Monitoring system for coating a substrate

• US 3,892,490 A
• Filed: 03/06/1974
• Issued: 07/01/1975
• Est. Priority Date: 03/06/1974
• Status: Expired due to Term

• Current Assignee: Mitsuo Okajima, Toshio Uetsuki, Yoshio Yuasa
• Original Assignee: Mitsuo Okajima, Toshio Uetsuki, Yoshio Yuasa
• Inventors: Uetsuki, Toshio, Okajima, Mitsuo, Yuasa, Yoshio
• Primary Examiner(s): Stern, Ronald J.
• Assistant Examiner(s): Godwin, Paul K.
• Application Number:
  US05/448,683
• Time in Patent Office: 482 Days
• Field of Search: 356/108,161 209/82 250/559,560 350/164,175 65/60
• US Class Current: 356/388
• CPC Class Codes: G01B 11/0633 using one or more discrete wavelengths
• CPC Class Codes: G01N 21/8422 Investigating thin films, e.g. matrix isolation method

Abstract

A monitoring system and method of producing a multi-layered coating such as a non-classical anti-reflecting coating on a substrate such as an optical lens is provided. The substrate is coated with material in a sealed housing. A beam of energy such as light having a variable wavelength across a predetermined range is directed to contact the coating material on the substrate. A portion of the beam is monitored after it contacts the coating material to provide a plurality of corresponding monitoring signals indicative of the optical thickness of the coating. The monitoring signals are compared with a predetermined range of values corresponding to the desired optical thickness. When all of the monitoring signals are respectively matched with the predetermined values, the deposition of material is stopped. The predetermined values and the monitoring signals can be simultaneously displayed on a visual display screen for comparison by an operator. The beam of energy can be monitored before it contacts the coating material and the resulting signal can be compared through a differential amplifier with the resulting monitoring signals to insure that any fluctuations in the energy source will not influence the monitoring signals. Alternatively, the beam can be filtered to provide a derivative single monitoring wavelength beam varying from the design wavelength that would provide an extreme limit of reflection for the desired optical thickness.

Claims

1. A monitoring system for controlling the depositing of a layer of material on a substrate comprising:

a source for producing a beam of energy having a variable wavelength across a predetermined range;

means receiving at least a portion of the beam of energy after it has contacted the material on the substrate for providing corresponding monitoring signals across the predetermined range representative of the material deposited on the substrate;

means for comparing the corresponding monitoring signals with a predetermined range of values representing a desired thickness of material; and

means for indicating when each of the monitoring signals are respectively matched with predetermined values whereby the desired thickness of material has been deposited on the substrate including a visual display screen for displaying both the monitoring signals and the predetermined range of values.

2. A monitoring system for controlling the depositing of a layer of material on a substrate comprising:

means for producing a beam of energy having a variable wavelength including a source of energy for providing a multi-wavelength beam and a plurality of interference filters rotatably mounted for filtering the beam;

means receiving at least a portion of the beam energy after it has contacted the material on the substrate for providing corresponding monitoring signals across the predetermined range representative of the material deposited on the substrate;

means for comparing the corresponding monitoring signals with a predetermined range of values representing a desired thickness of material; and

means for indicating when each of the monitoring signals are respectively matched with predetermined values whereby the desired thickness of material has been deposited on the substrate.

3. The invention of claim 2 further including means for receiving a portion of the beam of energy before it contacts the substrate and providing a corresponding reference signal indicative of the source that produces the beam of energy.

4. The invention of claim 3 wherein the means for receiving a portion of the beam of energy includes a beam splitter in the path of the energy beam and a photo-multiplier.

5. The invention of claim 3 further including means for comparing the source reference signal with the monitoring signals to eliminate any variations in intensity of the monitoring signals caused by any variations in intensity of the source.

6. The invention of claim 5 wherein the means for comparing the source reference signal with the monitoring signals includes a differential amplifier.

7. A monitoring system for controlling the depositing of a layer of material on a substrate comprising:

A source for producing a beam of energy having a variable wavelength across a predetermined range;

means for receiving a portion of the beam of energy before it contacts the substrate and providing a corresponding source reference signal indicative of the source that produces the beam of energy;

means for receiving at least a portion of the beam of energy after it has contacted the material on the substrate for providing corresponding monitoring signals, across the predetermined range representative, of the material deposited on the substrate;

differential amplifier means for comparing the source reference signal with the monitoring signals to eliminate any variations in intensity of the monitoring signals caused by any variations in intensity of the source;

means for comparing the corresponding monitoring signals with a predetermined range of values representing a desired thickness of material; and

means for indicating when each of the monitoring signals are respectively matched with predetermined values whereby the desired thickness of material has been deposited on the substrate.

8. A method of manufacturing a multi-layered optical coating on a lens substrate comprising the steps of:

enclosing at least one lens substrate in a sealed housing;

depositing a layer of coating material on the substrate;

simultaneously directing from a source of energy a beam of energy having a variable wavelength across a predetermined range so that it contacts the coating material on the substrate;

monitoring at least a portion of the beam of energy after it contacts the coating material on the substrate to produce a plurality of corresponding monitoring signals across the wavelength range;

comparing the monitoring signals with a predetermined range of values corresponding to the desired optical thickness of the coating layer;

displaying the monitoring signals and the predetermined range of values simultaneously on a visual display screen; and

stopping the deposition of coating material when each of the monitoring signals correspond to its respective predetermined value.

9. The invention of claim 8 wherein the means for indicating when each of the corresponding monitoring signals are respectively matched with predetermined values includes a visual display screen for displaying both the monitoring signals and the predetermined range of values.

10. The invention of claim 8 wherein the means for indicating when each of the corresponding monitoring signals are respectively matched with predetermined values includes a computer comparison circuit for comparing the reference predetermined values with the monitoring signals.

11. The invention of claim 8 wherein the means for producing a beam of energy having a variable wavelength includes a source of energy for providing the beam and a plurality of interference filters rotatably mounted for filtering the beam.

12. The invention of claim 8 wherein the means for providing corresponding signals includes a photo-multiplier.

13. A method of manufacturing a multi-layered optical coating on a lens substrate having a predetermined design optical thickness value for each layer of coating comprising the steps of:

a. enclosing at least one lens substrate in a housing;

b. depositing a layer of coating material, having a relatively variable index of refraction compared to one fixed theoretical value, on the substrate;

c. simultaneously directing from a source of energy a beam of energy having a variable wavelength across a predetermined range so that it contacts the coating material on the substrate;

d. monitoring at least a portion of the beam of energy after it contacts the coating material on the substrate to produce a plurality of corresponding monitoring signals across the wavelength range;

e. comparing the monitoring signals with a predetermined range of values corresponding to the desired optical thickness of the coating layer within the parameterS of the theoretical design multi-layered optical coating;

f. stopping the deposition of coating material when each of the monitoring signals correspond as close as possible to the respective predetermined value of the design layer;

g. determining any variances between the monitoring signals and the predetermined design values;

h. adjusting the predetermined range of values for the optical thickness of at least one subsequent layer of coating material to compensate for any actual variations in the preceding layer from its design predetermined optical thickness value;

i. depositing a subsequent layer of coating material having a different index of refraction than the preceding layer;

j. simultaneously directing from a source of energy a beam of energy having a variable wavelength across a predetermined range so that it contacts the coating material on the substrate;

k. monitoring at least a portion of the beam of energy after it contacts the coating material on the substrate to produce a plurality of corresponding monitoring signals across the wavelength range;

l. comparing the monitoring signals of the subsequent layer with the adjusted predetermined range of values corresponding to the adjusted desired optical thickness; and

m. stopping the deposition of the subsequent layer of coating material when each of the monitoring signals correspond to the respective adjusted predetermined range of values corresponding to the adjusted desired optical thickness.

14. The invention of claim 13 further including the step of displaying the monitoring signals and the predetermined range of values simultaneously on a visual display screen.

15. The invention of claim 14 further including the step of monitoring at least a portion of the beam of energy before it contacts the coating material on the substrate to provide a reference signal indicative of the condition of the source of energy.

16. The invention of claim 15 further including the step of comparing the source reference signal and the monitoring signals to provide secondary monitor signals that are independent of any fluctuation in the source, the secondary monitor signals are subsequently compared with the predetermined range of values.

17. A method of monitoring the deposition of a layer of material onto a substrate to form an anti-reflecting coating of a set optical thickness over a predetermined wavelength range about a design wavelength in accordance with a non-classical optical design comprising the steps of:

providing a source for producing a beam of light;

directing the light beam towards the material being deposited on the substrate to contact the material;

varying the wavelength of the light beam from the design wavelength to a monitoring wavelength that would provide an extreme limit of reflection for the desired set optical thickness of the non-classical optical coating;

receiving the monitoring wavelength after it contacts the coating layer and providing a representative signal; and

indicating when the representative signal is at the extreme limit of reflection for the desired optical thickness, whereby the depositing of the material can be stopped.

18. The invention of claim 17 wherein the wavelength is varied to provide the maximum reflection at the desired optical thickness.

19. The invention of claim 17 wherein the wavelength is varied to provide the minimum reflection at the desired optical thickness.