US3249005A - Pinhole projector for viewing furnace interiors - Google Patents

Pinhole projector for viewing furnace interiors Download PDF

Info

Publication number
US3249005A
US3249005A US346592A US34659264A US3249005A US 3249005 A US3249005 A US 3249005A US 346592 A US346592 A US 346592A US 34659264 A US34659264 A US 34659264A US 3249005 A US3249005 A US 3249005A
Authority
US
United States
Prior art keywords
crystal
muffle
pinhole
viewing
viewing port
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US346592A
Inventor
Foguel Max
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yissum Research Development Co of Hebrew University of Jerusalem
Original Assignee
Yissum Research Development Co of Hebrew University of Jerusalem
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yissum Research Development Co of Hebrew University of Jerusalem filed Critical Yissum Research Development Co of Hebrew University of Jerusalem
Application granted granted Critical
Publication of US3249005A publication Critical patent/US3249005A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/04—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method adding crystallising materials or reactants forming it in situ to the melt
    • C30B11/08—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method adding crystallising materials or reactants forming it in situ to the melt every component of the crystal composition being added during the crystallisation
    • C30B11/10—Solid or liquid components, e.g. Verneuil method
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D21/00—Arrangements of monitoring devices; Arrangements of safety devices
    • F27D21/02—Observation or illuminating devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10T117/10—Apparatus
    • Y10T117/1004—Apparatus with means for measuring, testing, or sensing
    • Y10T117/1012—Apparatus with means for measuring, testing, or sensing with a window or port for visual observation or examination
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10T117/10—Apparatus
    • Y10T117/1024—Apparatus for crystallization from liquid or supercritical state
    • Y10T117/1028—Crucibleless apparatus having means providing movement of discrete droplets or solid particles to thin-film precursor [e.g., Verneuil method]

Definitions

  • Another object of this invention is to provide an lifl' proved mufile furnace adapted for growing single crystals by flame-fusion (Verneuil method) with visual inspection of the crystal during growth to determine its size, shape, position and color, without subjecting it to sharp thermal gradients.
  • the mufi le is essentially a refractory enclosure
  • the object to undergo heat treatment is placed inside the mu .e.
  • the mutlie is heated by any suitable means either internally or ex ternally.
  • the advantages of this arrangement are numerous.
  • the mufile serves both as a thermal insulator and reservoir. By virtue of its insulating properties and large heat capacity the mufile evens out any sharp thermal changes that might be caused by draughts, sudden fiuc tuations in heat supply or wnbient temperature.
  • the temperature distribution inside the muliie can be accurately controlled.
  • a mufiie is indispensable when the heat treatment is to be conducted in an atmosphere other than air.
  • the size of the viewing port is reduced to a minimum whereby heat losses and gradients are completely eliminated without impairing the clearness of observation.
  • the present invention is based on the fact that an object at high temperature, is in itself a light source. In fact, it is often so highly luminous that it cannot be directly viewed without protection to the eyes.
  • the muflie and viewing port accordin to this invention comprise a refractory shell or enclosure provided with an essentially conical hole; the base of the cone being towards the interior of the muffle, facing the object, while its apex reaches slightly beyond the outer mufile wall so as to form a pinhole of such a size as to project a sharp image of the incandescent object on a screen located outside the mutile.
  • the conical hole is of any general shape, i.c., it is Patented May 3, 1966 conical only in the sense that it is bounded by two surfaces of greatly differing areas. The larger surface faces the object, while the much smaller surface defines a pinhole of a size appropriate to project an image.
  • the position of the conical hole relative to the mufilc and object, as well as the solid angle it subtends, depend solely on the desired field of view, i.e., on the size of the object and its position relative to the pinhole.
  • the pinhole dimensions are critical.
  • the definition of the image is inversely proportional to those dimensions while the intensity of the image is proportional to their square.
  • the pinhole cannot be made too small because of diffraction effects.
  • the practical pinhole size is determined by the distances of both object and image from the pinhole. it will be shown, hereinafter, that a satisfactory pinhole size can be found in practice.
  • the pinhole has the advantage of being free from the aberrations inherent to lenses.
  • By varying the positions of the object and screen relative to the pinhole an enlarged, reduced or actual size image can be obtained.
  • a suitable calibrated scale By attaching a suitable calibrated scale to the screen, the dimensions of the object and its position relative to any desired reference point can easily be measured.
  • the image Being free from chromatic aberration, the image is an exact colour replica of the object, with the intensity reduced. This offers a means for measuring the temperature of the object, at any corresponding point on the image, by optical pyrometry.
  • this pinhole viewing port causes only small heat losses whereby conditions inside the muifie are not disturbed to a large extent by its presence. Due to the smallness of the pinhole, convection and radiation losses are negligible and no temperature gradients are set up in the direction of the pinhole. The object is thus completely thermally isolated. It is therefore practicable to introduce more than one such pinhole, whereby the object might be viewed from several directions, without appreciably affecting the thermal muffle.
  • a muflle as described above is of particular importance in furnaces used for growing crystals by flame fusion, although the present invention is not restricted to any particular type furnace.
  • the crystal grows as if in a completely closed mufile. Also, determination of the crystal size, shape, position and colour are greatly simplified by attaching suitably calibrated scales on the screen. The use of sighting devices and dark glasses is eliminated.
  • FIGURE 1 is a schematical perspective view of a muffle according to this invention.
  • FIGURE 2 is a schematical vertical median cross-sectional view through another mufiie as used in crystal growth by flame fusion;
  • FIGURE 3 is a schematical perspective horizontal cross-sectional view through another muffle, taken at the plane defined by the axis of the conical hole.
  • a mufile according to the invention comprises in enclosure 11, provided with a conical recess 12.
  • the base of this recess is at the interior wall of the enclosure while its apex intersects the outer wall defining a pinhole of predetermined diameter.
  • FIGURE 2 A preferred embodiment of the invention is shown in FIGURE 2.
  • the cylindrical refractory muffle 21 is provided with a cylindrical hole 22 drilled perpendicularly to the mulfie wall.
  • the base of the conical hole is at the interior wall of the shell 21 while its apex intersects the outer wall of the plug 23 defining a pinhole 25 of predetermined size.
  • FIGURE 3 where -31 is a cylindrical alumina tube surrounded by snugly fitting rings of refractory brick 32.
  • a cylindrical hole 33 passes through 31 and 32.
  • a cylindrical plug 34 made of fired nugget-stone, fits snugly into 33.
  • the plug is provided with a conical recess 35 terminating in a pinhole 36.
  • the growing crystal 37 can be observed on a suitably located screen not shown in the drawing.
  • This cone dimensions and position depend on the dimensions and relative positions of the muflle, burner and crystal. With a cylindrical muilie of outer and inner diameters of 15 cm. and 5 cm. respectively used to grow crystals of up to 2 cm. diameter, a cone of about 25 and a pinhole of 0.05 cm. in diameter yield a sharp 1:1 image which can be clearly seen in an ordinarily lighted room.
  • a viewing port for viewing the interior of said muflle'during said crystal growing without substantially disturbing the thermal conditions within said mufiie, said muffie defining said viewing port as a conical recess with the base of said cone :facing the interior of said muflie and the apex of said cone intersecting the exterior wa l of said mufiie to define a pinhole, and screen means facing said pin-hole at a predetermined distance therefrom to receive an image of said crystal through said viewing port due to the incandescence of said crystal, said pin-hole being of such size as to provide a sharp image on said screen.
  • said mufiie portion defining said viewing port comprises a cylindrical plug provided with said conical recess, said plug being seated within a cylindrical hole extending through said muill'e.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Lenses (AREA)
  • Instruments For Viewing The Inside Of Hollow Bodies (AREA)

Description

M. FOGUEL 3,249,005
PINHOLE PROJECTOR FOR VIEWING FURNACE INTERIORS May 3, 1966 Filed Feb. 24, 1964 Fig.2
Fig.1
Fig.3
INVENTOR.
BY Max Fogue! f .1
United States Patent 3,249,005 PIYHOLE PRQEECTOR FOR VEEWING FURNAE INTERIQRS Max Foguel, Jerusalem, Israel, assignor to Yissum Research Development Company, Jerusalem, lsrael, a company of Israel Filed Feb. 24, 1964, Ser. N 346,592 Claims priority, application Israel, Feb. 27, 1963, 18,794 5 Claims. (Cl. 88-24) This invention concerns an improved mufiie furnace. A specific object of this invention is to provide improve ments in mufiie furnaces adapted for the visual inspec tion of the rnufiie interior during operation without disturbing the thermal conditions inside the mufile.
Another object of this invention is to provide an lifl' proved mufile furnace adapted for growing single crystals by flame-fusion (Verneuil method) with visual inspection of the crystal during growth to determine its size, shape, position and color, without subjecting it to sharp thermal gradients.
Other and further objects of this invention will be come apparent hereinafter.
In the high temperature treatment of materials use is often made of muife furnaces. The mufi le is essentially a refractory enclosure The object to undergo heat treatment is placed inside the mu .e. The mutlie is heated by any suitable means either internally or ex ternally. The advantages of this arrangement are numerous. The mufile serves both as a thermal insulator and reservoir. By virtue of its insulating properties and large heat capacity the mufile evens out any sharp thermal changes that might be caused by draughts, sudden fiuc tuations in heat supply or wnbient temperature.
Furthermore, by proper design of the muiile and heater shapes, the temperature distribution inside the muliie can be accurately controlled. Also a mufiie is indispensable when the heat treatment is to be conducted in an atmosphere other than air.
It is often necessary to visually observe the object inside the mufi'le during heat treatment in order to determine its size, shape, position or color. This is usually accomplished by cutting an opening through the muffle wall to serve as a viewing port. This opening has to be of a size comparable to the object.
Such an opening greatly defeats the chief purpose of the mutlie by introducing a sharp temperature gradient. This gradient is caused by the large heat losses through the opening, which at high temperatures are mainly due to radiation and convection. The introduction or" a transparent heat-resisting window hardly reduces radiation losses, and in cases where the heat treatment is accompanied by volatilization, vapours tend to condense on the relatively cold window rendering it opaque.
According to the present invention, the size of the viewing port is reduced to a minimum whereby heat losses and gradients are completely eliminated without impairing the clearness of observation.
The present invention is based on the fact that an object at high temperature, is in itself a light source. In fact, it is often so highly luminous that it cannot be directly viewed without protection to the eyes.
The muflie and viewing port accordin to this invention, comprise a refractory shell or enclosure provided with an essentially conical hole; the base of the cone being towards the interior of the muffle, facing the object, while its apex reaches slightly beyond the outer mufile wall so as to form a pinhole of such a size as to project a sharp image of the incandescent object on a screen located outside the mutile.
The conical hole is of any general shape, i.c., it is Patented May 3, 1966 conical only in the sense that it is bounded by two surfaces of greatly differing areas. The larger surface faces the object, while the much smaller surface defines a pinhole of a size appropriate to project an image. The position of the conical hole relative to the mufilc and object, as well as the solid angle it subtends, depend solely on the desired field of view, i.e., on the size of the object and its position relative to the pinhole.
The pinhole dimensions are critical. The definition of the image is inversely proportional to those dimensions while the intensity of the image is proportional to their square. The pinhole, however, cannot be made too small because of diffraction effects. The practical pinhole size is determined by the distances of both object and image from the pinhole. it will be shown, hereinafter, that a satisfactory pinhole size can be found in practice.
Optically, the pinhole has the advantage of being free from the aberrations inherent to lenses. By varying the positions of the object and screen relative to the pinhole, an enlarged, reduced or actual size image can be obtained. By attaching a suitable calibrated scale to the screen, the dimensions of the object and its position relative to any desired reference point can easily be measured. Being free from chromatic aberration, the image is an exact colour replica of the object, with the intensity reduced. This offers a means for measuring the temperature of the object, at any corresponding point on the image, by optical pyrometry.
The chief and most important advantage of this pinhole viewing port is that it causes only small heat losses whereby conditions inside the muifie are not disturbed to a large extent by its presence. Due to the smallness of the pinhole, convection and radiation losses are negligible and no temperature gradients are set up in the direction of the pinhole. The object is thus completely thermally isolated. It is therefore practicable to introduce more than one such pinhole, whereby the object might be viewed from several directions, without appreciably affecting the thermal muffle.
A muflle as described above is of particular importance in furnaces used for growing crystals by flame fusion, although the present invention is not restricted to any particular type furnace.
The construction of a conventional flame fusion furnace is well known (see Kirk-Othmer, Encyclopedia of Chemical Technology, vol. 7) and has changed but little since its invention by Verneuil at the turn of the century. In such a furnace an oxyhydrogen burner (some recent setups make use of a plasma torch) discharged its flame vertically into a refractory muffle shaped like a thick walled tube. Fine powder is fed centrally through the flame. The powder melts and collects on top of a re fractory pedestal carrying a seed crystal, and under suitable conditions a single crystal grows from the seed. The crystal grows upwards into hotter zones of the flame. To prevent it from melting completely, it is constantly lowered and kept at a constant distance from the burner, i.e., in a region of constant temperature. This can only be accomplished if the crystal can be observed and its position determined. To this end it is customary to cut an elongated opening through the muffie wall to serve as a viewing port. A suitable sighting device is placed in conditions inside the 3 ventional viewing port. Much heat is lost through the port by radiation and by convection through hot combustion gases.
By using a viewing port and mufile according to this invention, lateral temperature gradients are completely eliminated during both growth and cooling, yielding better and less strained crystals.
The crystal grows as if in a completely closed mufile. Also, determination of the crystal size, shape, position and colour are greatly simplified by attaching suitably calibrated scales on the screen. The use of sighting devices and dark glasses is eliminated.
Other objects of this invention and a fuller understanding of same may be had by referring to the following de scription and claims, taken in conjunction with the accompanying drawings in which:
FIGURE 1 is a schematical perspective view of a muffle according to this invention;
FIGURE 2 is a schematical vertical median cross-sectional view through another mufiie as used in crystal growth by flame fusion;
FIGURE 3 is a schematical perspective horizontal cross-sectional view through another muffle, taken at the plane defined by the axis of the conical hole.
As shown in FIGURE 1, a mufile according to the invention comprises in enclosure 11, provided with a conical recess 12. The base of this recess is at the interior wall of the enclosure while its apex intersects the outer wall defining a pinhole of predetermined diameter. When an object 13 situated inside the enclosure is heated to a high temperature (the heat source 15 is shown schematically in the drawing and it may be situated either inside or outside the enclosure) and thereby becomes incandescent, an inverted image 16 of the object is formed on the screen 17.
A preferred embodiment of the invention is shown in FIGURE 2.
The cylindrical refractory muffle 21 is provided with a cylindrical hole 22 drilled perpendicularly to the mulfie wall. A plug 23 provided with a conical hole 24 fits snugly into 22. The base of the conical hole is at the interior wall of the shell 21 while its apex intersects the outer wall of the plug 23 defining a pinhole 25 of predetermined size. When a crystal 26 supported on the pedestal 2-9 is grown by introducing powder from above through a burner, an upright image 30 of the crystal 26 is obtained on the screen 27 by means of the inverting lens 28. The size and sharpness of the image can be adjusted by changing the relative positions of the crystal, pinhole, lens and screen. It is clearly possible to provide more than one such plug with pinhole at any desired position. Crystals grown in such mufiie show very little internal strain.
It has been found that very satisfactory results can be obtained with the construction shown in FIGURE 3, where -31 is a cylindrical alumina tube surrounded by snugly fitting rings of refractory brick 32. A cylindrical hole 33 passes through 31 and 32. A cylindrical plug 34, made of fired nugget-stone, fits snugly into 33. The plug is provided with a conical recess 35 terminating in a pinhole 36. The growing crystal 37 can be observed on a suitably located screen not shown in the drawing. This cone dimensions and position depend on the dimensions and relative positions of the muflle, burner and crystal. With a cylindrical muilie of outer and inner diameters of 15 cm. and 5 cm. respectively used to grow crystals of up to 2 cm. diameter, a cone of about 25 and a pinhole of 0.05 cm. in diameter yield a sharp 1:1 image which can be clearly seen in an ordinarily lighted room.
Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure is by way of an example only and that many changes in the details of construction, and the combination and arrangement of parts, may be resorted to without departing from the scope and spirit of the invention.
What I claim is:
I. In a device for growing crystals including means to support the crystal, means to feed crystal forming material to said support, means to apply heat to said crystal form ing material to render said material incandescent, and a mufiie surrounding said supporting means to maintain said heat in the area or" said crystal formation, the improvement comprising a viewing port for viewing the interior of said muflle'during said crystal growing without substantially disturbing the thermal conditions within said mufiie, said muffie defining said viewing port as a conical recess with the base of said cone :facing the interior of said muflie and the apex of said cone intersecting the exterior wa l of said mufiie to define a pinhole, and screen means facing said pin-hole at a predetermined distance therefrom to receive an image of said crystal through said viewing port due to the incandescence of said crystal, said pin-hole being of such size as to provide a sharp image on said screen.
2. A mutfle as claimed in claim 1, wherein the size of the pin-hole is between 0.25 to 1.0 mm. in diameter.
3. A muffie furnace as claimed in claim 1, wherein there is provided a suitable optical lens between the pinhole and the screen so as to result in an upright image of the interior of the muffle during its operation.
4-. A device in accordance with claim '1 wherein said muffle comprises a generally cylindrical refractory furnace.
5. A device in accordance with claim 1 wherein said mufiie portion defining said viewing port comprises a cylindrical plug provided with said conical recess, said plug being seated within a cylindrical hole extending through said muill'e.
References Cited by the Examiner UNITED STATES PATENTS 773,202 10/1904 Ewing -64 OTHER REFERENCES The Review of Scientific Instruments, vol. 24, August

Claims (1)

1. IN A DEVICE FOR GROWING CRYSTALS INCLUDING MEANS TO SUPPORT THE CRYSTAL, MEANS TO FEED CRYSTAL FORMING MATERIAL TO SAID SUPPORT, MEANS TO APPLY HEAT TO SAID CRYSTAL FORMING MATERIAL TO RENDER SAID MATERIAL INCANDESCENT, AND A MUFFLE SURROUNDING SAID SUPPORTING MEANS TO MAINTAIN SAID HEAT IN THE AREA OF SAID CRYSTAL FORMATION, THE IMPROVEMENT COMPRISING A VIEWING PORT FOR VIEWING THE INTERIOR OF SAID MUFFLE DURING SAID CRYSTAL GROWING WITHOUT SUBSTANTIALLY DISTURBING THE THERMAL CONDITIONS WITHIN SAID MUFFLE, SAID MUFFLE DEFINING SAID VIEWING PORT AS A CONICAL RECESS WITH THE BASE OF SAID CONE FACING THE INTERIOR OF SAID MUFFLE AND THE APEX OF SAID CONE INTERSECTING THE EXTERIOR WALL OF SAID MUFFLE TO DEFINE A PINHOLE, AND SCREEN MEAN FACING SAID PIN-HOLE AT A PREDETERMINED DISTANCE THEREFROM TO RECEIVE AN IMAGE OF SAID CRYSTAL THROUGH SAID VIEWING PORT DUE TO THE INCANDESCENCE OF SAID CRYSTAL, SAID PIN-HOLE BEING OF SUCH SIZE AS TO PROVIDE A SHARP IMAGE ON SAID SCREEN.
US346592A 1963-02-27 1964-02-24 Pinhole projector for viewing furnace interiors Expired - Lifetime US3249005A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IL1879463 1963-02-27

Publications (1)

Publication Number Publication Date
US3249005A true US3249005A (en) 1966-05-03

Family

ID=11043246

Family Applications (1)

Application Number Title Priority Date Filing Date
US346592A Expired - Lifetime US3249005A (en) 1963-02-27 1964-02-24 Pinhole projector for viewing furnace interiors

Country Status (4)

Country Link
US (1) US3249005A (en)
CH (1) CH429036A (en)
DE (1) DE1235264B (en)
GB (1) GB1003461A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3337304A (en) * 1965-03-15 1967-08-22 Elmat Corp Crystal growth sampler

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US773202A (en) * 1901-02-12 1904-10-25 Thomas Ewing Jr Apparatus for producing images by apertures.

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US773202A (en) * 1901-02-12 1904-10-25 Thomas Ewing Jr Apparatus for producing images by apertures.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3337304A (en) * 1965-03-15 1967-08-22 Elmat Corp Crystal growth sampler

Also Published As

Publication number Publication date
GB1003461A (en) 1965-09-02
DE1235264B (en) 1967-03-02
CH429036A (en) 1967-01-31

Similar Documents

Publication Publication Date Title
Johnson et al. An electron microscope for filaments: emission and adsorption by tungsten single crystals
CA2122387A1 (en) Solid state formation of saphire using a localized energy source
CN107923065A (en) The manufacture method and device of monocrystalline
US20150264277A1 (en) Imaging Apparatus for Thermal Analyzer and Thermal Analyzer Including the Same
Wood LVIII. The fluorescence of sodium vapour and the resonance radiation of electrons
US3249005A (en) Pinhole projector for viewing furnace interiors
Schneider et al. Effect of environment upon the melting point of Al2O3
JP2018100195A (en) Production method of single crystal
Khattak et al. Correlation of sapphire quality with uniformity and optical properties
US4224099A (en) Method for producing R-plane single crystal alpha alumina
Halden et al. Verneuil Crystal Growth in the Arc‐Image Furnace
ES8104573A1 (en) Inspection of the interior of an enclosure
US1958879A (en) Apparatus for ascertaining the temperature of hot bodies
US7111477B2 (en) Production method of optical synthetic quartz glass, optical synthetic quartz glass, and annealing furnace
JP2011148698A (en) Manufacturing method of optical fiber porous preform
JPH11292696A (en) Fluorite production unit
US1323309A (en) Edwin f
JPS6071592A (en) Manufacture of single crystal
Mitchell After‐Heater Furnace for Verneuil Crystal Growing Technique
JPH054828A (en) Furnace for production of high-purity quartz glass
JPS62162636A (en) Sintering apparatus for porous preform for optical fiber
JP2826176B2 (en) Single crystal manufacturing equipment
JPH09196831A (en) Specimen cooling and observing device
Vasilieva et al. Investigating the flame with the aid of self-reversed contours of spectral lines
JP4762408B2 (en) Method for manufacturing optical fiber porous preform