BigPatents India

An on-line opacity monitor for detecting and monitoring of dust coming out of a duct, chimney or stack (p) comprises a LED source (a), a first lens (b), an aperture (c) and a second lens (d) provided on one side of the duct (p) to form the light from the LED source into a parallel light beam ; . a beam splitter (e) for splitting the light beam into a reference beam focused by a first focusing lens (f) onto a reference detector (g), and a transmitted beam ; a retroreflector (o) provided on the side of the stack remote from the LED source (a) to receive the transmitted beam from the beam splitter (e) through windows (m, n) provided on the stack (p), so that the transmitted beam is reflected back by the retroreflector (o) onto the beam splitter (e); a second focusing lens (h) for focusing the reflected transmitted beam from the beam splitter (e) to a test detector (i); a processing unit(j) having inputs (j1, j2) connected to the reference detector (g) and test detector (i) and an output (3) connected to a computer. No. of Pages : 19 No. of Claims : 6