PATENT DOCUMENT

Publication Number: US-9314871-B2
Application Number: US-201313921135-A
Country: US
Kind Code: B2

Title: Method for laser engraved reflective surface structures

Abstract:
Techniques or processes for providing markings on products are disclosed. In one embodiment, the products have housings and the markings are to be provided on the housings. For example, a housing for a particular product can include an outer housing surface and the markings can be provided on the outer housing surface so as to be visible from the outside of the housing. The markings may be precisely formed using a laser. Processing may be used to increase reflectivity of the markings.

Claims:
What is claimed is: 
     
       1. A method for marking an electronic device housing comprising:
 providing a substrate of the electronic device housing, the substrate having an outer surface; 
 substantially athermally ablating the outer surface of the substrate, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate, wherein a plurality of light scattering features are overlain on the athermally ablated surface layer; and 
 thermally melting the plurality of light scattering features, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. 
 
     
     
       2. A method as recited in  claim 1  wherein:
 substantially athermally ablating the outer surface of the substrate comprises using a first laser pulse having a first laser pulse duration; and 
 thermally melting the plurality of light scattering features comprises using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
 
     
     
       3. A method for marking an article as recited in  claim 1  wherein substantially athermally ablating the outer surface of the substrate comprises using a laser pulse having a laser pulse duration that is sufficiently short for ablating the outer surface substantially athermally. 
     
     
       4. A method for marking an article as recited in  claim 1  wherein thermally melting the plurality of light scattering features comprises using a laser pulse having a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features. 
     
     
       5. A method as recited in  claim 1  wherein substantially athermally ablating the outer surface of the substrate comprises substantially avoiding an appearance of thermal artifacts at the outer surface of the substrate. 
     
     
       6. A method as recited in  claim 1  wherein thermally melting the plurality of light scattering features comprises making the plurality of melted regions substantially optically smooth. 
     
     
       7. A method as recited in  claim 1  wherein the plurality of melted regions have a substantially glossy appearance. 
     
     
       8. A method as recited in  claim 1  wherein the plurality of melted regions overlaying the athermally ablated surface layer have a level of specular reflection that is substantially similar to a level of specular reflection of the outer surface of the electronic device housing. 
     
     
       9. A method as recited in  claim 1  further comprising bead blasting so that at least a portion of the outer surface of the electronic device housing has a bead blasted appearance. 
     
     
       10. A method as recited in  claim 9  wherein the plurality of melted regions overlaying the athermally ablated surface layer have an appearance that is substantially similar to the bead blasted appearance of the outer surface of the electronic device housing. 
     
     
       11. A method as recited in  claim 1  wherein substantially athermally ablating the outer surface of the substrate comprises forming at least one sidewall of the markings recessed into the outer surface of the substrate, wherein the outer surface of the substrate is substantially perpendicular to the sidewall. 
     
     
       12. A method as recited in  claim 1  wherein the substrate comprises metal. 
     
     
       13. A method as recited in  claim 1  wherein the substrate comprises anodized metal. 
     
     
       14. A method as recited in  claim 1  wherein the substrate comprises one of aluminum, titanium and stainless steel. 
     
     
       15. A method for marking an article comprising:
 providing a substrate of the article, the substrate having an outer surface; 
 substantially athermally ablating the outer surface of the substrate so as to provide first and second recessed markings disposed on the outer surface of the substrate, wherein each of the first and second recessed markings comprises a respective ablated surface having a respective plurality of light scattering features overlain thereon; and 
 selectively altering the plurality of light scattering features of one of the first and second recessed markings so that the first and second recessed markings have contrasting appearances. 
 
     
     
       16. A method for marking an article as recited in  claim 15  wherein selectively altering the plurality of light scattering features of one of the first and second recessed markings comprises thermally melting the plurality of light scattering features of the first recessed marking, so that the first recessed marking has a substantially lighter appearance than the second recessed marking. 
     
     
       17. A method for marking an article as recited in  claim 15  wherein selectively altering the plurality of light scattering features of one of the first and second recessed markings comprises thermally melting the plurality of light scattering features so as to be substantially optically smooth. 
     
     
       18. A method for marking an article as recited in  claim 15  wherein altering the plurality of light scattering features of one of the first and second recessed markings comprises thermally melting the plurality of light scattering features so as to have a substantially glossy appearance. 
     
     
       19. A method for marking an article as recited in  claim 15  wherein:
 substantially athermally ablating the outer surface of the substrate comprises using a first laser pulse having a first laser pulse duration; and 
 altering the plurality of light scattering features comprises thermally melting the plurality of light scattering features using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
 
     
     
       20. A method for marking an article comprising:
 providing a substrate of the article, the substrate having an outer surface; 
 substantially athermally ablating the outer surface of the substrate, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate, wherein a plurality of light scattering features are overlain on the athermally ablated surface layer, and wherein the markings are arranged in one or more textual or graphical indicia on the outer surface the substrate; and 
 thermally melting the plurality of light scattering features, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. 
 
     
     
       21. A method as recited in  claim 20  wherein:
 substantially athermally ablating the outer surface of the substrate comprises using a first laser pulse having a first laser pulse duration; and 
 thermally melting the plurality of light scattering features comprises using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
 
     
     
       22. A method as recited in  claim 20  wherein substantially athermally ablating the outer surface of the substrate comprises using a first laser pulse having a first laser pulse duration that is sufficiently brief to ablate substantially athermally. 
     
     
       23. A method as recited in  claim 20  wherein substantially athermally ablating the outer surface of the substrate comprises using a first laser pulse having a first laser pulse duration within a range from approximately picoseconds to less than approximately ten nanoseconds, so as to ablate substantially athermally. 
     
     
       24. A method for marking an article comprising:
 providing a substrate of the article, the substrate having an outer surface; 
 substantially athermally ablating the outer surface of the substrate, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate, wherein a plurality of light scattering features are overlain on the athermally ablated surface layer, and wherein the markings are arranged in a tactile texture on the outer surface the substrate; and 
 thermally melting the plurality of light scattering features, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. 
 
     
     
       25. A method as recited in  claim 24  wherein:
 substantially athermally ablating the outer surface of the substrate comprises using a first laser pulse having a first laser pulse duration; and 
 thermally melting the plurality of light scattering features comprises using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
 
     
     
       26. A method as recited in  claim 24  wherein the tactile texture on the outer surface the substrate comprises knurling.

Description:
BACKGROUND OF THE INVENTION 
     Consumer products, such as electronic devices, have been marked with different information for many years. For example, it is common for electronic devices to be marked with a serial number, model number, copyright information and the like. Conventionally, such marking is done with an ink printing or stamping process. Although conventional ink printing and stamping is useful for many situations, such techniques can be inadequate in the case of handheld electronic devices. Ink printing and stamping may not be very durable for handheld devices. Further, the small form factor of handheld electronic devices, such as mobile phones, portable media players and Personal Digital Assistants (PDAs), requires that the marking be very small. In order for such small marking to be legible, the marking must be accurately and precisely formed. Unfortunately, however, conventional techniques are not able to offer sufficient accuracy and precision. Thus, there is a need for improved techniques to mark products. 
     SUMMARY 
     The invention pertains to techniques or processes for providing markings on products. In one embodiment, the products have housings and the markings are to be provided on the housings. For example, a housing for a particular product can include an outer housing surface and the markings can be provided on the outer housing surface so as to be visible from the outside of the housing. The markings provided on products can be textual and/or graphic. The markings can be formed with high resolution and/or precision using a laser. Processing may be used to increase reflectivity of the markings. The markings are also able to be light or dark, even on metal surfaces. 
     In general, the markings (also referred to as annotations or labeling) provided on products according to the invention can be textual and/or graphic. The markings can be used to provide a product (e.g., a product&#39;s housing) with certain information. The marking can, for example, be used to label the product with various information. When a marking includes text, the text can provide information concerning the product (e.g., electronic device). For example, the text can include one or more of: name of product, trademark or copyright information, design location, assembly location, model number, serial number, license number, agency approvals, standards compliance, electronic codes, memory of device, and the like. When a marking includes a graphic, the graphic can pertain to a logo, a certification mark, standards mark or an approval mark that is often associated with the product. The marking can be used for advertisements to be provided on products. The markings can also be used for customization (e.g., user customization) of a housing of a product. 
     The invention can be implemented in numerous ways. Several embodiments of the invention are discussed below. 
     As a method for marking an electronic device housing, one embodiment can, for example, include at least providing a substrate of the electronic device housing, the substrate having an outer surface, substantially athermally ablating the outer surface of the substrate, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate, wherein a plurality of light scattering features are overlain on the athermally ablated surface layer, and thermally melting the plurality of light scattering features, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. 
     As a method for marking an article, one embodiment can, for example, include at least providing a substrate of the article, the substrate having an outer surface, substantially athermally ablating the outer surface of the substrate so as to provide first and second recessed markings disposed on the outer surface of the substrate, wherein each of the first and second recessed markings comprises a respective ablated surface having a respective plurality of light scattering features overlain thereon, and selectively altering the plurality of light scattering features of one of the first and second recessed markings so that the first and second recessed markings have contrasting appearances. 
     As a method for marking an article, another embodiment can, for example, include at least providing a substrate of the article, the substrate having an outer surface, substantially athermally ablating the outer surface of the substrate, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate, wherein a plurality of light scattering features are overlain on the athermally ablated surface layer, and wherein the markings are arranged in one or more textual or graphical indicia on the outer surface the substrate, and thermally melting the plurality of light scattering features, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. 
     As a method for marking an article, another embodiment can, for example, include at least providing a substrate of the article, the substrate having an outer surface, substantially athermally ablating the outer surface of the substrate, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate, wherein a plurality of light scattering features are overlain on the athermally ablated surface layer, and wherein the markings are arranged in a tactile texture on the outer surface the substrate, and thermally melting the plurality of light scattering features, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments by way of examples, not by way of limitation, are illustrated in the drawings. Throughout the description and drawings, similar reference numbers may be used to identify similar elements. The drawings are for illustrative purpose to assist understanding and may not be drawn per actual scale. 
         FIG. 1  is a diagram of a marking state machine according to one embodiment of the invention. 
         FIG. 2  is an illustration of a substrate having markings according to one embodiment. 
         FIG. 3  is a flow diagram of a marking process according to one embodiment. 
         FIGS. 4A-4D  are diagrams illustrating marking of a substrate according to one embodiment. 
         FIG. 5  is a flow diagram of a marking process according to another embodiment. 
         FIGS. 6A-6D  are diagrams illustrating marking of a substrate according to another embodiment. 
         FIGS. 7A and 7B  are flow diagrams of marking processes according to other embodiments. 
         FIG. 8A  is a diagrammatic representation of an exemplary product housing. 
         FIG. 8B  illustrates the product housing having markings according to one example embodiment. 
         FIG. 9  shows an alternative depiction that is substantially similar to what is shown in  FIGS. 4C and 6C . 
         FIG. 10  shows an alternative depiction that is substantially similar to what is shown in  FIG. 4D . 
         FIG. 11  shows an alternative depiction that is substantially similar to what is shown in  FIG. 6D . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The invention pertains to techniques or processes for providing engravings and/or markings on products. In one embodiment, the products have housings and the markings are to be provided on the housings. For example, a housing for a particular product can include an outer housing surface and the markings can be provided on the outer housing surface so as to be visible from the outside of the housing. The markings provided on products can be textual and/or graphic. The markings can be formed with high resolution and/or precision using a laser. Processing may be used to increase reflectivity of the markings. The markings are also able to be light or dark, even on metal surfaces. 
     In general, the markings (also referred to as annotations or labeling) provided on products according to the invention can be textual and/or graphic. The markings can be used to provide a product (e.g., a product&#39;s housing) with certain information. The marking can, for example, be used to label the product with various information. When a marking includes text, the text can provide information concerning the product (e.g., electronic device). For example, the text can include one or more of: name of product, trademark or copyright information, design location, assembly location, model number, serial number, license number, agency approvals, standards compliance, electronic codes, memory of device, and the like. When a marking includes a graphic, the graphic can pertain to a logo, a certification mark, standards mark or an approval mark that is often associated with the product. The marking can be used for advertisements to be provided on products. The markings can also be used for customization (e.g., user customization) of a housing of a product. 
     Example embodiments of the invention are discussed below with reference to  FIGS. 1-11 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments. 
       FIG. 1  is a diagram of a marking state machine  100  according to one embodiment of the invention. The marking state machine  100  reflects three ( 4 ) basic states associated with marking an electronic device. Specifically, the marking can mark a housing of an electronic device, such as a portable electronic device. 
     The marking state machine  100  includes a substrate formation state  102 . At the substrate formation state  102 , a substrate can be obtained or produced. For example, the substrate can represent at least a portion of a housing surface of an electronic device. Next, the marking state machine  100  can transition to a surface preparation state  104 . At the surface preparation state  104 , the surface can be prepared, for example using bead blasting. 
     A protective surface can be formed or applied to at least one surface of the substrate. The protective surface can be used to protect the surface of the substrate. For example, the protective surface can be a more durable surface than that of the surface. For example, the substrate can be a metal substrate, the surface can be a metal surface, and the metal can be anodized so that the protective surface can be an anodized surface. 
     Next, the marking state machine  100  can transition to a marking state  106 . At the marking state  106 , marking can be produced on the substrate. The marking can be provided with high resolution. Next, the marking state machine  100  can transition to a melt polish state  108 . The marking can be polished using a thermal process, which can melt light scattering features. Prior to melting, light scattering features may dull and/or darken appearance of the markings. Alternatively or additionally, the light scattering features may be designated as surface roughness, which may be on the nanometer scale and/or may be on the micrometer scale (and which may result from the substantially athermal ablation.) Melting of light scattering features may provide polishing, so as to brighten and/or lighten appearance of the markings. Alternatively or additionally, such melting may be designated as surface reflow and/or surface melting. 
       FIG. 2  is an illustration of a substrate  200  having recessed markings  203  according to one embodiment. The substrate  200  can represent at least a portion of a housing of an electronic device. The markings  203  being provided to the substrate can provide text and/or graphics to an outer housing surface of a portable electronic device. Alternatively or additionally, in some embodiments the markings  203  may be arranged in a tactile texture on the outer surface the substrate  200 . In some embodiments, the tactile texture may comprise knurling. The marking techniques are particularly useful for smaller scale portable electronic devices, such as handheld electronic devices. Examples of handheld electronic devices include mobile telephones (e.g., cell phones), Personal Digital Assistants (PDAs), portable media players, remote controllers, pointing devices (e.g., computer mouse), game controllers, etc. 
     The markings  203  are, in one embodiment, particularly well-suited for applying text and/or graphics to a housing of an electronic device. As noted above, the substrate can represent a portion of a housing of an electronic device. Examples of electronic devices, namely, handheld electronic devices, include mobile telephones (e.g., cell phones), Personal Digital Assistants (PDAs), portable media players, remote controllers, pointing devices (e.g., computer mouse), game controllers, etc. 
     The substrate  200  may having an outer surface  202 , and recessed markings  203  may be disposed on or adjacent the outer surface  202  the substrate of the electronic device housing. As mentioned previously, the substrate  200  of the electronic device housing may comprise metal. For example, the substrate  200  may comprise one of aluminum, titanium and stainless steel. The outer surface  202  of the substrate  200  may bead blasted and/or may be anodized, as highlighted in  FIG. 2  by hatching of outer surface  202 . Accordingly, it should be understood that the substrate  200  may comprise anodized metal. 
     As shown in  FIG. 2 , the recessed markings  203  may comprise an athermally ablated surface layer  204 , and a plurality of melted regions  206  overlaying the athermally ablated surface layer  204 . The athermally ablated surface layer  204  and/or the plurality of melted regions  206  overlaying the athermally ablated surface layer  204  may be substantially optically smooth. 
     The plurality of melted regions  206  may have a substantially glossy appearance. The plurality of melted regions  206  overlaying the athermally ablated surface layer  204  may have a level of specular reflection that is substantially similar to a level of specular reflection of the outer surface  202  of the electronic device housing. 
     As mentioned previously, at least a portion of the outer surface  202  of the electronic device housing may have a bead blasted appearance. The plurality of melted regions  206  overlaying the athermally ablated surface layer  204  may have an appearance that is substantially similar to the bead blasted appearance of the outer surface  202  of the electronic device housing. 
     As shown in  FIG. 2 , the recessed markings  203  may comprise at least one sidewall adjacent to the athermally ablated surface layer  204 . The outer surface  202  of the substrate  200  is substantially perpendicular to the sidewall adjacent to the athermally ablated surface layer  204 . As will be discussed in greater detail subsequently herein, short duration laser pulses may used to provide for substantially athermal ablation, which may help to provide such steep sidewalls. The appearance of such steep sidewalls may be desirable for the recessed markings  203 . Further, since the athermally ablated surface layer  204  may be ablated substantially athermally, this may provide an appearance of the outer surface  202  that is substantially free of thermal artifacts, such as burr, melt and/or discoloration of the outer surface  202 , which, may be desirable to substantially avoid. 
       FIG. 3  is a flow diagram of a marking process  300  according to one embodiment. The marking process  300  can be performed on an electronic device that is to be marked. The marking process  300  is for example, suitable for applying text or graphics to a housing (e.g., an outer housing surface) of an electronic device. The marking can be provided such that it is visible to users of the electronic device. However, the marking can be placed in various different positions, surfaces or structures of the electronic device. 
     The marking process can provide a metal structure and/or metal substrate for an article to be marked. The metal may comprise one of aluminum, titanium and stainless steel. The metal may be anodized. 
     The metal structure and/or metal substrate can pertain to a metal housing for an electronic device, such as a portable electronic device, to be marked. The metal structure and/or metal substrate can be formed of one metal layer. The metal structure and/or metal substrate can also be formed of multiple layers of different materials, where at least one of the multiple layers is a metal layer. 
     In accordance with the marking process  300  shown in  FIG. 3 , the process may begin with providing  302  the substrate to be marked. As mentioned previously, the substrate may have an outer surface. In some embodiments the outer surface may be bead blasted and/or anodized. 
     After the substrate of the electronic device housing has been provided  302 , the outer surface of the substrate may be substantially athermally ablated  304 , so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate. 
     Substantially athermally ablating  304  the outer surface of the substrate may comprise using a laser pulse having a laser pulse duration that is sufficiently short for ablating the outer surface substantially athermally. For example, as will be discussed in greater detail subsequently herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately fifteen picoseconds at approximately one Watt may be sufficiently short for ablating the outer surface substantially athermally. Athermal ablation may be substantial as a significant aspect of the ablation. Athermal ablation may be substantial in that athermal ablation processes may predominate in effect over other processes. 
     Substantially athermally ablating the outer surface of the substrate may comprise forming at least one sidewall of the markings recessed into the outer surface of the substrate, wherein the outer surface of the substrate may be substantially perpendicular to the sidewall. The short duration laser pulses as just discussed may provide for substantially athermal ablation, and further may help to provide such steep sidewalls. As mentioned previously herein, the appearance of such steep sidewalls may be desirable for the recessed markings. Further, since the athermally ablated surface layer may be ablated substantially athermally, this may provide an appearance of the outer surface that is substantially free of thermal artifacts, such as burr, melt and/or discoloration of the outer surface  202 , which may be desirable to substantially avoid. In other words, substantially athermally ablating the outer surface of the substrate may substantially avoid an appearance of thermal artifacts at the outer surface. 
     As a result of the substantially athermal ablation, a plurality of light scattering features may be overlain on the athermally ablated surface layer. The light scattering features may be undesirable, and may dull and/or darken appearance of the markings. As will be discussed next, melting of light scattering features may provide polishing, so as to brighten and/or lighten appearance of the markings. 
     After the outer surface of the substrate has been substantially athermally ablated  304 , the plurality of light scattering features may be thermally melted  306 , so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. Thermally melting  306  the plurality of light scattering features may comprise using a laser pulse having a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features. For example, as will be discussed in greater detail subsequently herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately thirty nanoseconds at approximately seven Watts may be sufficiently long for thermally melting the plurality of light scattering features. 
     Accordingly, from the foregoing it should be understood that substantially athermally ablating  304  the outer surface of the substrate may comprise using a first laser pulse having a first laser pulse duration. Further, thermally melting  306  the plurality of light scattering features may comprise using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
     Thermally melting  306  the plurality of light scattering features may comprise making the plurality of melted regions substantially optically smooth. The plurality of melted regions may have a substantially glossy appearance. 
     Furthermore, the plurality of melted regions overlaying the athermally ablated surface layer may have a level of specular reflection that is substantially similar to a level of specular reflection of the outer surface of the electronic device housing. As mentioned previously, the outer surface of the electronic device housing may be bead blasted, so that at least a portion of the outer surface of the electronic device housing may have a bead blasted appearance. The plurality of melted regions overlaying the athermally ablated surface layer may have an appearance that is substantially similar to the bead blasted appearance of the outer surface of the electronic device housing. Following the block  306  of thermally melting the plurality of light scattering features, the marking process  300  shown in  FIG. 3  can end. 
       FIGS. 4A-4D  are diagrams illustrating marking of a substrate according to one embodiment.  FIGS. 4A-4D  illustrate a substrate  400 , which may be a metal substrate  400 . For example, the substrate  400  may comprise one of aluminum, titanium and stainless steel. 
     As shown in  FIG. 4A , the substrate  400  may have an outer surface  402 . The outer surface  402  of the substrate  400  may bead blasted and/or may be anodized, as highlighted in  FIGS. 4B-4D  by hatching of outer surface  402 . For example,  FIG. 4B  highlights with hatching the outer surface  402 , which may be bead blasted and/or may be anodized. 
     As shown in  FIG. 4C , recessed markings  403  may be formed by suitably selected optical energy  407  produced by a suitably selected and operated laser  409 . The outer surface  402  of the substrate  400  may be substantially athermally ablated by a first laser  409 , so as to provide an athermally ablated surface layer  404  of markings  403  recessed into the outer surface  402  of the substrate  400 . In some embodiments, the outer surface  402  of the substrate  400  may be laser ablated under the action of a substantially athermal shock wave induced by the laser  409 , so as to provide a shock ablated surface layer  404  of markings  403  recessed into the outer surface  402  of the substrate  400 . Accordingly, the athermally ablated surface layer  404  may be alternatively or additionally designated as the shock ablated surface layer  404 . 
     The first laser  409  may include a galvanometer mirror or other arrangement for raster scanning a spot of the optical energy over the outer surface  402 , so as to form the recessed markings  403 . For example, laser pulses  407  from the first laser  409  may have a repetition rate of approximately one-thousand kilohertz (1000 kHz); and the spot of optical energy may be scanned at a rate of approximately two-thousand millimeters per second 2000 mm/sec). The spot of optical energy may be scanned in multiple passes of scan lines separated by a scan line pitch. For example, the spot of optical energy may be scanned in approximately two-hundred passes of scan lines separated by a scan line pitch of approximately ten microns. 
     Various alternatives may be suitable laser models, for use as the first laser  409  in marking the substrate  400 . One example is the Lumera Hyper Rapid. The Lumera Hyper Rapid is a picosecond type laser. The Lumera Hyper Rapid is available from Coherent, Inc., having an office at  5100 . Patrick Henry Drive Santa Clara, Calif. 95054 USA. 
     Substantially athermally ablating the outer surface  402  of the substrate  400  may comprise using a laser pulse  407  having a laser pulse duration that is sufficiently short for ablating the outer surface  402  substantially athermally. For example, first laser  409  may provide laser light  407  having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), and a laser pulse duration of approximately fifteen picoseconds at approximately one Watt, which may be sufficiently short for ablating the outer surface  402  substantially athermally. Athermal ablation may be substantial as a significant aspect of the ablation. Athermal ablation may be substantial in that athermal ablation processes may predominate in effect over other processes. 
     The substrate  400  shown in  FIG. 4C  can represent at least a portion of a housing of an electronic device. The recessed markings  403  may be disposed on or adjacent the outer surface  402  the substrate  400  of the electronic device housing. The markings  403  being provided to the substrate  400  can provide text and/or graphics to an outer housing surface of a portable electronic device. As mentioned previously, the marking techniques are particularly useful for smaller scale portable electronic devices, such as handheld electronic devices. Examples of handheld electronic devices include mobile telephones (e.g., cell phones), Personal Digital Assistants (PDAs), portable media players, remote controllers, pointing devices (e.g., computer mouse), game controllers, etc. 
     The markings  403  are, in one embodiment, particularly well-suited for applying text and/or graphics to a housing of an electronic device. As noted above, the substrate can represent a portion of a housing of an electronic device. Examples of electronic devices, namely, handheld electronic devices, include mobile telephones (e.g., cell phones), Personal Digital Assistants (PDAs), portable media players, remote controllers, pointing devices (e.g., computer mouse), game controllers, etc. 
     As shown in  FIG. 4C , substantially athermally ablating the outer surface  402  of the substrate  400  may comprise forming at least one sidewall of the markings  403  recessed into the outer surface  402  of the substrate  400 , wherein the outer surface  402  of the substrate  400  may be substantially perpendicular to the sidewall. The short duration laser pulses as just discussed may provide for substantially athermal ablation, and further may help to provide such steep sidewalls. As mentioned previously herein, the appearance of such steep sidewalls may be desirable for the recessed markings  403 . Further, since the athermally ablated surface layer  404  may be ablated substantially athermally, this may provide an appearance of the outer surface  402  that is substantially free of thermal artifacts, such as burr, melt and/or discoloration of the outer surface  402 , which may be desirable to substantially avoid. In other words, substantially athermally ablating the outer surface  402  of the substrate  400  may substantially avoid an appearance of thermal artifacts at the outer surface  402  of the substrate  400 . 
     As a result of the substantially athermal ablation, a plurality of light scattering features  405  may be overlain on the athermally ablated surface layer (the light scattering features  405  are highlighted in  FIG. 4C  using dark stippling.) The light scattering features  405  may be undesirable, and may dull and/or darken appearance of the markings  403 . As will be discussed in greater detail subsequently herein with respect to  FIG. 4D , thermally melting of the light scattering features  405  may provide polishing, so as to brighten and/or lighten appearance of the markings. 
     As shown in  FIG. 4D , the light scattering regions as just discussed may be thermally melted to form a plurality of melted regions  406  overlaying the athermally ablated surface layer  404 . The plurality of melted regions  406  may be formed by suitably selected optical energy  408  produced by a suitably selected and operated laser  410 , which may be designated as a second laser  410 . Accordingly, the plurality of melted regions  406  may be formed by a second laser  410 . The second laser  410  shown in  FIG. 4D  may be substantially different than the first laser  409  discussed previously herein with respect to  FIG. 4C . Alternatively or additionally laser  409  and laser  410  may be distinguished by employing substantially different laser operating parameters. 
     The second laser  410  shown in  FIG. 4D  may include a galvanometer mirror or other arrangement for raster scanning a spot of the optical energy of the second laser  410  over the recessed markings  403 , so as to form the plurality of melted regions  406  overlaying the athermally ablated surface layer  404 . For example, laser pulses  408  from the second laser  410  may have a repetition rate of approximately one-hundred kilohertz (100 kHz); and the spot of optical energy of the second laser  410  may be scanned at a rate of approximately twenty millimeters per second (2000 mm/sec). The spot of optical energy may be scanned in one or more passes of scan lines separated by a scan line pitch. For example, the spot of optical energy may be scanned in one pass of scan lines separated by a scan line pitch of approximately ten microns. 
     Various alternatives may be suitable laser models, for use as the second laser  410  in forming the plurality of melted regions  406  overlaying the athermally ablated surface layer  404 . One example is the FOBA DP20GS. The FOBA DP20GS is a Diode Pumped Solid State Neodymium-Doped Yttrium Orthovanadate (DPSS YVO4) type laser, which is available from FOBA Technology and Services GmbH, having offices at  159 . Swanson Road, Boxborough, Mass. 
     A laser pulse  408  of the second laser  410  may have a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features, so as to form the plurality of melted regions  406  overlaying the athermally ablated surface layer  404  as shown in  FIG. 4D . For example, for laser light  408  from the second laser  410  having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately thirty nanoseconds at approximately seven Watts may be sufficiently long for thermally melting the plurality of light scattering features. 
     Accordingly, from the previous discussion of  FIG. 4C , it should be understood that substantially athermally ablating the outer surface of the substrate may comprise using a first laser pulse having a first laser pulse duration. Further, from the subsequent discussion of  FIG. 4D , it should be understood that thermally melting the plurality of light scattering features (so as to form the plurality of melted regions  406 ) may comprise using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
     Additionally, it should be understood that the recessed markings  403  shown in  FIG. 4D  may comprise an athermally ablated surface layer  404 , and a plurality of melted regions  406  overlaying the athermally ablated surface layer  404 , as shown in  FIG. 4D . The athermally ablated surface layer  404  and/or the plurality of melted regions  406  overlaying the athermally ablated surface layer  404  may be substantially optically smooth. 
     The plurality of melted regions  406  may have a substantially glossy appearance. The plurality of melted regions  406  overlaying the athermally ablated surface layer  404  may have a level of specular reflection that is substantially similar to a level of specular reflection of the outer surface  402  of the electronic device housing. 
     As mentioned previously, at least a portion of the outer surface  402  of the electronic device housing may have a bead blasted appearance. The plurality of melted regions  406  overlaying the athermally ablated surface layer  404  may have an appearance that is substantially similar to the bead blasted appearance of the outer surface  402  of the electronic device housing. 
       FIG. 5  is a flow diagram of a marking process  500  according to another embodiment. The marking processes  500  can be performed on an electronic device that is to be marked, or more generally on an article to be marked. In accordance with the marking process  500  shown in  FIG. 5 , the process may begin with providing  502  the substrate to be marked. As mentioned previously, the substrate may have an outer surface. In some embodiments the outer surface may be bead blasted and/or anodized. 
     After the substrate has been provided  502 , the outer surface of the substrate may be substantially athermally ablated  504 , so as to provide first and second recessed markings disposed on the outer surface of the substrate. Each of the first and second recessed markings may comprise a respective ablated surface having a respective plurality of light scattering features overlain thereon. 
     Substantially athermally ablating  504  the outer surface of the substrate may comprise using a laser pulse having a laser pulse duration that is sufficiently short for ablating the outer surface substantially athermally. For example, as already discussed, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately fifteen picoseconds at approximately one Watt may be sufficiently short for ablating the outer surface substantially athermally. Athermal ablation may be substantial as a significant aspect of the ablation. Athermal ablation may be substantial in that athermal ablation processes may predominate in effect over other processes. 
     As a result of the substantially athermal ablation, a plurality of light scattering features may be overlain on the athermally ablated surface layer. The light scattering features may dull and/or darken appearance of the markings. As will be discussed next, the plurality of light scattering features of one of the first and second recessed markings may be selectively altered so that the first and second recessed markings can have contrasting appearances. Melting of light scattering features may provide polishing, so as to brighten and/or lighten appearance of one of the markings. Further, selective melt polishing may provide contrasting appearance, by melt polishing one of the markings but not the other of the markings. 
     Accordingly, after the outer surface of the substrate has been substantially athermally ablated  504  to form the first and second recessed markings, the plurality of light scattering features of one of the first and second recessed markings may be selectively altered  506 , so that the first and second recessed markings can have contrasting appearances. Selectively altering  506  the plurality of light scattering features of one of the first and second recessed markings may comprise thermally melting the plurality of light scattering features of the first recessed marking, so that the first recessed marking has a substantially lighter appearance than the second recessed marking. 
     For example, selectively altering  506  may comprise thermally melting the plurality of light scattering features of the first recessed marking using a laser pulse having a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features. For example, as discussed previously herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately thirty nanoseconds at approximately seven Watts may be sufficiently long for thermally melting the plurality of light scattering features. 
     Accordingly, from the foregoing it should be understood that substantially athermally ablating  504  the outer surface of the substrate may comprise using a first laser pulse having a first laser pulse duration. Further, selectively altering  506  may comprise thermally melting the plurality of light scattering features of the first recessed marking using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
     Furthermore, selectively altering  506  the plurality of light scattering features of one of the first and second recessed markings may comprise thermally melting the plurality of light scattering features of one of the first and second recessed markings, so as to be substantially optically smooth. Selectively altering  506  the plurality of light scattering features of one of the first and second recessed markings may comprise thermally melting the plurality of light scattering features of one of the first and second recessed markings, so as to have a substantially glossy appearance. Following the block  506  of selectively altering, the marking process  500  shown in  FIG. 5  can end. 
       FIGS. 6A-6D  are diagrams illustrating marking of a substrate according to another embodiment.  FIGS. 6A-6D  illustrate a substrate  600 , which may be a metal substrate  600 . For example, the substrate  600  may comprise one of aluminum, titanium and stainless steel. 
     As shown in  FIG. 6A , the substrate  600  may have an outer surface  602 . The outer surface  602  of the substrate  600  may bead blasted and/or may be anodized, as highlighted in  FIGS. 6B-6D  by hatching of outer surface  602 . For example,  FIG. 6B  highlights with hatching the outer surface  602 , which may be bead blasted and/or may be anodized. 
     As shown in  FIG. 6C , first and second recessed markings  603 A,  603 B may be formed by suitably selected optical energy  607  produced by a suitably selected and operated laser  609 . The outer surface  602  of the substrate  600  may be substantially athermally ablated by a first laser  609 , so as to provide respective first and second athermally ablated surface layer  604 A,  604 A of each of first and second markings  603 A,  603 B recessed into the outer surface  602  of the substrate  600 . 
     The first laser  609  may include a galvanometer mirror or other arrangement for raster scanning a spot of the optical energy over the outer surface  602 , so as to form the first and second recessed markings  603 A,  603 B. For example, laser pulses  607  from the first laser  609  may have a repetition rate of approximately one-thousand kilohertz (1000 kHz); and the spot of optical energy may be scanned at a rate of approximately two-thousand millimeters per second (2000 mm/sec). The spot of optical energy may be scanned in multiple passes of scan lines separated by a scan line pitch. For example, the spot of optical energy may be scanned in approximately two-hundred passes of scan lines separated by a scan line pitch of approximately ten microns. Various alternatives may be suitable laser models, for use as the first laser  609  in marking the substrate  600 . One example is the Lumera Hyper Rapid, as discussed previously. 
     Substantially athermally ablating the outer surface  602  of the substrate  600  may comprise using a laser pulse  607  having a laser pulse duration that is sufficiently short for ablating the outer surface  602  substantially athermally. For example, first laser  609  may provide laser light  607  having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), and a laser pulse duration of approximately fifteen picoseconds at approximately one Watt, which may be sufficiently short for ablating the outer surface  602  substantially athermally. 
     The substrate  600  shown in  FIG. 6C  can represent at least a portion of a housing of an electronic device. The first and second recessed markings  603 A,  603 B may be disposed on or adjacent the outer surface  602  the substrate  600  of the electronic device housing. The first and second recessed markings  603 A,  603 B being provided to the substrate  600  can provide text and/or graphics to an outer housing surface of a portable electronic device. 
     As a result of the substantially athermal ablation, a plurality of light scattering features  605  may be overlain on the athermally ablated surface layer (the light scattering features  605  are highlighted in  FIG. 6C  using dark stippling.) The light scattering features  605  may dull and/or darken appearance of the first and second recessed markings  603 A,  603 B shown in  FIG. 6C . As will be discussed next, the plurality of light scattering features of one of the first and second recessed markings  603 A,  603 B may be selectively altered so that the first and second recessed markings  603 A,  603 B can have contrasting appearances. Melting of light scattering features  605  may provide polishing, so as to brighten and/or lighten appearance of one of the markings. Further, selective melt polishing may provide contrasting appearance, by melt polishing one of the markings but not the other of the markings. 
     For example, thermally melting of the light scattering features  605  of the first recessed marking  603 A may provide polishing, so as to brighten and/or lighten appearance of the first recessed marking. Selective melt polishing of the first recess marking may provide contrasting appearance, by melt polishing one of the markings (e.g. first recessed marking  603 A) but not the other of the markings (e.g. second recessed marking  603 B.) 
     As shown in  FIG. 6D , the light scattering regions as just discussed may be thermally melted to form a plurality of melted regions  606  overlaying the first athermally ablated surface layer  604 A of the first recessed marking  603 A. The plurality of melted regions  606  may be formed by suitably selected optical energy  608  produced by a suitably selected and operated laser  610 . The plurality of melted regions  606  may be formed by a second laser  610 . The second laser  610  shown in  FIG. 6D  may be substantially different than the first laser  609  discussed previously herein with respect to  FIG. 6C . 
     The second laser  610  shown in  FIG. 6D  may include a galvanometer mirror or other arrangement for raster scanning a spot of the optical energy of the second laser  610  over the first recessed markings  603 A, so as to form the plurality of melted regions  606  overlaying the first athermally ablated surface layer  604 A. For example, laser pulses  608  from the second laser  610  may have a repetition rate of approximately one-hundred kilohertz (100 kHz); and the spot of optical energy of the second laser  610  may be scanned at a rate of approximately twenty millimeters per second (2000 mm/sec). The spot of optical energy may be scanned in one or more passes of scan lines separated by a scan line pitch. For example, the spot of optical energy may be scanned in one pass of scan lines separated by a scan line pitch of approximately ten microns. 
     Various alternatives may be suitable laser models, for use as the second laser  610 , in forming the plurality of melted regions  606  overlaying the athermally ablated surface layer  604 . One example is the FOBA DP20GS, as discussed previously herein. 
     A laser pulse  608  of the second laser  610  may have a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features, so as to form the plurality of melted regions  606  overlaying the first athermally ablated surface layer  604 A of the first recessed marking  603 A as shown in  FIG. 6D . For example, for laser light  608  from the second laser  610  having a wavelength of approximately one-thousand-sixty-four nanometers 1064 nm), a laser pulse duration of approximately thirty nanoseconds at approximately seven Watts may be sufficiently long for thermally melting the plurality of light scattering features. 
     Accordingly, from the previous discussion of  FIG. 6C , it should be understood that substantially athermally ablating the outer surface of the substrate may comprise using a first laser pulse having a first laser pulse duration. Further, from the subsequent discussion of  FIG. 6D , it should be understood that selectively altering by thermally melting the plurality of light scattering features of the first recessed marking  604 A (so as to form the plurality of melted regions  606  as shown in  FIG. 6D ) may comprise using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
     Additionally, it should be understood that the first recessed markings  603 A shown in  FIG. 6D  may comprise the first athermally ablated surface layer  604 A, and a plurality of melted regions  606  overlaying the first athermally ablated surface layer  604 A, as shown in  FIG. 6D . The first athermally ablated surface layer  604 A and/or the plurality of melted regions  606  overlaying the first athermally ablated surface layer  604 A may be substantially optically smooth. 
     The plurality of melted regions  606  may have a substantially glossy appearance. The plurality of melted regions  606  overlaying the first athermally ablated surface layer  604 A may have a level of specular reflection that is substantially similar to a level of specular reflection of the outer surface  602  of the electronic device housing. 
     As mentioned previously, at least a portion of the outer surface  602  of the electronic device housing may have a bead blasted appearance. The plurality of melted regions  606  overlaying the first athermally ablated surface layer  604  of the first recessed marking may have an appearance that is substantially similar to the bead blasted appearance of the outer surface  602  of the electronic device housing. 
     In view of all of the foregoing, it should be understood that the first and second recessed markings  603 A,  603 B shown in  FIG. 6D  may have contrasting appearances. 
     The first recessed marking  603 A may have a substantially lighter appearance than the second recessed marking  603 B. The first recessed marking  603 A may comprise the plurality of melted regions  606  overlain on the first ablated surface layer  604 A of the first recessed marking  603 A, so as to provide for the substantially lighter appearance of the first recessed marking  603 A. Providing contrast, the light scattering features  605  may dull and/or darken appearance of the second recessed markings  603 B shown in  FIG. 6D . 
       FIGS. 7A and 7B  are flow diagrams of marking processes according to other embodiments.  FIG. 7A  is a flow diagram of a marking process  700 A according to one embodiment. The marking processes  700 A can be performed on an electronic device that is to be marked, or more generally on an article to be marked. The marking processes  700 A is for example, suitable for applying text or graphics to a housing (e.g., an outer housing surface) of an electronic device. The marking process  700 A can provide a metal structure and/or metal substrate for the article to be marked. 
     In accordance with the marking process  700 A shown in  FIG. 7A , the process may begin with providing  702 A the substrate to be marked. As mentioned previously, the substrate may have an outer surface. In some embodiments the outer surface may be bead blasted and/or anodized. 
     After the substrate of the electronic device housing has been provided  702 A, the outer surface of the substrate may be substantially athermally ablated  704 A, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate. The markings may be arranged in one or more textual or graphical indicia on the outer surface of the substrate. 
     Substantially athermally ablating  704 A the outer surface of the substrate may comprise using a laser pulse having a laser pulse duration that is sufficiently short for ablating the outer surface substantially athermally. For example, as will be discussed in greater detail subsequently herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers 1064 nm), a laser pulse duration of approximately fifteen picoseconds at approximately one Watt may be sufficiently short for ablating the outer surface substantially athermally. Athermal ablation may be substantial as a significant aspect of the ablation. Athermal ablation may be substantial in that athermal ablation processes may predominate in effect over other processes. 
     As a result of the substantially athermal ablation, a plurality of light scattering features may be overlain on the athermally ablated surface layer. The light scattering features may be undesirable, and may dull and/or darken appearance of the markings. As will be discussed next, melting of light scattering features may provide polishing, so as to brighten and/or lighten appearance of the markings. 
     After the outer surface of the substrate has been substantially athermally ablated  704 A, the plurality of light scattering features may be thermally melted  706 A, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. Thermally melting  706 A the plurality of light scattering features may comprise using a laser pulse having a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features. For example, as will be discussed in greater detail subsequently herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately thirty nanoseconds at approximately seven Watts may be sufficiently long for thermally melting the plurality of light scattering features. 
     Accordingly, from the foregoing it should be understood that substantially athermally ablating  704 A the outer surface of the substrate may comprise using a first laser pulse having a first laser pulse duration. Further, thermally melting  706 A the plurality of light scattering features may comprise using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
     Thermally melting  706 A the plurality of light scattering features may comprise making the plurality of melted regions substantially optically smooth. The plurality of melted regions may have a substantially glossy appearance. Following the block  706 A of thermally melting the plurality of light scattering features, the marking process  700 A shown in  FIG. 7A  can end. 
       FIG. 7B  is a flow diagram of a marking process  700 B according to one embodiment. The marking processes  700 B can be performed on an electronic device that is to be marked, or more generally on an article to be marked. The marking processes  700 B is for example, suitable for applying a tactile texture to a housing (e.g., an outer housing surface) of an electronic device. The marking process  700 B can provide a metal structure and/or metal substrate for the article to be marked. 
     In accordance with the marking process  700 B shown in  FIG. 7A , the process may begin with providing  702 B the substrate to be marked. As mentioned previously, the substrate may have an outer surface. In some embodiments the outer surface may be bead blasted and/or anodized. 
     After the substrate of the electronic device housing has been provided  702 A, the outer surface of the substrate may be substantially athermally ablated  704 A, so as to provide an athermally ablated surface layer of markings recessed into the outer surface of the substrate. The markings may be arranged in a tactile texture on the outer surface the substrate. In some embodiments, the tactile texture may comprise knurling. 
     Substantially athermally ablating  704 B the outer surface of the substrate may comprise using a laser pulse having a laser pulse duration that is sufficiently short for ablating the outer surface substantially athermally. For example, as will be discussed in greater detail subsequently herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers 1064 nm), a laser pulse duration of approximately fifteen picoseconds at approximately one Watt may be sufficiently short for ablating the outer surface substantially athermally. Athermal ablation may be substantial as a significant aspect of the ablation. Athermal ablation may be substantial in that athermal ablation processes may predominate in effect over other processes. 
     As a result of the substantially athermal ablation, a plurality of light scattering features may be overlain on the athermally ablated surface layer. As mentioned previously, the light scattering features may be undesirable, and may dull and/or darken appearance of the markings. As will be discussed next, melting of light scattering features may provide polishing, so as to brighten and/or lighten appearance of the markings. 
     After the outer surface of the substrate has been substantially athermally ablated  704 A, the plurality of light scattering features may be thermally melted  706 A, so as to provide a plurality of melted regions overlaying the athermally ablated surface layer. Thermally melting  706 B the plurality of light scattering features may comprise using a laser pulse having a laser pulse duration that is sufficiently long for thermally melting the plurality of light scattering features. For example, as will be discussed in greater detail subsequently herein, for laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm), a laser pulse duration of approximately thirty nanoseconds at approximately seven Watts may be sufficiently long for thermally melting the plurality of light scattering features. 
     Accordingly, from the foregoing it should be understood that substantially athermally ablating  704 B the outer surface of the substrate may comprise using a first laser pulse having a first laser pulse duration. Further, thermally melting  706 B the plurality of light scattering features may comprise using a second laser pulse having a second laser pulse duration that is substantially longer than the first laser pulse duration. 
     Thermally melting  706 B the plurality of light scattering features may comprise making the plurality of melted regions substantially optically smooth. The plurality of melted regions may have a substantially glossy appearance. Following the block  706 B of thermally melting the plurality of light scattering features, the marking process  700 B shown in  FIG. 7B  can end. 
       FIG. 8A  is a diagrammatic representation of an example product housing  800 . The housing may be formed using aluminum or another suitable metal. The housing  800  may be a housing that is to be a part of an overall assembly, as for example a bottom of a cell phone assembly or portable media player. 
       FIG. 8B  illustrates the product housing  800  having markings  802  according to one exemplary embodiment. The markings  802  can be dull and/or dark markings in accordance with the dull and/or dark markings discussed previously herein. Alternatively or additionally, the markings  802  can be light markings in accordance with the light markings discussed previously herein. Further, the markings  802  can be contrasting light and dark markings. In this example, the labeling includes a logo graphic  804 , serial number  806 , model number  808 , and certification/approval marks  810  and  812 . 
     In some embodiments a tactile texture may be used. For example, logo graphic  804  may comprise a tactile texture. In some embodiments, the tactile texture may comprise knurling. For example, cross hatching is used in  FIG. 8B  for representative illustration of knurling in the tactile texture of logo graphic  804 . The tactile texture of the logo graphic  804  can employ light markings, in accordance with the light markings discussed previously herein. 
       FIG. 9  shows an alternative depiction that is substantially similar to what is shown in  FIGS. 4C and 6C  and what is discussed previously herein with respect to  FIGS. 4C and 6C . Similar to what was discussed previously herein with respect to  FIGS. 4C and 6C ,  FIG. 9  shows substrate  900 , outer surface  902 , recessed markings  903 , athermally ablated surface layer  904 , plurality of light scattering features  905 , and first laser  909  and corresponding optical energy  907 . However, from the alternative depiction of  FIG. 9 , it should be understood that prior to melting, the plurality of light scattering features  905  may substantially cover and/or may entirely cover a surface of the athermally ablated surface layer  904 . 
       FIG. 10  shows an alternative depiction that is substantially similar to what is shown in  FIG. 4D  and what is discussed previously herein with respect to  FIG. 4D . Similar to what was discussed previously herein with respect to  FIG. 4D ,  FIG. 10  shows substrate  1000 , outer surface  1002 , recessed markings  1003 , athermally ablated surface layer  1004 , plurality of melted regions  1006 , and second laser  1010  and corresponding optical energy  1008 . However, from the alternative depiction of  FIG. 10 , it should be understood that after melting the plurality of melted regions  1006  may substantially cover and/or may entirely cover a surface of the athermally ablated surface layer  1004 . 
       FIG. 11  shows an alternative depiction that is substantially similar to what is shown in  FIG. 6D  and what is discussed previously herein with respect to  FIG. 6D . Similar to what was discussed previously herein with respect to  FIG. 6D ,  FIG. 11  shows substrate  1100 , outer surface  1102 , first and second recessed markings  1103 A,  1103 B, first and second athermally ablated surface layers  1104 A,  1104 B, plurality of light scattering features  1105 , plurality of melted regions  1106 , and second laser  1110  and corresponding optical energy  1108 . From the alternative depiction of  FIG. 11 , it should be understood that the plurality of melted regions  1106  may substantially cover and/or may entirely cover a surface of the first athermally ablated surface layer  1004 A. From the alternative depiction of  FIG. 11 , it should be understood that the plurality of light scattering features  1105  may substantially cover and/or may entirely cover a surface of the second athermally ablated surface layer  1104 B. 
     The marking processes described herein are, for example, suitable for applying text or graphics to a housing surface (e.g., an outer housing surface) of an electronic device. The marking processes are, in one embodiment, particularly well-suited for applying text and/or graphics to an outer housing surface of a portable electronic device. Examples of portable electronic devices include mobile telephones (e.g., cell phones), Personal Digital Assistants (PDAs), portable media players, remote controllers, pointing devices (e.g., computer mouse), game controllers, etc. The portable electronic device can further be a hand-held electronic device. The term hand-held generally means that the electronic device has a form factor that is small enough to be comfortably held in one hand. A hand-held electronic device may be directed at one-handed operation or two-handed operation. In one-handed operation, a single hand is used to both support the device as well as to perform operations with the user interface during use. In two-handed operation, one hand is used to support the device while the other hand performs operations with a user interface during use or alternatively both hands support the device as well as perform operations during use. In some cases, the hand-held electronic device is sized for placement into a pocket of the user. By being pocket-sized, the user does not have to directly carry the device and therefore the device can be taken almost anywhere the user travels (e.g., the user is not limited by carrying a large, bulky and often heavy device). 
     Additional information on product marking as well as other manufacturing techniques and systems for electronic devices are contained in U.S. patent application Ser. No. 13/021,641, filed Feb. 4, 2011, and entitled “Marking of Product Housings” which is hereby incorporated herein by reference. 
     The various aspects, features, embodiments or implementations of the invention described above can be used alone or in various combinations. 
     Different aspects, embodiments or implementations may, but need not, yield one or more of the following advantages. One advantage may be that the light markings may provide an aesthetically pleasing and/or desired appearance. In particular, since the outer surface may have a bead blasted appearance, providing light markings having an appearance that is substantially similar to the bead blasted appearance of the outer surface may be aesthetically pleasing and/or desired. Another advantage may be that contrasting markings may be clearly distinguished from one another. Another advantage may be that substantially athermal laser ablation followed by laser melt polishing may form markings with a pleasing visual appearance that may also be formed with high resolution and/or precision. 
     The many features and advantages of the present invention are apparent from the written description. Further, since numerous modifications and changes will readily occur to those skilled in the art, the invention should not be limited to the exact construction and operation as illustrated and described. While use of laser light having a wavelength of approximately one-thousand-sixty-four nanometers (1064 nm) has been discussed, it should be understood that other suitable wavelengths may be used, for example, such as approximately 532 nanometer and/or approximately 355 nanometer. Accordingly, laser markings as discussed may comprise at least one of approximately 1064 nanometer laser markings, approximately 532 nanometer laser markings and approximately 355 nanometer laser markings. 
     Further, laser pulses may be used having pulse width that may be sufficiently brief to ablate substantially athermally. Accordingly the laser markings may comprise laser pulse markings of laser pulses that are sufficiently brief to ablate substantially athermally. For example, in additional to laser parameters discussed previously herein, substantially athermal ablation may likewise be performed using laser pulses employing various other laser operating parameters (e.g. a pulse duration of approximately four nanoseconds at approximately twenty Watts; a repetition rate of approximately five hundred kilohertz (500 kHz); and a scan rate of approximately two-thousand millimeters per second (2000 mm/sec) at a scan line pitch of approximately five microns.) More generally, substantially athermal ablation may be performed using laser pulses having pulse width within a range from approximately one or more picoseconds to less than approximately ten nanoseconds. Accordingly, laser markings may comprise laser pulse markings of laser pulses having pulse width within the range from approximately picoseconds to less than approximately ten nanoseconds, so as to ablate substantially athermally. 
     As another example, thermal melt polishing may likewise be performed using laser pulses employing various other laser operating parameters (e.g. a pulse duration of approximately two-hundred nanoseconds at approximately nine Watts; a repetition rate of approximately five hundred kilohertz (500 kHz); and a scan rate of approximately one-thousand millimeters per second (1000 mm/sec) at a scan line pitch of approximately five microns.) More generally, for the laser melt polishing laser pulses may be used having pulse width within a range from approximately twenty nanoseconds to approximately a microsecond or more. Accordingly, the melted regions overlaying the athermally ablated surface layer may comprise laser pulse melted regions of laser pulses having pulse width within a range from approximately twenty nanoseconds to approximately a microsecond or more. 
     Hence, all suitable modifications and equivalents may be resorted to as falling within the scope of the invention.

Metadata:
Filing Date: 20130618
Publication Date: 20160419
Grant Date: 20160419
Priority Date: 20130618
Inventors: NASHNER MICHAEL S.
RUSSELL-CLARKE PETER N.
Assignee: APPLE INC
CPC Classifications: [{"code": "B23K2203/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/0075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/544", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2203/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2203/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/0622", "inventive": true, "first": false, "tree": "[]"}, {"code": "B41M5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/365", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/0081", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K26/362", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/3576", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/0622", "inventive": true, "first": false, "tree": "[]"}, {"code": "B41M5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/3576", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2103/05", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/354", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K2103/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/354", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K2103/05", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/0622", "inventive": true, "first": false, "tree": "[]"}, {"code": "B41M5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/362", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2103/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/544", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2103/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2103/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2103/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 52018335