Lens­less ho­lo­gra­phic microsco­pe

Microsco­pes enable us to see and in­ves­ti­ga­te micro­ob­jects which would have other­wi­se been im­pos­si­ble to see with the naked eye. As a re­sult, they are used in a very wide range of ap­p­li­ca­ti­on fields. The lens­less ho­lo­gra­phic microsco­pe is a small, self­con­struc­ted microsco­pe on which the con­cept of in­li­ne ho­lo­gra­phy is based. A light sour­ce, a pin­ho­le in front of the light sour­ce, cover glass and a CCD ca­me­ra are the com­po­n­ents that are used to set it up. This co­he­rent light in turn il­lu­mi­na­tes the cover glass on which the micro­ob­jects are ex­amined (see Fi­gu­re 1). The dif­frac­ted light from the micro­ob­jects is su­per­im­po­sed with the un­al­te­red light that is trans­mit­ted through the cover glass. An in­ter­fe­rence pat­tern is pro­du­ced which can then be re­cor­ded as a ho­lo­gram by the CCD ca­me­ra be­hind the cover glass (see Fi­gu­re 2). By re­con­struc­ting this ho­lo­gram, one gets the am­pli­tu­de and phase dia­grams of the micro­ob­ject under in­ves­ti­ga­ti­on (see Fi­gu­re 3).

Fi­gu­re 1: Setup of the lens­less ho­lo­gra­phic microsco­pe

In com­pa­ri­son to the nor­mal microsco­pe, the lens­less ho­lo­gra­phic microsco­pe is a low cost al­ter­na­ti­ve. It was first de­si­gned by re­se­ar­chers at the Uni­ver­si­ty of Ca­li­for­nia, Los An­ge­les (UCLA) [1]. We have also built a pro­to­ty­pe of this microsco­pe in our de­part­ment. One ad­van­ta­ge of this microsco­pe over the clas­sic microsco­pe is the fact that in ad­di­ti­on to the am­pli­tu­de, the phase in­for­ma­ti­on of micro­ob­jects can also be extrac­ted. This al­lows for bet­ter stu­dies to be car­ried out on phase ob­jects such as bio­lo­gi­cal cells. Ano­ther ad­van­ta­ge is the fact that a lar­ger area of the samp­le can be in­ves­ti­ga­ted at one time [2]. Fur­ther­mo­re, this microsco­pe is very com­pact, ro­bust and pro­vi­des fast image ac­qui­si­ti­on, even in re­al-ti­me. Also non-tech­ni­cal ex­perts can use the lens­less ho­lo­gra­phic microsco­pe, due to the sim­ple setup and its un­com­pli­ca­ted hand­ling. The pro­po­sed sci­en­ti­fic ap­p­li­ca­ti­on fields of our lens­less ho­lo­gra­phic microsco­pe cover a large range from daily uses to sci­en­ti­fic ap­p­li­ca­ti­ons. It un­der­goes con­ti­n­uous de­ve­lop­ment con­cerning its setup and dif­fe­rent ap­p­li­ca­ti­ons.

Fi­gu­re 2: Ex­amp­le ho­lo­gram of yeast par­ti­cles, taken with our pro­to­ty­pe

Fi­gu­re 3: Re­con­struc­tion of the yeast par­ti­cles, am­pli­tu­de in­for­ma­ti­on left and phase in­for­ma­ti­on right



Size (weight)

CostsField of view
Light microsco­pefrom 0,2µmbig>10000€small
Lens­less ho­lo­gra­phic micrrosco­pe< 1µmvery small (about 95g)<500€larg (about 24 mm²)

Tab. 1: Com­pa­ri­son of light microsco­pe with the lens­less ho­lo­gra­phic microsco­pe


  • [1] S. Seo, T.-W. Su, D. K. Tseng, A. Er­lin­ger, and A. Ozcan, “Lens­free ho­lo­gra­phic ima­ging for on-chip cy­to­metry and dia­gnostics.,” Lab on a chip, vol. 9, no. 6, pp. 777–87, Mar. 2009.
  • [2] Ad­in­da-Oug­ba, A., Koukou­ra­kis, N., Ger­hardt, N. C., & Hof­mann, M. R., „Sim­ple con­cept for a wi­de-field lens­less di­gi­tal ho­lo­gra­phic microsco­pe using a laser diode”, Cur­rent Di­rec­tions in Bio­me­di­cal En­gi­nee­ring, 1(1), 261-264, 2015.


Postal Address

Ruhr-University Bochum
Faculty of Electrical Engineering
and Information Technology
Photonics and Terahertz Technology
Postbox ID 16
Universitätsstraße 150
D-44801 Bochum


Room: ID 04/327
Te­l.: (+49) (0) 234 32 - 23051
Fax: (+49) (0) 234 32 - 14167
E-Mail: ptt+office(at)rub.de
RUB campus map & travel instructions

Chair Holder

Prof. Dr.-Ing. Martin Hofmann
Building: ID 04/329
Te­l.: (+49) (0) 234 32 - 22259
Fax: (+49) (0) 234 32 - 14167
E-Mail: martin.hofmann(at)rub.de

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