Turbidimeter employing a semiconductor laser diode and a photodiode

A turbidimeter for measuring the turbidity of a test liquid comprising

• a hollow housing having first and second ends with an aperture located at the first end thereof, said housing being immersible in said test liquid to permit said test liquid to enter said housing through said aperture;
• a semiconductor laser diode mounted within said housing at said second end for emitting a laser light beam;
• a first light quide member made of light transmitting and heat insulating material, said first light guide member being arranged within said housing for guiding the laser light beam emitted by said laser diode into the first end of said housing and making said laser light beam incident upon the test liquid within said housing;
• a second light guide member made of light transmitting and heat insulating material, said second light guide member being arranged within said housing for guiding light emanating from the test liquid within said housing into the second end of said housing;
• a semiconductor photodiode arranged within said housing at said second end for receiving the light emanating from said second light guide member, said photodiode producing a signal corresponding to the turbidity of the test liquid;
• and
• means for compensating for the influence of temperature upon said semiconductor laser diode and said semiconductor photodiode, said means further preventing the flow of current through said semiconductor laser diode and said semiconductor photodiode when said diode and photodiode are subjected to high temperatures such as during sterilization of said turbidimeter.

A turbidimeter for measuring the turbidity of a test liquid, comprising

• a hollow housing having first and second ends with an aperture located at the first end thereof, said housing being immersible in said test liquid to permit said test liquid to enter said housing through said aperture;
• a semiconductor laser diode mounted within said housing at said second end for emitting a laser light beam;
• a first light guide member made of light transmitting and heat insulating material, said first light guide member being arranged within said housing for guiding the laser light beam emitted by said laser diode into the first end of said housing and making said laser light beam incident upon the test liquid within said housing;
• a second light guide member made of light transmitting and heat insulating material, said second light guide member being arranged within said housing for guiding light emanating from the test liquid within said housing into the second end of said housing;
• a semiconductor photodiode arranged within said housing at said second end for receiving the light emanating from said second light guide member, said photodiode producing a signal corresponding to the turbidity of the test liquid;
• a light scattering means arranged between the first light guide member and the second light guide member within the housing the scattering the light beam transmitted therethrough;
• and
• means for compensating for the influence of temperature upon said semiconductor laser diode and said semiconductor photodiode, said means further preventing the flow of current through said semiconductor laser diode and said semiconductor photodiode when said diode and photodiode are subjected to high temperatures such as during sterilization of said turbidimeter.