Prism design for scanning applications and illumination of microscopy sample

• US 8,139,288 B2
• Filed: 03/06/2009
• Issued: 03/20/2012
• Est. Priority Date: 01/16/2002
• Status: Active Grant

• Current Assignee: Illumina Cambridge Limited (Illumina Incorporated)
• Original Assignee: Illumina Cambridge Limited (Illumina Incorporated)
• Inventors: Osborne, Mark, Bryant, Jason, Obradovic, Bojan, Swerdlow, Harold
• Primary Examiner(s): Chapel, Derek S
• Application Number:
  US12/381,154
• Publication Number:
  US 20090237670A1
• Time in Patent Office: 1,110 Days
• Field of Search: None
• US Class Current: 359/385
• CPC Class Codes: G01N 21/648 using evanescent coupling or surface plasmon coupling for the excitation of fluorescence
• CPC Class Codes: G02B 21/002 Scanning microscopes scanning near field optical microscopes G01Q60/18
• CPC Class Codes: G02B 26/108 having one or more prisms as scanning elements
• CPC Class Codes: G02B 27/56 Optics using evanescent waves, i.e. inhomogeneous waves
• CPC Class Codes: G02B 5/04 Prisms

Abstract

A prism for use in scanning applications such as total internal reflection microscopy in which the prism is translated relative to an incident light beam. A geometry is disclosed which cancels walk of the beam footprint at the base of the prism. Walk of the beam footprint due to irregularities in a largely planar sample surface located at the prism base are cancelled by coupling movement of the incident light beam to movement of the sample in the field of view of an objective lens, for example as part of an autofocus arrangement.

Claims

1. A method for controlling the movement of a light beam in a scanning apparatus, as a function of variation in the length of the optical path of said beam, comprising

(a) directing said light beam to an angular prism, wherein said angular prism is coupled to a sample at a base interface;

characterised in that the base angle θ

_p of the prism satisfies the equations;

2. The method according to claim 1, wherein

θ

_p=θ

_c and θ

_i=0.

3. The method according to claim 1, wherein said apparatus is a total internal reflection microscopy apparatus and includes means for detecting interaction of the sample at the base of the prism with an evanescent wave formed by total internal reflection of the light beam at the base of the prism.

4. The method according to claim 3, wherein

θ

_c≧

sin <sup>−

1</sup>(n_s/n_p)

and wherein n_sis the refractive index of the sample medium.

5. The method according to claim 1, wherein said method comprises a method of total internal reflection microscopy, and further comprises the step of detecting interaction of a sample at the base of the prism with an evanescent wave formed by total internal reflection of the light beam at the base of the prism.