Spectrophotometer with drive means and Spectrophotometry using such

• US 6,727,988 B2
• Filed: 04/11/2001
• Issued: 04/27/2004
• Est. Priority Date: 12/01/2000
• Status: Expired due to Fees

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Kim, Kyung Chan, Oh, Se Baek, Kim, Soo Hyun
• Primary Examiner(s): Chang, Audrey
• Assistant Examiner(s): Curtis, Craig
• Application Number:
  US09/832,551
• Publication Number:
  US 20020101586A1
• Time in Patent Office: 1,112 Days
• Field of Search: 356/319, 356/401, 356/356, 318/116
• US Class Current: 356/319
• CPC Class Codes: G01J 3/2803 using photoelectric array detector

Abstract

A spectrophotometer and spectrophotometry method, using a precision drive at a photodiode array which precisely moves the photodiode array by a distance equal to the physical interval between the photodiodes of the photodiode array so that the spectrophotometer and spectrophotometry method primarily measures light intensities of incident light by the photodiode array, and when precisely moves the photodiode array using the drive by the distance equal to the physical interval between photodiodes of the photodiode array, measures the light intensities of the incident light at desired positions corresponding to the intervals.

Claims

1. A spectrophotometer, comprising:

a light source used for emitting a light beam having a predetermined wavelength range;

a light guide for guiding the light beam from the said light source to a target sample;

a spectrometer head including;

a light diffractor for diffracting the light beam transmitted through the target sample to produce optical spectra,

a light reflector for reflecting the diffracted light from the light diffractor,

a light intensity measuring arrangement for measuring intensity of incident light reflected by the light reflector, said light intensity measuring arrangement having a photodiode array with a plurality of photodiodes linearly arranged on a longitudinal mount at regular physical intervals,

a drive for reciprocating the light intensity measuring arrangement a distance equal to a physical interval between photodiodes of said photodiode array to at least two different discrete positions, and

a stop for limiting a reciprocating movement of the light intensity measuring arrangement; and

a signal-processing unit used for generating a combined distribution of light intensities measured by the light intensity measuring arrangement of the spectrometer head at each of the two different positions.

2. The spectrometer according to claim 1, wherein said light guide comprises a multimode optical fiber.

3. The spectrometer according to claim 1, wherein said light diffractor comprises a reflective diffraction grating.

4. The spectrometer according to claim 1, wherein said light reflector comprises a concave mirror.

5. The spectrometer according to claim 1, wherein said drive comprises a piezoelectric drive unit physically expandable or contractible in accordance with a level of applied voltage.

6. The spectrometer according to claim 1, wherein said drive comprises:

a bimorph piezoelectric drive plate physically expandable and contractible in accordance with a level of an applied voltage; and

a bimorph piezoelectric fixing plate cemented together with said bimorph piezoelectric drive plate, said bimorph piezoelectric fixing plate being physically expandable and contractible in accordance with the level of the applied voltage.

7. The spectrometer according to claim 1, wherein said stop comprises two stoppers arranged at predetermined positions around opposite ends of the light intensity measuring arrangement of the spectrometer head in a moving direction of said light intensity measuring arrangement so as to limit reciprocating movement of the light intensity measuring arrangement.

8. The spectrometer according to claim 5, wherein a displacement amplifier is attached to said piezoelectric drive unit for amplifying a displacement of the piezoelectric drive unit.

9. The spectrometer according to claim 6, wherein said bimorph piezoelectric drive plate and said bimorph piezoelectric fixing plate cemented together are different from each other in their coefficients of expansion and coefficients of contraction in response to an applied voltage.

10. The spectrometer according to claim 1, wherein at least one of said two different positions is defined by said light intensity measuring arrangement against the stop.

11. A spectrophotometry method using a spectrophotometer with a drive, comprising the steps of:

a light transmitting step of guiding a light beam from a light source to a target sample through a multimode optical fiber so as to allow the light beam to be partially transmitted through said sample;

a light diffraction step of receiving the light beam, transmitted through said sample, into a reflective diffraction grating, thus diffracting the light beam into discrete wavelengths to produce optical spectra;

a light reflection step of reflecting the optical spectra of the diffracted light beam by a concave mirror to a photodiode array;

a first intensity measurement step of measuring light intensities of the incident optical spectra by the photodiode array at a first position;

a step of moving the photodiode array using a drive by a distance equal to a physical interval between photodiodes of said photodiode array to a second position;

repeating the steps of light transmitting, light diffraction and a light reflection;

a second intensity measurement step of measuring light intensities of the incident optical spectra by the photodiode array corresponding to said intervals at the second position; and

an intensity distribution generation step of transmitting spectrometric analysis data, obtained at the first and second intensity measurement step, from the photodiode array to a signal-processing unit, and generating a combined light intensity distribution of the target sample by the signal-processing unit corresponding to measured light intensities at the first and second positions.