Multiple discrete analyzer test apparatus and method

• US 5,369,484 A
• Filed: 11/09/1992
• Issued: 11/29/1994
• Est. Priority Date: 11/09/1992
• Status: Expired due to Term

• Current Assignee: AKZO NV (Nouryon BV)
• Original Assignee: AKZO NV (Nouryon BV)
• Inventors: Haugen, Douglas G.
• Primary Examiner(s): Evans, F. L.
• Assistant Examiner(s): RASHID, PETER
• Application Number:
  US07/973,956
• Time in Patent Office: 750 Days
• Field of Search: 356/328, 356/326, 356/319, 356/320, 356/323, 356/325, 356/326, 356/328, 364/498, 364/526, 364/571.02
• US Class Current: 356/326
• CPC Class Codes: G01J 2001/083 Testing response of detector
• CPC Class Codes: G01J 2001/448 Array [CCD]
• CPC Class Codes: G01N 2021/0162 using microprocessors for control of a sequence of operations, e.g. test, powering, switching, processing
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 2201/04 Batch operation; multisample devices

Abstract

A computer based system for testing an optical monitoring system includes a program having program instruction and optical monitoring system parameters, for implementing a plurality of tests of an optical monitoring system. A computer includes at least one processor for executing the program instructions, storage components for storing program instructions and test data, including the optical system parameters, a user input for inputting commands, and a display for displaying a menu of available test commands, test results and other data. An interface is provided for interfacing the optical monitoring system to tile computer for exchange of control and data signals. A fixture is provided for mounting the optical monitoring system during testing.

Claims

1. A computer based method for testing an optical monitoring system which is electrically connected to a computer for exchanging control and data signals therewith, the computer having input means for selecting test commands and display means for displaying screens of information to a user, the method comprising:

displaying on the display means at least one screen showing a plurality of user selectable commands; and

performing programmed tests with the computer on the optical monitoring System based on user selected commands input with the input means;

wherein the optical monitoring system includes optical components and electrical circuitry, a light source, a light modifying wheel, a shutter, and a plurality of photodiode arrays having elements, the arrays being disposed at respective stations for receiving light from a respective plurality of optical channels; and

wherein the plurality of user selectable commands include a display command, an electrical systems test command, an optical dark test command, a beam alignment test command, a wavelength registration test command, a profile test command, and a filter test command.

2. The method according to claim 1, further comprising:

performing preliminary testing while monitoring the output of the optical monitoring system, the preliminary testing including commanding the optical monitoring system to rotate a light modifying wheel associated therewith to ensure the wheel is responsive, and monitoring the optical monitoring system to check a shutter associated therewith by checking for pulses associated therewith.

3. The method according to claim 1, wherein the photodiode arrays produce output signals and wherein upon selection of a display command, the method further comprises monitoring with the computer the photodiode array output signals from the optical monitoring system, displaying a screen representing the photodiode array output on the computer display means, and selectively varying at least the array represented by the screen, the elements of the arrays represented by the screen, and amplifier gain associated with an array element.

4. The method according to claim 1, wherein upon selection of an electrical systems test command, the method further comprises monitoring the output of the optical monitoring system while selectively performing at least:

an electrical dark test to check the levels of dark current and noise associated with the electrical circuitry of the system;

a digital bit test to check that all bits change state at least once on command in associated digital electrical circuitry of the system;

a shutter speed test to check the rotational speed of the shutter; and

a complete light modifying wheel test to test the accuracy of the light modifying wheel.

5. The method according to claim 4, wherein upon selection of an electrical dark test, the method further comprises:

instructing the user to disconnect or turn-off the light source in the optical monitoring system, and to cover the optical monitoring system to block ambient light to the photodiode arrays; and

monitoring the output of the optical monitoring system to check levels of dark current and noise associated with the electrical circuitry of the optical monitoring system.

6. The method according to claim 5, wherein the step of monitoring the output of the optical monitoring system comprises:

scanning a photodiode array a predetermined plurality of times;

after each scan in the scanning step, a rolling sum and a rolling standard deviation for each photodiode element is produced;

at the end of the predetermined plurality of scans, producing and comparing an average value for each photodiode element of the photodiode array scanned to minimum and maximum signal level criteria; and

determining a standard deviation for each photodiode element and comparing the standard deviations to maximum noise level criteria.

7. The method according to claim 6, wherein the predetermined plurality of scans is 100, the minimum signal level is 0 counts, the maximum signal level is 100 counts, and the maximum noise level is 2.5 counts.

8. The method according to claim 4, wherein the optical monitoring system includes at least a digital to analog converter, an analog to digital converter and an interface, and wherein upon selection of a digital bit test, the method further comprises checking at least the digital to analog converter, the analog to digital converter and the interface for stuck bits by sending and receiving signals to and from the optical monitoring system with the computer to ensure that each bit changes state at least once.

9. The method according to claim 4, wherein upon selection of a shutter speed test, the method further comprises:

polling interrupt signals from the optical monitoring system shutter for a predetermined period of time and keeping a count of the number said interrupt signals received;

dividing the number of interrupts counted by a clock timer of the computer to produce a calculated speed for the shutter; and

comparing the calculated speed to predetermined upper and lower acceptable speed values.

10. The method according to claim 4, wherein upon selection of a complete light modifying wheel test, the method further comprises:

commanding the light modifying wheel to move clockwise a predetermined plurality of positions and then back counterclockwise the predetermined plurality of positions;

determining the accuracy of position of the light modifying wheel; and

determining whether the light modifying wheel completes each respective move within a predetermined period of time.

11. The method according to claim 4, wherein upon completion of a test of said electrical systems test command which are selectively performed, the method further comprises storing test result data associated with the test performed.

12. The method according to claim 1, wherein upon selection of an optical dark test command, the method further comprises:

monitoring the output of the optical monitoring system with only a track area associated therewith covered to check for ambient light leaking into the optical monitoring system through a cabinet associated with the optical monitoring system.

13. The method according to claim 12, wherein the step of monitoring the output of the optical monitoring system comprises:

scanning a photodiode array a predetermined plurality of times;

after each scan in the scanning step, a rolling sum and a rolling standard deviation for each photodiode element is produced;

at the end of the predetermined plurality of scans, producing and comparing an average value for each photodiode element of the photodiode array scanned to minimum and maximum signal level criteria; and

determining a standard deviation for each photodiode element and comparing the standard deviations to maximum noise level criteria.

14. The method according to claim 13, wherein the predetermined plurality of scans is 100, the minimum signal level is 0 counts, the maximum signal level is 100 counts, and the maximum noise level is 2.5 counts.

15. The method according to claim 1, wherein upon selection of a beam alignment test command, the method further comprises monitoring the output of the optical monitoring system to check for cross-talk between optical channels of the optical monitoring system and for proper beam height.

16. The method according to claim 15, wherein checking for cross-talk comprises:

(a) instructing the user to be sure the light source is on and that a track associated with the optical monitoring system is reasonably covered;

(b) measuring dark current for 10 scans with the light modifying wheel in a blocked position;

(c) determining a first average based on the 10 scans for each photodiode element;

(d) instructing the user to place a blocking device in the track at one of a plurality of specified positions, thereby blocking at least one optical channel associated with a respective photodiode array with adjacent channels unobstructed;

(e) setting the signal gain for each photodiode array at a maximum level;

(f) measuring the photodiode current for the respective photodiode element associated with the at least one blocked optical channel for 10 scans with the blocking device at the specified position;

(g) determining a second average based on the 10 scans for each photodiode element;

(h) determining the difference between the first and second averages to thereby determine a cross-talk level;

(i) instructing the user to place the blocking device in the track at another one of the plurality of specified positions;

(j) repeating steps (f) to (i) a predetermined number of times; and

(k) comparing determined cross-talk levels with a predetermined acceptable maximum cross-talk.

17. The method according to claim 15, wherein checking for proper beam height comprises:

monitoring the signal from the optical monitoring system;

instructing the user to place a beam height gage in a predetermined position;

monitoring the signal with the beam height gage in place;

comparing the signal without the beam height gage to the signal with the beam height gage to determine a measured difference value; and

comparing the measured difference value to a predetermined acceptable difference value.

18. The method according to claim 1, wherein upon selection of a wavelength registration test command, the method further comprises monitoring the output of the optical monitoring system to determine the wavelength mid-frequency and bandwidth of each photodiode array element.

19. The method according to claim 18, wherein the method further comprises:

instructing the user to be sure the light source is on and that a track associated with the optical monitoring system is reasonably covered;

measuring dark current for 10 scans with the light modifying wheel in a blocked position;

determining a first average based on the 10 scans for each photodiode element;

performing a preliminary profile test to ensure that a minimum amount of light can be sensed by each array element;

normalizing the signal from the array by selecting individual gain values for each element so as to balance the signal at a preprogrammed level;

fitting a Gaussian curve to a respective signal detected with each of a plurality of filters in place to find a respective peak signal;

prompting the user to confirm that a peak for a filter position is acceptable;

prompting the user to select one of a plurality of options, the plurality of options including repositioning a filter and repeating the above steps, aborting the wavelength determination process, or continuing;

determining a linear regression using a least squares fit after all filters have been evaluated thereby producing coefficients and residual values of the least squares fit, and calculating a smallest wavelength and a largest wavelength using the coefficients; and

comparing the calculated smallest wavelength, the calculated largest wavelength, and the residual values of the least squares fit with predetermined values.

20. The method according to claim 1, wherein upon selection of a profile test command, the method further comprises monitoring the output of the optical monitoring system to measure the amount of light reaching the photodiode array elements and the signal to noise ratio for each optical channel under normal operating conditions.

21. The method according to claim 20, further comprising:

instructing the user to be sure the light source is on and that a track associated with the optical monitoring system is reasonably covered;

measuring dark current for 10 scans with the light modifying wheel in a blocked position;

determining a first average based on the 10 scans for each photodiode element;

setting the gain for each element to a predetermined value for all optical channels;

determining an element number based on each of a plurality of wavelengths to test;

interpolating the signal value for each wavelength from the closest discrete elements corresponding to the desired wavelength;

determining an average of the 10 scans;

comparing the average of the 10 scans with a maximum value and with a minimum value determined using a polynomial based on a typical signal; and

comparing the signal divided by a standard deviation for each element to an optical RMS noise value.

comparing the signal divided by a standard deviation for each element to an optical RMS noise value.

22. The method according to claim 1, wherein upon selection of a filter test command, the method further comprises monitoring the output of the optical monitoring system when different filters are used to test for proper operation.

23. The computer based method according to claim 22, wherein the filter test command tests the optical monitoring system with at least one of a schott glass BG36 filter and a liquid crystal clot simulator used.

24. The method according to claim 22, wherein a schott glass BG36 filter is used and the method further comprises:

instructing the user to be sure the light source is on and that a track associated with the optical monitoring system is reasonably covered;

measuring dark current for 10 scans with the light modifying wheel in a blocked position;

determining a first average based on the 10 scans for each photodiode element;

normalizing the signal from the array by selecting individual gain values for each element so as to balance the signal at a preprogrammed level;

setting the light modifying wheel in the schott glass BG36 filter position; and

determining a peak signal for each of a plurality of wavelengths corresponding to the peak transmittance of the filter by fitting a Gaussian curve to the signal detected around the element expected to show a peak for that wavelength.

25. The method of claim 22, wherein a liquid crystal clot simulator is used and the method further comprises:

instructing the user to be sure the light source is on and that a track associated with the optical monitoring system is reasonably covered;

measuring dark current for 10 scans with the light modifying wheel in a blocked position;

determining a first average based on the 10 scans for each photodiode element;

normalizing the signal from the array by selecting individual gain values for each element so as to balance the signal at a preprogrammed level;

setting the light modifying wheel in the liquid crystal clot simulator position; and

monitoring array output with the liquid crystal clot simulator in position and comparing the output to predetermined expected output values.

26. The computer based method according to claim 2, wherein the plurality of user selectable commands further includes an all tests command, the method further comprising:

upon selection of the all tests command, after performing the preliminary testing, performing the electrical systems test command, the optical dark test command, the beam alignment test command, the wavelength registration test command, the profile test command, and the filter test command automatically.

27. The computer based method according to claim 1, further comprising prompting the user to manually adjust certain portions of the optical monitoring system during performance of the test commands.

28. A computer based method for testing an optical monitoring system which is electrically connected to a computer for exchanging control and data signals therewith, the computer having input means for selecting test commands and display means for displaying screens of information to a user, the method comprising:

displaying on the display means at least one screen showing a plurality of user selectable commands; and

performing programmed tests with the computer on the optical monitoring system based on user selected commands input with the input means;

wherein each optical monitoring system has a unique serial number associated therewith and wherein the method further comprises confirming the programmed tests are suitable for use with the optical monitoring system prior to their execution.

29. A system for testing an optical module of an analytical device having optical components and electrical circuitry, the testing system comprising:

program means comprising program instructions and optical module parameters, for implementing a plurality of tests of at least one optical module;

programmable means comprising a data processing system having processor means for executing the program instructions, storage means for storing program instructions and test data including the optical module parameters, user input means for inputting commands, and display means for displaying screens of information to a user including a menu of available test commands and test results;

interface means for interfacing the optical module to the programmable means to facilitate exchange of control and data signals therewith; and

fixture means for test mounting the optical module during testing and simulating actual operational mounting on the analytical device.