# US 10,481,385 B2 · Endoscopic immersion probe end optics for laser spectroscopy

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- Number: US 10,481,385 B2
- Document ID: US10481385B2
- Status: Granted
- Kind: B2
- Application number: 15/592,506
- Filed: 2017-05-11
- Published: 2018-11-15
- Granted: 2019-11-19
- Earliest claimed: 2017-05-11
- Assignees: Kaiser Optical Systems
- Applicants: Kaiser Optical Systems Inc.
- Inventors: James M. Tedesco
- Web page: https://patentgrep.com/patent/US10481385B2

## CPC

- G02B 23/243: {Objectives for endoscopes}
- G01J 3/0208: {using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction}
- G01J 3/0218: {using optical fibers}
- G01J 3/44: Raman spectrometry; Scattering spectrometry {; Fluorescence spectrometry}
- G01N 21/645: {Specially adapted constructive features of fluorimeters}
- G01N 21/65: Raman scattering
- G01N 21/8507: {Probe photometers, i.e. with optical measuring part dipped into fluid sample}
- G02B 23/2446: {of the image relay (G02B23/26 takes precedence)}
- G02B 23/2469: {using optical fibres}
- A61B 1/00064: {Constructional details of the endoscope body}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

In one aspect of the present disclosure, improved end optics are disclosed that maximize the numerical aperture focused at a sample point while minimizing unwanted artifacts such as vignetting. The configurations also maintain centering of the excitation/collection beam on the objective if the probe tilts or bends. The disclosed configurations are particularly suited to probes wherein the excitation and/or collection paths between the probe and the laser/analyzer are coupled through multimode fibers, such as in Raman and other forms of laser spectroscopy. The disclosure includes the insertion of one or more additional lenses between the probe head and the focusing objective at the probe tip.

## Claims

### Claim 1

A spectroscopic probe, comprising:
a probe head including an input fiber directed to a collimating lens having an aperture, the input fiber configured to convey an excitation beam and the collimating lens embodied to collimate and focus a single counter-propagating excitation-collection beam, the probe head further including an output fiber configured to convey a collection beam to a spectrograph; and
an end optic comprising:
an optical support structure having a proximal end and a distal end defining a length, wherein the proximal end of the optical support structure interfaces to the probe head such that the optical support structure carries the excitation-collection beam to and from a sample;
an optical interface disposed at the distal end of the optical support structure, the optical interface including a focusing objective having an aperture for focusing the excitation-collection beam at one and only one focus point in the sample immediately adjacent to the optical interface; and
one or more intermediate lenses supported between the collimating lens and the optical interface by the optical support structure, wherein the one or more intermediate lenses having a focal length selected to generate an image of the collimating lens aperture at the focusing objective, to match an exposure of the focusing objective aperture with the excitation-collection beam and reduce vignetting, and to maximize coupling of optical energy in both directions between the input and output fibers to and from the focus point in the sample.

### Claim 2 (depends on 1)

The spectroscopic probe of claim 1, wherein the optical support structure is a hollow tube.

### Claim 3 (depends on 1)

The spectroscopic probe of claim 1, wherein the optical support structure is a hollow tube, and the optical interface disposed at the distal end of the tube is a window sealed to the tube as to enable the end optic to be immersed within the sample, wherein the sample is a liquid.

### Claim 4 (depends on 1)

The spectroscopic probe of claim 1, wherein the optical support structure is a hollow tube, and the optical interface disposed at the distal end of the tube is a cuvette or other sealed sample container.

### Claim 5 (depends on 1)

The spectroscopic probe of claim 1, wherein the one or more intermediate lenses includes a first intermediate lens disposed at or near the proximal end of the optical support structure and a second intermediate lens disposed between the first intermediate lens and the focusing objective.

### Claim 6 (depends on 5)

The spectroscopic probe of claim 5, wherein the first intermediate lens has a focal length selected to generate an image of the input fiber at or near the second intermediate lens, and wherein the second intermediate lens is operative to relay the collimating lens aperture to an image at or near the focusing objective.

### Claim 7 (depends on 6)

The spectroscopic probe of claim 6, wherein the second intermediate lens is operative to generate an image of the collimating lens aperture at a point beyond the focusing objective to increase beam filling of the focusing objective aperture and improve the numerical aperture at the focus point in the sample.

### Claim 8 (depends on 6)

The spectroscopic probe of claim 6, wherein the second intermediate lens is operative to steer the excitation-collection beam toward a center of the focusing objective in response to a bending of the optical support structure.

### Claim 9 (depends on 1)

The spectroscopic probe of claim 1, wherein the input optical fiber is a multimode optical fiber.

### Claim 10 (depends on 5)

The spectroscopic probe of claim 5, wherein the second intermediate lens is positioned in a region approximately midway along the length of the optical support structure.