WO2016174442A1

WO2016174442A1 - Lens support cuvette

Info

Publication number: WO2016174442A1
Application number: PCT/GB2016/051211
Authority: WO
Inventors: Benjamin COLDRICK; Thomas DREW; Colin Richards
Original assignee: Optimec Limited
Priority date: 2015-04-29
Filing date: 2016-04-28
Publication date: 2016-11-03
Also published as: GB2542082A; GB201507335D0; GB2542082B; GB201700148D0

Abstract

A lens support cuvette (110) for supporting a lens (12) during a measurement process, the lens support cuvette (110) comprising a cuvette body (124) and a lens holder (116). The cuvette body (124) has an at least in part light-transmissible base (120) and at least one wall (126) upstanding from the base (120) to define a lens bath (118). The lens holder (116) includes a lens holder body (134) having an aperture (136) therethrough and a plurality of support arms (140) projecting inwardly into the aperture (136), the plurality of support arms (140) defining a lens support region (142) inside the lens bath (118) which is spaced apart from the base (120) of the cuvette body (124). A lens interrogation system (200) for measuring a lens (12) inserted therein, a lens holder (116) for supporting a lens (12), and a method of interrogating a lens (12) are also provided.

Description

Lens Support Cuvette

The present invention relates to a lens support cuvette for supporting a lens, preferably during a measurement process, and preferably but not exclusively for the measurement of an ocular lens such as a contact lenses. The invention further relates to a lens interrogation system using such a lens support cuvette, and to a lens holder for supporting a lens during a measurement process inside a lens bath. Finally, there is also provided a method of interrogating a lens.

Contact lenses are a growing industry, with currently over 3 million contact lens wearers in the UK. There are a number of different types of contact lens, from the most basic spherical lens designs to complex rigid designs for corneal reshaping. Soft lenses made from oxygen permeable polymers, are formed partly from water and are hydrated during the manufacturing process. They are moved from a dehydrated to a hydrated state, and some properties of the lens are thus affected by this change. It is important during manufacture to be able to measure certain properties for classification and quality assurance purposes. There are a number of measurements which might be taken of a particular lens. The most commonly used are diameter, centre thickness and back curve optical radius (BCOR). While these measurements can easily be taken for a lens in dehydrated form, it is more important to measure the lens when it is in its final, fully hydrated state, as this is the state in which it will be when on an eye. However, the need for the lens to be hydrated complicates the measurement process. In addition, in recent years, the increasing complexity of lens designs has led to the need to measure additional parameters of lenses, which are often located away from the centre of a lens, such as the thickness at junction points of a lens or the sagittal height at points across the lens rather than centrally. Traditional geometric measurement techniques rely on mechanical methods of measurement or the use of optical projection systems to magnify images of contact lenses to allow for measurement against scales. More advanced measurement methods are becoming increasingly common, such as the usage of lasers in confocal measurement or optical coherence tomography. In one known method for use with projection based systems the lens to be measured is placed in a saline bath on a glass or similar surface at a specific incline, held in position using a barrier typically formed in a V-shape, or on a flat plane held in place by fluid pressure as described in international patent application WO2014122458A1. In another known method for projection and contact based measurements, a lens can be held in position by a cylinder and platform arrangement as described in British patent application GB2056702A. In another known method for usage in a laser based instrument, a lens can be held within a quartz cuvette which contains a small amount of fluid as described by Joannes, L., et al, Contact Lens & Anterior Eye, 2010. 33(1). Finally, in another known configuration for the measurement of contact lenses with a laser based method, a lens is held in place by capillary forces of a fluid within a cuvette as described by Karnowski, K., et al., Optics Letters, 2014. 39(16): p. 4727-4727.

Whilst it is important to hold the lens in place during measurement in a way that does not deform the lens, the applicant has noticed that all these methods necessitate the lens being held at an inclination or on top of an obstructive material, which interferes with certain complex measurement methods such as Optical Coherence Tomography, or when measuring from either or both sides of a lens. In addition, some of the methods in use for laser based measurement require complicated lens positioning methods or restrict the ability to insert or remove lenses which limits the practicality for a production and quality control environment. In addition, the capillary force methods require immersing a lens only a short way beneath the surface of the fluid, which can cause complications with extraneous signals being generated, requiring the usage of contrast enhancing agents which is not conducive to an industrial environment.

In laser based measurement, the presence of a support structure in the measurement area can complicate or prohibit measurements of a sample being made, either through obstruction of the laser signal or through causing extraneous signals to be generated. To enable accurate measurements to be made of a sample such as a lens, it is preferable for the sample to be measured in free space in an orientation perpendicular to the scanning laser, to avoid imaging artefacts from any support structure or the sample being at an angle pushing it outside of a measurement window. To be able to obtain accurate measurements, the orientation of the sample is critical and in the case of lenses, measurements typically should be made through the centre of a lens. A simple way to achieve this is to observe the whole outline of a lens, allowing the centre to be determined programmatically via a camera image. To enable a camera to be able to distinguish the outline of a sample, some form of rear illumination, typically either bright or dark field, is required. Therefore, a transparent base, which is transparent in the wavelengths suitable for the illuminating light source, in combination with an open view from above the sample should be utilised.

In addition, for complex lens designs, some form of marking can be used on the lens surfaces to indicate position and orientation of the lens features, the combination of illumination system and support mechanism therefore needs to work in tandem with each other to allow for measurement scans to be conducted at the appropriate places. These scans may not be required to pass through the centre of a lens, but offset to measure the correct features,

To enable suitable throughput of ocular lenses in a production and quality assurance environment, lenses should be able to be readily inserted and removed from a measurement instrument and equilibrate in an appropriate manner. Ideally being able to insert a lens into a temperature controlled fluid without having to remove obstructions before insertion or removal would be preferred.

The present invention seeks to provide a lens support cuvette which allows a lens to be measured without interference from the apparatus.

According to a first aspect of the invention, there is provided a lens support cuvette for supporting a lens during a measurement process, the lens support cuvette preferably comprises: a cuvette body having an at least in part light-transmissible base and at least one wall upstanding from the base to define a lens bath; and a lens holder including a lens holder body having an aperture therethrough and a plurality of support arms projecting inwardly into the aperture, the plurality of support arms defining a lens support region inside the lens bath which is spaced apart from the base of the cuvette body, so that a lens on or at the lens support region can be scanned between any two points without having to scan through any of the support arms in contact with the lens. Providing a means of supporting a lens in a fluid bath, which may contain a gaseous fluid such as air, or a liquid fluid such as saline solution, advantageously limits the potential for a lens to be deformed under gravity when resting on a planar transparent plate, as is common in the art. Contact lenses are typically at least partially flexible, and contact with a flat plate can cause deformation of the lens. The invention effectively permits the lens to be measured in near-optimal conditions, ensuring a more accurate measurement of its optical properties to be assessed. When viewed from a first aspect, it provides an apparatus for supporting a lens characterised in that it enables the lens to be optically scanned between any two points of the lens without having to scan through any support surfaces in contact with the lens. The lens bath allows for transmission of light from both above and below the cuvette into the lens holder, so as to allow measurement signals to pass therethrough.

Preferably, at least three said support arms may be provided equi-positioned about the aperture, preferably so as to be arranged radially around a circumference of the lens. Each of the plurality of support arms may be extendible and/or retractable relative to a centre of the lens holder to alter a size of the lens support region. Each of the plurality of support arms may preferably be elongate, the support arms being extended longitudinally towards or away from a central vertical axis of the apparatus to vary the size of the opening over which the lens rests. The provision of support arms which contact the lens around a radial extreme minimises the contact between the lens and the lens support region, further improving the accuracy of measurement by interrogation devices. Beneficially, extendible and retractable support arms allow for the measurement of different sizes of lens using a single lens support cuvette. Each of the plurality of support arms may be rotated, in particular, each support arm being rotatable about its own longitudinal axis, and/or the lens support region may be rotatable relative to the lens holder body.

Allowing for the support arms to be rotated not only improves the ease with which a lens can be seated on the lens support region, but also allows for some manipulation of the lens in situ, enabling portions of the lens to be interrogated which had previously been covered by the support arms.

In one embodiment, each of the plurality of support arms may be aligned with a horizontal plane of the lens holder body. Alternatively, each of the plurality of support arms may be tilted or angled with respect to a horizontal plane of the lens holder body, preferably by ±11 degrees from the horizontal plane. The lens support region may be vertically adjustable with respect to the base of the cuvette body. Optionally, each of the plurality of support arms has a rounded profile.

The support arms are preferably arranged in such a manner so as to minimise the degree of contact between the lens surfaces and the lens support region, thereby minimising the possibility of interference effects. Furthermore, tilted support arms can advantageously provide different lens support region configurations, allowing different regions of the lens to be interrogated, and furthermore, a sloping of the arms will allow for simple lens centralisation within the lens support region. The lens holder can preferably be adjusted within the device to allow for vertical movement, which may be important to allow the system to be adjusted due to the measurement medium, such as in liquid or air.

The lens support cuvette may further comprise a lens retaining ring to in use restrict displacement of a lens positioned on the lens support region. Furthermore, the apparatus may comprise a means for filling the interior with liquid, for instance the cuvette body may include a fluid inlet and fluid outlet to permit insertion and extraction of a fluid into the lens bath.

Retention of the lens in position within the lens support cuvette beneficially improves the accuracy of the measurements taken. The inlet and outlet ports allow for the introduction of fluids, which can be externally pumped from a temperature-controlled source or could be provided as an integral part of the apparatus.

The lens holder may be releasably engagable with, or alternatively may be integrally formed with, the cuvette body. Furthermore, the apparatus may comprise means for attachment to a larger instrument, such as an interrogation device.

The lens insertable into the apparatus may be an ocular lens which is soft or rigid. According to a second aspect of the invention, there is provided an apparatus for supporting a lens characterised in that it enables the lens to be optically scanned between any two points of the lens without having to scan through any support surfaces in contact with the lens. According to a third aspect of the invention, there is provided a lens interrogation system for measuring a lens inserted therein, or an instrument for the measurement of a lens, the lens interrogation system comprising: a lens support cuvette or apparatus preferably in accordance with the first or second aspects of the invention; and an interrogation device aligned with an optical axis of the lens interrogation system which passes through the lens support region and at least in part light-transmissible base of the cuvette body so as to, preferably optically, interrogate a lens positioned on the lens support region.

The interrogation device may include a laser, and/or the interrogation device may include a plurality of different interrogation types, that is, two or more different means for taking measurements of the lens, which may include a means for taking measurement of the lens using light.

A lens interrogation system utilising the lens support cuvette as previously described ensures that the lens is spaced apart from surfaces which might otherwise result in distortions to the measurements taken by the, preferably optical, interrogation device, such as a laser source and sensor, or a digital camera, or any combination of different sources.

According to a fourth aspect of the invention there is provided a lens holder for supporting a lens during a measurement process inside a lens bath, the lens holder comprising: a lens holder body having an aperture therethrough and a plurality of elongate support arms projecting inwardly into the aperture, the plurality of elongate support arms defining a lens support region.

Each of the plurality of elongate support arms may be extendible and retractable relative to a centre of the lens holder to alter a size of the lens support region. Furthermore, each of the plurality of elongate support arms may be tilted with respect to a horizontal plane of the lens holder body.

The provision of a separate lens holder to the lens bath simplifies insertion and removal of the lens, enabling for a simplified process by which the lens can be measured. This can positively affect the efficiency of the measurement process for large numbers of lenses.

According to a fifth aspect of the invention, there is provided a method of interrogating a lens, the method comprising the steps of: inserting the lens onto the lens support region of the lens support cuvette of a lens interrogation system, preferably in accordance with the second aspect of the invention, such that the lens is spaced apart from the base of the cuvette body and activating the interrogation device so as to interrogate at least part the lens without obstruction by the lens support region or cuvette body.

According to a sixth aspect of the invention, there is provided a method of taking one or more measurements of a lens, comprising a means for supporting the lens characterised in that it enables the lens to be optically scanned between any two points of the lens without having to scan through any support surfaces in contact with the lens. This may be performed using a laser, or two or more different types of measurement may be used to measure the contact lens. The measurements may be taken using light, such as light in the visible spectrum.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a diametric cross-sectional representation through one embodiment of a lens support cuvette in accordance with the state of the art; Figure 2 shows an exploded perspective representation of a first embodiment of a lens support cuvette, in accordance with the first or second aspect of the invention;

Figure 3 a shows a plan view from above of the lens support cuvette of Figure 2; Figure 3b shows a plan view from above of a second embodiment of a lens support cuvette in accordance with the first or second aspect of the invention;

Figure 4 shows a cross-sectional representation through line A-A indicated on the lens support cuvette of Figure 3 a; Figure 5 shows a cross-sectional representation through line B-B indicated on the lens support cuvette of Figure 3 a;

Figure 6a shows a cross-sectional representation through a third embodiment of a lens cuvette assembly in accordance with the first or second aspect of the invention, with a lens positioned in an upward-facing direction; Figure 6b shows a cross-sectional representation of the lens support cuvette of

Figure 6a, with a lens positioned in a downward-facing direction;

Figure 6c shows a cross-sectional representation through a fourth embodiment of a lens support cuvette in accordance with the first or second aspect of the invention, with a lens positioned in an upward-facing direction; Figure 6d shows a cross-sectional representation of the lens support cuvette of

Figure 6c, with a lens positioned in a downward-facing direction; and

Figure 7 shows a cross-sectional representation through one embodiment of a lens interrogation system in accordance with the third aspect of the invention, the lens interrogation system incorporating a lens support cuvette of Figure 2. Referring firstly to Figure 1, there is shown a lens support cuvette, indicated globally at 10, as is utilised in the present state of the art, for supporting a contact lens 12 for measurement using a fixed laser. The contact lens 12 is supported on a flat transparent plate 14 which forms the base of a lens holder 16 to define a bath 18 for the lens 12 and which can be filled with a solution such as saline. The lens holder 16 shown is uncapped, and thus the saline solution is open to the air. It will be appreciated, however, that any suitable liquid could be used which is able to maintain the desired degree of hydration of the contact lens 12 and which has suitable transmissive properties to allow the measurements of the lens 12 to be conducted. Conventionally a saline solution is used but it is envisaged that other liquids could be employed instead. The liquid is preferably filtered and maintained at a constant temperature.

Beneath the transparent plate 14 is a supporting base 20 which has a central hole 22 over which the lens 12 is positioned on the transparent plate 14. Optical or other interrogation of the lens 12 can then be performed. However, the contact of the lens 12 with the transparent plate 14 can lead to distortions in the measurements.

A lens support cuvette 110 in accordance with the present invention is shown in detail in Figures 2, 3a, 4 and 5. This apparatus 110 comprises a cuvette body 124 which is preferably cylindrical in shape, the cuvette body 124 having a base 120 which is at least in part light-transmissible, and an upstanding perimeter wall 126 which together define a lens bath 118. It will be appreciated that the term cuvette is here used to refer to a container suitable for containing a fluid within which an optical lens, such as a contact lens, can be measured using optical or non-optical interrogation instruments.

The base 120 of the cuvette body 124 may be formed so as to have a hole 122 therethrough to permit optical access to the lens bath 118, with the bath preferably including a transparent or similarly light-transmissible plate 114 which is sealingly engaged or formed with the base 120. This can be most readily seen in Figure 4. The plate 114 may be, for example, adhered into a recessed portion 128 of the base 120. The lens bath 118 may be filled and emptied via a fluid inlet 130 and/or fluid outlet 132 which may be formed in the cuvette body 124.

A lens holder 116 is also provided which acts to support the lens 12 in the lens bath 118. In the depicted embodiment, the lens holder 116 is formed so as to be releasably engagable with the cuvette body 124; however, it will be appreciated that the lens holder 116 and cuvette body 124 may be fixedly engaged with one another, or may be integrally formed so as to form a single lens support unit. Although a lens holder is suggested herein and throughout, any suitable vessel, preferably a laboratory vessel, which may be for holding a liquid may be considered for use. The depth of the hole 122 is preferably sufficient so as to ensure that the transparent plate 114 is sufficiently spaced apart from the lens holder 116 when in position such that the transparent plate 114 does not interfere with the contact lens measurement signals. As such, when a fluid measurement medium such as saline is utilise, the depth of the fluid above the apex of the contact lens 12 will be sufficient to ensure optimal image quality and no spurious artefacts. Said fluid medium can be any fluid compatible with ocular lenses and the measurement method, and is typically a buffered saline solution. The lens holder 116 is formed having a lens holder body 134 which has a preferably circular profile, and having a, preferably centrally positioned, aperture 136 which extends through the lens holder 116 in an axial direction. The aperture 136 may be formed so as to be similarly or identically dimensioned to the hole 122 in the base 120 of the cuvette body 124. Inwardly projecting into the aperture 136 from a retaining wall 138 thereof, so as to be aligned with a radius, diameter, or centre-line of the lens holder body 134, is a plurality of support arms 140 which collectively act as a lens support region 142. In the depicted embodiment, the support arms 140 are formed as elongate rods having a circular or round profile so as to minimise physical contact with the lens 12 in situ. As illustrated, there may be a clearance between the inward-facing ends of the support arms 140 such that there is a clear passage for at least optical access through the centre of the aperture 136. However, it will be appreciated that square-, elliptical or oval-profiled support arms may be provided. The support arms 140 are, as can be seen in Figure 4, taken as a cross-section through line A-A in Figure 3a, recessed into the lens holder body 134 and extend from the retaining wall 138 so as to project out of a horizontal plane of the lens holder 116. The inclination of the support arms 140 may, for instance be up to 11° from the horizontal, either pointing upwardly or downwardly with respect to the base of the lens holder 116. Whilst the lens support region 142 described above is spaced apart from the base 120 of the cuvette body 124, it will be appreciated that it may be possible for the support arms to be directly or indirectly mounted to the base 120 of the cuvette body 124, whilst still maintaining the lens 12 in a position which is spaced from the base 120. In this former case, a lower or lowermost surface of each support arm may be in contact with the base. As such, there may be no spacing between the support arms and the base, although the lens support region defined by the upper surface of each support arm will be spaced from the base. Figure 5 shows the clearance provided along line B-B, showing how a lens 12 can be spaced apart from the retaining wall 138 and support arms 140. The depth of the retaining wall 138 may be preferably chosen so as to prevent egress of the lens 12 from a rim of the lens support region 142 defined by the retaining wall 138 once fluid is introduced into the lens bath 118. The diameter of the retaining wall 138 also prevents the lens 12 from being displaced too far from a centre of the lens support region 142. Changing the inclination of the support arms 140 may advantageously allow for the adjustment of the vertical position of the lens support region 142; it will be appreciated that the support arms 140 could therefore be actuatable, for instance, by providing a tiltable geared arrangement, in order to change the vertical position of the lens support region 142 in use.

In one preferred embodiment of the invention, shown in Figure 3a, there are eight support arms 140, equi-spaced around the aperture 136, and thereby providing eight points of contact with a lens 12 placed onto the lens support region 142, that is, spaced at 45 degree angles from one another. However, it will be apparent that other arrangements are possible, such as six arms providing six points of contact and thus preferably spaced at 60 degrees from one another.

One alternative embodiment is shown in Figure 3b; the embodiment is substantially identical to that of the first embodiment described above, and identical or similar reference numerals will be used to refer to identical or similar components. Further detailed description will therefore be omitted.

The lens holder 116' in this second embodiment of the lens support cuvette 110' has a lens holder body 134' having an aperture 136' from which only three support arms 140' extend from the retaining wall 138', equi-spaced from one another at 120° angles. This will result in a lens support region 142' having three points of contact. Other arrangements may be possible, for example, an arrangement having four support arms, spaced at 90° angles to one another, but other geometric configurations will be apparent to the skilled person.

Referring again to the first embodiment of the lens support cuvette 110 may have support arms 140 which are preferably formed from a material which is suitable for immersion in a measurement fluid, such as saline, for instance a plastics material, or stainless steel. The support arms 140 preferably have a size and profile which causes as little obstruction as possible to an optical path aligned through the lens support cuvette 110, and also to reduce the surface area which is in contact with the lens 12 at any given time.

The support arms 140 may be fixed in position, so as to provide a stationary lens support region 142. However, it may also be possible to provide support arms 140 which are individually rotatable about a longitudinal axis of said support arm 140, for instance, via a user-operable lever. This may assist with manipulation of a lens 12 positioned on the lens support region 142. Additionally or alternatively, the support arms 140 may be rotatable as a unit relative to the lens holder body 134, for instance, by providing a geared arrangement mountable within the lens holder 116 with which each of the support arms 140 is engaged. A gear could be mounted at one end of the support arm 140, for example. Such an arrangement may assist with the seating of the lens 12 for measurement.

If the support arms 140 are fixed in position, then each lens holder 116 may only be used with lenses 12 of specific dimensions which are compatible with the size of the lens support region 142. However, it will be appreciated that lenses 12 are manufactured in many different sizes. It may therefore be advantageous to provide support arms 140 which can be moved so as to alter the size of the lens support region 142 in order to accept lenses 12 of different sizes, since the support arms 140 preferably will only contact a very edge of the lens 12. This may be achieved by allowing the support arms 140 to be actuatable to and from a centre-point of the aperture 136 of the lens holder 116, for example, by providing a geared arrangement for linear actuation of the support arms 140, or by allowing manual or automatic sliding of the support arms 140 so as to crate variable-length support arms 140.

If the support arms 140 are actuatable along this axis, it may also be preferable to allow alteration of the dimensions of the aperture 136 so as to correspondingly accommodate lenses 12 of differing sizes. This could be achieved, for instance, by providing the aperture 136 as a leaf shutter, allowing the diameter of the retaining wall 138 to be altered. This may also improve the ability of a user to extract a lens 12 in the lens support cuvette 110, for example, by providing additional room into which tweezers may be accommodated. For standard lenses 12 it is suggested that a range of 14mm to 20mm for the diameter or width of the retaining wall 138 may be appropriate. As an alternative, a plurality of lens holders 116 having differently dimensioned apertures 136 could be provided.

Further alternative configurations of the invention can be seen in Figures 6a to 6d, and again, similar or identical reference numerals will be used to refer to similar or identical components to those described above, and further detailed description is omitted for brevity. In Figures 6a and 6b, the lens support cuvette 110" has a lens holder 116" having downwardly projecting support arms 140" . Figure 6a shows how the lens 12 may sit upon the lens support region 142" with its concave surface in an upward-facing condition, whereas Figure 6b shows the same with the lens 12 with its concave surface in a downward-facing condition.

Figures 6c and 6d show a corresponding lens support cuvette 110" ' which has a lens holder 116" ' having upwardly projecting support arms 140" ' . Figure 6c shows how the lens 12 may sit upon the lens support region 142" ' with its concave surface in an upward-facing condition, whereas Figure 6d shows the same with the lens 12 with its concave surface in a downward-facing condition. Such arrangements of the lens support cuvette 110", 110" ' allows for different aspects of the lens 12 to be seen more clearly. Again, referring back to the first embodiment of lens support cuvette 110, although it will be clear that the following applies to all embodiments of the invention, the apparatus 110 can be used as part of a lens interrogation system 200, such as that shown in Figure 7. An interrogation device 244, here comprising an optical emitter 246 and optical sensor 248, is positioned such that an axis of optical interrogation O passes through the aperture 136 of the lens holder 116 and the light-transmissible portion of the cuvette body 124. It will be appreciated, however, that not-optical interrogation may also be useful, such as using ultrasound or visible spectrum analysis of the lens 12.

The lens 12 has been placed upon the lens support region 142, and the lens holder 116 inserted into the cuvette body 124 such that the lens 12 is spaced apart from the transparent plate 114 in the base 120 of the cuvette body 124, in particular, along the axis of optical interrogation O.

The lens bath 118 can be filled with an appropriate fluid, such as a saline solution, preferably via the fluid inlet 130, which is positioned above the lens holder 114, and this fluid is able to bathe the lens so as to achieve optimum contextual measurements. In order to retain the lens 12 in position once the fluid is inserted, it may be preferable to provide a lens retaining ring which can apply an axial retaining force to the lens 12 to prevent displacement during measurement. However, since the lens 12 is not positioned against a complete transparent plate, fluid can flow around both sides of the lens 12 in situ, allowing for an equalization of fluid pressure around the lens 12, which leads to a decreased possibility of deformation of the lens 12.

The interrogation device 244 can be activated in order to take measurements of the lens 12. This may be by laser interrogation of the lens 12, and one or more different types of interrogation could be performed, simultaneously or otherwise, of the lens 12 by the interrogation device 244.

The lens support cuvette 110 ensures that the axis of optical interrogation O of the interrogation device 244 is spaced apart from the support arms 140. The spacing of the support arms 140 also ensures that there is sufficient space between adjacent support arms 140 so as to allow for the interrogation device 244 to be able to scan across a full diameter of the lens 12, if desired, without interference with the support arms 140 or base 120 of the cuvette body 124. This can be repeated for several different diameters, dependent upon the geometry of the lens support region 142, and rotation of the support arms 140, if possible, can allow the user to interrogate the portions of the lens 12 which would otherwise be covered by the support arms 140 in the first configuration. The depicted embodiment of the lens interrogation system 200 shows a representative cross-section taken in a straight line from one side of the lens 12 to another. However, the invention is not limited to scanning a diameter of the lens 12; other cross-sections can be defined, for example, by starting in a central position and moving towards one edge of the lens 12. A further example would be to scan a cross-section between any two points within a boundary of the lens edge. Once measurement of the lens 12 has been completed, the fluid can be drained from the lens bath 118, via the fluid outlet 132, which is as close to the base 120 of the cuvette body 124 as possible, to ensure suitable drainage of the fluid measurement medium, and the lens 12 then extracted from the lens support cuvette 110. The present apparatus 110 is such that a lens 12 on or at the lens support region 142 can be scanned between any two points without having to scan through any of the support arms 140 in contact with the lens 12. The lens 12 can, in the present lens support cuvette 12, be interrogated across an extent thereof such that an edge region of the lens 12 can be measured. The spacing between adjacent support arms 140 enables the measurement of the edge region without interference by the support arms 140, which would otherwise be an issue with the use of a transparent plate as a support substrate wherein an entire perimeter edge or entire perimeter edge region of the lens contacts the transparent plate, thus impacting an accuracy of a scan.

It will be appreciated that whilst the depicted embodiments above are typically used in conjunction with the measurement of contact lenses for insertion in front of an eye of a patient, it is possible to utilise the present invention with any form of optical lens for measurement.

Laser based imaging and measurement can have complications when imaging or measuring samples on a surface. The present invention therefore allows for a plurality of images or data to be captured without the supporting structure from introducing spurious artefacts, allowing measurements of a lens as if it were freely suspended in air or fluid, and thereby reducing any potential for interference at the lens surfaces. The particular lens holder used can also be configured to make them suitable for a range of different ocular lenses. The holder allows of quick and simple insertion and removal of lenses in addition to the ability of the lens to be manipulated within the lens holder.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

1. A lens support cuvette (110) for supporting a lens (12) during a measurement process, the lens support cuvette (110) comprising: a cuvette body (124) having an at least in part light-transmissible base (120) and at least one wall (126) upstanding from the base (120) to define a lens bath (118); and a lens holder (116) including a lens holder body (134) having an aperture (136) therethrough and a plurality of support arms (140) projecting inwardly into the aperture (136), the plurality of support arms (140) defining a lens support region (142) inside the lens bath (118) which is spaced apart from the base (120) of the cuvette body (124), so that a lens (12) on or at the lens support region (142) can be scanned between any two points without having to scan through any of the support arms (140) in contact with the lens (12).

2. A lens support cuvette (110) as claimed in claim 1, wherein at least three said support arms (140) are provided equi-positioned about the aperture (136).

3. A lens support cuvette (110) as claimed in claim 1 or claim 2, wherein each of the plurality of support arms (140) is extendible and/or retractable relative to a centre of the lens holder (116) to alter a size of the lens support region (142).

4. A lens support cuvette (110) as claimed in any one of claims 1 to 3, wherein each of the plurality of support arms (140) is elongate.

5. A lens support cuvette (110) as claimed in claim 4, wherein each of the plurality of support arms (140) is rotatable about its own longitudinal axis.

6. A lens support cuvette (110) as claimed in any one of the preceding claims, wherein the lens support region (142) is rotatable relative to the lens holder body (134).

7. A lens support cuvette (110) as claimed in any one of the preceding claims, wherein each of the plurality of support arms (140) is aligned with a horizontal plane of the lens holder body (134).

8. A lens support cuvette (110) as claimed in any one of claims 1 to 6, wherein each of the plurality of support arms (140) is tilted with respect to a horizontal plane of the lens holder body (134).

9. A lens support cuvette (110) as claimed in any one of the preceding claims, wherein the lens support region (142) is vertically adjustable with respect to the base (120) of the cuvette body (124).

10. A lens support cuvette (110) as claimed in any one of the preceding claims, wherein each of the plurality of support arms (140) has a rounded profile.

11. A lens support cuvette (110) as claimed in any one of the preceding claims, further comprising a lens retaining ring to in use restrict displacement of a lens (12) positioned on the lens support region (142).

12. A lens support cuvette (110) as claimed in any one of the preceding claims, wherein the cuvette body (124) includes a fluid inlet (130) and fluid outlet (132) to permit insertion and extraction of a fluid into the lens bath (118).

13. A lens support cuvette as (110) claimed in any one of the preceding claims, wherein the lens holder (116) is releasably engagable with the cuvette body (124).

14. A lens support cuvette (110) as claimed in any one of claims 1 to 12, wherein the lens holder (116) is integrally formed with the cuvette body (124).

15. A lens interrogation system (200) for measuring a lens (12) inserted therein, the lens interrogation system (200) comprising: a lens support cuvette (110) as claimed in any one of the preceding claims; and an interrogation device (244) aligned with an optical axis of the lens interrogation system (200) which passes through the lens support region (142) and at least in part light-transmissible base (120) of the cuvette body (124) so as to optically interrogate a lens (12) positioned on the lens support region (142).

16. A lens interrogation system (200) as claimed in claim 15, wherein the interrogation device (244) includes a laser.

17. A lens interrogation system (200) as claimed in claim 15 or claim 16, wherein the interrogation device (244) includes a plurality of different interrogation types.

18. A lens holder (116) for supporting a lens (12) during a measurement process inside a lens bath (118), the lens holder (116) comprising: a lens holder body (134) having an aperture (136) therethrough and a plurality of elongate support arms (140) projecting inwardly into the aperture (136), the plurality of elongate support arms (140) defining a lens support region (142).

19. A lens holder (116) as claimed in claim 18, wherein each of the plurality of elongate support arms (140) is extendible and retractable relative to a centre of the lens holder (116) to alter a size of the lens support region (142).

20. A lens holder (116) as claimed in claimed 18 or claim 19, wherein each of the plurality of elongate support arms (140) is tilted with respect to a horizontal plane of the lens holder body (134).

21. A method of interrogating a lens (12), the method comprising the steps of: inserting the lens (12) onto the lens support region (142) of the lens support cuvette (110) of a lens interrogation system (200) as claimed in any one of claims 14 to 16 such that the lens (12) is spaced apart from the base (120) of the cuvette body (124); and activating the interrogation device (244) so as to interrogate at least part the lens (12) without obstruction by the lens support region (142) or cuvette body (124).