Spectoscopic sampling accessory having dual measuring and viewing systems

• US 5,225,678 A
• Filed: 11/13/1991
• Issued: 07/06/1993
• Est. Priority Date: 11/13/1991
• Status: Expired due to Fees

• Current Assignee: Connecticut Instrument Corporation
• Original Assignee: Connecticut Instrument Corporation
• Inventors: Messerschmidt, Robert G.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US07/792,195
• Time in Patent Office: 601 Days
• Field of Search: 250/339, 250/340, 250/341, 250/353, 356/51, 356/73, 356/326, 359/859
• US Class Current: 250/339.07
• CPC Class Codes: G01J 3/453 by correlation of the amplitudes
• CPC Class Codes: G01N 2021/1738 Optionally different kinds of measurements; Method being valid for different kinds of measurement
• CPC Class Codes: G01N 2021/558 Measuring reflectivity and transmission
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G02B 21/04 involving mirrors

Abstract

A microscope accessory uses symmetrical pairs of identical parabolic mirrors as an imaging optic to map a specimen plane with a remote focus. A mask at the remote focus defines at least one measuring area for making spectroscopic measurements while a separate viewing system simultaneously provides a wide field of view of the sample at higher magnification. The sample aperture, defines as 2T sterradians of solid angle surrounding each side of the specimen plane, is multiplexed between and among different functions--such as spectroscopic measurements and visual observations. The high numerical aperture possible using identical symmetrical aberration canceling (ISAC) optics facilitates the aperture multiplexing which has particular advantage in making reflectance measurements without any need for a significant loss of throughput efficiency.

Claims

1. A microspectrometer accessory, comprising:

a viewing system occupying a first segment of a sample aperture, the viewing system projecting an image of an observation area of a specimen plane to a remote visual image at a viewing magnification, and

a spectroscopic measuring system occupying a second segment of the sample aperture that is separate from the first segment, the spectroscopic measuring system comprising at least a first set of identical symmetrical aberration canceling imaging mirror optics that map the specimen plane with at least a first remote focus, the specimen plane including a measuring area, the spectroscopic measuring system having a specimen magnification that is less than the viewing magnification, and the measuring area being smaller than the observation area.

2. A microspectrometer accessory as claimed in claim 1, wherein the spectroscopic measuring system comprises:

a reflectance subsystem in which the spectroscopic measuring system maps the specimen plane with the remote focus, and

a transmittance subsystem in which the spectroscopic measuring system maps a second remote focus with the specimen plane.

3. A microspectrometer accessory as claimed in claim 1, further comprising at least a first mask positioned at the remote focus to delimit the measuring area.

4. A microspectrometer accessory as claimed in claim 2, wherein the spectroscopic measuring system has a numerical aperture at the specimen plane in the range of 0.8 -0.95.

5. A microspectrometer accessory as claimed in claim 2, further comprising a second mask at the second remote focus.

6. A microspectrometer accessory as claimed in claim 2, wherein the reflectance and transmittance subsystems share at least a part of a common output aperture.

7. A microspectrometer accessory as claimed in claim 1, wherein the first set of identical symmetrical aberration canceling imaging mirror optics comprise parabolic mirrors.

8. A microspectrometer accessory as claimed in claim 2, wherein both the reflectance and transmission subsystems comprise at least first and second pairs of identical symmetrical aberration canceling imaging mirror optics.

9. A microspectrometer accessory as claimed in claim 1, wherein

the spectroscopic measuring system comprises a transmission subsystem which includes the first set of identical symmetrical aberration canceling imaging mirror optics and a second st of identical symmetrical aberration canceling imaging mirror optics, the transmission subsystem transmitting radiant energy through the specimen plane, the second set of identical symmetrical aberration canceling imaging mirror optics forming a second remote focus, and the first set of identical symmetrical aberration canceling imaging mirror optics having a first hole through which visible light form the specimen plane can pass,

the spectroscopic measuring system further comprising at least one mask at least one of the first or second remote foci,

the spectroscopic measuring system further comprising a reflectance subsystem which includes the first set of identical symmetrical aberration canceling imaging mirror optics, the reflectance subsystem multiplexing incident and reflected radiant energy by having half of a beam of each occupy separate segments of the first set in a reflectance mode, and

the viewing system comprises a binocular viewer which receives the visible light via the first hole in the first set of identical symmetrical aberration canceling imaging mirror optics.

10. A microspectrometer accessory as claimed in claim 9, wherein the hole in the first set of identical symmetrical aberration canceling imaging mirror optics forms less than a right angle with the specimen plane.

11. A microspectrometer accessory as claimed in claim 10, wherein the hole forms an angle of 5 degrees with respect to a right angle with the specimen plane.

12. A method of spectroscopic measuring which involves mapping a specimen plane with a remote focus, comprising:

supplying more than half of a beam of radiant energy to a first segment of an aperture of an imaging mirror optic, the imaging mirror optic focusing the more than half of the beam of radiant energy at a specimen plane,

collecting most of any radiant energy that is specularly reflected from the specimen plane using a second segment of the aperture of the imaging mirror optic, the second segment being separate from the first segment, and

directing substantially all of the reflected radiant energy, as collected, to a detector to produce a spectrum.

13. A method of spectroscopic measuring as claimed in claim 12, wherein the radiant energy is infrared radiant energy.

14. A method of spectroscopic measuring as claimed in claim 12, wherein substantially an entire beam of radiant energy is supplied to the first segment.

15. A method of spectroscopic measuring as claimed in claim 12, wherein the imaging mirror optic comprises identical symmetrical aberration canceling imaging mirrors.

16. A method of spectroscopic measuring as claimed in claim 13, further comprising producing a spectrum from the infrared radiant energy.

17. A method of spectroscopic measuring as claimed in claim 15, wherein the first or second segments are large enough to give the imaging mirror optic a numerical aperture in the range of 0.8-0.95.

18. An accessory for multiplexing spectroscopic measuring using a spectrometer, comprising:

an imaging mirror objective having an input aperture, an output aperture and mapping a remote focus at a specimen plane with at least one remote focus,

a supply of a first type of radiant energy to a first segment of the input aperture,

a first optical system occupying a first segment of the output aperture,

a second optical system occupying a second segment of the output aperture that is separate from the first segment, and

a detector for the spectrometer, the detector being a part of at least one of the optical systems.

19. An accessory for multiplexing spectroscopic measuring as claimed in claim 18, wherein the mirror objective comprises identical symmetrical aberration canceling imaging mirrors.

20. An accessory for multiplexing spectroscopic measuring as claimed in claim 18, further comprising a supply of a second type of radiant energy to a second segment of the input aperture that is separate from the first segment of the input aperture.

21. An accessory for multiplexing spectroscopic measuring as claimed in claim 20, wherein the mirror objective comprises identical symmetrical aberration canceling imaging mirrors.

22. An accessory for multiplexing spectroscopic measuring as claimed in claim 18, wherein at least one of the first or second optical systems supplies at least one of the types of radiant energy to the detector for an infrared spectrometer.

23. An accessory for multiplexing spectroscopic measuring using a spectrometer, comprising:

a imaging mirror objective having an input aperture, an output aperture and mapping a specimen plane with at least one remote focus,

a supply of a first type of radiant energy to a first segment of the input aperture,

a supply of a second type of radiant energy to a second segment of the input aperture that is separated from the first segment,

a first optical system occupying a first segment of the output aperture, and

a detector for the spectrometer, the detector being a part of at least the first optical system.

24. An accessory for multiplexing spectroscopic measuring as claimed in claim 23, wherein the mirror imaging objective comprises identical symmetrical aberration canceling imaging mirrors.

25. An accessory for multiplexing spectroscopic measuring as claimed in claim 23, wherein the detector is for an infrared spectrometer.

26. An accessory for multiplexing spectroscopic measuring using a spectrometer, comprising

at least one set of identical symmetrical aberration canceling imaging mirrors having an aperture that occupies at least a segment of a sample aperture about a sample, the one set of identical symmetrical aberration canceling imaging mirrors mapping a remote focus with a specimen plane, the identical symmetrical imaging mirrors having first and second segments, the first segment being separate from the second segment,

a supply of more than half of a beam of radiant energy to the first segment, and

an output which directs from the second segment substantially all of the radiant energy from the first segment that is specularly reflected at the specimen plane to a detector for a spectrometer.

27. An accessory for multiplexing spectroscopic measuring as claimed in claim 26, wherein the identical symmetrical aberration canceling imaging mirrors have at least a third segment which receives at least a second beam of radiant energy, the third segment being separate from the first and second segments.

28. An accessory for multiplexing spectroscopic measuring as claimed in claim 27, wherein the first beam of radiant energy comprises infrared energy and the second beam of radiant energy comprises visible light.

29. A method of multiplexing spectroscopic measuring using a spectrometer, the spectrometer having a detector, an input aperture, an output aperture and at least one imaging mirror optic, comprising

imaging the input aperture with the output aperture by mapping a focus at a specimen plane with at least one remote focus,

supplying a first type of radiant energy to a first segment o the input aperture,

delimiting a measuring area on the specimen plane at the remote focus using the first type of radiant energy,

supplying a first type of radiant energy from the specimen plane to a first segment of the output aperture,

simultaneously supplying the first type of radiant energy from the specimen plane to a second segment of the output aperture that is separate from the first segment, and

directing the first type of radiant energy from at least one of the segments of the output aperture to the detector.

30. A method of multiplexing spectroscopic measuring as claimed in claim 29, further comprising producing an infrared spectrum.

31. A method of multiplexing spectroscopic measuring as claimed in claim 29, further comprising

simultaneously supplying a second type of radiant energy to a second segment of the input aperture, and

simultaneously delimiting the measuring area on the specimen plane at the remote focus using the second type of radiant energy.

32. A method of multiplexing spectroscopic measuring as claimed in claim 31, further comprising obtaining an infrared spectrum of at least one type of radiant energy from at least one of the segments of the output aperture.

33. A method of multiplexing spectroscopic measuring using a spectrometer, the spectrometer having a detector, an input aperture, an output aperture and at least one imaging mirror optic, comprising

imaging an input aperture with an output aperture by mapping a focus at a specimen plane with at least one remote focus,

supplying a first type of radiant energy to a first segment of the input aperture,

delimiting the measuring area on the specimen plane at the remote focus using the first type of radiant energy,

simultaneously supplying a second type of radiant energy to a second segment of the input aperture that is separate from the first segment,

simultaneously delimiting the measuring area on the specimen plane at the remote focus using the second type of radiant energy, and

supplying one of the first or second types of radiant energy from the specimen plane to the detector by way of a first segment of the output aperture.

34. A method of multiplexing spectroscopic measuring as claimed in claim 33, further comprising obtaining an infrared spectrum.