2.degree./90.degree. Laboratory scattering photometer

A photometer for measuring the light scattered by particles in a hydrosol at substantially 2.degree. and substantially 90.degree. simultaneously, comprising:

• a body having a passage for receiving the hydrosol;
• a light source;
• rotatable chopper means axially aligned with the light of said source for periodically interrupting said light;
• first optical means for directing the light passed through said chopper means toward the hydrosol in the passage as an incident beam having an optical first axis;
• light source detector means surrounding a portion of the outer periphery of said chopper means and emitting another beam of light through said chopper means and detecting the same for providing a reference signal to synchronously detect the light scattered by the hydrosol;
• a first photoelectric detector;
• second optical means for directing the light of the beam scattered by the hydrosol in the passage onto said first photoelectric detector and for thereby causing said first photoelectric detector to generate an electrical signal indicative of the amount of the scattered light;
• said second optical means having an optical second axis defining an angle of substantially 90.degree. relative to the first axis, said second optical means being spaced from the first axis;
• a second photoelectric detector;
• third optical means having a radiant energy mask with an aperture for directing light of the incident beam scattered by the hydrosol in the passage toward said second photoelectric detector, the axis of the portion of the incident beam linearly transmitted by the hydrosol in the passage and the rays of the incident beam scattered through the aperture of said radiant energy mask defining an angle of substantially 2.degree.;
• a light trap spaced from the point of intersection in the direction of the first axis away from said light source for absorbing the light of said source linearly transmitted by the hydrosol in the passage;
• and
• means in circuit with each of said photoelectric detectors for producing an indication of the amount of light directed towards said photoelectric detectors by the associated optical means respectively.