Spectrosensitometer

Year: 195?
Manufacturer: Astrophysical Observatory Workshops – Asiago
Materials: cast iron, aluminum, brass, steel, optical glass
Dimensions: L = 850 mm; P = 220 mm; H = 200 mm

Built-in the 1950s at the Asiago Astrophysical Observatory Workshops, the spectrosensitometer was used to calibrate the blackening scale of photographic plates, associating each degree of blackening with the corresponding light intensity.

The plate was positioned in the instrument’s photographic chamber, where a variable intensity light beam was projected through a diaphragm. This process created a linear graduated scale on the plate, the so-called characteristic curve, essential for subsequent measurements, such as those made with a microphotometer.

Two very thin wires, inserted in the slit as reference points, facilitated the reading and alignment of the scale.

The spectrosensitometer represents a crucial step in the standardization and precision of spectroscopic analyses.