GB1476793A - Nondestructively analysing biological cells using opto- electrical apparatus - Google Patents

Abstract

1476793 Blood cell analyzer COULTER ELECTRONICS Inc 16 Oct 1974 [23 Oct 1973] 44773/74 Heading G1A Apparatus for analyzing biological cells comprises means for illuminating at least part of each cell with light which includes at least light in a first narrow waverange, means for detecting discretely the amount of light in said narrow waverange from each cell part after absorption thereby, and means connected to it for generating a tag signal indicating the fixed location of each cell for which said amount of light is above or below a threshold value. In the embodiment of Fig. 1, light, including that of wavelength 415 nm, from flying spot scanner 12, is directed to slide 16 with a biological cell sample. Filter 20 passes light of approximately 415 nm and reflects the rest. Filter 30 passes only yellow and reflects blue. Thus photocells 22, 32 and 40 detect 415 nm, yellow and blue light respectively and photo-cell 47 provides a source average brightness signal causing on lead 54 a voltage as both a control for variable gain amplifiers 38 and 46 to compensate for brightness fluctuation and a threshold for comparator 28. If the signal from amplifier 26 falls below this, amplifier 56 receives a tag signal and gives an inhibit signal to cause electronic switches 58 and 60 to couple a voltage representative of background from potentiometer 62 to their outputs, to which they otherwise couple the outputs from amplifiers 38 and 46. Thus the images of red blood cells, which absorb light of 415 nm, are eliminated from the video processor. In the embodiment of Fig. 2 pulsed broadband light from source 66, passes through filter 68, transmitting a narrow band around 415 nm, and the slide 70 to Vidicon 74, controlled by circuitry 78. Comparator 82 gives a tag signal, when the signal from amplifier 80 is below that from potentiometer 84, to memory 86, which also stores XY co-ordinates at that instant. Motor 87 removes filter 68 substituting another and causes switch 88 to connect amplifier 80 via analogue to digital converter 90, which is optional, to gate 94, from which video processor 98 thus receives signals except at those XY co-ordinates for which it is inhibited by a tag signal on line 96. Processor 98 can store information. If reticulocytes are differentiated from erythrocytes using a supravital stain and a filter 106 passing 530 nm is used, density analysis computer 100, activitated by the tag signal on line 104, can produce density/number histograms to determine the percentage of reticulocytes in red blood cells.