Kodak reports to laboratories o n : materials for autoradiography... an old technique for color photomicrography of colorless objects Artist's choice
Autoradiography is the art of ar ranging for a radioactive substance to take its own picture. In calling it art, we choose our word with care, for everyone who practices it has his own problems and his own so lutions, which he knows are better than anyone else's solutions. Some prefer to bind their sub jects in contact with photographic plates. For them we supply Kodak Autoradiographic Plates, Type A or Type No-Screen. The former are chosen for fineness of grain, the latter for high sensitivity. Both have emulsions about 25μ thick that lo cate β- or 7-emitters. Some want plates with emulsions up to 200μ thick, in which paths of individual β- or α-particles are long enough to be plotted back to their origins. For them we supply Kodak Nuclear Track Plates in five differ ent sensitivities and six different emulsion thicknesses. Some prefer to peel the sensitive emulsion off its base and lay it down on the subject. For them we make Kodak Autoradiographic Strip ping Film, Type NTB, that comes like this
Permeable Base Stripping Film, where the emulsion is only 5μ thick and mechanically supported by 5μ of plain gelatin that provides sup port between the peeling and the mounting steps, goes on the out side after mounting to protect the emulsion during exposure, and is permeable to the solutions during processing. Others find this breadth of choice too narrow. Only with liquid emul sion, these brave souls plead, can they get the radiosensitive layer ex actly where they want it and as thick or as thin as they want it. But we, who have worked with liquid emulsion for 75 years, know what delicate, perishable, and variable stuff it is and that its handling is no whit less important than its com position and compounding. Believe us, it is neater all the way around to solve your autoradiographic problems with one of the above-italicized plates or films, obtained from a Kodak dealer. Nevertheless, those who have concluded that only liquid emulsion will do may state their cases by letter to Eastman Kodak Company, Special Products Sales Division, Rochester 4, Ν. Υ., and await developments. Yes, and we even go so far as to offer free reprints of the recent Nucleonics article, "AlphaParticle Autoradiography with Liquid Emulsion."
τ 10.,
EVULSION
Quekett, 1897 CELLULOSE EMEU
and winds up like this,
^—^~^
ΙΙΙΙΗΐηίΜΙΙΗΙΙ the impermeable layer serving to protect the emulsion and the speci men from each other. Some who strive for best resolu tion of blackened areas (rather than of individual particle tracks) want a thin emulsion and are more inter ested in how close to the specimen they can get it than in how well they can separate the two. For them we have Kodak Autoradiographic
Dental chap came in with a live hamster for help in photographing its molars, and when that was done, he asked what's new in photomi crography. We told him about Julius Rheinberg's papers in the Journal of the Quekett Microscopi cal Club for April and November, 1897. Some beautiful Ektachrome photomicrographs of tooth struc ture have come out of this. Wratten-Rheinberg is an adapta tion of dark-field microscope illumi nation to introduce color differ entiation in colorless objects by means of light rather than stains. It is accomplished by microscope substage filters obtainable at all of $3.75 each from a Kodak dealer, who can order in Kodak Wratten Rheinberg Differential Color Filters
even though he hasn't heard of them before. Seven of them are central diskstops, which consist respectively of a blue (No. 49), green (No. 63), red (No. 70), purple (No. 35), greenishblue (No. 45A), black (Neutral Density 4), or white matte (thin paper) 15-mm center in a thin 33mm glass disk. Four of them are peripheral ring-stops with clear 15-mm centers surrounded by 9mm-wide rings of red (No. 29), blue-green (No. 64), orange (No. 21), or blue (No. 38A). A central and a peripheral disk-stop are placed in tandem in the filter ring of the regular substage condenser, which is focused on the object. Then ^ e ™
Ϋ A
*eli
f>
™
-
—~ΙΡτ^T"E ^-•ft j ρ ENTEHING UGH
Ε LENS
&•,',","?;,„.„„ P I . . . H I . . L R..G-.IO*
'
one sees things like a red Parameci um swimming in a green pool, or vice versa as fancy and good seeing may dictate. Of course, this doesn't work with high-powered objec tives that take all the available aper ture of the condenser to fill them, in which case you had better look into phase microscopy after all. There is one more string to the Wratten-Rheinberg bow, however —the luxury model Sector Stop for $9.50. It's a peripheral, with alter nate 90° sectors of red and blue. Used with the black central diskstop and lined up with a trans versely striated object like a textile, it can make warp red and woof blue. Slow though the Wratten-Rhein berg technique may be in gaining momentum, we look forward to the avalanche. Questions about it should go to East man Kodak Company, Medical Division, Rochester 4, Ν. Υ. Prices quoted are subject to change without notice.
This is one of α series of reports on the many products and services with which the Eastman Kodak Company and
its divisions are... serving laboratories everywhere V O L U M E 2 7, NO. 12, D E C E M B E R
1955
Kodak 27 A
