Optical Machines

Abstract

An optical device for use with an analytical device arranged to direct an analytical beam along an analytical axis towards a sample in a sample chamber, the optical device including at least two collection optics attached to an arm, the arm being insertable or inserted into the sample chamber through a port in the sample chamber, a sealing element may be provided to seal the port, the sealing element including a window, the arm may be insertable or inserted into the sample chamber to position the at least two collection optics for separately directing light scattered or generated from a point on the sample out the window.

Description

[Technical field]

[0001] The present invention relates to an optical apparatus in an analytical apparatus for transmitting light scattered or generated from a point on a sample in a sample chamber, such as a vacuum chamber, to a detector outside the sample chamber. The analytical apparatus may be arranged to direct an analytical beam, such as an electron beam, towards the sample along an analytical axis. The analytical apparatus may include an electron microscope. The optical apparatus may be an adapter arranged to be retrofitted to the analytical apparatus. The optical apparatus may be for performing spectroscopy, such as Raman spectroscopy. [Background technology]

[0002] International Patent Application WO 99 / 58939 discloses an analytical system for a scanning electron microscope which projects an electron beam onto a sample along an analytical axis. A parabolic mirror is mounted generally in the analytical axis above the sample, with an aperture in the mirror allowing the electron beam to pass to the sample. The mirror is mounted on a mirror holder assembly having an optical axis generally transverse to the analytical axis. The mirror holder assembly is capable of retracting the mirror between its operative position and a non-operative position away from the analytical axis.

[0003] International Patent Application WO03 / 014794a discloses an electron microscope combined with a spectroscopy system. A parabolic mirror is mounted on a mirror holder. The mirror holder is attached to a retractable arm, which is capable of moving the parabolic mirror between operative and non-operative positions. The retractable arm is attached to a guide rail and can be retracted or unretracted along the guide rail by a retraction screw. The retraction screw can be driven by a motor. The guide rail and the retraction screw are placed outside the vacuum to the electron microscope chamber.

[0004] It is desirable to perform spectroscopy, sometimes referred to as mapping, at multiple points on a sample in an electron microscope with the optical axis of the spectroscopy system substantially coaxial with the electron beam. Moreover, it is desirable that such a spectroscopy system is retrofittable to multiple types of electron microscopes. It is rare for a customer to purchase a spectroscopy device at the same time as purchasing an electron microscope. Therefore, a customer may consider whether the electron microscope can be combined with a spectroscopy device only after acquiring the electron microscope. If the spectroscopy device is limited to use with only one or a few electron microscopes, the market size for such devices is limited. In order to reduce the need to provide multiple software modules for the spectroscopy system and the constant adaptation of the software due to changes in the electron microscope control software, it is desirable that a retrofittable spectroscopy device is capable of performing mapping of a sample in a vacuum vessel without being matched to the electron microscope. In this way, the need to provide a control system of the spectroscopy device compatible with each different type of electron microscope is avoided. Summary of the Invention

[0005] According to a first aspect of the present invention there is provided an optical apparatus for use with an analytical instrument arranged to direct an analytical beam along an analytical axis towards a sample in a sample chamber, the optical apparatus comprising a collection optic attached to an arm, the arm being insertable or inserted into the sample chamber through a port in the sample chamber, where the arm is insertable or inserted into the sample chamber to position the collection optic to direct light scattered or generated from a point on the sample out of the sample chamber.

[0006] The optical device may include sealing elements for sealing the port. The sealing elements may include a window, and the arm may be insertable or inserted into the sample chamber to position collection optics for directing light scattered or generated from a point on the sample out of the sample chamber through the window. In this way, the port of the sample chamber is sealed when the arm is inserted into the sample chamber. This may allow a controlled atmosphere, such as a vacuum, to be maintained in the sample chamber.

[0007] The optical device may include a drive mechanism for moving the collection optics within the sample chamber. The drive mechanism may be arranged to move the collection optics in at least two lateral directions (e.g., translation (linear motion) of the collection optics in at least two lateral directions). The drive mechanism may be arranged such that when the arm is inserted into the sample chamber to position the collection optics for directing light, the collection optics is movable in two lateral directions that are substantially perpendicular to the analysis axis. In this manner, the collection optics can direct scattered or generated light from a number of different points on the sample. Hence, two-dimensional mapping of the sample can be performed by moving the collection optics within the sample chamber, rather than the sample. This obviates the need for the optical device to communicate with the analysis device to cause movement of the sample holder to move the sample. Thus, the light delivery device may be arranged to move the collection optics to direct scattered or generated light from a number of different points on the sample, with the sample located on the analysis axis. In this manner, spectroscopic imaging / mapping of the sample using light can be performed while the sample is under the analysis beam.

[0008] The drive mechanism may be arranged to move the arm, where movement of the arm causes movement of the collection optics. The drive mechanism may be arranged to move the arm in at least two lateral directions, preferably at least two orthogonal directions. The drive mechanism may include a translation mechanism for translating the arm. Translation of the arm may cause translation of the collection optics. The drive mechanism may include a Cartesian coordinate manipulator arranged to move the arm in at least two different lateral directions, preferably three different lateral directions, preferably orthogonal directions.

[0009] The drive mechanism may include collection optics and optionally actuators for actuating movement of the arms in at least two lateral directions.

[0010] The drive mechanism may be positioned so that when the arm is inserted into the sample chamber to position the collection optics for directing the light, the drive mechanism is located outside the sample chamber. In this way, the translation mechanism and / or actuator used is not limited to a type suitable for use in an atmosphere formed in the sample chamber, such as a vacuum. For example, the translation mechanism and / or actuator may use a lubricant that is not suitable for use in a vacuum, for example, because the lubrication would contaminate the vacuum if used in a vacuum. The term vacuum as used herein means an atmosphere in which the pressure is significantly lower than atmospheric pressure, for example, less than 3 Pa.

[0011] The drive mechanism may include a first linear axis that is substantially parallel to the longitudinal axis of the arm. The drive mechanism may be arranged such that the range of movement along the first linear axis is sufficient to withdraw the collection optics from the path of the analysis beam. The drive mechanism may be arranged such that the range of movement along the first linear axis is sufficient to withdraw all parts of the optical device from the path of the analysis beam. In this way, other equipment can be inserted into the analysis beam from other ports within the sample chamber. The drive mechanism may include a second linear axis that is transverse to the first linear axis. The range of movement along the first linear axis may exceed the range of movement along the second linear axis. The drive mechanism may include a third linear axis that is transverse to the first and second linear axes. The range of movement along the first linear axis may exceed the range of movement along the third linear axis. The movement along the second and third linear axes may need only be sufficient for mapping, while the movement along the first linear axis may be for mapping and withdrawing the optical device from the analysis axis.

[0012] The collection optics may have an aperture to allow the analytical beam to pass therethrough. The collection optics may be a mirror, such as a parabolic mirror. The collection optics may be arranged to be held stationary relative to the arm during mapping. In one embodiment, the collection optics may be fixed relative to the arm. The arm may be arranged to extend through a port in the sample chamber. The arm may be arranged to move relative to the port through which it extends.

[0013] The arm may include a tube, and the collection optics are arranged to direct light along the tube. It will be understood that the term "tube" as used herein is not limited to a hollow cylinder, but may also use other hollow shapes, such as shapes having a polygonal cross section. Preferably, the tube is a hollow cylindrical tube. The tube, particularly the hollow cylindrical tube, provides a rigid structure to support the collection optics.

[0014] The sealing element may include a flange for sealing a port to the sample chamber. The flange may include an opening through which light is directed by the collection optics. The arm may be movably mounted relative to the flange within the opening. The opening is sealed by a window fixed to the arm and a seal that seals a portion of the opening between the window and the flange. The seal may include a tube and a hermetic seal that prevents air from passing through the opening between the tube and the flange. The hermetic seal may be an expandable element, such as a bellows, attached around the outside of the tube and to the flange around the opening. The window may be attached to the distal end of the tube such that it is located within the sample chamber. Thus, most, if not all, of the inside volume of the tube is sealed from the sample chamber (and is at ambient / atmospheric pressure in use). The window acts as a barrier between elements of the optical device that, during use, are exposed to air (the "air-side") and elements that, during use, are exposed to a vacuum-like atmosphere within the sample chamber (the "sample chamber side").

[0015] The optical device may include a detection optical train for transmitting the light that has passed through the window to a photodetector. For example, the optical train may be arranged to transmit the light to an optical fiber. The optical fiber may be connectable to a spectrometer, such as a Raman spectrometer, for analyzing the light. The optical device may include at least one photodetector for detecting the light. The optical device may include multiple photodetectors in a one-dimensional array or a two-dimensional array. The optical device may include a CCD detector or a CMOS detector.

[0016] The optical device may include a delivery optical train for delivering illumination or excitation light from a light source, such as a laser light source or a white light source, to the collection optical system so that the illumination or excitation light is incident on the sample. The optical device may include a plurality of delivery optical trains, each delivery optical train for delivering light from a different light source to the collection optical system or a corresponding collection optical system. The optical device may include at least two collection optical systems, one for directing laser light to the sample, e.g. for spectroscopy, and another for directing incoherent light onto the sample, e.g. for illuminating the sample for imaging. The collection optical system may include a parabolic mirror. The parabolic mirror may be suitable for directing the laser beam to the sample and directing light scattered by or generated from the sample along the arm at the point illuminated by the laser beam. The collection optical system includes a plane mirror and, optionally, a lens. The plane lens may be suitable for imaging the sample. The at least two collection optical systems may include a parabolic mirror and a plane mirror.

[0017] Each optical train may share some, but not all, optical components with another optical train, which may be accomplished using beam splitters or one or more movable optical elements that can be inserted into the beam paths of the light sources. The optical trains may be arranged to direct light from each light source into a common optical path. The common optical path may include a light path along the arm, such as through a tube. In this way, the width of the tube may be smaller than would be required to transmit multiple non-coincidental optical paths. It may be desirable to minimize the width of the arm to maximize the range of movement of the arm within the port.

[0018] The optical device may include a collection optic interchange device for exchanging the collection optics in the common optical path. The collection optic interchange system may include a holder to which the collection optics are attached, the holder being arranged to be movable relative to the optical path to place each collection optic in the common optical path. The holder may be attached to the arm, preferably at a distal end of the arm. The holder may be rotatably attached to the arm such that the holder can be rotated to a plurality of different positions, each position corresponding to a different one of the collection optics to be placed in the optical path. The collection optic interchange device may include an actuator for moving the holder. The actuator may be arranged at a position in the optical device such that, in use, when the holder is placed in the sample chamber, the actuator is arranged outside the sample chamber and a transmission linkage is arranged for transmitting movement of the actuator outside the sample chamber to movement of the holder within the sample chamber. The transfer linkage may convert rotational motion about an axis substantially parallel to the common optical path, or linear motion along that axis, into motion of the holder that is transverse to the common optical path.

[0019] The optical device may include a light source.

[0020] The drive mechanism may include a drive control system for restricting the movement of the arm to a specified range, which is programmable to adjust the specified range. The drive mechanism may include encoders for measuring the position of the or each axis of the drive mechanism. The drive control system may restrict the movement range of the arm based on the specified range and the position measurements generated by the encoders. The encoder may be an absolute position encoder. The absolute position encoder obtains the position of the drive mechanism without the need to move to a reference position. In this way, the optical device can be adapted to different analytical devices having various geometries within the sample chamber, thereby avoiding collision of the arm with other components within the sample chamber (so-called "geofencing").

[0021] The optical device may include a brake for holding the drive mechanism against a force on the arm resulting from a pressure difference between the atmosphere in the sample chamber and the atmosphere outside the sample chamber. For example, in use, a vacuum may be formed in the sample chamber, such that the arm is pushed into the sample chamber by the pressure difference of the external atmosphere and the vacuum, even though no force is applied to the arm. When power is not supplied to the actuator, such as when there is a loss of power or to avoid the need to constantly power the actuator, the brake may maintain the position of the arm against the force resulting from the pressure difference. Thus, the brake may be on (in normal operation) when power is not supplied.

[0022] The optical device may include a pressure sensor for measuring the pressure in the sample chamber. For example, the pressure sensor may be arranged to measure the pressure in an expandable seal, such as a bellows, or the pressure on the sample chamber side of a flange. The optical device may include a light source control system configured to cause at least one light source, such as a laser, to be switched off (or reduced in intensity) if the measured pressure in the sample chamber deviates from a preset operating pressure. For example, the light source control system is configured to cause at least one light source, such as a laser, to be switched off (or reduced in intensity) if the measured pressure in the sample chamber is substantially the same as the outside pressure. The pressure sensor may measure a difference between the pressure in the sample chamber and the pressure outside the sample chamber, and the light source control system is configured to cause at least one light source, such as a laser beam, to be switched off (or reduced in intensity) if the measured difference is substantially zero. In this way, when a user opens a door to the sample chamber, the light source, such as a laser beam, is switched off or reduced in intensity, thereby avoiding exposure of the user to potentially harmful light, such as high intensity laser light. This eliminates the need to configure the optical instrument control system to communicate with the analytical instrument control system to determine when the door to the sample chamber has been opened.

[0023] According to a second aspect of the present invention, there is provided a method of collecting light scattered or generated from a sample in a sample chamber of an analytical device, the analytical device being arranged to direct an analytical beam along an analytical axis towards the sample in the sample chamber, the method comprising the step of manipulating one or more actuators external to the sample chamber to move collection optics within the sample chamber, such that for each of a plurality of positions of the collection optics within the sample chamber, the collection optics directs light from different points on the sample.

[0024] According to a third aspect of the present invention, there is provided a method for collecting light scattered or generated from a sample in a sample chamber of an analytical device, the analytical device being arranged to irradiate an analytical beam along an analytical axis towards a sample in the sample chamber, the method comprising the step of manipulating one or more actuators outside the sample chamber to change which one of a plurality of collection optics in the sample chamber is positioned to a position within the sample chamber where the collection optics directs light scattered or generated from the sample out of the sample chamber through a window.

[0025] According to a third aspect of the invention there is provided a probe for use with a sample chamber comprising: a probing element attached to an arm, the arm being insertable, or inserted, into the sample chamber to position the probe element within the sample chamber, a drive mechanism for moving the arm, movement of the arm causing movement of the probe element within the sample chamber, and a drive control system for restricting movement of the arm to a specified range, the drive control system being programmable to adjust the specified range.

[0026] The drive mechanism may include an encoder for measuring the position of the or each axis of the drive mechanism. The drive control system may limit the range of movement of the arm based on a specified range and the position measurements generated by the encoder. The encoder may be an absolute position encoder. In this way, the probe can be adapted to different sample chambers having various geometries within the sample chamber, thereby avoiding collision of the arm with other components within the sample chamber (so-called "geofencing").

[0027] According to a fourth object of the present invention there is provided a probe for use with a sample chamber arranged to maintain an internal atmosphere at a different pressure to an external atmosphere, the probe comprising: a probe element attached to an arm, the arm being insertable or inserted into the sample chamber to position the probe element within the sample chamber, a drive mechanism for moving the arm, movement of the arm causing movement of the probe element within the sample chamber, and a brake for holding the drive mechanism against a force on the arm resulting from a difference in pressure between the internal and external atmospheres.

[0028] The brake may be arranged to hold the drive mechanism when power is not supplied to the probe.

[0029] According to a fifth aspect of the invention there is provided an adaptor for retrofitting a sample chamber arranged to maintain an internal atmosphere at a different pressure to an external atmosphere, the adaptor comprising: a light source and delivery optics mounted on an arm insertable into the sample chamber for positioning the optics for directing light generated by the light source to a target within the sample chamber, a pressure sensor for measuring pressure within the sample chamber, and a light source control system configured to switch off the light source if a measured pressure measured by the pressure sensor deviates from a preset operating pressure.

[0030] The light source control system may be configured to cause the light source to be switched off when the measured pressure within the sample chamber is substantially the same as the outside pressure. The pressure sensor measures a difference between the pressure within the sample chamber and the pressure outside the sample chamber, and the light source control system is configured to cause the light source to be switched off when the measured difference is substantially zero.

[0031] The light source may be a laser. [Brief description of the drawings]

[0032] [Figure 1] 1 is a perspective view showing an optical device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram illustrating the optical device shown in FIG. [Diagram 3] FIG. 3 is a perspective view of the optical arrangement shown in FIGS. 1 and 2 with components removed to show an actuator for moving a holder of the collection optics. [Figure 4] FIG. 4 is an embodiment diagram of the optical arrangement shown in FIGS. 1 to 3 with components removed to show an actuator for moving a holder of the collection optics. [Diagram 5] FIG. 5 is a perspective view of the optical device shown in FIGS. 1 to 4 from a different perspective. [Figure 6] FIG. 2 is a perspective view showing the distal end of the arm of the optical device and the holder for the collection optics, seen from above. [Figure 7] FIG. 13 is a perspective view showing the distal end of the arm, the holder for the collection optics, and the collection optics, seen from below. [Figure 8] FIG. 13 is a plan view showing the distal end of the arm, the holder for the collection optics, and the collection optics, as viewed from below. [Figure 9] 9 is a cross-sectional view showing the distal end of the arm, the holder for the collection optics, and the collection optics along line CC shown in FIG. 8. [Figure 10] FIG. 13 is a cutaway view showing the distal end of the arm, the holder for the collection optics, and the collection optics. [Figure 11] FIG. 2 is a perspective view showing a flange of the optical device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] 1-8 show an optical arrangement 100 for use with an electron beam microscope, where an electron beam is directed along an analysis axis A towards a sample in a sample chamber. The optical arrangement 100 includes collection optics 101a, 101b mounted on a movable holder 104 at the distal end of an arm 102, which is insertable into the sample chamber through a port for positioning the collection optics 101a, 101b to direct light scattered or generated from a point on the sample along the arm 102. In this embodiment, the arm 102 includes a cylindrical tube 103, where the collection optics 101a, 101b can be positioned by the holder 104 to direct light along the inside of the tube 103.

[0034] A flange 105 is provided to seal the port to the sample chamber through which the arm 102 is inserted. The flange 105 has bolts or other fasteners to secure the flange 105 to the sample chamber. This alone may be sufficient to hold the optical device in place while it is cantilevered from the side of the sample chamber. In another embodiment, the optical device may be further supported from below, for example by a bench. The flange 105 includes an opening 106 through which the arm 102 extends, the arm being movable relative to the flange 105. The opening 106 is sealed by a window 107 optically transparent to light fixed to the distal end of the tube 103 and a stretchable sealing element that seals the portion of the opening 106 between the window 107 and the flange 105. In this embodiment, the sealing element includes the tube 103 and a bellows 108 that prevents air from passing through the opening 106 between the tube 103 and the flange 105. Bellows 108 is attached around the outside of tube 103 and to a flange 105 around opening 106 .

[0035] The collection optics 101a is for performing spectroscopy and has an aperture therein to allow the electron beam to pass therethrough. A drive mechanism 109 is provided for moving the arm 102 within the sample chamber, and consequently the collection optics 101a, 101b attached to the arm 102.

[0036] The drive mechanism 109 is arranged to move the arm 102 in three orthogonal directions using linear translation stages 112a, 112b, 112c. Each stage 112a, 112b, 112c includes a carriage 113a, 113b, 113c mounted on a rail 114a, 114b, 114c. Actuators (not shown) are provided for moving the carriages 113a, 113b, 113c on the rails 114a, 114b, 114c. The drive mechanism 109 is located on the "air-side" of the flange 105 such that when the arm 102 is inserted into the sample chamber to position the collection optics 101a, 101b for directing light, the drive mechanism 109 is located outside the sample chamber. In this manner, the translation stages 112a, 112b, 112c, and / or actuators used are not limited to types that are suitable for use in the vacuum formed in the sample chamber. For example, the translation stages 112a, 112b, 112c, and / or actuators may use lubricants that are not suitable for use in a vacuum, for example, because the lubricant would contaminate the vacuum if used in the vacuum.

[0037] The translation stage 112a moves the arm 102 in a direction parallel to the longitudinal axis of the arm 102 (labeled "Y-axis"). The translation stage 112b is mounted on the carriage 113a and moves the arm 102 in a direction perpendicular to the longitudinal axis of the arm 102 and perpendicular to the analysis beam (labeled "X-axis"). The translation stage 112c is mounted on the carriage 113b and moves the arm 102 in a direction perpendicular to the longitudinal axis of the arm 102 and parallel to the analysis beam (labeled "Z-axis"). The rail 114a of the Y-axis translation stage 112a is longer than the rails 114b, 114c of the other translation stages 112b, 112c. This is because the Y-axis translation stage 112a is not only used to map the sample, but also to pull the optical device out of alignment with the electron beam so that other devices can be inserted at this location.

[0038] The optical device includes an integrated motor and brake 128. The motor (actuator) drives the movement along the Y-axis, and the brake is arranged to hold the Y-axis translation stage 112a against a force on the arm 102 resulting from a pressure difference between the vacuum in the sample chamber and the atmosphere outside the sample chamber. The brake 128 maintains the position of the Y-axis translation stage 112a when the motor of the Y-axis translation stage is not powered, such as when there is a power loss or to avoid the need to constantly power the motor. Thus, the brake 128 is normally on when power is not provided.

[0039] The drive mechanism 109 includes a drive control system 127 that controls the movement of the translation stages 112a, 112b, 112c. The drive mechanism 109 includes encoders (not shown) for measuring the position of each translation stage 112a, 112b, 112c. In this embodiment, the encoders are absolute position encoders.

[0040] The position measurement signals from the encoders are sent to a drive control system 127. The drive control system 127 is programmable for movement limits for each translation stage 112a, 112b, 112c. These limits can be programmed by an installation engineer who retrofits the optical device to the electron microscope based on the internal geometry of the electron microscope sample chamber. The drive control system 127 controls the movement of the translation stages 112a, 112b, 112c to perform a Raman map of the sample based on feedback from the encoders. The control system 127 stops further movement of the translation stages 112a, 112b, 112c in a direction when the position measured by the corresponding encoder corresponds to the programmed limit.

[0041] A mirror box 115 housing three sets of mirrors 116a, 116b, 117a, 117b, 118a, 118b is mounted on the Z-axis carriage 112c, with each set of mirrors aligned to transmit a corresponding laser beam from a laser source, in this embodiment Raman probes 131a, 131b, 131c, along a common optical path through tube 103 to collection optics 101a, 101b. Mirrors 116a, 116b, 117a, 118a are fixed in position within mirror box 115. The mirrors 117b, 118b are movable from a position aligned to transmit the corresponding (indicated by dotted lines) laser beam along a common optical path to a position out of the path of the other laser beam (movable mirror 117b moves into the path of the laser beam directed by mirrors 116a, 116b, mirror 118b moves into the path of both of the other laser beams). The mirrors 117b, 118b move in a direction parallel to the plane of the mirrors 117b, 118b to minimize / eliminate changes in the direction of the laser beam due to inaccuracies in the displacement of the mirrors 117b, 118b in this direction. The laser beams directed by each mirror pair are of different wavelengths. This allows the optical setup to perform spectroscopy using excitation light of different wavelengths. In this manner, mirrors 116a, 116b, 117a, 117b, and 118a, 118b, along with other optical components in the common optical path, form laser beam delivery optics for transmitting the excitation light from the laser to the collection optics, so that the excitation light is incident on the sample.

[0042] The light collected by the collection optical system 101a is directed back along the common optical path to mirrors 116a, 116b, 117a, 117b, or 118a, 118b (which mirror set depends on whether mirrors 117b and 118b are in the mirror path). The mirrors 116a, 116b, 117a, 117b, or 118a, 118b direct the light to Raman probes 131a, 131b, 131c, which couple the light to corresponding optical fibers 120a, 120b, 120c. The optical fibers 120a, 120b, 120c can be connected to a Raman spectrometer (not shown) for performing an analysis of the Raman spectra of the light. Thus, the analysis of the spectrum of the light is performed outside the optical device 100.

[0043] Each Raman probe 131a, 131b, 131c collimates an excitation laser beam transmitted through an optical fiber 132a, 132b, 132c and directs the collimated laser beam to a corresponding optical train. Additionally, each Raman probe 131a, 131b, 131c couples light received from the optical train to an optical fiber 120a, 120b, 120c.

[0044] The mirror box also houses a beam splitter 119 (shown in Figures 3 and 4), which allows the laser light to pass through it but reflects the broad spectrum light used to image the sample. The optical arrangement includes incoherent broadband light generated by an LED light source 110, which generates a broad beam of light. The light from the light source 110 is directed along a common optical path via a mirror 111 and the beam splitter 119. The mirror box further includes a photodetector array, in this embodiment in the form of a CCD camera 140, for imaging the light reflected from the sample, to which the light reaches via the beam splitter 119 and the mirror 111. In this way, the beam splitter 119 and the mirror 111, together with any other optical components in the common optical path, form a broadband light delivery optical train for transmitting illumination light from the broadband light source to the collection optics 101b so that the light is incident on the sample, and an imaging optical train for transmitting light reflected from the sample to a photodetector, which in this embodiment is a CCD.

[0045] In this embodiment, the collection optics includes a parabolic mirror 101a for directing the excitation laser light onto the sample in the sample chamber to generate a Raman spectrum, and for directing the Raman light emitted from the sample back along a common optical path. Additionally, the collection optics includes a plane mirror 101b and a lens 101c for directing the illumination light onto the sample and directing the light reflected from the sample to the camera. The optical systems 101a, 101b, and 101c are mounted in a holder 104. The collection optics 101a is mounted along an optical path 121a of the holder 104 that is different from the optical path 121b to which the collection optics 101b and 101c are mounted. In this embodiment, the optical paths 121a and 121b of the holder 104 join at an end distal to the end collection optics 101a and 101b. Holder 104 is attached to arm 102, which allows holder 104 to rotate about axis BB to two positions defined by stops (not shown): in one position, optical path 121a, including collection optic 101a, is aligned with the common optical path, and in the other position, optical path 121b, including lens 101c and collection optic 101b, is aligned with the common optical path.

[0046] In use, when the holder 104 is positioned within the sample chamber, movement of the holder 104 is actuated by an actuator 122 outside the sample chamber. A transfer linkage 123 transfers the motion of the actuator 122 to the holder 104. The transfer linkage 123 includes a hooked end portion 124 connected to the holder 104. When the transfer linkage 123 is rotated along its longitudinal axis, the hooked end portion 124 moves the holder 104 against the biasing force of a spring 125 between a position where the collection optic 101a is aligned with the common optical path and a position where the collection optic 101b is aligned with the common optical path. In this embodiment, the spring 125 is a planar spring having an "isle of man" construction with three legs extending generally circumferentially and radially outward from a center located on the axis of rotation of the holder 104. The position of the stops is adjustable in this embodiment via adjustment screws 126a, 126b.

[0047] Thus, the holder 104, the actuator 122, the transmission linkage 123, and the spring 125 function as an optic interchange device for exchanging the collection optics 101a, 101b in the common optical path. The collection optics 101a, 101b located in the common optical path differ depending on the type of imaging to be performed, i.e., Raman imaging / Raman mapping using the parabolic mirror 101a or visible light imaging using the flat mirror 101b.

[0048] A collision guard 133 is attached to the arm 102 and partially surrounds but is separate from the holder 104. The collision guard 133 and holder 104 include electronic contacts that, in use, are typically spaced apart. However, the collision guard 133 is flexible such that if the collision guard 133 comes into contact with an element in the sample chamber, the collision guides will deflect, allowing the electronic contacts to make electrical contact. Closing of the electrical contacts activates an alarm, such as a buzzer, to stop further movement of the arm 102.

[0049] The optical device includes a pressure sensor 129 for measuring the pressure in the bellows 108 and a light source control system 130 configured to switch the laser off if the measured pressure in the bellows 108 deviates above a preset operating pressure.

[0050] It will be appreciated that changes and modifications can be made to the embodiments described above without departing from the scope of the present invention as defined herein.

Claims

1. 1. An optical arrangement for use with an analysis instrument arranged to direct an analysis beam along an analysis axis towards a sample in a sample chamber, comprising: at least two collection optics attached to an arm, the arm being insertable or insertable into the sample chamber through a port in the sample chamber; a sealing element for sealing the port, the sealing element including a window; and Equipped with An optical device, wherein the arm is insertable or inserted into the sample chamber to position the at least two focusing optics to separately direct light scattered or generated from a point on the sample out of the window.

2. The optical device of claim 1 , wherein one of the at least two collection optics is for directing Raman light out of the window.

3. The optical device of claim 2 , wherein the other of the at least two focusing optics is for imaging the sample.

4. 4. The optical apparatus according to claim 1, further comprising a focusing optical system replacement device for replacing the focusing optical system arranged to direct light scattered or generated from a point on the sample out of the window.

5. 5. The optical device of claim 4, wherein the focusing optics exchange device includes a holder to which the focusing optics are attached, the holder being relatively movably arranged to position each focusing optic and direct light scattered or generated from a point on the sample out of the window.

6. The optical device of claim 5 , wherein the holder is attached to the arm.

7. 7. The optical apparatus of claim 6, wherein the holder is rotatably mounted to the arm such that the holder can be rotated to a plurality of different positions, each position corresponding to a different collection optic positioned to direct light scattered or generated from a point on the sample out the window.

8. The light collecting optical system replacement device includes: an actuator for moving the holder, the actuator being arranged at a position within the optical device such that, in use, when the holder is placed in the sample chamber, the actuator is located outside the sample chamber; a transmission linkage for transmitting movement of the actuator outside the sample chamber to movement of the holder within the sample chamber; 8. An optical device according to claim 5, comprising:

9. 9. An optical arrangement according to claim 1, wherein at least one of the collection optics comprises an aperture for allowing the analysis beam to pass therethrough.

10. 10. The optical device of claim 1 , further comprising a transmission optical train for transmitting illumination or excitation light from a light source to a corresponding one of the at least two focusing optical systems so that the illumination or excitation light is incident on the sample.

11. The optical device of claim 10 comprising a plurality of transfer optical trains, each transfer optical train transmitting light from a different light source to the corresponding collection optic.

12. 14. The optical apparatus of claim 13, wherein the at least two focusing optics include a focusing optic for directing laser light onto the sample and another focusing optic for directing incoherent light onto the sample.

13. 13. An optical device according to claim 11 or 12, wherein the transmission optical train is arranged to direct light from each light source along a common optical path.

14. The optical device of claim 13 , wherein the common optical path includes an optical path along the arm.

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