Optics, scan, detector, and product design of fast scan infrared detection and measuring instrumen

Chunko, P.

Mathis, G.

Vanzetti, R.

English

NASA Technical Reports Server

RAY THEON COMPANY 
Communications and Data Process ing  Operation 
Norwood, Massachusetts 
for period 
October 1, 1964 through October 31, 1964 
for 
Contract No. NAS 8-11604 
GSO No. 48064 
MONTHLY PROGRESS REPORT 
Fast Scan Infrared Detection 
and Measuring Instrument 
November 16, 1964 
R. Vanzetti 
P. Chunko 
G. Mathis 
https://ntrs.nasa.gov/search.jsp?R=19650011054 2020-03-17T00:30:42+00:00Z
Monthly Progress Report 
FAST SCAN INFRARED DETECTION & MEASURING INSTRUMENT 
November 16, 1964 
1. SUMMARY 
During the month of October, 1964, technical progress was further 
delayed by serious problems revealed by more detailed analysis of 
optical and scan systems. Extension of Phase I by six to eight weeks 
is indicated. Pr imary 
achievement during this period was completion of all but a small 
part  of the electrical requirements and determination of initial 
product design concept. 
tion of the Study Phase Terminal Report was ordered by Contracts 
Admini strati  on. 
Rate of expenditure is about 66% of plan. 
Indefinite delay of preparation and publica- 
2. PROJECT ADMINISTRATION 
Elapsed time schedule (attached) indicates schedule extensions re- 
quired in Phase I for studies in optics, scan, detector, and product 
design. The problems discussed in Section 3 have delayed comple- 
tion of optics and scan studies by four weeks and have prevented 
profitable studies in  product design. The delay in detector study 
was explained in Section 3. 3 of the prior report dated October 15, 
1964. Electrical studies affecting system design a r e  complete. 
Technical personnel participating during the current period are:  
C u r r  ent Previously 
Name & Title Period Reported Total to Date --- 
164 hr  s. 172 hr  s,  G. Mathis, Project Manager 8 hrs .  
P. Chunko, Project Engineer 160 504 664 I I  
W. Bauke, Senior Engineer 66 - 66 l 1  
M. Hinkle, Mathematician 24 - 24 It  
R. Powden, Technician 40 - 40 
R. Gallipeau, Consultant 70 4 74 
- 2 -  
3 .  TECHNICAL PROGRESS 
3.1 Optics 
e 
Quality profile analysis of the optical system defined in the 
September report has disclosed excessive blurr c i rc le  diameters 
when off-axis distances of 0. 5 m m  a r e  required; 
of conjugates resulted in systems: 
Re-alignment 
/ 
Original Revised 
Objective Spherical Aspheric a1 
Obj. dia. 200 mm 200 107 107 
(200 mm stopped down) 
Focal length 100 mm 200 200 2 00 
Image distance 585 mm 17 24 260 266.2 
Convergence Angle 18' 40' 6 O  38' 2 9O 23O 12' 
Magnification x 5  Xi'. 6 x1 xo. 3 
Refractive Element None One doublet 
i A refractive element was introduced to minimize blur circle 
diameter and achieve an effective spot diameter of , 003 inch maxi- 
mum across entire field. This addition affected scan requirements 
and resulted in  a review of scan systems. 
3.2 Scan -
Introduction of the refractive element limits space allo:' et2 to 
scan system insertion to approximately five inches along beam 
axis between refractive element and detector aperture. At 
present i t  appears doubtful that this space is adequate for the 
reflective scanner originally made the prime choice. Recon- 
sideration of diffractive scan by means of pierced drum (or 
disc) is a solution to the space problem. However, the penalty 
is limitation of scan versatility by rigorous coupling of line and 
frame frequency. In addition, the advantage of lower back- 
ground noise attributed to the reflective system is being ques- 
tioned on the basis of excessive modulation. 
background at or  near ambient temperature appears to be 
acceptable if maintained at constant level. 
indicates the probability of unacceptable modulation components 
originating at the line scan element during fly-back time. 
titative analysis of this effect is continuing. 
Any reasonable 
Qualitative study 
Quan- 
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- 3 -  
3. 2 Scan (Cont'd. ) -
The third choice scan method involving a vibrating optical 
fiber has undergone limited tests designed to check mechanical 
response and reliability of presently available fibers. Both 
coated (epoxy) and uncoated samples in lengths of 0. 5, 1.0 and 
2. 0 inches have been vibrated harmonically under the following 
c ondi t ion s : 
a. F ree  fiber, uncoated, frequency 0 to 200 cps, tip excursion 
0. 5 inch max. 
b. Steel encased fiber, uncoated, frequency 400 to 500 cps, 
tip excursion 0.4 inch max. 
c. F ree  fiber, epoxy coated, frequency 0 to 200 cps, tip 
excursion 0. 5 inch max. 
During test (c)  epoxy shedding was obvious. All tests indicated 
that no fiber breakage occurred until excursion exceeded 0. 375 
inch. Maximum time duration of test was 50 hours. 
3. 3 Detector 
/ - Design compatibility with the optical system has fixed the de- 
tector aperture dimensions at . 0762 mm minimum diameter 
and divergency angle 3 O  19' (total angle 6 O  38') This optical 
cone is usually achieved by a ser ies  of stepped/cylinders, the 
maximum diameter being determined by enclosure wall thick- 
ness. 
System sensitivity improvement by addition of a second detec- 
tor element affected by background only has been given con- 
sideration. Although not proven experimentally, this step may 
more than justify cost and could possibly compensate modula- 
tion components to a point permitting further consideration of 
the reflective scan system. 
3.4 Signal Processing 
W2th the exception of circuit details of the logarithmic preampli 
f ier between detector and voltage amplifier and the built-in test 
circuits, electrical design is complete2 Commercially avail- 
able units have been selected but not ordered. 
purchase orders is being held until possible effects of unsolved 
optical and scan problems can be accurately determined, 
Issuance of 
- 4 -  
3. 5 Product Design 
Initial concepts have been reviewed. It appears at present 
that the system will require a desk type console for  the op- 
tical head and operating controls and a standard electronic 
cabinet for the larger signal processing, recording and 
synchronizing units and their power supplies. 
must await solution of the optical and scan problems. 
Final concept 
3. 6 Mathematical Model 
Definition of a mathematical model for  the difractive scan 
system and compatible optics is complete? This model 2 covers energy balance from target through optics to the de- 
tector and defines the effectiveness of the drum o r  disc scan. 
J 
4. PLAN FOR NEXT PERIOD --- 
4.1 Optics 
Quality profile of the microscope optics will be determined, 
and type of asymmetry (conic section or figured) of the ob- 
jective mirror  will be defined. Shape and material for the 
refractive element will be determined. 
(breadboard) system will be constructed to check optical re- 
sponse. 
a r e  satisfactorily solved. 
An experimental 
Parts will be ordered as soon as all known problems 
4. 2 Scan -
The plan for October did not materialize. Therefore, the ex- 
perimental scan system will be constructed in  very preliminary 
form as part  of the optical breadboard. 
struction and early test results during November is doubtful, 
but useful data will be seen early in December, 
permit investigation of both reflective and difractive methods. 
The conclusion of the effort under 4. 6 will dictate the final 
choice of scanning system to be adopted as f i rs t  solution. 
Completion of con- 
Time will not 
4. 3 Detector 
Comparison study of Hg:Ge and Cu:Ge sensors will be completed 
and will guide final choice, 
use Au:Ge and/or Cu:Ge sensors now on hand. 
The intended breadboard tests will 
4.4 Signal Processing 
All circuit details will be completed. 
4. 5 Product Design 
Initial concepts will be revised to accommodate optical and 
scan changes, and design guides (both isometric and ortho- 
graphic) will be prepared. It is doubtful that detailed design 
will s tar t  on schedule. 
4. 6 Mathematical Model 
Continuation of the mathematical model to include definition 
of a reflective scan system is planned. 
4.7 Reports 
Notification to delay preparation and public ation of the Study 
Phase Terminal Report was forwarded through Contracts 
Administration. Release of the hold order has not been re-  
ceived. 
illustrate the material on hand. 
Approximately two weeks will be required to edit and 
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Fast scan infrared detection and measuring instrument monthly progress report, oct. 1-31, 1964

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