GODDARD SPACE FLIGHT CENTER

GREENBELT. MARYLAND
GRANITE 4-9000 TWX: BYN MD 867

 

IN REPLY REFER TO

SSD:613:LD:pa

January 31, 1961

Professor Joshua Lederberg
Department of Genetics

Medical Center, Stanford University
Palo Alto, California

Dear Professor Lederberg:

Perhaps I can catch up with our exchange of correspondence
which I regret I temporarily left up in the air since receipt
of your letter of December 8, 1960. While excuses are frequently
useless, they may at least indicate some of the projects with
which we are occupied and may serve to illustrate those tools
and bits of data in the field of ultraviolet technology which
may also be of use in your program. We have been concerned
with (not in order of importance or attention):

(a) The measurement of multilayer dielectric filters

for the middle ultraviolet.

(b) The investigation of characteristics of alkali
telluride photocathodes recently furnished to us
in the form of simple photodiodes and photomultipliers.

(c) Absolute photometry short of 3000A.

(d) Preparation of a rocket experiment to determine
directly by photoelectric photometry the solar
flux at 2600A and 2200A.

(e) Preparation and study of ion chambers in the region
1050A to 1400A with and for our colleagues who are
in the midst of an interesting stellar flux survey
rocket program.

(f) Planning our ultraviolet airglow experimental
program.

(g) taking leave for the holidays.
(h) Shoveling snow.

(i) Enjoying the festivities (as you well know)
of inauguration time.

Now to get on with some unfinished replies which I’1l
take up in the order in which you raised the questions.

(A)

(B)

(C)

(D)

(E)

NRL Report 4647 (Refer your letter of Oct. 21, 1960).
The nickel sulfate sorbital complex preparation did
indeed involve a series of negative results but

these negative results were not published and I expect
they will not be. My notebooks had to remain at

NRL and I have asked my former colleague, Donald

Field of the Chemistry Division of NRL to look in

the notebooks (especially his since he did the chemistry)
and extract the negative highlights. I agree

with you that negative results certainly can save
further investigators a great deal of trouble. You will
hear from him directly on this.

Nickel sulphate hexahydrate. The situation on this
is excellent, thanks to Dr. William McBride of

NOTS. We are enclosing several crystal discs similar
to that which we fly in our UV rocket photometers.

 

Cellulose caprate. Don Field will shortly send you
a jar of cellulose caprate granules and his report
which will probably give you the information you
need on its use as an optical cement.

 

A research associate with a strong background in
optics and electronics. We are Iooking for the

same type. We shall certainly steer those who

prefer the West Coast, in your direction. I do not
recall a Dr. Tanner and I can't think where our

paths could have crossed. Relative to personnel
recruitment we are actively looking for an airglowist.

 

 

I certainly found the documents which you enclosed
with your letter of Oct. 21, 1960 most interesting.
Without attempting to comment on your program and
associated projects, I should like to say, at least,
that obtaining the spectrum of the earth should be
most interesting for its own sake and point up the
problems involved in evaluating Mars, etc.
(F) Hoshino - Yoshida filter. While I have been aware
of their work, {I have had no direct experience with
it, particularly because our needs at that time
required a very high rejection ratio rather than
transmittances as high at 47%. I am enclosing several
documents which will add to collection of information
on selective UV band pass filters.

 

(G) Image Intensifier Photographs (which you returned
with your letter of December 8, 1960). The ERDL
of Fort Belvoir were kind enough to make available
additional copies so now I can send them back for
your retention. I believe you’11 be interested in
having a report of the Bendix image intensifier
project: emplying the channel electron multiplier.
I am enclosing with Bendix report No. 1658 a copy
of a forwarding memorandum I have sent to the
members of the Ad Hoc Committee for the AEC on
Image Intensifiers.

 

(H) Vidicon system at threshold light intensities.
(Your letter of October 3I, 1960). TI have checked
with M. Klein your observation on a great increase
in sensitivity of your vidicon system during
transient adjustments of the target voltage. While
neither he nor I have had such experience, however,
Mr. Klein has observed this while working with the
image orthicon. I may have more information when
I see the members of the AEC Image Intensifier
Committee later this week in New York where they
are meeting during the Physical Seciety Meeting.
Either I or someone else will comment further on
your observation.

 

There are also rumblings from both astronomical and
military circles which should lead to a Image Intensifier
Symposium late this year. ['’11 keep you posted.

Sincerely yours,

ae 4 Uae ite cee
Lawrence Dunkelman

Head, Detector Section
Astrophysics Branch

Enclosures:

Absorption Spectra of Halide Complexes of Cobalt (II) in
Aqueous Solution by D. A. Fine - NAVWEPS Report 7590.

Photographs of M. Klein's paper on Image Intensifiers.
Enclosures (continued)
Final Report on Research on the Design and Development of
a new Type of Image Intensifier - Bendix Report No. 1658
with L. Dunkelman memo to AEC Ad Hoc Committee on Image
Intensifiers dated January 31, 1961.
Lectern draft of ICO5 paper on Spectrally Selective Ultraviolet
Detectors (a few more details than given in original preprint
which you have).
Baum and Dunkelman - J. Opt. Soc. Am 45, 166(1955).
Dunkelman and Scolnik - J. Opt. Soc. Am 49, 356(1959).
First and Second Bi-monthly Report from Bausch & Lomb
(Turner & Bartle) on "R & D of Multilayer Dielectric Optical
Filters for the Middle Ultraviolet."

Enclosure (separate cover)

Cellulose Caprate (500 gm) from NRL.

Two discs of NiSO, - 6 H90.