Dec. 31, 1946. E. C. BIERMAN - 2,413,600 ' METHOD OF MAKING RETICLES Filed June 25, 1942 zvem ? a.W mn, I Bfwentor. @‘LS (Ittomeg 2,413,500 Patented Fee. 31, 1946 UNITED STATES PATENT OFFICE 2,413,600, METHOD oF MAKING RETICLES Everett 0. Bierman, Charlotte, N. 0., assignor to Semagraph Company, Charlotte, N. C., a cor poration of Delaware Application June 23, 1942, Serial vNo. 448,114 2 Claims. (01. 95-5) 1 My invention relates to reticles and more par ticularly to an improved, photographic, method of producing reticles on glass. Such reticles are adaptable for use in telescopes, gun sights and 2 to enable subsequent positive photographic repro duction onto the ?nal glass plate or glass disks. This multiple photographing to produce the mas ter negative, is done by means of a photocom posing machine having the conventional means to move the machine laterally and vertically in stepwise manner and thereby produce a large number of photographic negatives in proper various optical instruments. The most common present method of making reticles involves the time consuming and meticu lous task of engraving the design in metal, by spaced relationship. hand or machine, or the etching of the design When desired, the reverse photographic pro with hydro?uoric acid. My invention avoids all 10 cedure may be used; that is, the original negative of the disadvantages and limitations of these prior rather than the original positive may be em practices by eliminating entirely the engraving ployed in the photocomposing machine to pro and etching procedures. duce the reticles on the master plate as photo One of the characterizing and commercially ad graphic positives. vantageous features of my invention is the exclu The details of construction and mode of opera sively photographic method for producing the tion will be understood from the following de reticles on glass without the necessity of etching soription taken in conjunction with the accom or engraving the glass. The reticle lines photo panying drawing, in which: graphed on the glass are markedly resistant to Fig. 1 is a top plan view of an illustrative form handling. Also, they are resistant to a number of reticle holder, showing transparent, pres'haped, of optical cleaning agents including denatured circular, reticle blanks placed in the holder cavi alcohol. ties preparatory to having the reticles photo Another valuable feature of my invention is the manufacture of reticles in multiple from a master photographic plate that enables quantity produc tion of the reticles in a relatively very short time. This procedure constitutes a marked improvement over the prior methods of making individual reti cles in such a manner that each reticle requires - graphically produced thereon, one of the cavities .- being vacant to show more clearly the form there of ; . Fig. 2 is a view partly in side edge elevation and partly in longitudinal section on the line 2-—2 of Fig. 1; > Fig. 3 is a top plan view of a glass plate having repetition of the complete process. 30 a multiplicity of ?nished reticles photographed In‘accordance with my invention, I produce the reticles by making or obtaining a photograph of thereon; , Fig. 4 is a side edge elevation of the glass plate the original reticle design and then by relatively shown in Fig. 3; rapid, consecutive, photographic exposures I make ~ Fig. 5 is an isometric detail View of a ?nished a number of photographic reproductions on glass or ?lm, to produce a master, photographic nega reticle; and, Fig. 6 is a plan view of a modi?ed reticle design. Referring now to the drawing, the numeral l0 designates one type of suitable holder for indi vidual circular glass disks I I on which the reticles of positive prints on a single glass plate or upon 40 are to be photographed. The holder, as shown, is rectangular, preferably made of metal, al a plurality of separate glass disks. The separate though any other suitable material may be used, glass disks may be previously cut and ground to and provided with a multiplicity of circular, bev the size and shape necessary for ultimate use in eled recesses l2. The recesses are of proper size the optical device. Where a single glass plate is used the reticles produced thereon in spaced re and shape to receive the respective individual lationship are subsequently out out to form indi disks l I with a snug lit. The holder 10 is of sub vidual disks. stantially the same thickness as the glass disks In preparing the ?rst single photographic neg 1 I so that the inserted disks will be approximately ative from the original drawing or other illustra flush with the top face of the holder. Adhesive tion of the reticle, a process camera or contact strips, shown at l3, may beused to retain, releas printing may be used. This original negative ably, the disks in the recesses. may then be printed to make a positive on ?lm ' tive, having a plurality of the reticles located in spaced relationship. This master negative may then be used for producing simultaneously by photographic contact printing, a duplicate series or glass. To produce a master negative this pOSiq tive is photographed a number of times onto a The photographic method, referred to above and now to be described more in detail, which glass or film and the negatives spaced properly 56 produces“ the reticle design on the disks, is both £2,413,600 3 4 expeditious and economical and enables accurate Various types of materials may be used to render the surface of the reticle body light sensi tive, but for the speci?c purpose of making reti reproduction in large quantities. In carrying out this method, the original mas ter negative or positive is placed in direct con cles, in accordance with my present invention, I tact and in registry with the disks H and the reticles are photographically reproduced simul taneously onto the plurality of glass disks II in have found it of advantage to use a material made according to the following formula: Formula the holder it. When a master negative is used Water _________________________ __ounces__ 32 it may have the same number of reticles and in __ dn 5 the same group arrangement as the disks H 50 10 Glue ____ Gelatin _________________________ __grains__ 60 that they will register with the disks l I which Ammonium bichromate __________ __ounces__ 3/1 are placed in the several receptacles l2 and have been previously coated on their top faces with some suitable light sensitive photographic mate rial. An illustrative but non-limiting example of the reticle design is shown in Fig, 3 photographically produced on a glass plate M. It comprises ascale The procedure which I advantageously follow sighting through a telescopic sight in a gun or in binoculars. However, any additional lines or de signs may also be used such as parallel lines shown generally at [6. The reticles shown in multiple in this Fig. 3 are produced from a cor responding master negative as described above. When the photographic process has been com glass. Following this, the plate is submerged in a dye solution comprised of the following: for preparing and using the above formula is as follows: The glass plate or disks, is covered with the above solution, then exposed to light and then developed in the usual way. Next, a solution of acetic acid and Water is generally indicated at l5. In some instances this ?owed over the developed plate. This hardens may constitute the entire reticle design used for 20 the photographieally produced image on the Du Pont Negrosine W. S. P. Powder Dye ___________________________ __ounces__ 6 pleted the reticles produced thereby on the glass Du Pont Orange II Dye (conc.) ____ __do____ 6 Du Pont Negeria Black CX _________ __do____ 6 plate It may then be cut out to form individual Acetic acid __________________________do____ 2 reticles, as shown in Fig. 5. The peripheral edges 30 Distilled water __________________ "gallons" 1 of the reticle may be ground to obtain the desired During this dye treatment the photographic reticle size. plate is rocked or agitated to give uniform treat My invention is not limited to the speci?c ment of the photographic image. This requires reticle design shown in Fig. 5 but is applicable about 30-45 minutes depending upon the tem generally to any and all types of design, which perature of the dye solution which may be from are subject to photographic reproduction. An about room temperature or up to about 100° F. example of another design is shown in Fig. 6. It Following this, the photographic plate is re comprises a scale ll extending across the reticle moved from the dye and placed in a solution of: disk I! parallel with and below the horizontal Ounces diameter thereof.v This scale, as shown, is inter Water __________________________________ __ 24 sected by a right-angular scale l8 at the right of Potassium alum _________________________ __ 1A1 the vertical diameter of the disk II. The divi sions of the horizontal scale‘ ll are equal, but the for a few minutes time. This increases the hard divisions of the vertical scale l8 progressively ness of the photographic image. increase in size from top to bottom. As shown, The plate is then rinsed with water and dried the divisions of the scales I‘! and H; are respec tively numbered as at l9 and 2B. In the same and then baked slightly by application of heat manner, the scale id of the reticle shown in Figs. may be used to bake the photographic image more uniformly and reduce the risk of glass breakage. Various modi?cations and changes may be made in the above described materials and meth ods without departing from the scope of my in 3 and 5 may be characteristically numbered or otherwise marked. In the reticle shown in Fig. either in the open or in an oven. Infra red light 6 there are provided short horizontal parallel lines 2! coincident with the vertical diameter of the disk H and middle division line of the scale vention, some of the novel features of which are l1, while at the left end of said scale there is de?ned in the appended claims. another series of short parallel lines 22. I claim: 7 The reticle body disks H may be of any con 1. A method of making an article suitable for ventional or approved shape, other than circular use in an optical instrument comprising coating as shown;_ and the holder l0 accordingly modi an article of glass or similar material with an ?ed to conform to and accommodate the disks. aqueous solution of glue, gelatin and ammonium Instead of glass other transparent material may 60 bichromate, exposing said coated article to light be used, provided it possesses the necessary re projected through a photographic negative of a fractive and other optical properties required for reticle to produce a photographic positive of said reticles. some of the high quality transparent reticle on said article, developing said photo plastics, such as for example “Lucite” may pos graphic positive, andremoving all other deposit sibly be used. 65 of said light sensitive coating, washing said arti The light sensitive coating material used on cle with an aqueous solution of acetic acid to the disks H or plate 43 is of such character that the portions of the coating unaffected by the light, during the photographic exposure and de harden the photographic positive, subjecting said photographic positive to a dye solution for a sub stantial length of time to dye or darken said pho veloping process, is removable by water‘ or some 70 tographic positive, then washing it with alum to other suitable solvent, but the portions that have been affected, and thus constitute the reticle de sign remain in permanent form on the glass and are markedly resistant to handling, even to the effects of heat, certain chemicals, and abrasion. increase the hardness of the photographic posi tive, again Washing with water, and ?nally heat ing the article to bake the photographic positive reticle to’ a permanent, non-soluble, abrasion ‘re sistant‘ form, while‘ leaving the‘ entirev remainder 2,413,600 5 6 and glue composition, exposing the coating to a body, removing the unexposed areas of the coat ing, washing said transparent body with an acetic acid solution to effect hardening of said lines, and heating the acetic acid hardened lines to effect further hardening thereof, whereby a pho tographic positive reticle resistant to abrasion light projected image of ?ne lines to effect a and solvents is produced on the transparent body. of the article uncoated and in clean transparent form. 2. A photographic method of producing reticles comprising coating a transparent body with a light sensitive, ammonium bichromate, gelatin, reproduction of said lines on said transparent ' EVERETT C. BIERMAN.