and diicult to maintain.
  • the invention provides a synchronously operated pair of variable slits, having all of the above desired attributes, which is relatively inexpensive to manufacture and requires no tedious alignment and adjustment procedures whatsoever.
  • the slit mechanisms of the invention are inherently selfadjusting.
  • the individual slit jaws defining each of the two slits are inherently coplanar, since a single jaw and its reflection in a plane mirror define each of the slits.
  • the edge of each slit jaw is maintained parallel to the mirror surface by semiautomatic or self-regulating adjustment relative thereto, thereby assuring that the slit has parallel edges at all variable width settings.
  • a semiautomatic or self-adjusting operation assures that the movable slit jaw is (during use) at a known standard position relative to the means for varying the slit width.
  • the invention additionally assures not only that each of the individual slits are so adjusted, but also self-regulates the position of the movable jaws of both slits to the same desired known standard position relative to the variable slit width driving means. This insures that both variable slits will be in synchronous tracking adjustment relative to each other.
  • the invention allows this multiple self-adjustment to occur whenever desired (including between every use of the instrument) without any expenditure of time or energy of the operator.
  • slit mechanisms according to the invention may be relatively inexpensively manufactured and assembled because very few of the parts require high precision in either their making or assembly.
  • the object of the invention is the provision of a variable width slit mechanism, particularly of the double slit type, which maintains to a high degree of precision the desired relationships and attributes mentioned above, but which is relatively inexpensive to manufacture, simple to assemble, and requires no tedious readjustment during use.
  • FIG. 1 is a plan view of one example of the entire variable-width, double-slit mechanism.
  • FIG. 2 is a front elevational view of the same system, looking in the direction indicated at 2-2 in FIG. 1.
  • the device comprises the slit mechanism proper mounted on a mechanism plate 10 and a cam 12 for varying the widthof the slits in a manner which will be described hereinafter.
  • Rigidly mounted on plate 10 is a prism 14 having at reflecting outer surfaces at 16 and 17.
  • prism 14 is shown as attached to the upper end of a post 15, the lower end of which is rigidly attached in a suitable manner to the mechanism plate 10.
  • Each of the at rellecting surfaces 16 and 17 of this prism are adjacent to and cooperate with a different movable mounted slit jaw 18 and 19 respectively.
  • These slit jaw elements are preferably in the form of thin-plates, each having a relatively sharp straight edge (at 20 and 21, respectively) closely adjacent to the respective rellecting surfaces 16 and 17. It has been found that commercially available razor blades may be used as the slit jaw elements.
  • Slit jaw 18 is ultimately supported by bracket 22, which comprises a horizontal portion 24 and an integral or at least rigidly connected vertical portion 26.
  • This right-angle support bracket 22 1s mounted for pivotal movement about a vertical axis by being loosely secured (near one end of horizontal portion 24) by a screw 40 in a manner which will be subsequently described.
  • a pin 28 rigidly extends from near the center of the surface of vertically extending portion 26 toward the slit jaw 18.
  • a magnetized plate 30, apertured to allow passage of pin 28, is positioned between the adjacent surfaces of vertical portion 26 and slit jaw element 18.
  • slit jaw 18 has an aperture at 32 which loosely receives pin 28.
  • This aperture is illustrated as a horizontally extending central slot, since certain types of commercially available razor blades are so apertured.
  • the aperture may be of any shape which will loosely engage pin 28, since only the right-hand internal edge of the aperture 32 (as seen in FIG. 2) need be precisely located relative to pin 28, as will be subsequently explained.
  • slit jaw 18 By utilizing ferrous materials for both the slit jaw element 18 (as is true of commercially available razor blades) and the support bracket 22 (or at least vertical portion 26 thereof), magnetic plate 30 will be attracted to the latter and will in turn magnetically hold the former. For this reason slit jaw 18 is securely held against the adjacent face of magnetic plate 30, which in turn is held securely to the confronting surface of vertical portion 26, Nevertheless slit jaw 18 need overcome only a moderate amount of frictional resistance to move in any direction in its own plane, including angular motions therein (i.e., about a horizontal axis).
  • the pin (28) and slot (32) connection restrains the possible movement of slit jaw 18 to a very small vertical movement and a moderate horizontal movement, but does not restrict any pivotal motion thereof in its own vertical plane.
  • Support bracket 22 is pivotally mounted on mechanism plate by means of screw 40 and washer 42 of very low coeflicient of friction material (which may be, for example, Tellon).
  • a long actuating arm 44 carrying at its other end a camfollowing roller 46 bearing on cam 12.
  • Arm 44 carries near its middle an upstanding pin 48, which supports one end of tension spring 50, the other end of which is attached to pin 52 rigidly mounted on mechanism plate 10.
  • tension spring 50 therefore biases arm 44 in a counterclockwise direction about a pivot defined by screw 40 so as to cause cam follower 46 to press against cam 12.
  • a second washer 56 (which may be identical to washer 42) is positioned on screw 40 between the lower surface of long arm 44 and the mechanism plate 10.
  • This second washer 56 is also of a material having an extremely low coefficient of friction relative to the material (any conventional structural metal) of arm 44, so that the frictional drag is substantially below the tension force supplied by spring 50; in fact the second washer 56 acts as a moderately low friction bearing surface.
  • washers 42 and 56 may be somewhat different, it is entirely practical to make them both of the same material as long as the total frictional drag of both washers combined is substantially less than the torque supplied by spring 50.
  • variable width slit involving the parts already described is as follows.
  • the rotational position of the support bracket 22 relative to the long control arm 44 is rst overset and then set to a standard or adjusted position.
  • the first overset condition is obtained by moving arm 44 in a clockwise direction (in FIG. 1) sutciently to assure that edge portion 24' of the support bracket 22 not only meets limit pin 60 but is arrested thereby before rotational movement of arm 44 ceases. This assures that arm 44 is more advanced clockwise (relative to support bracket 22) than a certain standard relationship desired to be obtained.
  • the oversetting or the adjustment or both may be readily accomplished by manual movement of, say, arm 44, the above described setting of the standard or adjusted position may be readily incorporated in the otherwise conventional means for automatically programming the width of slits, as is used in various optical instruments (and especially in monochromators as incorporated in various spectrometers). Since a rotating edge cam is commonly used to program the width of the variable slits in such optical instruments, the exemplary means shown is of this type; however other means may be used instead. For pusposes of illustration cam 12 is assumed to rotate in a clockwise direction about axis 13 in synchroni-sm with, say, the wavelength drive of a monochromator of a program-med spectrometer.
  • the edge 54 of cam 12 has a slit width programming curve extending over the major portion of this edge between points 70 and 72 (counterclockwise in FIG. 1).
  • a typical slit width program is indicated on this portion of the edge of the cam. Specifically the starting portion 70 is somewhat higher than a low point 74 so that the wavelength scan is initiated with the slit jaws open somewhat beyond their minimal setting.
  • the cam edge then recedes somewhat between .points 70 and 74 so as to cause gradual closing of the slits to their minimal opening. After maiutaining this minimal radius for some time, the cam edge then constantly increases this distance from the center of rotation of the cam, thereby causing the slits to open more and more. The highest point 72 of this gradual increasing radius portion of the cam is at the end of the normal scan program.
  • a somewhat different contour of the cam edge is shown in dotted line at 80.
  • the -use of spacers 62 and 64 is considered optional. If they are not used, the edge 20 of sl-it jaw 18 will obviously abut directly on prism surface 16 during the adjustment phase. rThis wil-l obviously cause the standard or correctly adjusted relationship between the arm 44 and the rest of the slit mechanism to occur at a zero width opening (i.e., edge 20 completely tight against prism surface 16). Since it is obviously undesirable to allow the slit to ever close during an optical measurement, the optional cam edge contour 80 would be provided if spacers 62 and 64 are not used.
  • Optional contour l80 contains portions more recessed than any other part of cam edge 54, to insure that no other part of the cam program will cause the slits to completely close.
  • the adjustment to the correct standard position will occur at a position corresponding to zero width adjustment; and the optional deeper recessed portion 80 insures that the slits will not close at any other part of the controlled cycle.
  • the standard or correctly adjusted position will be set with the slits at least as much closed as they will ever be used.
  • the other slit mechanism is substantially identical in every respect, except for two differences.
  • all of the elements thereof are related to the elements of the already described slit 'in the same manner as a righ-t hand is related t-o a left hand, and therefore operate in exactly the opposite angular directions. All of these elements (numbered lbetween 19 and 65) are otherwise identical to the corresponding elements numbered one lower, already described.
  • the second exception is that there are no elements exactly corresponding to long arm 44, cam follower 46 or cam 12 (or any of its parts 54 and 70-80).
  • the second slit mechanism has a relatively short actuating plate 144 -which frictionally engages the lower part of horizontal portion 2S of support bracket 23 in essentially the same manner as long arm 44 engages the corresponding horizontal plate portion 24 of the already-described first slit mechanism.
  • a follower portion 146 of actuating plate 144 extends toward the adjacent portion ⁇ of long arm 44, and is engaged by a driving nose portion 112 of arm 44, as may best be seen in FIG. 1.
  • Spring 51 biases actuating plate 144 in a counterclockwise direction so as to cause follower portion 146 to remain in engagement with driving linger 112 at all times.
  • elements 112 and 146 operate at least somewhat analogously to elements 12 and 46, while actuating plate 144 is even more closely comparable to actuating arm 44.
  • all of the elements of the second (i.e., right-'hand in FIG. 2) slit mechanism 4 are both structurally and functionally the same (except for being mirror images and rotating in t'he opposite direction) to the corresponding parts already fully described of the left-hand slit.
  • the exact position of the overset limit pins 60, 61 requires no great degree of precision. All that is necessary is that they be far enough from the center of the double slit so as not to engage the adjacent portions of the support brackets 22 and 23 at any (i.e., the widest) slit width actually used in the slit program, but are sufiiciently close to the center line to assure that these adjacent portions (24', 25') press against these pins when the highest point of cam 12 (or other means) pushes the arm 44 to its most clockwise position.
  • slit jaws 18 and 19 may be razor blades, thus providing extremely precise edges 20, 21 at very low cost.
  • the spacers 62-65 may comprise readily available inexpensive shim stock. All of these elements may therefore be replaced from time to time at minimal expense.
  • Prism 14 need not be of optical glass or other expensive material, only its reecting surfaces 16 and 17 being used. Thus all of the elements requiring a high degree of precision may be obtained at low expense.
  • the reecting surfaces are the limiting factor in the height of the usable slit, elongating these surfaces ill obviously increase the usable slit length (the spacers6 65, if used, being positioned near the ends of whatever is the limiting element of the slit length).
  • the spacers6 65 if used, being positioned near the ends of whatever is the limiting element of the slit length.
  • the upper and lower edges of the slit will be defined by the upper and lower edges of an auxiliary element, for example, an opaque mask having a rectangular opening; and the spacers 62-65 would be just obscured by such a mask.
  • FIG. 1 An exemplary light path is indicated in FIG. 1.
  • the incoming light beam will follow ray 90 so as to be retiected off the surface 17 of prism 14 along the direction indicated by ray 92.
  • Edge 21 of slit jaw 19 and its reection in mirror 17 will therefore define a variable width entrance slit (of narrow rectangular shape) to, say, the monochromator of a spectroscopic optical instrument.
  • the beam represented by ray 92 will then pass through the, say, monochromator (which will disperse the radiant energy according to its wavelength). At least some of the radiation (in this case a particular wavelength thereof) will return from the monochromator along ray path 94 to the second slit defined by edge 20 of slit jaw 18 and its reflection in mirror surface 16. After passing through this exit slit, the beam will be traveling along ray path 96, ultimately to fall upon, say, a radiation detector.
  • a single variable position slit jaw e.g., 18, 20
  • a single reecting surface (16) may be utilized to form a single variable width optical slit, if only one such slit is required.
  • the particular illustrated embodiment achieves not only a precise, reproducibly tracking variable slit, but additionally provides a pair of such slits that inherently maintain synchronous width adjustment, so that it is particularly applicable to such double slit requirements.
  • variable-width optical slits having all the desirable relationships previously mentioned between the variable effective slit jaws, that are self-adjusting and relatively inexpensive to manufacture and assemble.
  • the invention is not limited to any of the details of the specific illustrated embodiment, lbut rather is defined by the scope of the appended claims.
  • a self-adjusting optical slit mechanism of variable width comprising:
  • moving means for moving said actuating means and for forcing said actuating means to move relative to said slit jaw through said slippable connection when the movement of said slit jaw reaches the open or closed extreme;
  • a second slit jaw is in confronting relationship with said variable position slit jaw means
  • variable width slit is defined between said second slit jaw and said variable position slit jaw means.
  • said second slit jaw comprises al fixed mirror surface
  • variable position slit jaw means causing a reflected image of said variable position slit jaw means to act as an effective second confronting variable slit jaw
  • said moving means comprises in part, first and second portions of a single cam
  • said single cam comprises a third portion for causing a programmed variation in the position of said slit jaw means
  • a self-adjusting optical slit mechanism for forming pair of slits of variable width comprising:
  • an actuating means for moving each of said slit jaw means including a slippable connection having substantial drag between each said slit jaw and its corresponding actuating means;
  • moving means for moving said actuating means and for forcing said actuating means to move relative to each of said slit jaws through said slippable connections when the movement of each of said slit jaws reaches the open or closed extreme;
  • each said slit jaw means and its said actuating means are caused to assume a known standard position relative to each other, so that subsequent movement of each of said actuating means will cause movement of its corresponding slit jaw means in a precisely known tracking manner.
  • a self-adjusting slit mechanism in which:
  • coupling means connect each of said actuating means; whereby each of said variable position slit jaw means is moved by its actuating means in a similar manner; thus assuring synchronous tracking of both said slit jaw means.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Telescopes (AREA)
US558481A 1966-06-17 1966-06-17 Self-adjusting slit mechanism Expired - Lifetime US3451744A (en)

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US55848166A 1966-06-17 1966-06-17

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US3451744A true US3451744A (en) 1969-06-24

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US (1) US3451744A (xx)
CH (1) CH479061A (xx)
DE (1) DE1572796A1 (xx)
FR (1) FR1526715A (xx)
GB (1) GB1185085A (xx)
IL (1) IL27712A (xx)
NL (1) NL6708020A (xx)
SE (1) SE311767B (xx)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753618A (en) * 1972-02-10 1973-08-21 Ultra Violet Products Inc Monochromator
WO2006138417A2 (en) * 2005-06-16 2006-12-28 Gatan, Inc. Energy selecting slit and energy selective sample analysis systems utilizing the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2533167B (en) 2014-12-12 2017-08-30 Thermo Fisher Scient (Bremen) Gmbh An adjustment mechanism

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2236379A (en) * 1938-09-02 1941-03-25 American Cyanamid Co Monochromator
US2896508A (en) * 1953-05-21 1959-07-28 Agfa Ag Diaphragm suitable for photometers
US3009390A (en) * 1958-02-13 1961-11-21 Beckman Instruments Inc Photometer slit mechanism

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2236379A (en) * 1938-09-02 1941-03-25 American Cyanamid Co Monochromator
US2896508A (en) * 1953-05-21 1959-07-28 Agfa Ag Diaphragm suitable for photometers
US3009390A (en) * 1958-02-13 1961-11-21 Beckman Instruments Inc Photometer slit mechanism

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753618A (en) * 1972-02-10 1973-08-21 Ultra Violet Products Inc Monochromator
WO2006138417A2 (en) * 2005-06-16 2006-12-28 Gatan, Inc. Energy selecting slit and energy selective sample analysis systems utilizing the same
WO2006138417A3 (en) * 2005-06-16 2007-03-01 Gatan Inc Energy selecting slit and energy selective sample analysis systems utilizing the same

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Publication number Publication date
FR1526715A (fr) 1968-05-24
GB1185085A (en) 1970-03-18
NL6708020A (xx) 1967-12-18
CH479061A (de) 1969-09-30
SE311767B (xx) 1969-06-23
DE1572796A1 (de) 1970-03-19
IL27712A (en) 1971-02-25

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