Fiber-coupled liquid sample analyzer with liquid flow cell

In a liquid sample analyzing system including

• a flow cell in the form of a light pipe of tubular construction having first and second ends,
• first and second end caps sealed to said first and second ends of said light pipe,
• an input passage formed in said first end cap spaced from the first end of the light pipe,
• a multimode optical fiber extending into and sealed to said first end cap with its end optically coupled to said one end of said light pipe so that all fiber optic optical modes are captured by said light pipe to propagate therealong,
• an annular space around the end of said multimode optical fiber extending between said input passage and the first end of said light pipe whereby input liquid flows around and along said end of said optical fiber into said light pipe to provide a smooth flow of liquid sample past the end of said fiber,
• an output passage formed in said second end cap spaced from the second end of the light pipe,
• an output optical fiber extending into and sealed to said second end cap with its end optically coupled to said second end of said light pipe so that all optical modes which propagate along said light pipe are captured by the optical fiber, and
• the longitudinal alignment of the input and output optical fiber with respect to the input and output light pipe core is optimized to keep the RI below ±7 mAU, and
• an annular space around the end of said output optical fiber between said output passage and the second end of said light pipe whereby liquid flowing from said light pipe flows around and along the end of said output optical fiber to provide a smooth flow of sample past the end of said output fiber.

In a liquid sample analyzing system including

• a flow cell in the form of a light pipe of tubular construction having first and second ends,
• first and second end caps sealed to said first and second ends of said light pipe,
• an input passage formed in said first end cap spaced from the first end of the light pipe,
• a multimode optical fiber extending into and compression sealed within said first end cap with its end optically coupled to said one end of said light pipe so that all fiber optic optical modes are captured by said light pipe to propagate therealong,
• an annular space around the end of said multimode optical fiber extending between said input passage and the first end of said light pipe whereby input liquid flows around and along said end of said optical fiber into said light pipe to provide a smooth flow of liquid sample past the end of said fiber,
• an output passage formed in said second end cap spaced from the second end of the light pipe,
• an output optical fiber extending into and compression sealed within said second end cap with its end optically coupled to said second end of said light pipe so that all optical modes which propagate along said light pipe are captured by the optical fiber,
• an annular space around the end of said output optical fiber between said output passage and the second end of said light pipe whereby liquid flowing from said light pipe flows around and along the end of said output optical fiber to provide a smooth flow of sample past the end of said output fiber.

In a liquid sample analyzing system including

• a flow cell in the form of a light pipe of tubular construction having first and second ends, and disposed in a gas impermeable environment or container,
• first and second end caps sealed to said first and second ends of said light pipe,
• an input passage formed in said first end cap spaced from the first end of the light pipe,
• a multimode optical fiber extending into and sealed to said first end cap with its end optically coupled to said one end of said light pipe so that all fiber optic optical modes are captured by said light pipe to propagate therealong,
• an annular space around the end of said multimode optical fiber extending between said input passage and the first end of said light pipe whereby input liquid flows around and along said end of said optical fiber into said light pipe to provide a smooth flow of liquid sample past the end of said fiber,
• an output passage formed in said second end cap spaced from the second end of the light pipe,
• an output optical fiber extending into and sealed to said second end cap with its end optically coupled to said second end of said light pipe so that all optical modes which propagate along said light pipe are captured by the optical fiber,
• an annular space around the end of said output optical fiber between said output passage and the second end of said light pipe whereby liquid flowing from said light pipe flows around and along the end of said output optical fiber to provide a smooth flow of sample past the end of said output fiber.

In a liquid sample analyzing system including

• a flow cell in the form of a light pipe of tubular construction having first and second ends,
• first and second end caps sealed to said first and second ends of said light pipe,
• an input passage formed in said first end cap spaced from the first end of the light pipe,
• a multimode optical fiber extending into and sealed to said first end cap with its end optically coupled to said one end of said light pipe so that all fiber optic optical modes are captured by said light pipe to propagate therealong,
• an annular space around the end of said multimode optical fiber extending between said input passage and the first end of said light pipe whereby input liquid flows around and along said end of said optical fiber into said light pipe to provide a smooth flow of liquid sample past the end of said fiber,
• an output passage formed in said second end cap spaced from the second end of the light pipe,
• an output optical fiber extending into and sealed to said second end cap with its end optically coupled to said second end of said light pipe so that all optical modes which propagate along said light pipe are captured by the optical fiber, where the inner diameter of the light pipe core is tapered with the larger diameter at the input optical fiber and the diameter of the taper at the output optical fiber is smaller than the output optical fiber,
• an annular space around the end of said output optical fiber between said output passage and the second end of said light pipe whereby liquid flowing from said light pipe flows around and along the end of said output optical fiber to provide a smooth flow of sample past the end of said output fiber.

In a liquid sample analyzing system including

• a flow cell in the form of a light pipe of tubular construction and made of Teflon AF with an index of refraction less than 1.31, and having first and second ends,
• first and second end caps sealed to said first and second ends of said light pipe,
• an input passage formed in said first end cap spaced from the first end of the light pipe,
• a multimode optical fiber extending into and sealed to said first end cap with its end optically coupled to said one end of said light pipe so that all fiber optic optical modes are captured by said light pipe to propagate therealong,
• an annular space around the end of said multimode optical fiber extending between said input passage and the first end of said light pipe whereby input liquid flows around and along said end of said optical fiber into said light pipe to provide a smooth flow of liquid sample past the end of said fiber,
• an output passage formed in said second end cap spaced from the second end of the light pipe,
• an output optical fiber extending into and sealed to said second end cap with its end optically coupled to said second end of said light pipe so that all optical modes which propagate along said light pipe are captured by the optical fiber,
• an annular space around the end of said output optical fiber between said output passage and the second end of said light pipe whereby liquid flowing from said light pipe flows around and along the end of said output optical fiber to provide a smooth flow of sample past the end of said output fiber.

A liquid sample analyzer including

• a light source,
• means for introducing light from said light source into an optical cable,
• a flow-through cell for receiving a sample to be analyzed, said flow-through cell including
• a light pipe formed of a low refractive index material having a core diameter of predetermined size coupled to said optical cable,
• said light pipe having an inner diameter equal to or greater than the diameter of the optical cable, the end of said optical cable being positioned relative to said light pipe so that refracted light from the optical cable is accepted by the light pipe core,
• an output optical cable with a core diameter equal to or greater than the core diameter to the light pipe core for receiving light from the input fiber transmitted along the light pipe,
• said input optical cable having a numerical aperture less than or equal to the numerical aperture of the light pipe,
• said output optical cable having a numerical aperture greater than or equal to the numerical aperture of the light pipe,
• means for receiving the light from said output optical cable and processing the light to obtain a measure of absorbance as a function of wavelength of the light transmitted through the light pipe.