A dual acting control system for mass spectrometers is described, which permits adjustment of the collimating slit width and centering of the collimating slit while using only one vacuum penetration. Coaxial shafts, each with independent vacuum bellows are used to independently move the entire collimating assembly or to adjust the slit dimension through a parallelogram linkage

Struthoff, G. L.

English

NASA Technical Reports Server

United States Patent [191 I1 11 4,213,05 1 ~ - struthoff 1451 Jul. 15, 1980 
[54] DUAL ACI'ING SLIT CONTROL 
MECHANISM 
[76] Inventor: Robert A. Froscb, Administrator of 
the National Aeronautics and Space 
Administration with respect to an 
invention of Cuetav L. Struthoff, Seal 
Beach, Calif. 
[21] Appl. No.: 940,689 
[22] Filed: Sep. 8,1978 
[51] Int. Cl.2 ........................... HOlJ 9/38; G21F 5/04 
[52] U.S. c1. .................................... 250/457; 250/491; 
2 W 5  13 
[58] Field of Search ............... 250/513, 511, 512, 400, 
250/442, 457, 281, 283 
1561 References Cited 
U.S. PATENT DOCUMENTS 
3,603,787 9/1971 Powers ................................. 250/283 
3,655,963 4/1972 BNMee ............................... 250/511 
3,778,621 12/1973 Mikajiri ................................ 250/442 
Primary Examiner-Harold A. Dixon 
Attorney, Agent, or Firm-Howard J. osborn; John R. 
Manning 
A dual acting control system for mass spectrometers 
which permits adjustment of the collimating slit width 
and centering of the collimating slit while using only 
one vacuum penetration. Coaxial shafts, each with inde- 
pendent vacuum bellows are used to independently 
move the entire collimating assembly or to adjust the 
slit dimension through a parallelogram linkage. 
1571 ABSTRACT 
8 Claims, 1 Drawing Figure 
f- VACUUM ATMOSPHERE - 
12 I IO 
https://ntrs.nasa.gov/search.jsp?R=19800020185 2020-03-21T03:00:08+00:00Z
U.S. Patent Jul. 15, 1980 4,213,051 
2 
ence of the penetration of the barrier by vacuum seal 18. 
Outer shaft 20 is similarly attached to outer bellows 16 
at vacuum seal 22. Outer bellows 16 is a conventional 
vacuum bellows which permits outer shaft 20 to move 
5 axial without involving a sliding joint that requires 
vacuum integrity. Inner bellows 24 is attached to outer 
bellows 16 at vacuum seal 26 and inner shaft 28 is con- 
nected to inner bellows 24 at connection point 30, both 
by conventional sealing techniques. Because of the 
lo spring action of the bellows, the configuration then has 
the characteristic that comDreSSion or expansion of 
4,2 13,05 I 
1 
DUAL ACFING SLIT CONTROL MECHANISM 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
jezt to the provisions of Section 305 of the National 
Aetonautics and Space Act of 1958, Public Law 85-568 
(72 Stat. 435; 42 USC 2457). 
BACKGROUND OF THE INVENTION 
This invention relates generally to mass spectrometer 
controls and more specifically to control of slit mecha- 
nismir of adjustable width. The invention may, however, 
be applied to other areas in which mechanical controls l5 shaft 28. 
are required to penetrate a vacuum-tight barrier. 
outer bellows 16 will move both shaft 20 and-inner shaft 
28 laterally, while compression or expansion of inner 
bellows 24 d l  am lateral movement of only inner 
The preferred embodiment of the invention shown in 
depicts one method of independent com- 
to vacuum mer 
In the field of mass spectrometry, the collimator Or 
size of the ion beam. While several such mechanisms are 
available in the prior art, as shown in U.S. Pat. No. 2o 14 and mates at outer threads 
such prior art Operates Only to Or 
widen the slit dimension and none yields any adjustment 
for centering the slit paition. Such adjustments are left 
must then rquiie vacuum penetrations. Since 
b c r d g  the numb of increases 
the ofvacuum leaks, it is to minimize such 
penetrations. 
the 
fi~ed member 32 is riddly 
adjustable slit Inechanism is f r q m t b  used to limit the pression of the two bellows. In the FIGURE, outer 
with outer b o b  2,964398 by Middlatadt and U.S. pat. No. 3,171401 by bly 36. Rotation of outer h o b  assembly 36 cBu9e9 it to 
traverse axially relative to fued member 32 and relative 
to vacUUm batrier 14. outer knd, essembly 36 thus 
and thus compresses outer bellows 16 relative to vac- 
uum barrier 14 and moves outer shaft 20 axially. The 
extent of the axial motion is measured by the vernier 
scale markings 42 upon outer scale member 44 and fued 
adjusts the slit d b e m  and noa thg  member 38 is risidly attached to outer bel- 
moves the entire & assembly for purpcwes ofalignment lows 16 at the point remote from vacuum barrier 14 and 
with the ion beam. This is mmpl i&ed  through a is provided with inner threads 46 which mate with inner 
aingie vacuum penetration, thus minimizing the risk of h o b  assembly 48. When rotated, inner knob assembly 
vacuum leaks and highly simplifying vacuum maink- 35 I travetses axially relative to floating member 38 and 
nance. relative to outer shaft 20 compressing inner bellows 24 
by acting at bearing point 50. Inner shaft 28, which is 
rigidly attached to inner bellowa 24 at connection point 
invention is a dualsting, ~ a c u ~ m  penmting 30 thus moves relative to outer shaft 20. The relative 
control aPparahlk It is essentially two coaxial Shafts 40 displacement is indicated by marking 49 on inner scale 
W h  with a separate micrometer control outside the member 51. 
VaCUUm and with a V(ICUUII1 bCllOWS at the VaCUUm 
penetration to accOmmOdatc axial motion. The outer motion of the shaffs 
eh.ft and ~ C X ' O m e ~  move the entire collimator 8$SCm- 
bly relative to *= wall Of & vacuum chamber* The 45 mator frame 52, thus causing lateral movement of the 
h C r  haft and UkrOmCtCr knob are CarCIed by cormtor -blY a follows 
the motion Of the Outer shaft and provide movement of outer shaft 20. Movement of inner Bhaft 28 
axial motion relative to the reat of the co l l i i t o r  assem- relative to outer shaft cau8tB acmtor plate sa, which bly. This motion actuates a parallelogram linkage is rigidly connected to Bhaft a, to slide within 
slit dimension independently of the motion of the colli- 58 and pivot 813118 which totate about pivot pins 62 mator aascmbly. The two shab thus yield independent 
laterally, fvat slit plate 64, rigidly attached to it, moves lateral motion of the entire slit. 
55 with it, forming one edge of collimator slit 66. The 
other ends of pivot arms 60, attached to follower plate 
68 by follower pins 70, cause follower plate 68 to move 
to ~eparrk control mechanisms which by the nature, 25 upon outer l6 at bearing point 1o 
The present invention makes available a simple dual- 30 mmber 32. 
control which 
SUMMARY OF THE INVENTION 
I d &  the V(ICUM ~~~t 12 the independent 
shaft u) is rigidly connected to calli- 
the desired 
djusments. 
within the c-~l l i i to r  -bly which in adjusts the mllhtor 52, in ph by actuator pins 
control of the Opening and cl&g of the slits and of the fued to collimator 52' AS actuator Plate 56 Illoves 
BRIEF DESCRIPTION OF THE DRAWING 
ne mourn is a simDlifid d d  c- section of 
the invention showing thk v a c u k  penetration. 
DETAILED DESCRIPTION OF THE 
INVENTION 
The basic concept of the invention is illustrated in the 
FIOURE where atmospheric pressure environment 10 
is isolated from the vacuum environment 12 by vacuum 
barrier 14 and in which all parts shown in cross section 
are essentially cylinders. Outer bellows 16 is attached to 
vacuum barrier 14 by conventional vacuum seal means 
such as welding, brazing or clamping at the circumfer- 
opp i t e ly  from actuator plate 56. Follower plate 68 
carries with it second slit plate 72 which moves toward 
60 first slit plate 68 causing the dimension of slit 66 to be 
reduced. 
Pin 74 is soldered or otherwise attacbed to follower 
plate 68. Spring 73 is anchored to collimator frame 54 
and presses against pin 74 and keeps follower plate 68 
Rotating inner knob 48 outside the vacuum thereby 
ultimately causa the adjustment of the width of colli- 
mator slit 66 within the vacuum, while rotating outer 
65 springloaded to prevent backlash of slit plate 72. 
3 
4,213,051 
4 
knob 36 causes the lateral movement of the entire slit 4. An apparatus for control of a mass spectrometer 
within the vacuum. slit mechanism as in claim 2 wherein said tension means 
It is to be understood that the form of the invention is a spring bearing against said follower plate means in a 
herein shown is merely a preferred embodiment. Vari- manner tending to separate said fvst and second dit 
ous changes may be made in size, shape and arrange- 5 plate means. 
ment of parts; equivalent means may be substituted for 5. An apparatus for control of two independent 
those illustrated and described, and certain features may mechanisms within a vacuum environment comprising: 
be used independently from others without departing a vacuum chamber, 
from the spirit and scope of the invention as defined in a single opening defined in said vacuum chamber; 
the following claims. at least two shafts carried by said vacuum chamber 
What is claimed as new and desired to be secured by and having portions thereof projecting into said 
Letters Patent of the Unitedl States is: chamber through said single opening; 
1. An apparatus for control of two independent means for moving each of said shafts independently 
mechanisms within a vacuum environment comprising: relative to said vacuum chamber and relative to 
a vacuum chamber; 15 each other; 
a single opening defined in said vacuum chamber; a first mechanism within said vacuum chamber at- 
at least two shafts carried by said vacuum chamber tached to and operated by the fmt of said shafts; 
and having portions thereof projecting into said a second mechanism within said vacuum chamber 
chamber through said single opening; attached to and operated by the second of said 
means for moving each of said shafts independently 20 shafts; and 
relative to said vacuum chamber and relative to vacuum seal means including a fust vacuum bellows 
each other; sealed to said first shaft and a second vacuum bel- 
a collinator frame means of a mass spectrometer lows sealed to said second shaft. 
within said vacuum chamber attached to and oper- 6. Apparatus for control of two independent mecha- 
ated by the fust of said shafts; 25 nhms within a vacuum environment as in claim 5 
slit adjustment means of a mass spectrometer within whereh the means for moving the shafts independently 
said vacuum chamber attached to and operated by is a first compression means attached to said first vac- 
the second of said shatts; and uum bellows and a second compression means attached 
vacuum seal means joining the shafts to the vacuum to said second vacuum bellows. 
chamber for maintaining the vacuum integrity of 30 7. An apparatus for control of two independent 
the chamber. mechanisms as in claim 6 wherein the fust compression 
meanscomprises: 
a fmt outer cylindrical member rigidly mounted 
upon the vacuum chamber and containing a section 
of threads on an inner cylindrical surface; and 
an outer knob assembly of cylindrical configuration 
axially aligned with and of approximately the ra- 
dim of said first bellows vacuum seal and with 
threads on an outer cylindrical surface mating with 
the threads on said fued outer cylindrical member 
which when rotated thereby traverses d l y  rela- 
tive to said fixed outer cylindrical member and 
relative to the vacuum chamber and thus wm- 
ptesses said first bellows vacuum d. 
8. An amaratus for control of a maas armtrometcr 
IO 
2. An apparatus for control of two independent 
mechanisms as in claim 1 wherein the slit adjustment 
mans  comprisezx 
actuator plate means rigidly attached to said second 35 
shaft and moved by said second shaft; 
tirst slit plate means rigidly attached to said actuator 
plate means and forming the first side of a collima- 
tor slit; 
at least two actuator pin means attached to and mov- 40 
ing with said actuator plate m- 
at least two parallel pivot arm means, pivoting on 
pivot pins attached to said collimator frame and 
driven by said actuator pin means at fmt holes 
matinst with said actuator bin means and containinn 45 
-2 holes at the end o&mite from said actwit& 
pin means; 
follower plate means to which are attached at kgpt 
two follower pin means which mate with said s e o  
ond holes in said pivot arm means and which is 
thereby driven by said pivot arm means in a lateral 
direction opposite from the motion of said actuator 
plate means; and 
sccond slit plate means rigidly attached to said fol- 
lower plate means and forming the second side of 
the collimator slit, which has equal and opposite 
motion to said first side of the collimator slit when 
said second shaft moves laterally. 
3. An apparatus for control of a mass spectrometer 
slit mecha&m as in claim 6 wherein the s'?cond com- 
pression means comprises: 
a h t i n g  inner cylindrical member rigidly mounted 
upon said fmt bellows vacuum seal at the end most 
remote from the vacuum chamber and containing a 
section of threads on a inner cylindricd surface; 
and 
an inner knob assembly of Cylindrical configuration 
axially aligned with, and of approximately the ra- 
dius of, said second bellows vacuum seal and with 
threads on an outer cylindrical surface mating with 
the threads on said floating inner cylindrical mem- 
ber which when rotated thereby traverses axially 
relative to said first bellows vacuum seal and 
50 
55 
slit mechahm as in claim 2 wherein tens& means is 60 
lash thereof. 
thereby compresses said second bellows vacuum 
seal. applied to said second slit plate means to prevent back- * * + * +  
65 


Dual acting slit control mechanism

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