Abstract:
An optical apparatus ( 10 ) is provided for non-destructive examination of characteristics of an object ( 102 ). The apparatus has a light source ( 28 ) for directing a beam of NIR Light towards the object ( 102 ), an aperture ( 24 ) for diverging the NIR beam through or reflected from the object, a collimating lens ( 30 ) for collimating the divergent beam, a diffraction device ( 32 ) for separating the collimated beam into wavelength components and focusing lens ( 36 ) for focusing the wavelength components onto a matrix of photodetectors ( 34 ) which in turn produce electrical output signals proportional to energy levels in the wavelength components. The apparatus ( 10 ) can be made compact so that it can be used to examine objects in fields. In one example the apparatus ( 10 ) has a pistol-shaped housing with a slot ( 12 ) in its turret ( 18 ) and a body ( 16 ) with a display monitor ( 14 ). The body ( 16 ) also has an opening through which a correlation device ( 26 ) in the form of a PCMCIA card can be connected to the apparatus ( 1 ). The apparatus ( 1 ) is typically used to examine physiological stages of plants in fields so that the grower can determine the appropriate actions required for acceptable plant growth.

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates to an optical apparatus for examining an object and in particular but not limited to an optical apparatus for examining carbohydrate constituents in a plant. 
     BACKGROUND OF THE INVENTION 
     Current methods for optically examining objects such as strawberries and other plants require obtaining samples of the objects and examining the samples in laboratories. These methods are inconvenient as the apparatuses for examination cannot be used on the objects in situ or in the fields. They are also destructive as samples must be taken off the objects. 
     The existing optical apparatuses for the examination do not have the resolution nor the sensitivity which are sufficiently high for reliably examining constituents in fruits or plants in general. They also cannot be easily adapted for examining relative concentrations of the constituents. 
     These apparatuses have a light source arranged to direct light onto an object and a light detector arranged for detecting reflected or scattered light from the object. The detector must be positioned outside the light path of the source and at some distance from the object in order not to interfere with the light from the source. 
     The detectors of these prior art apparatuses receive light reflected off the surface of and light scattered from within the object, together with reflected and scattered light from other surfaces. The light received by the detectors therefore include a high degree of noise signals. 
     The prior art apparatuses also require a relatively high powered light source as a large amount of the light from the source do not reach the target regions of the object. 
     OBJECT OF THE INVENTION 
     An object of the present invention is to alleviate or to reduce to a certain degree one or more of the prior art disadvantageous. 
     SUMMARY OF THE INVENTION 
     In one aspect the present invention resides in an optical apparatus for examining an object. The apparatus comprises a light source adapted to direct a beam of light towards an object under examination, an aperture arranged for receiving the light reflected from, scattered within or passing through the object and, for the beam of light to diverge therefrom means for collimating light arranged so that the beam of light through the aperture incident thereat is collimated. The apparatus also comprises means for dispersing the collimated beam of light from the collimating means into wavelength components, and means for providing electrical output signals which are respectively proportional to energy levels in the wavelength components. 
     In preference, the apparatus further comprises means for processing the output signals and thereby providing one or more indication signals for respectively indicating one or more characteristics of the object. 
     An indication means can be arranged for receiving the one or more indication signals and indicating the or each said indication signals in a suitable form. Desirably the indication means is a printer, a display monitor or a combination thereof. 
     The apparatus may have an interface means to which a computer may be selectively connected thereto for storing the one or more indication signals and/or for further processing the one or more indication signals. 
     Typically the processing means includes a data correlation device adapted to relate the or each of said indication signals to a characteristic of the object. 
     The data correlation device may have a set of correlation data for one object or a plurality of sets of correlation data for different types of objects. 
     Each said characteristic may be any constituent or a relative concentration of any constituent of the object. Examples of the constituents are carbohydrates, starch and sugars including sucrose, glucose, fructose and the like. The characteristic may also relate to any physiological state of the object The physiological states may include growth state, maturity state in plant and the like. 
     Desirably each said characteristics is a signature of vigour of growth, maturity for picking or any other physiological state of a plant. 
     Conveniently the data correlation device is removably connectable to the apparatus so that the apparatus can be selectively connected to the data correlation device having a set of correlation data for a particular object under examination. 
     The data correlation device may conveniently be in the form of a printed circuit card such as a PCMCIA card. 
     Preferably the output signal providing means includes an detection arrangement for detecting the wavelength components. 
     It is further preferred that the apparatus has a focusing arrangement for focusing the wavelength components onto the detection arrangement. 
     The light source may include an illuminator for producing an annulus of light onto the object. The illuminator comprises a hollow body having a reflective interior surface, and one or more lamps disposed so that at least some portions of the light from said one or more lamps are reflected from the reflective surface. The reflective surface is configured so that the light reflected therefrom forms an annulus of light on a region of the object. 
     In preference said hollow body is substantially conical or half egg shell shaped. The hollow body may also have a substantially parabolic cross section. 
     Suitably the annulus of light is arranged around a light detection probe for detecting scattered light from said object. The detection probe is suitably positioned along an axis of the hollow body and the light source is positioned at an angle to said axis. 
     Advantageously the illuminator is provided with a shroud downstream of the light reflected from said reflective surface. In one from the shroud is substantially frusto-conical or curvilinear in shape 
     The shroud may have a partly or wholly reflective interior surface for redirecting portions of the light from said light source and/or said interior surface of the body to said region of the object. 
     The shroud may have a rear wall arranged to direct light towards the annulus. The rear wall may be curve shaped or formed as a Fresnel lens. 
     It is desired that the shroud is removably fixed so that it can be easily replaced. The shroud may be configured for a particularly shaped object. The illuminator can therefore be used for different objects by selecting suitable shrouds for the different objects. 
     It is also preferred that the apparatus comprises an optical conveying means for conveying the beam of light reflected from or through the object to the aperture. The conveying means may include an optical fibre such as a 500 μm diameter optical fibre with a 11° numerical opening. The optical fibre may be arranged within a protective probe. 
     The aperture can be positioned at about the focal length of the collimating means. It may have one or more parallel slits of a suitable width. In one example the width is 10 μm. Typically the one or more slits are vertically oriented. 
     Desirably, the position of the collimating means relative to the aperture is adjustable so that the desired resolution and intensity of the apparatus can be easily changed. 
     Suitably, the collimating means is a collimating lens and typically an achromatic lens. 
     The dispersing means may include one or more prisms of any suitable configuration. The one or more prisms are preferably equilateral prism(s). 
     The focusing arrangement may include one or more focusing lenses for focusing the wavelength components onto the detection arrangement. Desirably the one or more focusing lenses are configured so that a linear dispersion of the spectrum can be provided across the detection arrangement. Plano-convex lenses are examples of the focusing lenses. 
     The detection arrangement preferably includes a plurality of detection elements which provide the electrical output signals in response to detection of the wavelength components. 
     More preferably the detection elements are arranged in a matrix of at least 2×2 (4) detection elements. Typically the matrix has 32×32 (2048) or 64×64 (4096) detection elements. 
     The detection arrangement conveniently has a charge coupled device (CCD) and the detection elements are in the form of picture elements (pixels). 
     The light source may be selected from any suitable known sources. It is preferred that the light source is near infrared radiation (NIR). 
     Desirably, the apparatus has a housing means in which components of the apparatus are located. The housing means may have a substantially light proof first housing member in which the collimating means, the dispersing means and electrical signal providing means are located. The first housing member reduces or eliminates interference from background radiation and reflections from optical surfaces. More desirably the aperture is also located within the first housing member. 
     More desirably, the housing means is compact so that the apparatus can be used on field or in situ. Typically the housing means is arranged so that in use a user can hold the apparatus in one hand. Alternatively it can be arranged so that it can be worn on a part of the user body such as on a wrist. The housing means may be shaped like a wrist watch, a hand pistol or any other suitable configuration. 
     The housing means may have a second housing member in which the light source is located and the second housing member has a gap into which at least part of the object can be inserted. It is advantageous that the second, housing member is removably connectable to the first housing member so that the second housing member can be selected from a plurality of second housing members adapted for examining particular kinds of objects. 
     Where the apparatus is provided with an optical conveying means the conveying means is preferably located in the second housing member. 
     The first housing member advantageously has the indication means arranged therein. It is also advantageous that the first housing means has the data correlation device removably connected thereto so that the apparatus can be used for different objects. 
     In one example, the first housing member is shaped like the body of a hand pistol and the second housing member is shaped like a turret of the pistol. 
     Said reflective surface of the hollow body may be formed according to a method comprises the steps of: 
     (a) selecting one portion of the reflective interior surface; 
     (b) calculating the orientation of said portion which will reflect a ray of light from a light source disposed within the hollow body onto the annulus of light in the same axial plane as said ray of light; 
     (c) stepping to another portion which is in the same vertical plane as said one portion and repeating step (b); 
     (d) repeating step (c) until said portions can be joined to form a ring; and 
     (e) repeating steps (a) to (d) for forming another ring adjacent to said ring until the rings extend to a desired area. 
     Preferably in the step (c) the direction of stepping reverses on completion of half a revolution. 
     The adjacent portions in each ring may be joined at the intersection of the respective planes containing said adjacent portions, or at about mid way between the intersection and one of said adjacent portions. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     In order that the present invention can be readily understood and put into practical effect the description will now be made in reference to the accompanying drawings which illustrate non-limiting embodiments of the present invention, and wherein: 
     FIG. 1 shows an embodiment of the optical apparatus according to the present invention being used by an operator for examining a strawberry plant in a field; 
     FIG. 2 shows a pistol-shaped embodiment of the optical apparatus according to the present invention; 
     FIG. 3 is a diagrammatic representation of the components of the apparatus according to the present invention; 
     FIG. 4 is another diagrammatic representation of the components of the apparatus according to the present invention; 
     FIG. 5 shows a typical spectrum obtained with the optical apparatus according to the present invention; 
     FIG. 6 shows a typical spectrum obtained with a prior art optical apparatus; 
     FIG. 7 shows a comparison of the spectra of mature and immature green pawpaw sample obtained with the optical apparatus according to the invention; 
     FIG. 8 shows a spectrum of a sample of lychee fruit obtained with the optical apparatus according to the present invention; 
     FIG. 9 shows spectrum of another sample of lychees fruit obtained with optical apparatus according to the present invention; 
     FIGS. 10 to  12  shows graphs of calibration data for constituent sugars in a plant. 
     FIG. 13 is a side view of a hand gun shaped embodiment of the optical apparatus according to the present invention; 
     FIG. 14 shows a rear view of the apparatus shown in FIG. 13; 
     FIG. 15 is a schematic drawing of an embodiment of the illuminator according to the present invention; 
     FIG. 16 is a schematic drawing of another embodiment of the illuminator according to the present invention; 
     FIG. 17 is a rear view of the illuminator shown in FIG. 16; 
     FIG. 18 is a diagram showing the steps in computing the portions forming the reflective surface of the illuminator; 
     FIG. 19 shows a typical annulus of light produced by the illuminator of the present invention; and 
     FIG. 20 is a schematic diagram showing illumination of the annular light on the surface of a fruit and a detector disposed to detect scattered light from within the fruit. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, there is shown an optical apparatus  10  according to the present invention being used by an operator  100  to examine a characteristic, in this case the state of growth (vigour), of an object  102  (strawberry plant) in a field  104 . 
     The apparatus  10  in this example is pistol-shaped. It has a slot  12  (shown more clearly in FIG. 2) for receiving a leave of the strawberry plant  102  under examination. An indication means  14  exemplified by a palm-top computer is connected to the apparatus  10  for indicating a characteristic spectrum of the strawberry plant  102 . 
     FIG. 2 is another embodiment of the optical apparatus  10  and in this case the apparatus  10  is in the shape of a pistol. The apparatus  10  has a housing made up of a pistol body shaped first housing member  16  which is substantially light proof and a turret shaped second housing member  18 . The second housing member  18  is removably connected to the first housing member  16 . 
     The second housing member  18  has a slot  12  for receiving a part of an object to be examined. On one side of the slot  12  is located a light source  28  (see FIGS. 3 and 4) and on the opposite side is a light conveying means  22  in the form of an optic fibre. 
     The first housing member  16  has a slit  24  (see FIGS. 3 and 4) positioned to receive light from the optic fibre  22 . It also has a removably connectable data correlation device  26  in the form of a PCMCIA card. The card  26  has a memory in which correlation data for one or more varieties of plants are stored. The indication means  14  which in this example is an LCD screen is provided for displaying output signals relating to one or more characteristics of an object under examination. 
     The removable card  26  can be easily replaced so that the apparatus  10  can be used for a variety of different objects. As an example if the apparatus  10  is to be used for examining sugars in a strawberry plant, a card  26  having correlation data for sugars in strawberry plants is selected and inserted into the first housing member  16 . 
     FIG. 3 shows a diagrammatic representation of the apparatus  10  according to one embodiment of the present invention. In this embodiment the apparatus  10  has a resolution defining slit  24  arranged for receiving a beam of light from a light source  28  and at about the focal length of a collimating lens  30 . The beam of light enters the slit  24  and travels divergently onto the collimating lens  30  which collimates the light into a parallel beam of light. A dispersing means  32  in the form of a diffraction device is positioned in the path of the collimated beam. The diffraction device  32  separates the collimated beam into its wavelength components. A detection means  34 , in this case a photodetecting device, is positioned downstream of the diffraction device  32  for detecting the wavelength components and to produce electrical output signals proportional to energy levels in the wavelength components. 
     Focusing means  36  in the form of a focusing lens is positioned between the diffraction device  32  and the detection means  34  so that the discrete component wavelengths are brought to a sharp or focused point on the detection means  34 . 
     A light proof first housing member  16  is used to minimise interference from light reflected from other surfaces. 
     The electrical output signals from the detection means  34  are then amplified in an amplifier  38  and converted to digital form by an analogue to digital converter  40 . A processing means (microprocessor)  42  is arranged for processing the digital signals in accordance with instructions in a suitable program and the data in a data correlation device. The processed signals are displayed on indication means  14  (LCD monitor in this example). 
     A computer  44  is also connected to the processing means  42  for downloading or further processing the signals. 
     FIG. 4 shows another embodiment of the apparatus  10 . In this embodiment the apparatus  10  has a light conveying means (an optic fibre)  46  for conveying the light through the object  102  to the slit  24 . The means  46  is a 500 μm diameter optic fibre with 11° numerical aperture. The slit  24  is a vertical parallel slit of 10 μm width and is mounted at about the focal length of the collimating means  30 . An achromatic lens is employed as the collimating means  30 . 
     The dispersion means  32  in this case are dual equilateral prisms which provide higher resolution. Two plano-convex lenses are used as the focusing means  36  in order to have a substantially linear dispersion of the spectrum across the detection means  34 . In this case, means  34  is a charge coupled device (CCD) having 2048 pixel and a polymer window with pixel dimensions of 14 μm (h) by 12 μm (w) on a 14 μm spacing). Typically integration times for the collection of spectra are in the range of 10-100 ms. 
     A calibration source  48  such as a commercially available mercury-argon discharge source sold under the name of Ocean Optic HG 1 can be removably coupled to the optic fibre  46  for calibrating the apparatus  10 . 
     The light source  28  in this embodiment is a 90-100 w tungsten halogen bulb powered by a low ripple DC power supply. The bulb is mounted at the primary focus of an elliptically reflector. 
     The object  102  under examination is positioned at about the secondary focus of the reflector. 
     In a test the apparatus  10  as shown diagrammatically in FIG. 4 is used to obtain spectrum of a mercury-argon discharge source. The test result is shown in FIG.  5 . 
     The same test is repeated using a commercial prior art spectrometer and the result is shown in FIG.  6 . 
     When the test results are compared it is noted that both the apparatus  10  according to the invention and the prior art spectrometer display a wide useful bandwidth from about 400-1025 nm. But the apparatus  10  demonstrates a superior performance in terms of resolution and sensitivity. 
     As can be seen the apparatus  10  is about three times more sensitive as spectra of similar intensity were recorded in about 15 ms compared to 50 ms for the prior art. The resolution of the apparatus  10  varies from about 4 nm (FWHM) at a wavelength of 696 nm to about 9 nm (FWHM) across the same band width. FWHM refers to full width at half maximum. 
     The apparatus  10  as shown in FIG. 4 has been used to examine the NIR transmission spectra of various fruits. FIG. 7 shows the respective NIR transmission spectra of 60 mm thick sections of immature and mature green paw paws (Canica papaya). The figure shows a definite shift in the wave length of peak light transmission from 755 mm in the immature sample to 730 in the mature sample. 
     Thus the apparatus  10  can be used to determined when green pawpaws can be picked as fruits will not continue to ripen to an edible state when picked while in the immature state. 
     FIGS. 8 and 9 show spectra of two different samples of lychee fruits. The differences between the two spectra can be used to indicate certain characteristic of the samples. 
     FIGS. 10 to  12  show graphical correlation data of three constituents of the vigour sugars in a fruit for determination by the apparatus  10  The respective slopping dotted and firm lines represent slope and bias corrections. The data obtained for the calibrations of the constituents are as outlined in the following correlation data tables. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Constituent 1 correlation data 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Instrument Reading X 
                 Lab Measurement Y 
               
               
                   
               
             
          
           
               
                 Mean X 
                 16.709 
                 Mean Y 
                 17.042 
                 B (Slope) 
                 0.955 
               
               
                 Stand Dev X 
                 2.894 
                 Stand Dev Y 
                 3.279 
                 A (Slope Bias) 
                 1.079 
               
               
                 X min 
                 12.000 
                 Y min 
                 12.240 
                 Bias (No Slope) 
                 0.333 
               
               
                 X max 
                 22.840 
                 Y max 
                 23.210 
               
               
                   
               
             
          
           
               
                   
                 RMS 
                 1.803 
                 Correlation Coeff 
                 0.843 
               
               
                   
                 Standard Error 
                 1.768 
                 Coeff of 
                 0.711 
               
               
                   
                 (Bias Corrected) 
                   
                 Determination 
               
               
                   
                 Standard Error 
                 1.885 
               
               
                   
                 (Slope and Bias Corrected) 
               
               
                   
                   
               
             
          
           
               
                   
                 Lab 
                 Instrument 
                   
                   
                   
               
               
                   
                 Measure- 
                 Reading 
                 Difference 
                 Predictions 
                 Difference 
               
               
                   
                 ment Y 
                 X 
                 Y-X 
                 Y (e) 
                 Y-Y (e) 
               
               
                   
                   
               
             
          
           
               
                 1 = 37 
                 12.24 
                 12.00 
                 0.24 
                 12.54 
                 −0.30 
               
               
                 2 = 28 
                 15.15 
                 14.76 
                 0.39 
                 15.18 
                 −0.03 
               
               
                 3 = 44 
                 17.76 
                 15.70 
                 2.06 
                 16.08 
                 1.68 
               
               
                 4 = 41 
                 14.68 
                 17.50 
                 −2.82 
                 17.80 
                 −3.12 
               
               
                 5 = 43 
                 14.69 
                 16.08 
                 −1.39 
                 16.44 
                 −1.75 
               
               
                 6 = 25 
                 19.92 
                 16.75 
                 3.17 
                 17.08 
                 2.84 
               
               
                 7 = 19 
                 17.66 
                 17.88 
                 −0.22 
                 18.16 
                 −0.50 
               
               
                 8 = 24 
                 18.07 
                 16.87 
                 1.20 
                 17.20 
                 0.87 
               
               
                 9 = 14 
                 23.21 
                 22.84 
                 0.37 
                 22.90 
                 0.31 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Constituent 2 correlation data 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Instrument Reading X 
                 Lab Measurement Y 
               
               
                   
               
             
          
           
               
                 Mean X 
                 12.109 
                 Mean Y 
                 12.109 
                 B (Slope) 
                 1.000 
               
               
                 Stand Dev X 
                 1.818 
                 Stand Dev Y 
                 2.424 
                 A (Slope Bias) 
                 −0.004 
               
               
                 X min 
                 10.040 
                 Y min 
                 8.420 
                 Bias (No 
                 0.000 
               
               
                 X max 
                 14.770 
                 Y max 
                 14.870 
                 Slope) 
               
               
                   
               
             
          
           
               
                   
                 RMS 
                 1.603 
                 Correlation Coeff 
                 0.750 
               
               
                   
                 Standard Error 
                 1.603 
                 Coeff of 
                 0.563 
               
               
                   
                 (Bias Corrected) 
                   
                 Determination 
               
               
                   
                 Standard Error 
                 1.714 
               
               
                   
                 (Slope and Bias Corrected 
               
               
                   
                   
               
             
          
           
               
                   
                 Lab 
                 Instrument 
                   
                   
                   
               
               
                   
                 Measure- 
                 Reading 
                 Difference 
                 Predictions 
                 Difference 
               
               
                   
                 ment Y 
                 X 
                 Y-X 
                 Y (e) 
                 Y-Y (e) 
               
               
                   
                   
               
             
          
           
               
                 1 = 37 
                 12.33 
                 14.77 
                 −2.44 
                 14.77 
                 −2.44 
               
               
                 2 = 28 
                 8.42 
                 10.04 
                 −1.62 
                 10.04 
                 −1.62 
               
               
                 3 = 44 
                 14.87 
                 13.24 
                 1.63 
                 13.24 
                 1.63 
               
               
                 4 = 41 
                 14.80 
                 13.49 
                 1.31 
                 13.49 
                 1.31 
               
               
                 5 = 43 
                 14.80 
                 14.23 
                 0.57 
                 14.23 
                 0.57 
               
               
                 6 = 25 
                 11.05 
                 11.31 
                 −0.26 
                 11.31 
                 −0.26 
               
               
                 7 = 19 
                 9.81 
                 10.44 
                 −0.63 
                 10.44 
                 −0.63 
               
               
                 8 = 24 
                 10.04 
                 11.02 
                 −0.98 
                 11.02 
                 −0.98 
               
               
                 9 = 14 
                 12.86 
                 10.44 
                 2.42 
                 10.44 
                 2.42 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Constituent 3 correlation data 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Instrument Reading X 
                 Lab Measurement Y 
               
               
                   
               
             
          
           
               
                 Mean X 
                 14.021 
                 Mean Y 
                 14.020 
                 B (Slope) 
                 1.000 
               
               
                 Stand Dev X 
                 5.535 
                 Stand Dev Y 
                 6.264 
                 A (Slope Bias) 
                 0.001 
               
               
                 X min 
                 4.120 
                 Y min 
                 6.810 
                 Bias (No 
                 −0.001 
               
               
                 X max 
                 24.000 
                 Y max 
                 23.460 
                 Slope) 
               
               
                   
               
             
          
           
               
                   
                 RMS 
                 2.933 
                 Correlation Coeff 
                 0.884 
               
               
                   
                 Standard Error 
                 2.933 
                 Coeff of 
                 0.781 
               
               
                   
                 (Bias Corrected) 
                   
                 Determination 
               
               
                   
                 Standard Error 
                 3.135 
               
               
                   
                 (Slope and Bias Corrected 
               
               
                   
                   
               
             
          
           
               
                   
                 Lab 
                 Instrument 
                   
                   
                   
               
               
                   
                 Measure- 
                 Reading 
                 Difference 
                 Predictions 
                 Difference 
               
               
                   
                 ment Y 
                 X 
                 Y-X 
                 Y (e) 
                 Y-Y (e) 
               
               
                   
                   
               
             
          
           
               
                 1 = 37 
                 6.81 
                 4.12 
                 2.69 
                 4.12 
                 2.69 
               
               
                 2 = 28 
                 15.27 
                 13.90 
                 1.37 
                 13.90 
                 1.37 
               
               
                 3 = 44 
                 8.20 
                 11.43 
                 −3.23 
                 11.43 
                 −3.23 
               
               
                 4 = 41 
                 8.16 
                 13.19 
                 −5.03 
                 13.19 
                 −5.03 
               
               
                 5 = 43 
                 8.17 
                 9.90 
                 −1.73 
                 9.90 
                 −1.73 
               
               
                 6 = 25 
                 20.09 
                 16.86 
                 3.23 
                 16.86 
                 3.23 
               
               
                 7 = 19 
                 17.80 
                 17.77 
                 0.03 
                 17.77 
                 0.03 
               
               
                 8 = 24 
                 18.22 
                 15.02 
                 3.20 
                 15.02 
                 3.20 
               
               
                 9 = 14 
                 23.46 
                 24.00 
                 −0.54 
                 24.00 
                 −0.54 
               
               
                   
               
             
          
         
       
     
     The spectrometer instrument used for obtaining correlation data is Zelta ZX100F Near Infrared (NIR) analyser. 
     For each of the constituents 1 to 3, 9 samples were randomly selected. The sample identifications corresponding to the selected samples are indicated in each case. 
     The prediction values Y (e) are values after slope and bias corrections. 
     As can be seen the results are as follows: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Constituent 
                 Correlation 
                 Standard Error 
               
               
                   
               
             
             
               
                 1 
                 0.86 
                 1.8 
               
               
                 2 
                 0.75 
                 1.7 
               
               
                 3 
                 0.88 
                 2.9 
               
               
                   
               
             
          
         
       
     
     The correlation data allows identification of the constituents in the sample. 
     As the constituents of the sample absorb some energy levels but allow other energy levels (or wavelength components) to pass, the apparatus  10  can be used to determined relative concentrations of the constituents by monitoring the energy levels (or wavelength components) which pass through he sample and which do not pass through. 
     Any mathematical analysis method can be employed. The applicant prefers partial least squares (PLS) regression analysis or minimum message length (MML) single and multiple factor analysis such as described. 
     Referring initially to FIG. 13, there is shown a near infrared (NIR) optical apparatus  50  according to another embodiment of the present invention. The apparatus  50  in this example has a substantially hand gun shaped casing  52 . In the body  52  are arranged a light detection probe  54  positioned at substantially in the center axis of an illuminator  56 . The probe  54  extends from just within a frustoconical shaped shroud  58  to immediately before a mirror  60 . 
     As can be seen the light beams detected by the probe  54  are deflected off the mirror  60  onto a diffraction grating  62 . The grating  62  directs the beams substantially parallelly onto an array of charge coupled diodes (CCD) or photodiodes  64 . 
     A trigger  66  for activating the apparatus  50  is provided for pressing by a finger of a user. 
     The components of the apparatus  50  are mounted on a frame (not shown) made of a stable aluminium or titanium based cast or machined alloy for thermal stability and mechanical strength. The frame is mounted into the casing  52  which in this example is made of a plastic material. 
     The cutaway section in FIG. 14 reveals a reference fibre  68  positioned adjacent to the sample fibre of the probe  54 . 
     Referring to FIG. 15 the illuminator  56  has a substantially parabolic shaped hollow body  70  with an aperture  72  in which a lamp  74  is positioned. As can be clearly seen more clearly in FIG. 17 the lamp  74  is off centre and spaced from the probe  54  and the reference fibre  68  The body  70  is shaped so that its interior reflective surface  76  illuminates an annulus  78  of light onto an object  90  such as a strawberry. It should be noted that the object may be any plant, biological sample, chemical sample or mineral sample. 
     The shroud  58  has a rearwall  80  extending to the probe  54  and the fibre  68 . 
     The shroud  58  and the hollow body  70  may be integrally formed as a unit from a suitable solid plastic, e.g. polycarbonate or acrylic. However in this example they are separately formed and the shroud  58  can be detached for replacement. The interior surfaces of the shroud  58  and the body  70  are suitably metalized so that they are highly reflective. 
     The shroud  58  is shaped so that deflects parts of the light from the lamp  74  and from the reflective surface  76  of the body  70  towards the regions of the annulus  78  This improves the intensity of the annular illumination. 
     The rear surface of the wall  80  i.e., the entry surface for the NIR illumination, is Fresnel lensed for directing the illumination to the regions of the annular  78 . Instead of a Fresnel lens the rear surface may be curved to concentrate the illumination at the regions. 
     The shroud  58  performs a number of other most useful functions including: 
     i) It protects the illuminator  56  from the environment and the metal tube sheath of the probe  54  robustly from the intended applications where dropping the gun is probable. 
     ii) It, at least partially, affords some ambient light shading of the object being measured. 
     iii) It conveniently separates and or displaces unwanted object or other material, etc, away from the desired area as the gun is pushed toward the sample to be measured. 
     iv) It allows ready wiping and cleaning with material likely to be on hand, i.e., a shirt tail or handkerchief. 
     v) It can be made replaceable. 
     vi) It can be made replaceable for alternative applications, e.g., much larger fruit (watermelons, etc), by unscrewing. In this instance, care has to be taken to ensure proper coupling of the probe  54  and reference fibre  68  ends into the apparatus  50 . 
     FIG. 16 shows an embodiment of the illuminator  56  and the shroud  58  for a larger object  90 . As can be seen the detecting end of the probe  54  in this case is substantially flush with the shroud  58 . 
     The illuminator  56  is arranged to produce an annulus of bright, NIR rich, light surrounding the probe  54  such that the ring of light is as shown in FIG.  19 . The region ‘b’ is the concentrated NIR illumination annulus and ‘a’ is a region designed not to be (directly) illuminated. This is to maximise, in as much as possible, that light received via the probe  54  which has diffused within the object  90  as shown in FIG.  20 . 
     As shown in FIG. 20 it is clear that the incident annular illumination  78 , which can enter the sampling probe fibre  54 , must have (mostly) scattered from the region shown as “c”. This minimises noise signals such as light which travels directly along the immediate surface or in the skin of the object or fruit  90  from being detected by the probe  54 . 
     It is also clear from FIG. 20 that the fibre support probe  54 , akin to a hypodermic “flanened-end” needle not only provides rigid and maintainable support for the fibre, but also acts as a most effective light shield from ambient and surface scattered light, which would otherwise enter the probe  54  via object or fruit surface irregularities and “cracks and voids”. 
     The reference probe  68  is designed to capture part of the illumination light and minimise any reflected light from the object or fruit  90 . Such light, indicative of the spectral characteristic of the illumination is captured by reflection off the shroud&#39;s rear surface. This rear surface of the wall  80  is mirrored at a small area or alternatively, roughened slightly to aid its backscatter. In the event the shroud  58  is essentially a solid plastic part, this reference light may be sampled by viewing the back of the illumination lamp, or lamps, by similar fibre, or fibres, capturing means. 
     The fibre probes  54  and  68 , and especially the sample probe  54 , are intended to be essentially coincident with an imaginary “gun barrel” axis. 
     The reflective surface  76  of the illuminator  56  is computer designed to optimally produce the annular illumination  78 . 
     The annular illumination  78  allows light to scatter or diffuse in the object  90  being tested before entering the probe  54 . This arrangement prevents bright light immediately around the detector probe  54  and thereby avoiding the disadvantage of having a major proportion of light which travels just a very short distance in the close, thin, skin region of the sample being inspected. NIR spectral properties of this small depth, and indeed small area, of the skin is not a reliable indication of the properties desired to be measured. 
     The reflective surface  76  is formed using an optical ray tracing method as shown in FIG.  18 . Individual light rays, considered to be emanating from the very small filament of the illumination lamp  74  (which is off center) are directed in small rotational angular displacements toward the rear most portion of the illuminator  56  (immediately adjacent the hole through which the reference and sample fibre probes  54  and  68  pass). By the simple law of reflection, the angle of a very small (essentially rectangular) section  1  of that surface  76 , then, can be computed so that for the ray being considered, the reflected part  1 A is directed towards the center of the annular ring  78  at the same rotational angle. By stepping emanating rays, one by one, from the lamp(s) through small increments around a half revolution, each ray generates an angled, essentially rectangular shaped, small piece of “flat” reflector directing the rays toward equispaced “dots” around the middle of the annular ring  78 . By three dimensional geometry, these reflector facet surfaces schematically shown as  1  to  4  are joined edge to edge. 
     Once one piece is computed, the program then proceeds to calculate a reflection angle required on that surface to properly direct the adjacent ray  2 A. Choosing a new surface  2  at that point with the proper angle, and repeating the above steps for another nearby section  3 , it can compute the line of intersection of the two planar elements at their joining edge. 
     At the completion of a half revolution each way, the two “faceted” reflector rings should join, so checking the calculations. 
     When one faceted ring of the reflective surface  76  is computed, another, adjacent, faceted ring may be computed similarly such that its inner edges meet the outer edges of the previously computed reflector ring. 
     And in this manner, a series of “concentric” faceted reflector “rings” can be computed progressing around the axis of the reflective surface in rings, and each ring incrementally stepping away from the fibre probes&#39; hole to the outermost edge at the front of the gun&#39;s&#39; reflective surface. 
     It transpires that these faceted segments can be smoothed to a continuously complex curved surface such that the reflecting angle at the centre of each original facet, and its position, remains the same at points on the new smoothed surface. This forms the basic reflector shape and such design process can accommodate an arbitrary number of lamps, each placed in arbitrary positions. 
     Whilst the above has been given by way of illustrative example of the present invention many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as herein set forth.