---
_id: '6901'
abstract:
- lang: eng
  text: Freeform optics belong to the increasingly important elements in optical research
    and industry, which pose several challenges regarding design and highly precise
    manufacturing. First being used in cameras and for focusing, nowadays freeform
    optics are used in a broad range of applications, from lighting to LiDAR, from
    endoscopy to photovoltaics, and from astronomical instruments to quantum cryptography.
    Designing freeform optics can be based on different theories and methods. Fabrication
    is possible by mechanical methods, such as diamond turning or high-precision milling,
    often followed by different polishing techniques, as well as laser-based techniques,
    mainly applying different lithographic techniques. Here, we give an overview of
    recent design and optimization methods, production methods used during the last
    years, and applications of freeform optics, including the possibility to combine
    freeform optics with tunability for different applications. We describe the opportunities
    of new applications as well as common problems and give an outlook towards future
    directions of research and development.
article_number: '35'
article_type: review
author:
- first_name: Tomasz
  full_name: Blachowicz, Tomasz
  last_name: Blachowicz
- first_name: Guido
  full_name: Ehrmann, Guido
  last_name: Ehrmann
- first_name: Johannes
  full_name: Fiedler, Johannes
  last_name: Fiedler
- first_name: Reinhard
  full_name: Kaschuba, Reinhard
  last_name: Kaschuba
- first_name: Andrea
  full_name: Ehrmann, Andrea
  id: '223776'
  last_name: Ehrmann
  orcid: 0000-0003-0695-3905
  orcid_put_code_url: https://api.orcid.org/v2.0/0000-0003-0695-3905/work/214321986
citation:
  alphadin: '<span style="font-variant:small-caps;">Blachowicz, Tomasz</span> ; <span
    style="font-variant:small-caps;">Ehrmann, Guido</span> ; <span style="font-variant:small-caps;">Fiedler,
    Johannes</span> ; <span style="font-variant:small-caps;">Kaschuba, Reinhard</span>
    ; <span style="font-variant:small-caps;">Ehrmann, Andrea</span>: Freeform Micro-Optical
    Elements—Recent Production Techniques, Opportunities and Challenges. In: <i>Micro</i>
    Bd. 6, MDPI AG (2026), Nr. 2'
  ama: Blachowicz T, Ehrmann G, Fiedler J, Kaschuba R, Ehrmann A. Freeform Micro-Optical
    Elements—Recent Production Techniques, Opportunities and Challenges. <i>Micro</i>.
    2026;6(2). doi:<a href="https://doi.org/10.3390/micro6020035">10.3390/micro6020035</a>
  apa: Blachowicz, T., Ehrmann, G., Fiedler, J., Kaschuba, R., &#38; Ehrmann, A. (2026).
    Freeform Micro-Optical Elements—Recent Production Techniques, Opportunities and
    Challenges. <i>Micro</i>, <i>6</i>(2). <a href="https://doi.org/10.3390/micro6020035">https://doi.org/10.3390/micro6020035</a>
  bibtex: '@article{Blachowicz_Ehrmann_Fiedler_Kaschuba_Ehrmann_2026, title={Freeform
    Micro-Optical Elements—Recent Production Techniques, Opportunities and Challenges},
    volume={6}, DOI={<a href="https://doi.org/10.3390/micro6020035">10.3390/micro6020035</a>},
    number={235}, journal={Micro}, publisher={MDPI AG}, author={Blachowicz, Tomasz
    and Ehrmann, Guido and Fiedler, Johannes and Kaschuba, Reinhard and Ehrmann, Andrea},
    year={2026} }'
  chicago: Blachowicz, Tomasz, Guido Ehrmann, Johannes Fiedler, Reinhard Kaschuba,
    and Andrea Ehrmann. “Freeform Micro-Optical Elements—Recent Production Techniques,
    Opportunities and Challenges.” <i>Micro</i> 6, no. 2 (2026). <a href="https://doi.org/10.3390/micro6020035">https://doi.org/10.3390/micro6020035</a>.
  ieee: T. Blachowicz, G. Ehrmann, J. Fiedler, R. Kaschuba, and A. Ehrmann, “Freeform
    Micro-Optical Elements—Recent Production Techniques, Opportunities and Challenges,”
    <i>Micro</i>, vol. 6, no. 2, 2026.
  mla: Blachowicz, Tomasz, et al. “Freeform Micro-Optical Elements—Recent Production
    Techniques, Opportunities and Challenges.” <i>Micro</i>, vol. 6, no. 2, 35, MDPI
    AG, 2026, doi:<a href="https://doi.org/10.3390/micro6020035">10.3390/micro6020035</a>.
  short: T. Blachowicz, G. Ehrmann, J. Fiedler, R. Kaschuba, A. Ehrmann, Micro 6 (2026).
date_created: 2026-05-11T20:35:02Z
date_updated: 2026-05-12T05:18:08Z
doi: 10.3390/micro6020035
file:
- access_level: open_access
  content_type: application/pdf
  creator: aehrmann
  date_created: 2026-05-11T20:34:29Z
  date_updated: 2026-05-11T20:34:29Z
  file_id: '6902'
  file_name: _2026_Blachowicz_Micro6_35.pdf
  file_size: 6220358
  relation: main_file
  success: 1
file_date_updated: 2026-05-11T20:34:29Z
has_accepted_license: '1'
intvolume: '         6'
issue: '2'
keyword:
- photopolymerization
- tunable micro-optical freeform elements
- two-photon polymerization
- multiphoton lithography
- direct laser writing
- diamond turning
language:
- iso: eng
oa: '1'
project:
- _id: 0ec202b7-cd76-11ed-89f4-a9e1a6dbdaa7
  name: Institut für Technische Energie-Systeme
publication: Micro
publication_identifier:
  eissn:
  - 2673-8023
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: Freeform Micro-Optical Elements—Recent Production Techniques, Opportunities
  and Challenges
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
urn: urn:nbn:de:hbz:bi10-69017
user_id: '220548'
volume: 6
year: '2026'
...