Spectrophotometer

• US 7,336,354 B2
• Filed: 02/27/2004
• Issued: 02/26/2008
• Est. Priority Date: 02/27/2003
• Status: Active Grant

• Current Assignee: Agilent Technologies Australia (M) Pty., Ltd. (Agilent Technologies, Inc.)
• Original Assignee: Varian Australia Pty., Ltd. (Agilent Technologies, Inc.)
• Inventors: Sun, Yin Sheng, Masters, Martin Keith
• Primary Examiner(s): Evans; F. L.
• Assistant Examiner(s): Giglio; Bryan J
• Application Number:
  US10/546,886
• Publication Number:
  US 20060290926A1
• Time in Patent Office: 1,460 Days
• Field of Search: 356/318, 356/319, 356/331, 356/334, 356/326, 356/328
• US Class Current: 356/318
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0224 using polarising or depolarising elements
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 21/253 for batch operation, i.e. multisample apparatus analytical automats G01N35/00

Abstract

A spectrophotometer having an optical system for directing a beam of substantially monochromatic excitation light to a liquid sample contained in a well (3) of a well plate for interaction with the sample for absorption or emission measurements to analyse the sample. The optical system includes two apertures (46, 28) for establishing a Kohler illumination region outside the well, that is an excitation beam region between conjugate images (18, 21) of the two apertures. This excitation beam region is then demagnified and imaged (10, 9) into the well (3). The invention provides for the shape of the Kohler illumination region to correspond to the shape of the well space so that all of the liquid sample is uniformly illuminated without the well obstructing any portion of the illuminating excitation beam of light. Advantages of the invention are that the Kohler illumination region of the excitation beam is convenient for insertion of filters (20), apertures and polarisers (19) into the excitation optical system and permits use of small and thus cheaper filters and polarisers. Also the invention provides for accurate absorption or emission measurements from a liquid sample in a well notwithstanding that the sample may only partially fill the well.

Claims

1. A spectrophotometer comprising:

an optical system for directing a beam of substantially monochromatic light into a liquid sample in a well, the optical system comprising;

a first aperture and a second aperture and focussing means forming conjugate images of the first and the second apertures outside of the well to establish therebetween a beam region of monochromatic light, wherein the first and second apertures are sized and shaped for said beam region to have a shape that is similar to the internal shape of the well; and

imaging means imaging said region of the beam to a size corresponding to the internal size of the well at the well for the imaged said region of the beam of monochromatic light to illuminate substantially all of the liquid sample in the well without the well obstructing any portion of the imaged said region of the beam.

2. The spectrophotometer as claimed in claim 1, wherein conjugate images of the first and second apertures are of substantially equal size whereby said region of the beam of light is of substantially constant cross section.

3. The spectrophotometer as claimed in claim 1, wherein the focussing means providing the conjugate images of the first and second apertures is a telecentric mirror.

4. The spectrophotometer as claimed in claim 1, wherein the imaging means imaging said region of the beam of light into the well is an off-axis ellipsoidal mirror.

5. The spectrophotometer as claimed in claim 1, comprising a monochromator providing the beam of substantially monochromatic light, whereby said first aperture is an entrance slit of the monochromator and the second aperture is the aperture of a diffraction grating thereof.

6. The spectrophotometer as claimed in claim 1, further comprising an emission optical system and a detector detecting fluorescently or phosphorescently emitted light from the liquid sample, the emission optical system further comprising:

(i) imaging means providing an image of the bottom surface of the well and an image of the top surface of the liquid sample in the well whereby there is established outside of the well and between said images of the well and liquid sample a region of the emitted light having a shape that is similar to the internal shape of the well,

(ii) focussing means and means providing substantially monochromatic light from the emission light, the focussing means focussing the region of emitted light of similar shape onto the means providing substantially monochromatic light;

the detector is arranged to detect the substantially monochromatic emission light from the means providing such light.

7. The spectrophotometer as claimed in claim 6, wherein the region of the emitted light of similar shape has a substantially constant cross-section.

8. The spectrophotometer as claimed in claim 6, wherein the imaging means providing the images to establish the region of emitted light of similar shape is an off-axis ellipsoidal mirror.

9. The spectrophotometer as claimed in claim 6, wherein the focussing means for the emission light is a telecentric mirror.

10. The spectrophotometer as claimed in claims 6, wherein the means providing the substantially monochromatic emission light is a monochromator.

11. A spectrophotometer comprising:

a light source;

a sample position;

an optical system directing a beam of substantially monochromatic light derived from the light source to a liquid sample when contained in a well when located at the sample position, the well having an internal shape, the optical system comprising;

(i) an entrance aperture, through which the beam of substantially monochromatic light is derived, followed by a second aperture associated with means providing the substantially monochromatic light,

(ii) focussing means providing conjugate images of the entrance and second apertures whereby there is established between the conjugate images a region of the beam of substantially monochromatic light that has a particular shape as determined by the shape and size of the conjugate images, and

(iii) imaging means demagnifying and imaging the region of the beam of light of particular shape into the well for interaction with the liquid sample therein, wherein the particular shape of the region of the beam of light corresponds with the internal shape of the well for substantially all of the liquid sample to be uniformly illuminated without the well obstructing any portion of the beam of light; and

a detection system detecting light from the liquid sample after interaction of the substantially monochromatic beam of light therewith.

12. A spectrophotometer comprising:

a light source;

a sample position;

an excitation optical system directing a beam of substantially monochromatic light derived from the light source to a liquid sample when contained in a well when located at the sample position; and

an emission optical system and a detector, the emission optical system directing light emitted from the liquid sample after interaction of the beam of substantially monochromatic light therewith to the detector, the emission optical system comprising;

(i) imaging means providing an image of the bottom surface of the well and an image of the top surface of the liquid sample in the well whereby there is established outside of the well and between the images a region of the emitted light having a shape that is similar to the internal shape of the well,

(ii) focussing means and means providing substantially monochromatic light from the emission light, the focussing means focussing the region of emitted light of similar shape onto the means providing substantially monochromatic light,

the detector arranged to detect the substantially monochromatic emission light from the means for providing such light.

13. The spectrophotometer as claimed in claim 12, wherein the region of the emitted light of similar shape has a substantially constant cross-section.

14. The spectrophotometer as claimed in claim 12, wherein the imaging means providing said images to establish the region of emitted light of similar shape is an off-axis ellipsoidal mirror.

15. The spectrophotometer as claimed in claim 12, wherein the focussing means is a telecentric mirror.

16. The spectrophotometer as claimed in claim 12, wherein the means providing the substantially monochromatic emission light is a monochromator.