Patent Publication Number: US-9891103-B2

Title: Assembling method of spectrometer and assembling system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of patent application Ser. No. 13/747,216, which is filed on Jan. 22, 2013 and claims the priority benefit of Taiwan Patent Application No. 101142874, filed on Nov. 16, 2012, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light instrument, associated assembling method and assembling system, and more particularly relates to a spectrometer, its associated assembling method and assembling system. 
     2. Description of Related Art 
     A spectrometer can typically disperse light of complex composition into a light spectrum, and may include a prism or a diffractive grating. Spectrometers can measure how much light is reflected from or transmitted through an object. Optical signals captured by a spectrometer can be developed on photographic films or be displayed and analyzed by a computer to give information on elemental compositions of the object to be measured. Based on optical principles, spectrometers are often used to observe, analyze, and process the structure and composition of matters. There are several advantages associated with spectrometers, including: high precision and accuracy, large measurement range, high speed and smaller amount of sample used, etc. Therefore, spectrometers have been widely used by agencies and institutes in the areas of metallurgy, geology, petroleum and chemical industries, medicine and health, and environmental protection. In addition, spectrometers are also a necessity for applications in military reconnaissance, space exploration, and resources and hydrological surveys. 
     SUMMARY OF THE INVENTION 
     The present invention provides a spectrometer which can improve the optical quality of spectra measured by the spectrometer. 
     The present invention also provides a method for assembling a spectrometer which can improve the optical quality of spectra measured by the spectrometer. 
     The present invention further provides a system, for assembling a spectrometer, through which relative positions of a diffractive component and a light sensor can be precisely adjusted. 
     According to one aspect, a spectrometer may comprise a waveguide module, a diffractive component, and a light sensor. The waveguide module may include a first reflective surface, a second reflective opposite to the first reflective surface, and a light channel located between the first reflective surface and the second reflective surface. The diffractive component may include a diffractive surface with a plurality of strip-shaped diffractive structures. A sharpness of a profile of the strip-shaped diffractive structures at a first side of the diffractive surface may be greater than a sharpness of the profile of the strip-shaped diffractive structures at a second side of the diffractive surface. The first side of the diffractive surface may be located between the first reflective surface and the second reflective surface, with the first side of the diffractive surface spaced apart from the second reflective surface, when viewed along a direction generally perpendicular to the second reflective surface. The light sensor may receive diffracted light after light transmitted in the light channel is diffracted into the diffracted light by the diffractive surface. 
     In at least one embodiment, the waveguide module may comprise a first base body and a second base body. The first base body may include the first reflective surface. The second base body may include the second reflective surface. The light channel may be formed between the first base body and the second base body. The diffractive component may be disposed on at least one of the first base body or the second base body. 
     In at least one embodiment, the spectrometer may further comprise a heightening component disposed between the diffractive component and at least one of the first base body or the second base body. 
     In at least one embodiment, the spectrometer may further comprise a light input port. At least a part of light entering into the spectrometer via the light input port may be transmitted within the light channel to the diffractive surface of the diffractive component. 
     In at least one embodiment, a light output channel may be formed between the diffractive component and the second base body. The light output channel may be adjacent to the heightening component. A part of the light entering into spectrometer via the light input port may exit the light channel via the light output channel. 
     In at least one embodiment, the heightening component and the diffractive components may be formed integrally. 
     In at least one embodiment, the heightening component may comprise a plurality of spacers spaced apart with respect to each other in a direction substantially parallel to the second reflective surface. 
     In at least one embodiment, the heightening component may include a light absorbing surface. 
     In at least one embodiment, the heightening component may comprise a transparent component. 
     In at least one embodiment, the heightening component may comprise at least one light confinement groove, located on a surface of the heightening component facing the light channel, such that light entering into the at least one confinement groove is repeatedly reflected by and confined in the at least one light confinement groove. 
     In at least one embodiment, the heightening component may comprise at least one position reference mark that indicates relative positions of the diffractive component and the heightening component. 
     In at least one embodiment, the second base body may comprise a case and a reflective plate disposed on the case. A surface of the reflective plate may be the second reflective surface, and the heightening component may be disposed on the reflective plate. 
     In at least one embodiment, the second base body may comprise a case and a reflective plate disposed on the case. A surface of the reflective plate may be the second reflective surface, and the heightening component may be disposed on the case. 
     In at least one embodiment, the waveguide module may comprise a first base body, having the first reflective surface, a second base body, having the second reflective surface, and an adhesive material. The light channel may be formed between the first base body and the second base body. The adhesive material may secure the diffractive component to at least one of the first base body or the second base body. 
     In at least one embodiment, the diffractive component may include a backside opposite to the diffractive surface. The adhesive material may connect the backside of the diffractive component to the second base body such that the diffractive component is secured on the second base body. 
     In at least one embodiment, the waveguide module may comprise a first base body, having the first reflective surface, and a second base body, having the second reflective surface. The light channel may be formed between the first base body and the second base body. At least one of the first base body or the second base body may include a fixing component that secures a position of the diffractive component. 
     In at least one embodiment, the waveguide module may comprise a light guiding body provided as the light channel, a first reflective film disposed on the light guiding body, and a second reflective film disposed on the light guiding body such that the light guiding body is between the first reflective film and the second reflective film. An interface between the first reflective film and the light guiding may form the first reflective surface. An interface between the second reflective film and the light guiding body may form the second reflective surface. 
     In at least one embodiment, the diffractive component may comprise a notch having a bottom surface and the diffractive surface. The diffractive surface may be inclined relative to the bottom surface. The bottom surface may be inclined relative to the second reflective surface such that the diffractive surface is approximately parallel with a normal vector of the second reflective surface. 
     In at least one embodiment, the strip-shaped diffractive structures may be substantially parallel with respect to each other. The diffractive surface may be a curved concave surface. 
     In at least one embodiment, the diffractive component may comprise a notch and a surface. The notch may include a respective diffractive surface and a bottom surface connected to the respective diffractive surface. The surface may be connected to the bottom surface. At least a portion of the surface may face the light channel and may be coated with a light absorbing material. 
     In at least one embodiment, the diffractive surface may be formed by etching started from the first side of the diffractive surface. 
     In at least one embodiment, the spectrometer may further comprise a positioning means for setting a position of the first side of the diffractive surface such that the first side of the diffractive surface is spaced apart from the second reflective surface when viewed from a direction perpendicular to the second reflective surface. 
     In at least one embodiment, the diffractive component may comprise a notch and an allocation surface. The notch may include a respective diffractive surface and a bottom surface connected to the respective diffractive surface. The allocation surface may be connected to the bottom surface of the notch. The allocation surface may face the second reflective surface and may be coated with a reflective material. 
     In at least one embodiment, the waveguide module may comprise a first base body, having the first reflective surface, and a second base body, having the second reflective surface. The light channel may be formed between the first base body and the second base body. The spectrometer may further comprise a connecting unit that connects the diffractive component to the first base body of the waveguide module. A deformation of the first base body due to a temperature change in the spectrometer may cause a change in a dimension of the diffractive component. 
     In at least one embodiment, the connecting unit may comprise a fixing component and a plurality of pieces of an adhesive material. The fixing component may be disposed on the first base body. The fixing component may include a plurality of first through holes. A first part of the first through holes may expose a portion of the diffractive component, and a second part of the first through holes may expose a portion of the first base body. The plurality of pieces of an adhesive material may be filled in the first through holes. Some of the pieces of the adhesive material filled in the first part of the first through holes may connect the fixing component to the diffractive component. Some other pieces of the adhesive material filled in the second part of the first through holes may connect the fixing component to the first base body. 
     In at least one embodiment, the connecting unit may comprise a gasket disposed between the diffractive component and the fixing component. The gasket may include at least one second through hole interlinked with the first part of the first through holes such that the first part of the first through holes and the at least one second through hole are filled with the adhesive material to connect the fixing component, the gasket, and the diffractive component together. 
     In at least one embodiment, the first base body may comprise a reflective plate and a case. The reflective plate may be disposed on the second base body and may include the first reflective surface. The connecting unit may connect the diffractive component and the reflective plate. A deformation of the reflective plate due to a temperature change in the spectrometer may cause a change in a dimension of the diffractive component through the connecting unit. The case may cover the reflective plate. 
     In at least one embodiment, the reflective plate may include a side to which the diffractive component is secured by the connecting unit. The connecting unit may comprise an adhesive material. 
     According to another aspect, a spectrometer may comprise a waveguide module, a diffractive component, and a light sensor. The waveguide module may include a first reflective surface, a second reflective surface opposite to the first reflective surface, and a light channel located between the first reflective surface and the second reflective surface. The diffractive component may include an allocation surface and a notch located on a side of the allocation surface. The notch may include a diffractive surface that is inclined relative to the second reflective surface such that the diffractive surface is generally parallel with a normal vector of the second reflective surface. The light sensor may receive diffracted light after light transmitted in the light channel is diffracted into the diffracted light by the diffractive surface. 
     In at least one embodiment, the waveguide module may comprise a first base body, having the first reflective surface, and a second base body, having the second reflective surface. The light channel may be formed between the first base body and the second base body. The diffractive component may be disposed on at least one of the first base body or the second base body. 
     In at least one embodiment, the spectrometer may further comprise a heightening component disposed between the diffractive component and the second base body and disposed on a side of the diffractive component away from the diffractive surface. 
     According to one aspect, a method for assembling a spectrometer may comprise: disposing a diffractive component along a side of a light channel of a waveguide module, wherein the waveguide module comprises a first reflective surface and a second reflective surface opposite to the first reflective surface, wherein the light channel is located between the first reflective surface and the second reflective surface, and wherein the diffractive component has a diffractive surface; disposing a light sensor on one end of the light channel; transmitting light to the diffractive surface via the light channel such that at least a portion of the light is diffracted into diffracted light by the diffractive surface and the diffracted light is incident on the light sensor; adjusting at least one of a position of the diffractive surface along a direction substantially perpendicular to the second reflective surface or an angle between the diffractive surface and the second reflective surface, and measuring a corresponding spectrum of light incident on the light sensor; determining whether the spectrum of the light incident on the light sensor meets a predefined first sharpness condition; and securing the diffractive component when the spectrum of the light incident on the light sensor meets the predefined first sharpness condition; or adjusting either or both of the position and the angle of the diffractive surface until the spectrum of the light incident on the light sensor meets the predefined first sharpness condition. 
     In at least one embodiment, transmitting light to the diffractive surface may comprise transmitting the light to the diffractive surface sequentially through a light input port and the light channel. The method may further comprise adjusting the position of the diffractive surface along a direction that is substantially parallel to the second reflective surface and substantially perpendicular to a line connecting the light input port and the diffractive surface. 
     In at least one embodiment, transmitting light to the diffractive surface may comprise transmitting the light to the diffractive surface sequentially through a light input port and the light channel. The method may further comprise adjusting a distance between the diffractive surface and the light input port. 
     In at least one embodiment, the method may further comprise adjusting a first rotation angle of the diffractive surface. The first rotation angle may be an angle around an axis that is substantially parallel to a normal vector of the second reflective surface. 
     In at least one embodiment, transmitting light to the diffractive surface may comprise transmitting the light to the diffractive surface sequentially through a light input port and the light channel. The method may further comprise adjusting a second rotation angle of the diffractive surface. The second rotation angle may be an angle around an axis that is substantially parallel to a line connecting the light input port and the diffractive surface. 
     In at least one embodiment, securing the diffractive component may comprise securing the diffractive component to at least one of the first or the second base bodies by an adhesive material. The first base body may include the first reflective surface, and the second base body may include the second reflective surface. 
     In at least one embodiment, the method may further comprise adjusting at least one of a position or an angle of the light sensor with respect to the light channel. 
     In at least one embodiment, the method may further comprise: adjusting at least one of a position or an angle of the light sensor with respect to the light channel after securing the diffractive component, and measuring a corresponding spectrum of the light incident on the light sensor; determining whether the corresponding spectrum of the light incident on the light sensor meets a predefined second sharpness condition; and securing the light sensor when the corresponding spectrum of the light incident on the light sensor meets the predefined second sharpness condition; or adjusting at least one of the position or the angle of the light sensor until the corresponding spectrum of the light incident on the light sensor meets the predefined second sharpness condition. 
     In at least one embodiment, adjusting at least one of a position of the diffractive surface in a direction substantially perpendicular to the second reflective surface or an angle between the diffractive surface and the second reflective surface may comprise determining at least one of the position or the angle of the diffractive surface in a second measurement based on the at least one of the position or the angle of the diffractive surface used to obtain a spectrum in a first measurement. 
     According to one aspect, an assembling system may comprise: a carrier that carries a waveguide module, the waveguide module having a first reflective surface, a second reflective surface opposite to the first reflective surface, and a light channel located between the first reflective surface and the second reflective surface; a first fixture that carries a diffractive component having a diffractive surface disposed along a side of the light channel, the first fixture configured to adjust at least one of a position of the diffractive component along a direction substantially perpendicular to the second reflective surface or an angle between the diffractive surface and the second reflective surface; and a second fixture that carries a light sensor disposed at one end of the light channel, the second fixture configured to adjust at least one of a position or an angle of the light sensor. 
     In at least one embodiment, one end of the waveguide module may include a light input port. The first fixture may adjust a position of the diffractive surface along a direction that is substantially parallel to the second reflective surface and substantially perpendicular to a line connecting the light input port and the diffractive surface. 
     In at least one embodiment, one end of the waveguide module may include a light input port. The first fixture may adjust a distance between the diffractive surface and the light input port. 
     In at least one embodiment, the first fixture may adjust a first rotation angle of the diffractive surface. The first rotation angle may be an angle around an axis that is substantially parallel to a normal vector of the second reflective surface. 
     In at least one embodiment, one end of the waveguide module may include a light input port. The first fixture may adjust a second rotation angle of the diffractive surface. The second rotation angle may be an angle around an axis that is substantially parallel to a line connecting the light input port and the diffractive surface. 
     In at least one embodiment, the assembling system may further comprise an adhesive dispenser. The adhesive dispenser may apply an adhesive material onto the diffractive component to secure the diffractive component to at least one of a first base body having the first reflective surface or a second base body having the second reflective surface. 
     In at least one embodiment, the assembling system may further compose a first actuator that drives the first fixture, a second actuator that drives the second fixture, and a controller electrically connected to the first actuator and the second actuator to control operations of the first actuator and the second actuator. 
     In at least one embodiment, the controller may be electrically connected to the light sensor and the adhesive dispenser. The controller may receive spectral signals measured by the light sensor and determining at least one of a position or an angle of the diffractive component and at least one of a position or an angle of the light sensor based on the received spectral signals. The controller may determine whether a sharpness of the spectral signals meets a standard based on a determination procedure such that, when the standard are met. The controller may command the adhesive dispenser to apply the adhesive material onto the diffractive component, otherwise, the controller may command the first actuator and the second actuator to adjust the at least one of the position or the angle of the diffractive component or the at least one of the position or the angle of the light sensor until the sharpness of the spectral signals meets the standard. As to the spectrometer in accordance with the embodiments of the present invention, when viewed along a direction perpendicular to the second reflective surface, the first side of the diffractive surface is positioned between the first reflective surface and the second reflective surface with a distance away from the second reflective surface, a portion of light transmitted in the light channel with higher intensity is diffracted by the part of the diffractive surface having a sharper profile. As a result, the optical quality of the spectra measured by the spectrometer can be enhanced. As to the spectrometer in accordance with the embodiments of the present invention, since the allocation surface of the diffractive component is inclined relative to the second reflective surface, the diffractive surface is generally parallel with the normal vector of the second reflective surface. As a result, the optical quality of the spectra obtained can be enhanced. As to the method for assembling spectrometers in accordance with the embodiments of the present invention, since the diffractive component is secured after at least one of the position and angle of the diffractive component has been adjusted until the spectrum obtained meets the predefined sharpness condition, the diffractive component can be secured at an appropriate position. As a result, the optical quality of the spectra obtained can be enhanced. As to the system for assembling the spectrometer in accordance with the embodiments of the present invention, since the first fixture and the second fixture are configured to adjust the diffractive component and the light sensor, respectively, the relative positions of the diffractive component and the light sensor can be accurately adjusted. As a result, the optical quality of the spectra obtained can be enhanced. 
     Detailed description of selected embodiments of the present invention is provided below with reference to the attached figures to aid better understanding of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a side view of a spectrometer in accordance with one embodiment of the present invention. 
         FIG. 1B  is a top view of the spectrometer of  FIG. 1A . 
         FIG. 1C  is a perspective view of a diffractive grating and a heightening component of the spectrometer of  FIG. 1A . 
         FIG. 2  is a graph showing distribution of light intensity on a plane located at a junction of a diffractive component and a light channel. 
         FIG. 3A  is a diagram of a bulk semiconductor used to make the diffractive component. 
         FIG. 3B  is a diagram showing the bulk semiconductor of  FIG. 3A  being etched to form a heightening component. 
         FIG. 4  is a side view of a spectrometer in accordance with another embodiment of the present invention. 
         FIG. 5A  is a perspective view of a spectrometer in accordance with yet another embodiment of the present invention. 
         FIG. 5B  is an exploded perspective view of the spectrometer of  FIG. 5A . 
         FIG. 5C  is a perspective view of a heightening component of the spectrometer of  FIG. 5A . 
         FIG. 6  is diagram of a variation of the heightening component of  FIG. 5C . 
         FIG. 7  is a perspective view of a diffractive component and a heightening component in accordance with another embodiment of the present invention. 
         FIG. 8  is a side view of a spectrometer in accordance with still another embodiment of the present invention. 
         FIG. 9  is a partial side view of a spectrometer in accordance with another embodiment of the present invention. 
         FIG. 10  is a side view of a spectrometer in accordance with yet another embodiment of the present invention. 
         FIG. 11  is a side view of a spectrometer in accordance with still another embodiment of the present invention. 
         FIG. 12  is a side view of a spectrometer in accordance with another embodiment of the present invention. 
         FIGS. 13A to 13E  are diagrams illustrating an assembling system in accordance with one embodiment of the present invention to explain the associated assembling procedure. 
         FIG. 14A  is a side view of a spectrometer in accordance with a further embodiment of the present invention. 
         FIG. 14B  is a top view of the spectrometer of  FIG. 14A  after a case  214  is removed. 
         FIG. 14C  is a perspective view of the spectrometer of  FIG. 14A  after the case  214  is removed. 
         FIG. 15  is a side view of a spectrometer in accordance with another embodiment of the present invention. 
         FIG. 16  is a top view of a spectrometer with a case partially removed in according with yet another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1A  a side view of a spectrometer in accordance with one embodiment of the present invention.  FIG. 1B  is a top view of the spectrometer of  FIG. 1A . In order to aid readers in understanding the relative positions of the light input port, the diffractive component, and the light sensor, the first base body and the second base body in  FIG. 1A  are omitted in  FIG. 1B .  FIG. 1C  is a perspective view of a diffractive grating and a heightening component of the spectrometer of  FIG. 1A . Referring to  FIGS. 1A, 1B and 1C , a spectrometer  100  of the present embodiment includes a waveguide module  200 , a diffractive component  300 , and a light sensor  110 . In the present embodiment, the spectrometer  100  includes a light input port  120  through which light L 1 , to be measured, enters into the spectrometer  100 .  FIG. 1A  is a side view of  FIG. 1B , as viewed from the light input port  120  towards the light sensor  110 ; therefore, in  FIG. 1A , the light sensor  110  is located behind the light input port  120 . 
     The waveguide module  200  includes a first reflective surface  212 , a second reflective surface  222  opposite to the first reflective surface  212 , and a light channel C located between the first reflective surface  212  and the second reflective surface  222 . The diffractive component  300  has a diffractive surface  310  with a plurality of strip-shaped diffractive structures  320  thereon. The sharpness of the profile of the strip-shaped diffractive structures  320  on a first side  312  of the diffractive surface  320  is greater than that of the strip-shaped diffractive structures  320  on a second side  314  of the diffractive surface  320 . In the present embodiment, the diffractive component  300  includes an allocation surface  350  with a notch  305  provided on one side of the allocation surface  350 . The notch  305  has a bottom surface  330  and a diffractive surface  310  connected to the bottom surface  330 . In addition, in the present embodiment, the diffractive component  300  is made of a semiconductor material, such as silicon for example but not limited thereto. The notch  305  is formed, for example, by a semiconductor etching process. A bulk semiconductor material is etched, along a direction from the first side  312  towards the second side  314  through a photomask or a mask with the diffractive structure profile, until the bottom surface  330  is reached. The strip-shaped diffractive structures  320  are also formed during this etching process. The semiconductor etching process is, for example, the etching process used in fabricating micro-electro-mechanical systems (MEMS). Since the etching is along a direction from the first side  312  towards the second side  314 , the sharpness of the profile of the strip-shaped diffractive structures  320  in the present embodiment decreases along the direction from the first side  312  towards second side  314 . 
     The diffractive surface  310  diffracts light L 1 , transmitted in the light channel C, and the diffracted light is transmitted to the light sensor  110 . In the present embodiment, the light sensor  110  is an image sensor, such as a one-dimensional image sensor for example. However, in other embodiments, the light sensor  110  may be a two-dimensional image sensor. The light input port  120  is, for example, a slit, which may extend in a direction substantially parallel to the extending direction of the stripe-shaped diffractive structures  320 . At least a portion of the light L 1  that enters into the spectrometer  100  via the light input port  120  is transmitted in the light channel C to the diffractive surface  310  of the diffractive component  300 . More specifically, at least a portion of the light L 1  that enters into the light channel C via the light input port  120  is continuously reflected by the first reflective surface  212  and the second reflective surface  222 , and then transmitted to the diffractive surface  310 . The diffractive surface  310  diffracts light L 1 , forming diffracted light of numerous different orders, LC 0 , LC 1 , LC 2 , LC 3 , LC 4 . At least a portion of the diffracted light LC 0 , LC 1 , LC 2 , LC 3 , LC 4  is transmitted to the light sensor  110  where a spectrum is formed. 
       FIG. 2  is graph showing distribution of light intensity on a plane located at a junction of the diffractive component  300  and the light channel C. In  FIG. 2 , a direction from the first reflective surface  212  to the second reflective surface  222  is represented by the vertical direction, while a direction from a first end E 1  on the diffractive surface  310  which is away from the light input port  120  to a second end E 2  on the diffractive surface  310  which is closer to the light input port  120  is represented by the horizontal direction. As shown in  FIG. 2 , in the present embodiment, since the intensity of the light L 1  entering through the light input  120  has, for example, a Gaussian distribution, and the light L 1  is continuously reflected by the first reflective surface  212  and the second reflective surface  222 , the maximum intensity of the light L 1  is located approximately on a midplane between the first reflective surface  212  and the second reflective surface  222 . The distance between the midplane and the first reflective surface  212  is substantially equal to the distance between the midplane and the second reflective surface  222 . In addition, since the first end E 1  is further away from the light input port  120  compared to the second end E 2 , in the horizontal direction, the intensity of the light L 1  tends to gradually increase along a direction from the first end E 1  towards the second end E 2 . 
     In the present embodiment, when viewed along a direction perpendicular to the second reflective surface  222 , the first side  312  of the diffractive surface  310  is located between the first reflective surface  212  and the second reflective surface  222  with a spacing, or gap, T between the first side  312  of the diffractive surface  310  and the second reflective surface  222 . That is, when viewed from either the top or the bottom of  FIG. 1A , the first side  312  is located between the first reflective surface  212  and the second reflective surface  222  with the spacing T between the first side  312  and the second reflective surface  222 . Due to the greater sharpness of the profile of the strip-shaped diffractive structures  320  on the first side  312  of the diffractive surface  310  and the resulting better diffraction effect, and due to the lower intensity of the light L 1  in the vicinity of the first reflective surface  212  and the second reflective surface  222  as well as the higher intensity of the light L 1  in the vicinity of the midplane between the first reflective surface  212  and the second reflective surface  222 , a height position of the first side  312  (i.e., the position in a direction perpendicular to the second reflective surface  222 ) is located between the first reflective surface  212  and the second reflective surface  222 . This allows the portion of the light L 1  with higher intensity to be diffracted by the portion of the stripe-shaped diffractive structures  320  with sharper profile, thereby enhancing the optical quality (e.g., the resolution and/or sensitivity) of the spectra measured by the light sensor  110 . Furthermore, in  FIG. 1C , when a surface  340  faces the optical channel C, light L 1  will be incident on the surface  340  to produce stray light. However, in  FIG. 1A , the presence of the heightening component  130  causes the position of the surface  340  to shift to a side facing a reflective plate  216 , thus effectively reducing the formation of stray light. 
     In the present embodiment, the waveguide module  200  includes a first base body  210 , which has the first reflective surface  212 , and a second base body  220 , which has the second reflective surface  222 . The light channel C is formed between the first base body  210  and the second base body  220 , and the diffractive component  300  is disposed on the second base body  220 . In the present embodiment, the first base body  210  includes a case  214  and the reflective plate  216 , which is disposed on the case  214 . The first reflective surface  212  serves as the surface of the reflective plate  216 . Similarly, the second base body  220  may also include a case  224  and a reflective plate  226 , which is disposed on the case  224 . The second reflective surface  222  serves as the surface of the reflective plate  226 . In addition, the reflective plate  216  is disposed between the reflective plate  226  and the case  214 , and the reflective plate  226  is disposed between the reflective plate  216  and the case  224 . In the present embodiment, the light channel C is the space formed between the reflective plate  216  and the reflective plate  226  such that a waveguide is formed between the reflective plate  216  and the reflective plate  226 . 
     In the present embodiment, the spectrometer  100  also includes a positioning means so as to position the first side  312  of the diffractive surface  310  between the first reflective surface  212  and the second reflective surface  222  and to keep the spacing T between the first side  312  of the diffractive surface  310  and the second reflective surfaces  222 , when viewed along a direction perpendicular to the second reflective surface  222 . In the present embodiment, the positioning means may be the heightening component  130 , disposed between the diffractive component  300  and the second base body  220 . In the present embodiment, the heightening component  130  is disposed on the reflective plate  226 , and the diffractive component  300  is disposed on the heightening component  130 . However, in other embodiments, the heightening component  130  may also be disposed on the case  224 , and the diffractive component  300  may be disposed on the heightening component  130 . In the present embodiment, the heightening component  130  is, for example, a gasket. In the present embodiment, the heightening components  130  can increase the height of the allocation surface  350  so as to change the position of the diffractive surface  310 , thereby positioning the first side  312  of the diffractive surface  310  closer to the midplane between the first reflective surface  212  and the second reflective surface  222 . Due to the higher intensity of light on the midplane, positioning the first side  312  (where the sharpness of the profile of the stripe-shaped diffractive structures  320  is greater) closer to the midplane can enhance the diffraction effect of the diffractive surface  310 . In other embodiments, the heightening component  130  may also be integrally formed with the diffractive component  300 . For example, both the heightening component  130  and the diffractive components  300  can be made of the same semiconductor material (such as silicon). Before using the semiconductor etching process to form the notch  305 , a bulk semiconductor material  50  (as shown in  FIG. 3A ) can be etched to form the heightening component  130  first as shown in  FIG. 3B . Subsequently, the remaining portion  60  of the bulk semiconductor material  50  can be further etched to form the notch  305  and the diffractive surface  310  as shown in  FIG. 1C . 
     In the present embodiment, a light output channel A adjacent to the heightening component  130  is formed between the diffractive component  300  and the second base body  220 , through which another portion of the light L 11  coming from the light input port  120  exits the light channel C. In the present embodiment, the heightening components  130  may be in the form of a triangle, and a space (i.e., the light output channel A) next to the hypotenuse of the triangle can be provided to allow the light L 11  to pass through. In this way, the light L 11  can exit the light channel C via the light output channel A rather than being reflected by the heightening component  130  to generate stray light inside the light channel C to thereby impact the quality of the spectra measured by the light sensor  110 . This design advantageously reduces the noise level of the spectra. In the present embodiment, the heightening component  130  includes a surface  133  that can be, for example, a light absorbing surface that absorbs the part of the light L 1  that is incident on the heightening component  130 . As a result, no stray light would be derived from this part of the light L 1  to affect the quality of the spectra. However, in other embodiments, the heightening component  130  may also be a transparent component, so that the part of the light L 1  incident on the heightening component  130  can directly pass through the heightening component  130  and exit the light channel C without forming stray light in the light channel C to affect the quality of the spectra. In other embodiments, the heightening component  130  may also be in a non-triangular form to provide the light output channel A. Rather, the heightening component  130  may have a shape generally corresponding to the shape of the diffractive component  300  (e.g., in a rectangular form) with no light output channel A formed. In addition, the heightening component  130 , which has a shape generally corresponding to the shape of the diffractive component  300 , may have a light absorbing surface, or the heightening component  130  may also be transparent so as to reduce the formation of stray light. 
     In the present embodiment, the strip-shaped diffractive structures  320  are positioned substantially parallel with respect to each other, and the diffractive surface  310  is a curved concave surface. In other words, these strip-shaped diffractive structures  320  are arranged substantially parallel with respect to each other on a curved surface. In this way, light L 1  diffracted by the diffractive surface  310 , which is curved, can be transmitted in a converging manner to the light sensor  110 . Accordingly, between the diffractive surface  310  and the light sensor  110 , either no lens for the purpose of focusing the diffracted light L 1  is needed or fewer lenses would be needed to focus the diffracted light L 1 . As a result, the volume or size of the spectrometer  100  can be effectively reduced. 
       FIG. 4  is a side view of a spectrometer in accordance with another embodiment of the present invention. Referring to  FIG. 4 , the spectrometer  100   a  of the present embodiment is similar to the spectrometer  100  shown in  FIG. 1A . Differences between the spectrometer  100   a  and the spectrometer  100  are described below. The thickness of the heightening component  130   a  in the spectrometer  100   a  of the present embodiment is less than the thickness of the heightening component  130  shown in  FIG. 1A ; therefore, at least a part of the surface  340  of the diffractive component  330  that is connected to the bottom surface  330  ( FIG. 4 , near the bottom portion) is facing the light channel C. In addition, a light absorbing material  140  may be applied on the part of the surface  340  facing the light channel C. Thus, when the light L 1  transmitted in the light channel C is incident on the surface  340 , the light L 1  will be absorbed by the light absorbing material  140  rather than reflected by the surface  340  to form stray light. In other embodiments, the entire surface of the surface  340  may be coated with the light absorbing material  140 . In addition to being coated on the surface  340 , the light absorbing material  140  may also be coated on other surfaces of the diffractive component  300  except the diffractive surface  310  such as, for example, those surfaces on which the light L 1  may be incident. 
       FIG. 5A  is a perspective view of a spectrometer in accordance with yet another embodiment of the present invention.  FIG. 5B  is an exploded perspective view of the spectrometer of  FIG. 5A .  FIG. 5C  is a perspective view of the heightening component of the spectrometer of  FIG. 5A . Referring to  FIGS. 5A-5C , the spectrometer  100   b  of the present embodiment is similar to the spectrometer  100  shown in the  FIGS. 1A and 1B , and the major difference between the two is the difference between the heightening components  130   b  and  130 . In  FIGS. 5A and 5B , in order to allow the reader to clearly see the internal structure of the spectrometer  100   b , the case  214  of the first base body  210  (shown in  FIG. 1A ) is removed. The shape of the reflective plate  216  in  FIG. 5A  may be used as a reference for the three-dimensional shapes of the reflective plates  216  and  226  in  FIG. 1A , and the shape of the case  224  in  FIG. 5A  may be used as a reference for the three-dimensional shape of the case  224  in  FIG. 1A . In the present embodiment, the case  224  may be produced by, for example, a computer numerical control (CNC) system. In the present embodiment, the heightening component  130   b  includes at least one light confinement groove  134   b  ( FIG. 5C  shows a plurality of light confinement grooves  134   b  as an example) located on a surface  133   b  of the heightening component  130   b  that faces the light channel C. The position of the surface  133   b  with respect to the light channel C is essentially identical to the position of the surface  133  of the heightening component  130  with respect to the light channel C in  FIG. 1C . The difference between the surface  133   b  and the surface  133  is that the surface  133   b  has light confinement grooves  134   b  while the surface  133  is a flat surface. Therefore, similar to the heightening component  130 , beside the surface  133   b  of the heightening component  130   b , there is also a light output channel A. In the present embodiment, after passing through the light input port  120 , a portion of the light L 1  is diffracted by the diffractive surface  310 , another portion of the light L 1  exits the light channel C via the light output channel A, and the remaining portion of the light L 1  is trapped by the light confinement groove(s)  134   b.    
     Light L 1  incident on the at least one light confinement groove  134   b  is repeatedly reflected by each of the at least one light confinement groove  134   b  and is confined within the at least one light confinement groove  134   b . Specifically, each light confinement grooves  134   b  may have two opposed inclined guide surfaces  1342  connected by an annular-shaped reflective surface  1344  with a notch  1343  thereon. Light L 1  incident on the surface  133   b  will be reflected by the inclined guide surfaces  1342  and enters into the space surrounded by the annular-shaped reflective surface  1344  via the notch  1343 . Since the dimension of the notch  1343  is smaller than that of the space defined by the annular-shaped reflective surface  1344 , light L 1  in the space will be repeatedly reflected by the annular-shaped reflective surface  1344 , making the escape of the light very difficult. Since every reflection will cause a slight attenuation of the light intensity, after multiple reflections light L 1  will be absorbed by the annular-shaped reflective surface  1344  and disappear within the space. In this way, the light confinement groove(s)  134   b  can avoid formation of stray light, thus enhancing the quality of the spectra measured by the light sensor  110 . 
     In the present embodiment, the heightening component  130   b  includes position reference marks  1345  and  1346 , which can serve as the references for the relative position of the diffractive component  300  and the heightening component  130   b . The position reference marks  1345  and  1346  may be openings. Specifically, as shown in  FIG. 5A , when the diffractive component  300  is disposed on the heightening component  130   b , an assembler can determine whether the diffractive component  300  is positioned correctly based on a ratio of the position reference marks  1345  and  1346  covered by the diffractive component  300 . After the diffractive component  300  is determined to be in the correct position, the diffractive component  300  can be fixed, or otherwise secured, by an adhesive material. The adhesive material may be applied to the reflective plate  226  or the case  224  (please refer to  FIG. 1A ), situated below the openings (i.e., the position reference marks  1345  and  1346 ), through these openings, thereby fixing or securing the relative positions of the diffractive component  300 , the heightening component  130   b , and the second base body  220  (shown in  FIG. 1A ). 
     Furthermore, in the present embodiment, the reference marks  1345  and  1346  may extend in different directions such as, for example, in substantially mutually perpendicular directions. In this way, when judging whether the diffractive component  300  is correctly positioned, reference marks in two different directions can be used as the reference points. In addition, the heightening component  130   b  may include a positioning hole  135 , and the case  224  may include a positioning unit  2242  such as, for example, a positioning post. When the heightening component  130   b  is disposed on the reflective plate  226 , the positioning unit  2242  may be inserted in the positioning hole  135 , for example, so that the positioning portion  2242  is tightly fit in the positioning hole  135 . In this way, the heightening component  130   b  can be secured. 
     In the present embodiment, the heightening component  130   b  also includes slits  1362 ,  1364  and  1366 . The slit  1362  connects the reference mark  1345  to the reference mark  1346 , and the slit  1364  connects the reference mark  1346  to the positioning hole  135 . The slit  1366  extends through a side of the heightening component  130   b , connecting the positioning hole  135  to the space outside the side of the heightening component  130   b . As a result, the heightening component  130   b  can be formed simply by cutting once with a cutting tool when the heightening component  130   b  is formed by cutting a plate-shaped material. In addition, when the heightening component  130   b  is mounted on the positioning unit  2242  through the slit  1366 , the positioning hole  135  can be slightly enlarged by the positioning unit  2242  so as to enable easy assembly of the heightening component  130   b  on the positioning unit  2242  while still maintaining the tight fit effect. In another embodiment, as shown in  FIG. 6 , the heightening component  130   c  may include slits  1362  and  1364 , but not the slit  1366  of  FIG. 5C . This design allows the heightening component  130   c  to be formed by cutting twice with the cutting tools. Alternatively, in other embodiments, no slits  1262  and  1364  are provided in the heightening component  130   c , and accordingly the heightening component  130   c  may be formed by cutting multiple times. 
     Referring to  FIGS. 5A to 5C  again, the spectrometer  100   b  of the present embodiment also includes an adapter  150  and a mask component  160 . The adapter  150  is configured to connect to one end of a light fiber while the other end of the light fiber receives the to-be-measured light L 1  from the light source. When the light L 1  is transmitted to the adapter  150  via the light fiber and then incident on the mask component  160  via an opening  152  of the adapter  150 , a portion of the light L 1  can be transmitted to the light channel C via the light input port  120  since the light input port  120  is formed on the mask component  160  (as shown in  FIG. 1A , for example, as a slit). However, in other embodiments, there would be no adapter  150  in the spectrometer  100   b . A portion of the light L 1  to be measured is directly incident on the light input port  120 , and then transmitted to the light channel C via the light input port  120 . 
       FIG. 7  a perspective view of a diffractive component and a heightening component in accordance with another embodiment of the present invention. Referring to  FIG. 7 , the heightening component  130   d  of the present embodiment is similar to the heightening component  130  shown in  FIG. 1C . Differences between the two are described below. In the spectrometer of the present embodiment, the heightening member  130   d  includes multiple spacers  131   d  that are spaced apart with respect to each other. These spacers  131   d  are located between the diffractive component  300  and the second base body  220 . The spacers  131   d  may be transparent or light absorbing to reduce the formation of stray light. Moreover, these spacers  131   d  may be disposed on a part of the diffractive component  300  so as to form a light output channel A along a side of the spacers  131   d , thereby reducing the formation of stray light. 
       FIG. 8  is a side view of a spectrometer in accordance with still another embodiment of the present invention. Referring to  FIG. 8 , the spectrometer  100   e  of the present embodiment is similar to the spectrometer  100  shown in  FIG. 1A . Differences between the two are described below. Referring to  FIG. 8 , unlike the spectrometer in  FIG. 1A  where the heightening component  130  is used to raise the height of the diffractive component  300 , the spectrometer  100   e  of the present embodiment includes an adhesive material  130   e  that secures the diffractive component  300  to at least one of the first base body  210  and the second base body  220  (in the example shown in  FIG. 8 , the diffractive component  300  is secured to the second base body  220 ). In the present embodiment, the adhesive material  130   e  is, for example, adhesive glue. A part of the adhesive material  130   e  is provided between the diffractive component  300  and the reflective plate  226  so that the diffractive component  300  is attached to the reflective plate  226 . In addition, another part of the adhesive material  130   e  is applied to the reflective plate  226 , the case  224 , and the diffractive component  300 . The diffractive component  300  may be secured by the adhesive material  130   e  at a suitable height, so that the first side  312  of the diffractive surface  310  is positioned between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222 . As a result, the diffraction effect of the diffractive component  300  is enhanced. 
       FIG. 9  is a partial sectional side view of a spectrometer in accordance with another embodiment of the present invention. Referring to  FIG. 9 , the spectrometer  100   f  of the present embodiment is similar to the spectrometer  100  shown in  FIG. 1A . Differences between the two are described below. In the present embodiment, at least one of the first base body  210   f  and the second base body  220   f  of the waveguide module  200   f  includes a fixing component (in the example shown in  FIG. 9 , the first base body  210   f  has a fixing component  215   f  on the case  214   f  and the second base body  220   f  has a fixing component  225   f  on the case  224   f ) to secure the position of the diffractive component  300 . Specifically, the fixing component  215   f  and fixing component  225   f  may be, for example, convex portions. The diffractive component  300  may be held between the fixing component  225   f  and the elastic fixing component  215   f  disposed on the case  214  to achieve the effect of securing the diffractive component  300 . In the present embodiment, the fixing component  215   f  is made of, for example, elastic silicone. The diffractive component  300  is fixed to a suitable height by the elastic fixing component  215   f  and the fixing component  225   f  such that the first side  312  of the diffractive surface  310  is positioned between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222  with a spacing or gap maintained between the first side  312  of the diffractive surface  310  and the second reflective surface  222 . This design enhances the diffraction effect of the diffractive component  300 . 
     In other embodiments, the fixing component may be provided on the first base body  210   f  instead and not on the second base body  220   f , or each of the first base body  210   f  and the second base body  220   f  is respectively provided with a fixing component, so that the diffractive component  300  can be fixed to a suitable height to enhance the diffraction effect. In addition, in other embodiments, other components or structures may be adopted to secure the diffractive component  300  to a suitable height so that the first side  312  of the diffractive surface  310  is positioned between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222 . These components and structures are all within the scope of protection of the present invention. 
       FIG. 10  a side view of a spectrometer in accordance with yet another embodiment of the present invention. Referring to  FIG. 10 , the spectrometer  100   g  of the present embodiment is similar to the spectrometer  100  shown in  FIG. 1A . Differences between the two are described below. Referring to  FIG. 10 , the waveguide module  200   g  of the spectrometer  100   g  in the present embodiment includes a light guiding body  230 , a first reflective film  216   g , and a second reflective film  226   g . The light guiding body  230  forms a light channel C. The first reflective film  216   g  is disposed on the light guiding body  230 , and the second reflective film  226   g  is disposed on the light guiding body  230 . The light guiding body  230  is disposed between the first reflective film  216  and the second reflective film  226 . An interface between the first reflective film  216   g  and the light guiding body  230  forms the first reflective surface  212 , and an interface between the second reflective film  226   g  and the light guiding body  230  forms the second reflective surface  222 . The light guiding body  230  is made of, for example, a transparent material such that light L 1  can be transmitted within the light guiding body  230  and continuously reflected by the first reflective film  216   g  and the second reflective film  226   g . The first reflective film  216   g  and the second reflective film  226   g  may be, for example, a metal coated film or a non-metal coated film. In other words, the light guiding body  230 , the first reflective film  216   g , and the second reflective film  226   g  together form a solid waveguide. In other embodiments, the waveguide module  200   g  may include a light guiding body that can guide light by total reflection, and Light L 1  can be transmitted within the light guiding body through total internal reflection. As a result, there is no need to form reflective films by further processing. 
     In the present embodiment, the heightening component  130   g  is disposed on the case  224  to locate the diffractive component  300  at a suitable height, and to allow the first side  312  of the diffractive surface  310  to be positioned between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222 . As a result, the diffraction effect of the diffractive component  300  is enhanced. In other embodiments, an adhesive material, a fixing component on the case  214  or case  224 , or any other component or structure on which the diffractive component  300  can be secured may be employed to position the first side  312  of the diffractive surface  310  between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222 . 
       FIG. 11  is a side view of a spectrometer in accordance with still another embodiment of the present invention. Referring to  FIG. 11 , the spectrometer  100   h  of the present embodiment is similar to the spectrometer  100  disclosed in  FIG. 1A . Differences between the two are described below. In the present embodiment, the diffractive surface  310  of the notch  305  on the diffractive component  300  of the spectrometer  100   h  is inclined relative to the bottom surface  330 . Specifically, when a semiconductor material is etched using the semiconductor etching process, the processing conditions may result in an undercut, thus the bottom surface  330  becomes the end surface of etching. As a result, the diffractive surface  310  will be inclined relative to the bottom surface  330 . In the present embodiment, the bottom surface  330  is inclined relative to the second reflective surface  222  so that the diffractive surface  310  is generally parallel with the normal vector of the second reflective surface  222 . Specifically, when the undercut occurs, the diffractive surface  310  is not perpendicular to the second reflective surface  222 . In order to have the diffractive surface  310  positioned nearly perpendicular to the second reflective surface  222 , the diffractive components  300  is tilted, i.e., the bottom surface  330  is tilted. In this way, light L 1  can be incident on the diffractive surface  310  approximately perpendicularly. As a result, the diffraction effect (i.e., resolution) can be enhanced. 
     In the present embodiment, the heightening member  130   h  may be disposed between the diffractive component  300  and the second base body  220  and away from one side of the diffractive surface  310  of the diffractive component  300 , i.e., below the end of the diffractive component  300 . In this way, the end of the diffractive component  300  will be raised up to tilt the bottom surface  330  and to position the diffractive surface  310  nearly vertically. 
       FIG. 12  is a side view of a spectrometer in accordance with another embodiment of the present invention. Referring to  FIG. 12 , the spectrometer  100   i  of the present embodiment is similar to the spectrometer  100   h  disclosed in  FIG. 11 . Differences between the two are described below. In the present embodiment, except that the diffractive surface  310  of the notch  305  on the diffractive component  300  of the spectrometer  100   i  is inclined relative to the bottom surface  330 , the first side  312  of the diffractive surface  310  is also located between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222 . Thus, in addition to the fact that light L 1  may be perpendicularly incident on the diffractive surface  310 , a portion of the light L 1  with higher intensity may be incident on the portion of the strip-shaped diffractive structures  320  with sharper profile (as shown in  FIG. 1C ). In this way, the diffractive surface  310  can better diffract light L 1  and enhance the optical quality of the resulting spectra. 
     In the present embodiment, the heightening component  130   i  not only increases the height of the diffractive component  300  but also tilts the diffractive component  300 . For example, one side of the heightening component  130   i  that is further away from the diffractive surface  310  has a thickness greater than the other side that is closer to the diffractive surface  310 , thus achieving heightening and tilting effects at the same time. 
     In addition to utilizing the heightening component  130   h  of  FIG. 11  and the heightening component  130   i  of  FIG. 12  as described above to set the diffractive component  300  at an optimal position and angle, in other embodiments, an adhesive material or other components or structures may also be used to adjust the position and angle of the diffractive component. 
       FIGS. 13A to 13E  are diagrams illustrating an assembling system in accordance with one embodiment of the present invention to explain the associated assembling procedure. Referring to  FIGS. 13A to 13E , the assembling method in the present embodiment can be used to assemble the spectrometer  100   e  as shown in  FIG. 8  or other spectrometers described above. Hereafter, the assembly of the spectrometer  100   e  disclosed in  FIG. 8  is described as an example. The method for assembling a spectrometer in the present embodiment includes the following steps. First, as shown in  FIG. 13A , a waveguide module  200  is provided. For example, a carrier  410  in an assembling system  400  may be used to carry the waveguide module  200 . Then, as shown in  FIG. 13B , the diffractive component  300  is disposed adjacent to the light channel C (as shown in  FIG. 1A ), for example, by a first fixture  420  in the assembling system  400 . Next, as shown in  FIG. 13C , the light sensor  110  is disposed on one end of the light channel C, for example, by a second fixture  430  in the assembling system  400 . Thereafter, light L 1  is transmitted to the diffractive surface  310  via the light channel C such that at least a portion of the light L 1  is diffracted by the diffractive surface  310  and then transmitted to the light sensor  110 . For example, light L 1  from a light source  450  is transmitted to the diffractive surface  310  after passing through the light input port  120  and the light channel C sequentially. In the present embodiment, the light source  450  may be a standard lamp of known spectral radiance and/or intensity. 
     Then, either or both the position of the diffractive surface  310  along a direction substantially perpendicular to the second reflective surface  222  (e.g., direction D 1 ) and an angle .theta.1 between the diffractive surface  310  and the second reflective surface  222  (as shown in  FIG. 8 ) is adjusted, and the corresponding spectrum of the light L 1  incident on the light sensor  110  is measured. For example, the first fixture  420  may be used to adjust either or both the position of the diffractive surface  310  along a direction substantially perpendicular to the second reflective surface  222  and angle .theta.1 between the diffractive surface  310  and the second reflective surface  222 . The first fixture  420  may achieve this effect by shifting or rotating the diffractive component  300 . 
     In the present embodiment, the first fixture  420  may also be used to adjust the position of the diffractive surface  310  along a direction that is substantially parallel to the second reflective surface  222  and substantially perpendicular to a straight line connecting the light input port  120  (as shown in  FIG. 1A ) and the diffractive surface (e.g., direction D 2 ). The light input port  120  is provided on one end the waveguide module  200 , for example, on the mask component  160 . Moreover, in the present embodiment, the first fixture  420  may also be used to adjust the distance between the diffractive surface  310  and the light input port  120  (e.g., a distance along a direction parallel to direction D 3 ). Moreover, in the present embodiment, the first fixture  420  may be used to adjust a first rotation angle .theta.2 of the diffractive surface of  310 . The first rotation angle .theta.2 is defined as an angle around an axis A 2  that is substantially parallel to the normal vector of the second reflective surface  222 . Furthermore, in the present embodiment, the first fixture  420  may be used to adjust a second rotation angle .theta.3 of the diffractive surface  310 . The second rotation angle .theta.3 is defined as an angle around an axis A 3  that is substantially parallel to a straight line connecting the light input port  120  and the diffractive surface  310 . 
     In this way, the first fixture  420  may adjust not only the position of the diffractive surface  310  in three directions D 1 , D 2  and D 3 , but also the angle .theta.1, the first rotation angle .theta.2, and the second rotation angle .theta.3 of the diffractive surface  310 . Accordingly, the first fixture  420  is capable of performing six-axis adjustments to the diffractive component  300 . 
     Afterwards, referring to  FIG. 13D , it is determined whether the spectrum of the light L 1  measured by the light sensor  110  meets a predefined first sharpness condition. If the spectrum of the light L 1  measured by the light sensor  110  meets the predefined first sharpness condition, the diffractive component  300  is secured. Otherwise, at least one of position and angle of the diffractive surface  310  will be adjusted until the first sharpness condition is met. Specifically, whether the spectrum meets the predefined first sharpness condition is determined by a controller  490  (as shown in  FIG. 13E ). When the spectrum meets the predefined first sharpness condition, an adhesive material  442  is applied to the diffractive component  300  by an adhesive dispenser  440  in the assembling system  400  so as to fix or secure the diffractive component  300  on at least one of the first base body  210  and the second base body  220 .  FIG. 13D  shows the example of the diffractive component  300  being fixed on the reflective plate  226  of the second base body  220 . In the present embodiment, the adhesive dispenser  440  is controlled, for example, by the controller  490 . In addition, in the present embodiment, the predefined first sharpness condition may be, for example, a predefined spectral sensitivity or a predefined spectral resolution having a value greater than a preset threshold within a specified wavelength range. 
     Furthermore, in the present embodiment, the position and the angle used to obtain the spectrum in a previous measurement may be used to determine the adjustment of at least one of the position and angle of the diffractive surface  310  in a current measurement. 
     Next, referring to  FIG. 13E , after the diffractive component  300  is secured, either or both of position and angle of the light sensor  110  relative to the light channel C is adjusted, and the corresponding spectrum of the light L 1  incident on the light sensor  110  is measured. Subsequently, it is determined whether the spectrum of the light L 1  incident on the light sensor  110  meets a predefined second sharpness condition. If the condition is met, the light sensor  110  is secured. Otherwise, the adjustment of either or both of position and angle of the light sensor  110  relative to the light channel C will be continued until the condition is met. In the present embodiment, the predefined second sharpness condition may be, for example, a predefined spectral sensitivity or a predefined spectral resolution having a value greater than a preset threshold within a specified wavelength range. The first sharpness condition and the second sharpness condition may be the same or different depending on the requirements. 
     Specifically, either or both of position and angle of the light sensor  110  can be adjusted by a second fixture  430  that is similar to the first fixture  420 . Moreover, in the present embodiment, the second fixture  430  can move the light sensor  110  in three directions, namely a direction parallel to the light channel C, a direction perpendicular to the light channel C and the second reflective surface  222 , and a direction perpendicular to the light channel C but parallel to the second reflective surface  222 . Alternatively, the second fixture  430  can rotate the light sensor  110  around three rotation axes, namely a rotation axis parallel to the light channel C, a rotation axis perpendicular to the light channel C and the second reflective surface  222 , and a rotation axis perpendicular to the light channel C but parallel to the second reflective surface  222 . In other words, in the present embodiment, the second fixture  430  is capable of performing six-axis adjustments to adjust the position of the light sensor  100 . Furthermore, in the present embodiment, when the spectrum measured by the light sensor  110  meets the second sharpness condition, an adhesive material  462  is applied to the light sensor  110  by the adhesive dispenser  460  in the assembling system  400  so as to secure the light sensor  110  on one end of the light channel C, for example, on one or both of the first base body  210  and the second base body  220 . 
     Referring to  FIG. 13E , the assembling system  400  further includes a first actuator  470 , a second actuator  480 , and a controller  490 . The first actuator  470  drives the first fixture  420 , and the second actuator  480  drives the second fixture  430 . The controller  490  is electrically connected to the first actuator  470  and the second actuator  480  to control the actions of the first actuator  470  and the second actuator  480 . In other words, the first actuator  470  and the second actuator  480  can drive the first fixture  420  and the second fixture  430 , respectively, to adjust positions and angles of the diffractive component  300  and the light sensor  110 , respectively. Moreover, the way that the first actuator  470  drives the first fixture  420  and that the second actuator  480  drives the second fixture  430  is subject to the control of the controller  490 . The controller  490  is, for example, a control chip, a processor, a computer, or another appropriate controller. 
     In the present embodiment, the controller  490  is electrically connected to the light sensor  110  and the adhesive dispensers  440  and  460 . The light sensor  110  sends signals of measured spectral back to the controller  490 . The controller  490  determines either or both of the position and angle of the diffractive component  300 , as well as either or both of the position and angle of the light sensor  110 , based on these spectral signals. The controller  490 , through a determination process, determines whether the sharpness of the spectral signals measured by the light sensor  110  meets preset standards (e.g., the first sharpness condition and the second sharpness condition). When the standards are met, the controller  490  commands the adhesive dispenser  440  to apply the adhesive material onto the diffractive component  300 . Otherwise, the controller  490  commands the first actuator  470  and second actuator  480  to adjust either or both of the position and angle of the diffractive component  300 , or either or both of the position and angle of the light sensor  110 , until the sharpness of the spectral signals meets the standards. 
     In addition, in the present embodiment, the controller  490  may also be electrically connected to the adhesive dispenser  460 . When the controller  490  determines that the spectrum measured by the light sensor  110  meets the second sharpness condition, the controller  490  commands the adhesive dispenser  460  to apply the adhesive material onto the light sensor  110  so as to secure the position and angle of the light sensor  110 . 
     After the diffractive component  300  and the light sensor  110  are secured with the adhesive material using the procedures described above, the first side  312  of the diffractive surface  310  is positioned between the first reflective surface  212  and the second reflective surface  222  in a direction perpendicular to the second reflective surface  222  with a spacing or gap maintained between the second reflective surface  222  and the first side  312 . Alternatively, the diffractive surface  310  is positioned to be substantially parallel with the normal vector of the second reflective surface  222 . Alternatively, the diffractive surface  310  is positioned in the above-mentioned two positions simultaneously. Thus, a spectrometer having good spectral qualities can be obtained, according to the assembling method and the assembling system  400 , such as the spectrometer  100   e , for example, and variations thereof (such as the one with an inclined bottom surface  330 ) may be obtained. 
     In the present embodiment, the example given involves securing the light sensor  110  after the diffractive component  300  is secured. However, in another embodiment, the diffractive component  300  and the light sensor  110  may be secured with the adhesive material after positions of both the diffractive component  300  and the light sensor  110  has been adjusted (i.e., both of the first sharpness condition and the second sharpness condition are met, where the first sharpness condition and the second sharpness condition may be the same or different). During the adjustment of the positions of the diffractive component  300  and the light sensor  110 , various combinations of the relative positions of the diffractive component  300  and the light sensor  110  may be generated. The controller  490  may store the information related to the spectral senility, the spectral resolution and the ratio of stray light of the spectra of these combinations measured by the light detector  110  in a data storage medium. In addition, the controller  490  may select one or more of the combinations having optimal spectral signals, so that in subsequent assemblies, the controller  490  may first position the diffractive component  300  and the light sensor  110  at specific positions according to the one or more selected combinations. Alternatively, the controller  490  may perform an interpolative estimation of the positions of the diffractive component  300  and the light sensor  110  in advance according to these combinations, thus effectively shortening the assembly time. 
     The description above pertains to an example of an automatic mode through which the positions of the diffractive component  300  and the light sensor  110  are adjusted. However, in other embodiments, positions of the diffractive component  300  and the light sensor  110  may also be adjusted manually. When manual adjustment is adopted, the first fixture  420  and the second fixture  430  are replaced by manually-operated fixtures. The manually-operated fixtures may include at least one sliding rail and at least one rotating lever. In the present embodiment, when the position of the diffractive component  300  or the light sensor  110  is to be adjusted along the six axes, the first fixture  420  may be replaced with three sliding rails and three rotating levels, and the second fixture  430  may also be replace with three sliding rails and three rotating levels. For example, the three sliding rails may be used to adjust the positions of the diffractive surface  310  along three directions D 1 , D 2 , and D 3 , respectively, while the three rotating levers can be used to adjust the angle .theta.1, the first rotation angle .theta.2, and the second rotation angle .theta.3 of the diffractive surface  310 , respectively. 
     In addition, when manual adjustment is used, an example illustrating a method to adjust the light sensor  110  and determine whether the spectrum meets the predefined sharpness condition is described below. Firstly, a mercury lamp may be used as the light source  450 . Then, the position of the light sensor  110  is adjusted along a direction perpendicular to the second reflective surface  222  and the light channel C by observing whether the peak of the spectrum is long and thin. When the peak value reaches the highest and the peak shape becomes the longest and the thinnest, the light sensor  110  will be set at this position. The peak value is the number of counts of the spectrum representing the light energy received by the light sensor  110 . When the light sensor  110  continuously receives the light L 1  within an integrated time period, the number of counts will be increased as time elapses. Therefore, the determination of whether the peak value reaches the highest is based on whether the number of counts of the peak value reaches the maximum with respect to those at other wavelengths. In other words, the number of counts of the spectrum can be viewed as the relative intensity of light at different wavelengths. 
     Next, the position of the light sensor  110  is adjusted along a direction substantially parallel to the light channel C, i.e., the distance between the light sensor  110  and the diffractive component  300  is adjusted. After the peak value of each wavelength in the spectrum becomes the largest and at the same time the peak shape at each wavelength becomes elongated, and before some of the peak values increase and some of the peak values decrease, the light sensor  110  is set at this position. 
     Afterwards, the position of the light sensor  110  is secured. In this way, the light sensor  110  can be secured at a position with a relatively better spectral resolution and a relatively high peak value. The same procedure may be followed to move or rotate the light sensor  110  along or around other directions. 
     Moreover, the above-described procedure for adjusting the position of the light sensor  110  and determining whether a sharper spectrum is obtained may be applied to the diffractive component  300 . Furthermore, in order to shorten the assembly time, the diffractive component may also be first moved or rotated to a limited number of specified positions based on prior adjustments, and then the sharpness of each of corresponding spectra is determined. The diffractive component  300  is then secured at one position with the sharpest spectrum. In this way, the diffractive component  300  only needs to be adjusted at fewer positions and angles to observe the corresponding spectra rather than being continuously adjusted at various positions and angles during observation of the spectra. By doing so, assembly time can be effectively shortened. In other words, the position and the angle of the diffractive component  300  only need to be roughly adjusted. After the diffractive component  300  is secured, the position and angle of the light sensor  110  are fine-tuned. Accordingly, the spectrum with high spectral quality can still be obtained. 
     After the light sensor  110  is secured, a halogen lamp may be used as the light source  450 , and some wavelengths of the light L 1  measurable by the light sensor  110  may be filtered out by the filter. Next, the number of counts of those wavelengths being filtered out may be compared to the number of counts of unfiltered wavelengths, and the ratio of these counts may be used to determine the influence of stray light on the light sensor  110 . A larger ratio normally indicates a greater effect of stray light. 
     Next, a light source with calibrated intensity of light may be used as the light source  450 , which may be used to calibrate the intensity of light measured by the light sensor  110 . 
       FIG. 14A  is a side view of a spectrometer in accordance with a further embodiment of the present invention.  FIG. 14B  is a top view of the spectrometer of  FIG. 14A  with the case  214  removed.  FIG. 14C  is a perspective view of the spectrometer of  FIG. 14A  with the case  214  removed. Referring to  FIGS. 14A to 14C , the spectrometer  100   j  of the present embodiment is similar to the spectrometer  100  shown in  FIG. 1A . Differences between the two are described below. In the present embodiment, the spectrometer  100   j  also includes a connecting unit  505   j  connecting the diffractive component  300  to the first base body  210 . Since the diffractive component  300  is connected to the first base body  210  by the connecting unit  505   j , when temperature changes of the spectrometer  100   j  result in deformation (e.g., increase in width and length) of the first base body  210 , changes will also occur on the diffractive component  300  through the connecting unit  550   j . When the position of the diffractive component  300  changes with the deformation of the first base body  210 , the connection between the diffractive component  300  and the first base body  210  or the strength of the connection is less susceptible to thermal stress. In this way, the reliability and durability of the spectrometer  100   j  can be effectively improved. 
     In the present embodiment, the connecting unit  505   j  connects the diffractive component  300  to the reflective plate  216 . When temperature changes cause deformation of the reflective plate  216  of the spectrometer  100   j , changes will also occur on the diffractive component  300  via the connecting unit  505   j . When the position of the diffractive component  300  changes with the deformation of the reflective plate  216 , the connection between the diffractive component  300  and the reflective plate  216  or the strength of the connection is less susceptible to damage by thermal stress. 
     In the present embodiment, the connecting unit  505   j  includes a fixing component  510   j  and multiple pieces of an adhesive material  520   j . The fixing component  510   j , having multiple first through holes  512   j , is disposed on the first base body  210 . A first portion  512   j   1  of the first through hole  512   j  exposes a part of the diffractive component  300 , and a second portion  512   j   2  of the first through holes  512   j  exposes a part of the first base body  210  (in the present embodiment, a part of the reflective plate  216  is exposed; in other embodiments, a part of the case  214  may be exposed). The first through holes  512   j  are filled with the adhesive material  520   j . The adhesive material  520   j  in the first portion  512   j   1  of the first through holes  520   j  connects the fixing component  510   j  to the diffractive component  300 , while the adhesive material  520   j  in the second portion  512   j   2  of the first through holes connects the fixing component  510   j  to the first base body  210 . In the present embodiment, the fixing component  510   j  is, for example, a fixing plate disposed on the reflective plate  216 . However, in other embodiments, the fixing plate  510   j  may be disposed on the case  214 . 
     In the present embodiment, the connecting unit  505   j  also includes a gasket  130   j , which has at least one second through hole  132   j , located between the diffractive component  300  and the fixing component  510   j  (in the example of  FIG. 14A  multiple second through holes  132   j  are shown). Each of the second through holes  132   j  is interlinked with a corresponding first through hole  512   j   1 . Some of the pieces of the adhesive material  520   j  are filled in the first through holes  512   j   1  and the second through holes  132   j  to connect the fixing component  510   j , the gasket  130   j , and the diffractive component  300  together. 
     In the present embodiment, the first through holes  512   j   1  are distributed at different locations, and the quantity of the first through holes  512   j   1  is at least three. This allows the adhesive material  520   j  filled in the first through holes to provide a better control over the degree in which the diffractive component  300  is leveled horizontally or inclined. However, in other embodiments, one first through hole  512   j   1  is provided. 
     In addition, in the present embodiment, the connecting unit  505   j  may include at least one positioning hole  530   j  (in the example of  FIG. 14C  multiple positioning holes  530   j  are shown) extending through the diffractive component  300  and the gasket  130   j , and exposing a part of the upper surface  360  of the diffractive component  300 . When using the adhesive material  520   j  to secure the diffractive component  300 , a gasket is disposed between the reflective plate  226  and the diffractive component  300  first, and then the fixture is abutted against the surface  360  of the diffractive component  300  through the positioning hole  530   j  so as to temporarily secure the position of the diffractive component  300 . Subsequently, the adhesive material  520   j  is filled into the first through hole  512   j   1  and the second through hole  132   j . The diffractive component  300  is secured after the adhesive material  520   j  is cured. At this point, the gasket is removed from the reflective plate  226  and the diffractive component  300 ; meanwhile, the fixture may also be removed from the positioning hole  530   j.    
     In this way, the diffractive component  300  is secured above the second base body  220  with a spacing or gap in between. By doing so, stray light can exit the spectrometer  100   j  through the spacing between the diffractive component  300  and the second base body  220 . It noteworthy that in the present embodiment, the allocation surface  350  of the diffractive component  300  facing the reflective plate  226  may be coated with a reflective material to form a mirror. As a result, stray light can more easily exit the spectrometer  100   j  via the spacing between the diffractive component  300  and second base body  220 . In other words, in the present embodiment, the positioning may be achieved by the fixing component  510   j , the gasket  130   j  and the adhesive material  520   j . The position and the degree of inclination of the diffractive surface  310  may be controlled by the thickness and the degree of inclination of the lower surface of the gasket  130   j , respectively. 
     In the present embodiment, the fixing component  510   j , the gasket  130   j  and the reflective plate  216  are made of metal such as, for example, aluminum. The adhesive material  520   j  is, for example, a UV curable adhesive, an AB glue or another adhesive material. Because the thermal expansion coefficient of metal is smaller than that of the adhesive material, when the adhesive material  520   j  is attached to the inner walls of the first through hole  512   j   1  and the second through hole  132   j , the expansions of the fixing component  510   j  and the gasket  130   j  under heat are smaller. As a result, the fixing component  510   j  and the gasket  130   j  can effectively limit the expansion of the adhesive material  520   j . In this way, the height of the diffractive component  300  in a direction perpendicular to the first reflective surface  212  is less susceptible to ambient temperature changes. 
     In the present embodiment, the fixing component  510   j  and the reflective plate  216  may be made of the same material or different materials as long as the thermal expansion coefficients of the fixing component  510   j  and the reflective plate  216  are substantially the same. Thus, when the length or the width of the reflective plate  216  increases due to ambient temperature changes, the fixing component  510   j  can react to these changes, thereby producing a corresponding deformation. As a result, the position of the diffractive component  300  is changed correspondingly to minimize possible damage due to thermal stress caused by the connection between the diffractive component  300  and the reflective plate  216 . However, in other embodiments, the thermal expansion coefficient of the fixing component  510   j  may be different from that of the reflective plate  216 . 
     In other embodiments, when the diffractive component  300  is thick enough, no gasket  130   j  is needed. The diffractive component  300  may be abutted against the fixing component  510   j  directly. 
       FIG. 15  is a side view of a spectrometer in accordance with another embodiment of the present invention. Referring to  FIG. 15 , the spectrometer  100   k  of the present embodiment is similar to the spectrometer  100   j  shown in  FIG. 14A . Differences between the two are described below. In the spectrometer  100   k  of the present embodiment, the diffractive component  300   k  is secured to a side  2162  of the reflective plate  216  by the connecting unit  505   k . Specifically, the connecting unit  505   k , an adhesive material for example, is used to affix the diffractive component  300   k  to the reflective plate  216 . Such construction allows the position of the diffractive component  300   k  to be shifted corresponding to the expansion or contraction of the reflective plate  216 . Accordingly, the connection between the diffractive component  300   k  and the reflective plate  216  is less susceptible to damage by thermal stress. 
       FIG. 16  is a top view of a spectrometer with a case partially removed in according with yet another embodiment of the present invention. Referring to  FIG. 16 , the spectrometer  100   m  of the present embodiment is similar to the spectrometer  100   e  shown in  FIG. 8 . Differences between the two are described below. In the spectrometer  100   m  of the present embodiment, the diffractive component  300  has a backside  370  opposite to the diffractive surface  310 . The backside  370  is connected to the second base body  220  by an adhesive material  130   m  (the example of  FIG. 16  shows the backside  370  connected to the reflective plate  226  of the second base body  220 ), thus securing the diffractive component  300  to the second base body  220 . In addition, in the present embodiment, no adhesive material  130   m  is applied to a side surface  380  of the diffractive component  300  that connects the backside  370  with the diffractive surface  310 . In this way, when there is a significant change in the ambient temperature, the position of the diffractive component  300  can vary by a larger margin, thus the connection between the diffractive component  300  and the second base body  220  is less susceptible to damage by thermal stress. In another embodiment, the side surface  380  of the diffractive component  300 , connecting the backside  370  and the diffractive surface  310 , may be coated with the adhesive material  130   m.    
     In summary, in the spectrometers in accordance with the various embodiments of the present invention, since the first side of the diffractive surface is positioned between the first reflective surface and the second reflective surface in a direction perpendicular to the second reflective surface, a portion of light transmitted in the light channel that has higher intensity will be diffracted by the part of the diffractive surface having a sharper profile. As a result, the optical quality of the spectra measured by the spectrometer can be enhanced. In the spectrometers in accordance with the embodiments of the present invention, since the bottom surface of the notch of the diffractive component is inclined relative to the second reflective surface, the diffractive surface is generally parallel with the normal vector of the second reflective surface. As a result, the optical quality of the spectra obtained can be enhanced. In the methods for assembling spectrometers in accordance with the embodiments of the present invention, since the diffractive component is secured after either or both of the position and angle of the diffractive component has been adjusted and after the spectrum obtained has been determined to be sharp, the diffractive component can be secured at a suitable position. As a result, the optical quality of the spectra obtained can be enhanced. In the assembling system in accordance with the embodiments of the present invention, since the first fixture and the second fixture are adopted to adjust the relative positions of the diffractive component and the light sensor, respectively, the relative positions of the diffractive component and the light sensor can be accurately adjusted. As a result, the optical quality of the spectra obtained can be enhanced. 
     From the foregoing it would be appreciated that, although specific embodiments of the present invention have been described for purpose of illustration, by no means they are to be interpreted as limiting the scope of the present invention. Various modifications may be made without departing from the spirit and scope of the present invention. Accordingly, the scope of the present invention is to be determined entirely by the following claims.